Targets

adipogenesis, apoptosis, cancer, cell cycle, diabetes, fatty acid, inflammation, other, signal transduction, starvation, UCP

 

small review in (Ricote, Huang et al. 1999) Table 1

table of targets taken from (Berger and Moller 2002)

Gene

Regulation

Potential function(s)

aP2 – adipocyte fatty acid binding protein

Up in WAT

Intracellular fatty acid binding

Acyl-CoA synthetase

Up in WAT

Lipogenesis and/or catabolism

PEPCK – phosphoenolpyruvate carboxykinase

Up in wat

Glycerol synthesis (for TAGs)

LPL – lipoprotein lipase

Up in WAT

Hydrolysis of TAG-containing particles

CD36

Up in WAT

Cell surface fatty acid transporter

FATP-1

Up in WAT, lower in muscle

Cell surface fatty acid transporter

UCP1

Up in BAT, up in WAT

Uncouple mitochondrial respiration

UCP3 (+/-) UCP2

Up in WAT

Uncouple mitochondrial respiration

CPT1 – carnitine palmitoyl transferase1

Up in WAT

Translocation of fatty acids into mitochondria

c-CBL-associated protein

Up in WAT

Insulin signaling toward glucose transport

IRS-2 - Insulin receptor substrate-2

Up in WAT

Insulin receptor-mediated signaling

PDK4 - Pyruvate dehydrogenase kinase 4

Up in WAT, lower in muscle

Inhibition of pyruvate dehydrogenase (inhibition of glucose oxidation)

Acrp30 - Adipocyte complement-related factor 30

Up in WAT

Fat-specific secreted protein; beneficial metabolic effects on liver/muscle (?)

TNFa

Down in WAT

Pro-inflammatory, potential mediator of insulin resistance

Leptin

Down in WAT

Fat-derived hormone that inhibits food intake

11b-HSD-1 - 11b hydroxysteroid dehydrogenase-1

Lower in WAT, lower in liver

Controls ingracellular conversion to active cortisol

 

Inflammatory Targets

            1.  SR-A (a scavenger receptor class, see section below)

                        a)  a reporter is inhibitied by PGJ2 in Raw cells (Ricote, Li et al. 1998)

                                    1)  antagonizes AP-1, STAT, and NFkB (Ricote, Li et al. 1998) 

                        b)  SR-A is activated by PPARg (reviewed in (de Villiers and Smart 1999), but unsure)

                        c)  SR-A is post-transcriptionally regulated by troglitazone (Moore, Fitzgerald et al. 2001)-6

            2.  iNOS is repressed by PPARg

                        a)  IFNg and LPS induced expression of iNOS is inhibited by liganded PPARg (Wang, Fu et al. 2001)-40,50

                                    1) does not involve direct binding to the iNOS promoter

                                    2)  cotransfectoin in RAW264.7 cells does the same thing to induction of iNOS with LPS (Li, Pascual et al. 2000)

                        b)  IFNg and LPS which stimulate an iNOS reporter in RAW cells is stopped by pGJ2 and PGD2 (Ricote, Li et al. 1998)

                                    1)  other PPARg ligands also work:  GW9820, GW2090, GW2334 (Ricote, Li et al. 1998)

                        c)  transrepression is thought to occur by PPARg antagonizing the activities of STAT1, NFkB, and AP-1 which mediate the effects of IFNg and LPS (Li, Pascual et al. 2000)-25,40

                        d)  iNOS transcription is inhibited by PPARg in the macrophage (Ricote, Huang et al. 1999)-23,60

            3.  TNFa

                        **  PPARg opposes TNFa signaling responses

                        a)  PPARg activators partially reduce TNFa mediated lipolysis (Souza, Yamamoto et al. 1998)

            4.  targets of PPARg in macrophages

                        lipoprotein lipase

                        CD36 – positive regulation (Ricote, Huang et al. 1999)-30,36

                        iNOS negative - (Ricote, Huang et al. 1999)-23,60

                        MMP-9 (gelatinase-B) (Ricote, Huang et al. 1999)-23,29,73

                        Scavenger receptor A (Ricote, Huang et al. 1999)-23

                        IL-1b (Ricote, Huang et al. 1999)-27

                        IL-6 (Ricote, Huang et al. 1999)-27

                        TNFa (Ricote, Huang et al. 1999)-27

            5.  CD36/FAT - (Schoonjans, Peinado-Onsurbe et al. 1996; Motojima, Passilly et al. 1998)

                        a)  PPARg stimulates synthesis of CD36 (Tontonoz, Nagy et al. 1998)

                                    1)  mRNA synthesis inhibited by PKC inhibitor calphostin C (0.5mM) and Go6983 (2mM) in RAW cells (Feng, Han et al. 2000)

                                    2)  cell surface expression is increased after 14 hour treatment with OxLDL or 15dPGJ2

                        b)  OxLDL upregulates CD36 via activation of PPARg (Nagy, Tontonoz et al. 1998; Tontonoz, Nagy et al. 1998)

                                    1)  RAW264.7 cells treated with either 15dPGJ2 or OxLDL both had induction of CD36 (Feng, Han et al. 2000)

                                                a)  PKC inhibitor treatment stopped induction of this gene (Feng, Han et al. 2000)

                        c)  although CD36 expression was induced by both pGJ2 and OxLDL, only pGJ2 caused a translocation of PKCa to the cell surface (Feng, Han et al. 2000)

                        d)  positively regulated by PPARg (Ricote, Huang et al. 1999)-30,36

                        e)  positively regulated by rosiglitazone in macrophages of mice (Welch, Ricote et al. 2003)

            6.  NGAL – neutrophil gelatinase-associated lipocalin

                        a)  role

                                    1)  blunt inflammatory responses by binding to and sequestering hydrophobic molecules that serve as neutrophil chemattractants (Gupta, Brockman et al. 2001)-43

                                                a)  molecules like retinoids

                                                b)  bacterial formyl peptides (Gupta, Brockman et al. 2001)-67

                                                c) leukotriene B4 and platelet-activating factor

                        b)  expression

                                    1)  epithelial cells from multiple organs that are exposed to microorganisms (Gupta, Brockman et al. 2001)-66

                        b)  structure

                                    1)  25kDa

                        c)  activated by PPARg ligand in colon carcinoma using array (Gupta, Brockman et al. 2001)

                                    1)  activated most strogly after 24 hours of ligand treatment (Gupta, Brockman et al. 2001)

                        l)  rosiglitazone downregulates the expression of CCR2 (the MCP-1 receptor) in human and murine monocytes (Moore, Fitzgerald et al. 2001)-24

            7.  Gelatinase B

                        a)  a reporter is inhibitied by PGJ2 in Raw cells (Ricote, Li et al. 1998)

            8.  aromatase (negative) (Rubin, Zhao et al. 2000)

                        a)  treatment of human breast adipose stromal cells with Dex (250nM) and OSM (5ng/ml) or TNFa (5ng/ml) for 24 hours causes large increase in production of aromatase gene

                        b)  aromtase enzymatic activity induced with Dex and OSM is inhibited by PPARg ligands when cotreated for the same 24 hour time period

                        c)  gene expression of aromtase induced by Dex and OSM is inhibited by troglitazone (20mM) and 15d-PGJ2 (2mM) as measured by PCR

                        d)  the upstream element of aromtase at –774-+14 is negatively regulated by PPARg ligands

                                    1)  this element has AP-1, GAS GRE, SP1 elements

                        NOTE:  it could be that TNFa induced AP-1 or class I cytokine-induced STAT3/JNK are the targets of PPARg-mediated inhibition.

            9.  COX-2

                        a)  role

                        b)  regulation by PPARg 

                                    1)  although PPARg ligands prevented iNOS induction, apoptosis, and necrosis induced by injected LPS and IFNg, a COX inhibitor did not do this (Heneka, Klockgether et al. 2000)

                                    2)  therapeutic effects of NSAIDs occur at concentrations higher than those that inhibit COX (Lehmann, Lenhard et al. 1997; Jiang, Ting et al. 1998)

                                    3)  COX inhibitor aspirin does not exert protective effects in alzheimer’s disease (Stewart 1997 626)

                                    4)  HT-29 cells treated with ciglitazone (10mM) and 9-cis-RA (1mM) have lower COX-2 expression (Yang and Frucht 2001)

                                                a)  not inhibited by cotreatment with caspase inhibitors ZVAD-fmk  (Yang and Frucht 2001)

                                                b)  because ciglitazone-mediated induction of apoptosis in HT-29 cells is inhibited by caspase inhibitors, but COX-2 inhibition is not, perhaps COX-2 inhibition somehow induces apoptosis through a caspase dependent manner (Lefebvre, Chen et al. 1998)

                                    5)  PPARg activation does not affect COX-2 expression in HT-29 cells (Lefebvre, Chen et al. 1998)

                                                a)  COX-2 expression after 24 hours was not altered

                                    6)  monocytes treated with rosiglitazone (1uM) for 7 hours had Cox-2 protein and mRNA induced (Pontsler, St Hilaire et al. 2002)

                                                a)  induce PGE excretion from human monocytes in a COX-2 dependent manner (Pontsler, St Hilaire et al. 2002)

                                                b)  activated through  a PPRE

                                    7)  PGJ2 inhibits COX-2 expression in a PPRE-independent manner (5mM) for 16 hours in RAW264.7 (Pontsler, St Hilaire et al. 2002)

            10.  plasminogen activator inhibitor type 1

                        a)  repressed by PPARg ligands in vascular endothelial cells (Sugawara, Uruno et al. 2002)-16

            11.  matrix metalloproteinase-9

                        a)  repressed by PPARg ligands in VSMCs (Sugawara, Uruno et al. 2002)-15

            12.  TX synthase

                        a)  repressed in macrophages in response to PPARg ligands (Sugawara, Uruno et al. 2002)-17

            13.  TXR – thromboxane receptor

                        a)  suppressed by PPARg ligands (Sugawara, Uruno et al. 2002)

                        b)  repression mediated by inhibition of Sp1 binding by PPARg interaction with Sp1 (Sugawara, Uruno et al. 2002)

                                    1)  dependent on GC box upstream of TXR promoter

                                    2)  physical interaction of PPARg with Sp1 shown by pull-down assays

            14.  IL-2

                        a)  IL-2 expression in mitogen-activated splenocytes is lowered by treatment with ciglitazone 50uM (Cunard, Ricote et al. 2002)

                        b)  PPARg inhibits IL-2 production by physically interacting with NFAT to prevent its activation of the promoter (Clark 2002)-87

            15.  IFNg

                        a)  IFNg expression in mitogen-activated splenocytes is lowered by treatment with ciglitazone 50mM (Cunard, Ricote et al. 2002)

                                    1)  secretion is lowered by treatment with ciglitazone (Cunard, Ricote et al. 2002)

Fatty Acid Metabolism and Cholesterol

            1.  adipose FABP=aP2

                        a)  forced expression of mPPARg2 causes induction of aP2 enhancer in fibroblasts (Tontonoz, Hu et al. 1994)

            2.  lipoprotein lipase LPL -  – (Schoonjans, Peinado-Onsurbe et al. 1996)

                        1)  BRL 49653 induces LPL mRNA expression in 3T3-L1 cells (Schoonjans, Peinado-Onsurbe et al. 1996)

                        2)  works through a –169 TGCCCTTTCCCCC –157 PPRE

                        3)  LPL can also be induced in PPARg independent manner by 22-HC (Akiyama, Sakai et al. 2002)

                        4)  induced in THP-1 monocyte cells in response to troglitazone treatment (Iida, Kawakami et al. 2002)

            3.  fatty acid transport protein – FATP - (Martin, Schoonjans et al. 1997)

                        a)  role

                                    1)  increases the uptake of oleate (Frohnert, Hui et al. 1999)

                        b)  regulation by PPARg

                                    1)  upregulated 5-7 fol due to adipose conversion (Schaffer and Lodish 1994; Man, Hui et al. 1996)

                                    2)  upregulated by PPARa activators in mouse liver (Martin, Schoonjans et al. 1997)

                                    3)  upregulated by PPARg activators in white adipose tissue (Motojima, Passilly et al. 1998)

            3.  L-FABP

                        a)  role

                                    1)  adipose differentiation-related protein

                                    2)  involved in fatty acid transport or storage (Gupta, Brockman et al. 2001)-41

                        b)  activated by PPARg ligand in colon carcinoma using array (Gupta, Brockman et al. 2001)

                                    1)  activated most strogly after 24 hours of ligand treatment (Gupta, Brockman et al. 2001)

            4.  leptin (De Vos, Lefebvre et al. 1996; Kallen and Lazar 1996; Zhang, Graziano et al. 1996)

                        a)  role

                                    1)  cytokine-like hormone produced by adipocytes – (Zhang, Proenca et al. 1994)                                   

                        b)  PPARg regulation

                                    1)  PPARg negatively regulates leptin, which prevents eating in mice

                                    2)  TZD-mediated activation of PPARg inhibits leptin gene expression, without apparent binding of PPARg to regulatory sequences (Lowell 1999)-(Hollenberg 1997)

                                    3)  PPARg inhibition of leptin in inhibited by cyclohexamide (Berger, Tanen et al. 2001)

                                    4)  PPARg inhibition of leptin does not require a binding site (Berger, Tanen et al. 2001)-38

            5.  acyl-CoA synthetase (Schoonjans, Staels et al. 1993; Schoonjans, Watanabe et al. 1995)

            6.  aquaporin adipose (AQ-Pap)

                        a)  role

                                    1)  expressed only in human adipose tissue

                                    2)  aids secretion of glycerol from adipose tissue in normal and insulin-resistant conditions (Kishida, Shimomura et al. 2001)-3,4

                                    3)  helps maintain glucose homeostasis in the whole body

                        b)  regulation

                                    1)  increased by fasting, and decreased by refeeding (Kishida, Shimomura et al. 2001)-3

                        c)  PPARg regulation

                                    1)  induced by mice treated with pioglitazone (0.01%) for 2 weeks (Kishida, Shimomura et al. 2001)

                                                a)  10mM pioglitazone treatment of 3T3-L1 adipocytes after 7 days of differentiation caused a good induction of AQPap mRNA expression

                                    2)  much less induction and overall expression in heterozygous mice for PPARg (Kishida, Shimomura et al. 2001)

                                    3)  induction through a –141/+63 construct

                                                a)  dependent on PPRE in there (Kishida, Shimomura et al. 2001)

                                                b)  binds well in a GSA to the PPRE, but not when mutated (Kishida, Shimomura et al. 2001)

                                                c)  is also PPARa responsive, but PPARa needs to be transfected into the 3T3-L1 adipocytes for response to Wy (10mM) (Kishida, Shimomura et al. 2001)

            2.  PEPCK – phosphoenolpyruvate carboxykinase

                        a)  role

                                    1)  a marker of terminal adipocyte differentiation

                                    2)  participates in glucose and lipid homeostasis (Eubank, Duplus et al. 2001)-23,24

                                                a)  critical gluconeogenic enzyme in the liver and kidney (Eubank, Duplus et al. 2001)-25

                                    3)  glyceroneogenesis in adipocytes (Eubank, Duplus et al. 2001)-24

                                                a)  this process accounts for 10-60% of triglyceride production during fasting in humans (Eubank, Duplus et al. 2001)-27

                                                b)  increases the production of 3-glycerophosphate for the reesterification of free FAs released by lipolysis

                                    4)  liver-specific knockouts have fatty livers (Eubank, Duplus et al. 2001)-25,27

                                    5)  expressed in the liver and kidney, and adipocytes

                        b)  regulation

                                    1)  PPARg-regulated  (Tontonoz, Hu et al. 1995)

                                                a)  rosiglitazone activates PEPCK, but not in pre-adipocytes (Eubank, Duplus et al. 2001)

                                    2)  regulated by PPARg/RXR (Eubank, Duplus et al. 2001)-13,29,30,34

                                                a)  two PPARg/RXR binding sites

                                                            gAF1/PCK1 450 bp US

                                                            PCK2 990 bp US

                                                            1)  similar affinity in vitro (Eubank, Duplus et al. 2001)-30,35

                                    3)  reporter with both REs shows that increasing COUP-TFII transfected into NIH-3T3 cells prevents transactivation by PPARg/RXR (Eubank, Duplus et al. 2001)

                                    4)  PPARy regulates adipocyte but not hepatocyte PEPCK (Eubank, Duplus et al. 2001)-29-31

                                    5)  glucocorticoids repress PEPCK transcription in adipocytes but induce it in hepatocytes (Eubank, Duplus et al. 2001)-24

                                                1)  WHY?  increases fuel release in both tissues by stimulating hepatocytes and inhibiting adipocytes (Eubank, Duplus et al. 2001)-24,32,33

                                    6)  PPRE knockout effects on expression and function

                                                a)  knockouts have lower expression in the liver (qOlswang, Cohen et al. 2002)

                                                b)  fat pads from knockouts release more FFA from adipose tissue during fasting than wts (qOlswang, Cohen et al. 2002)

                                                c)  causes lipodystrophy in some of the animals (qOlswang, Cohen et al. 2002)

            3.  SCD1 – stearoyl-CoA desaturase 1

                        a)  role

                                    1)  a d-9 desaturase

                                    2)  catalyzes the conversion of stearic (C18:0) to oleic acid (C18:1 ω9) and palmitic (C16:0) to palmitoleic acid (C16:1 ω7)

                        b)  regulation by PPARg

                                    1)  troglitazone and pioglitazone downregulate SCD1 gene expression in 3T3-L1 adipocytes in a dose-dependent manner (Wahl, Kausch et al. 2002)-30

            4.  HMG-CoA synthase

                        a)  role

                        b)  regulation by PPARg

                                    1)  increased mRNA expression in response to troglitazone treatment of THP-1 monocyte cells for 2 and 24 hours (Iida, Kawakami et al. 2002)

                                                a)  inhibited by introduction of decoys for PPRE

                                                b)  still induced after THP-1 monocyte differentiation to macrophages

            5.  HMG-CoA reductase

                        a)  role

                        b)  regulation by PPARg

                                    1)  increased mRNA expression in response to troglitazone treatment of THP-1 monocyte cells for 2 and 24 hours (Iida, Kawakami et al. 2002)

                                                a)  inhibited by introduction of decoys for PPRE

                                                b)  still induced after THP-1 monocyte differentiation to macrophages

            6.  ACBP - acyl-CoA-binding protein 

                        a)  role

                                    1)  10kDa intracellular protein

                                    2)  binds acyl-CoA esters with high affinity

                                    3)  regulates availability of acyl-CoA esters for various metabolic and regulatory purposes

                                    4)  abundant in cells with high lipogenesis and de novo fatty acid synthesis

                        b)  regulation

                                    1)  induced during adipogenesis

                                    2)  PPARg activates through a PPRE in intron 1 (Helledie, Grontved et al. 2002)

            7.  ADRP – lipid droplet-associated protein

                        a)  induced by rosiglitazone treatment in mouse macrophages (Welch, Ricote et al. 2003)

            8.  ABCG1

                        a)  induced by rosiglitazone treatment in mouse macrophages (Welch, Ricote et al. 2003)

            9.  enoyl coenzyme A hydratase (Ech1)

                        a)  induced by rosiglitazone treatment in mouse macrophages (Welch, Ricote et al. 2003)

            10.  peroxisomeal biogenesis factor 11a (Pex11a)

                        a)  induced by rosiglitazone treatment in mouse macrophages (Welch, Ricote et al. 2003)

            11.  a mannosidase II

                        a)  induced by rosiglitazone treatment in mouse macrophages (Welch, Ricote et al. 2003)

            12.  carnitine palmitoyl transferase (Cpt1a)

                        a)  induced by rosiglitazone treatment in mouse macrophages (Welch, Ricote et al. 2003)

Signal Cascade Targets

            1.  regulation of transcription factors

                        a)  GAS elements, AP-1, and NFkB are all negatively regulated by the presence of PPARg and ligand (Ricote, Li et al. 1998)

            2.  d-6 desaturase

                        a)  role

                                    1)  rate-limiting enzyme which catalyzes the conversion of linoleic acid (C18:2 ω6) into g-linolenic acid (C18:3 ω6), arachidonic acid (C20:4 ω6), and other metabolites

                                    2)  expressed in liver, muscle, and other human tissues (Wahl, Kausch et al. 2002)-16,17

                        b)  regulation by PPARg

                                    1)  troglitazone treatment up to 11.5uM cause a dose-dependent decrease in d-6 desaturase mRNA in skeletal muscle cell cultures (Wahl, Kausch et al. 2002)

                                    2)  treatment of cells for 4 days with 11.5uM troglitazone decreased d-6 desaturase expression to 40% (Wahl, Kausch et al. 2002)

                                                a)  consequently, the ω6-C18:3/C18:2 ratio increases (Wahl, Kausch et al. 2002)

Cell Cycle and Apoptosis

            1.  cyclin D

                        a)  protein levels and mRNA are decreased following pGJ2 treatment of MCF-7 cells at 10uM for 6 hours (Wang, Fu et al. 2001)

                        b)  directly represses a cyclin D reporter construct 10 mM pGJ2 in MCF-7 cells (Wang, Fu et al. 2001)

                        c)  pGJ is most effective (10mM), while BRL49653 (0.1mM) and troglitazone (2.5mM) were less effective (Wang, Fu et al. 2001)

                        d)  residue importance

                                    1)  PPARg L468A/E471A had no effect on cyclin D1 repression, but PPARg S112A/D was functional  (Wang, Fu et al. 2001)

                        e)  AP-1 and CRE sites are important for the downregulation of cyclin D1 mRNA expression in response to pGJ2 treatment for 24 hours in MCF-7 cells (Wang, Fu et al. 2001)

            2.  HGF – hepatocyte growth factor

                       

                        a)  contains a functional PPRE from –246 to –233 – GGGCCAGGTGACCT

                                    1)  inverted RGGTCA motif, with two spacer rather than DR1 with one spacer.  (Jiang, Johnson et al. 2001)-23,24

                                    2)  COUP-TF, an orphan nuclear receptor, can also bind to this site to negate the effects of PPARg stimulation (Jiang, Johnson et al. 2001)

                        b)  PPARg regulation of this gene is competed by other transcription factors

                                    1)  NF1 and AP2 (Jiang, Johnson et al. 2001)

                        c)  PGJ2 stimulates the expression of endogenous HGF mRNA and protein in fibroblasts (Jiang, Johnson et al. 2001)

            3.  VEGF

                        a)  role

                        b)  regulation by PPARγ

                                    1)  treatment of bladder cancer cells human for 24 hours with 10u[jpg1] M BRL  causes 5X induction of VEGF mRNA expression (Fauconnet, Lascombe et al. 2002)

                                    2)  protein synthesis dependent

 

Cancer

Starvation and Diabetes

            1.  CAP – c-Cbl-associated protein (Ribon, Johnson et al. 1998)

                        a)  c-Cbl-associated protein which interacts with the insulin receptor and c-Cbl protooncogene (Ribon, Johnson et al. 1998)

                        b)  thiazolidinedione treatment potentiates c-Cbl tyrosine phosphorylation (Ribon, Johnson et al. 1998)

            2.  c-Cbl associated protein (Ribon, Johnson et al. 1998)

            3.  11b-hyydroxysteroid dehydrogenase (11b-HSD)

                        a)  role

                                    1)  two isoforms

                                    2)  11b-HSD-1 is expressed in adipose, liver, gonadal, and CNS

                                                a)  converts cortisone to cortisol, the glucocorticoid receptor agonist

                                                b)  omental tissue has more 11b-HSD-1 activity than subcutaneous adipose tissue and that preadipocytes form omental adipose tissue can differentiate more readily into adipocytes by cortisone (Berger, Tanen et al. 2001)-12

                                    3)  knockouts resist diet-induced insulin resistance and hyperglycemia (Berger, Tanen et al. 2001)-13

                                    4)  potential for NIDDM (Berger, Tanen et al. 2001)-14

                                    5)  expression increases in 3T3-L1 cells as they proceed through the differentiation process (Berger, Tanen et al. 2001)-39 (Berger, Tanen et al. 2001)

                                    6)  repression increases insulin sensitivity

                                                a)  treatment with carbenoxolone increases insulin sensitivity in human subjects (Berger, Tanen et al. 2001)-45

                                    3)  expressed in aldosterone target cells like the kidney and colon where it inactivates cortisol through deuydrogenase

                                    4)  prevents excessive activation of mineralocorticoid receptor and sequelae associated with hypertension

                        b)  PPARg regulates expression

                                    1)  HSD1 is decreased in differentiated 3T3-L1 cells exposed to rosiglitazone for 48 hours (Berger, Tanen et al. 2001)

                                                a)  mRNA levels are noticeably decreased at 6 hours, and reach maximum repression by 24 hours (Berger, Tanen et al. 2001)

                                                b)  rosiglitazone dose of 1mM is enough for maximum inhibition, but a noticeable difference at .1mM (Berger, Tanen et al. 2001)

                                                c)  cyclohexamide reduced levels of HSD, but also prevented the PPARg-mediated inhibition of this gene (Berger, Tanen et al. 2001)

            4.  glucagon

                        a)  role

                                    1)  functional antagonist of insulin stimulating hepatic glucose output

                        b)  regulation by PPARg

                                    1)  TZDs inhibit glucagons gene transcription in a pancreatic cell line when PPARg is coexpressed (Schinner, Dellas et al. 2002)

                                                a)  lower glucagons secretion and glucagons tissue levels in primary pancreatic islets (Schinner, Dellas et al. 2002)

                                    2)  regulated through a PISCES motif (pancreatic islet cell-specific enhancer sequence) in the promoter element (Schinner, Dellas et al. 2002)

                                                a)  binds to paired domain transcription factor Pax6

                                                b)  PPARg mediates its repression through some sort of inhibition of Pax6 (Schinner, Dellas et al. 2002)

            5.  IRS-2

                        a)  regulation by PPARg

                                    1)  increased in cultured adipocytes and human adipose tissue incubated with PPARg agonists (Berger and Moller 2002)-77

            6.  11b-HSD-1 - 11b-hydroxysteroid dehydrogenase 1

                        a)  role

                                    1)  highly expressed in adipocytes and hepatocytes

                                    2)  converts cortisone to cortisol, a GR agonist

                        b)  regulation

                                    1)  PPARg agonists decrease expression of this gene

            7.  Acrp30 – adipocyte-related complement protein 30

                        a)  role

                                    1)  secreted adipocyte-specific protein

                                    2)  decreases glucose, TAG, and FFAs (Berger and Moller 2002)-80,81

                                    3)  diabetics have lower Acrp30 (Berger and Moller 2002)-83

                        b)  regulation

                                    1)  diabetic mice treated with PPARg ligands have increased plasma Acrp30 (Berger and Moller 2002)-82

                                    2)  rosiglitazone (but not fenofibrate) increases expression of Acrp30 (Berger and Moller 2002)-82

            8.  Reg-1A

                        a)  role

                                    1)  cancer marker

                                    2)  thought to be a secreted protein that works through a receptor

                                    3)  pro-neoplastic gene

                        b)  regulation by PPARg

                                    1)  repressed

            9.  TSC-22

                        *  covered by Gupta and DuBois

                        a)  role

                                    1)  repressor homodimer

                                    2)  overexpression inhibits cell growth

                        b)  structure

                                    1)  leucine zipper, transcription factor, 22kDa

                        c)  regulation

                                    1)  TGFB1 induced

                        d)  regulation by PPARg

                                    1)  rosiglitazone in various lines induces

            10.  myc

                        a)  downregulated in leukemic cells in response to PPARg ligand treatment

                                    1)  troglitazone treatment blocks myc within 24 hours after treatment (Yamakawa-Karakida, Sugita et al. 2002)

                                                a) due to block of Tcf-4 (Yamakawa-Karakida, Sugita et al. 2002)

 

Role Adipogenesis

            1.  adipophilin

                        a)  role

                                    1)  adipose differentiation-related protein

                                    2)  involved in fatty acid transport or storage (Gupta, Brockman et al. 2001)-40

                        b)  activated by PPARg ligand in colon carcinoma using array (Gupta, Brockman et al. 2001)

                                    1)  activated most strogly after 24 hours of ligand treatment (Gupta, Brockman et al. 2001)

            2.  PCK2 regulation

                        a)  role

                                    1)  required for expression of the PEPCK promoter in adipose tissue of transgenic mice (Eubank, Duplus et al. 2001)-29

                        b)  regulation by PPARg

                                    1)  only response element for thiazolidinedione action

            3.  PCK1 / gAF1 regulation

                        a)  role

                                    1)  important for PEPCK expression

                                                a)  may play a more important role in regulating PEPCK gene expression in fully differentiated cells

                                                b)  does not developmentally regulate adipocyte-specific PEPCK promoter expression in transgenic mice (Eubank, Duplus et al. 2001)-29

                                    2)  part of a complex hormone RE in hepatoma cells (Eubank, Duplus et al. 2001)-37,38

                                                a)  required for full glucocorticoid responsiveness (Eubank, Duplus et al. 2001)-37,38

                                                b)  can be bound by COUP-TFs, HNF4, RAR/RXR, and PPARa that activate the PEPCK promoter (Eubank, Duplus et al. 2001)-39-41

                                                c)  glucocorticoids inhibit fibrate and thiazolidinedione-induced PEPCK gene expression in adipocytes (Eubank, Duplus et al. 2001)-31

                                                            1)  a mutated site stops the glucocorticoid-mediated inhibition (Eubank, Duplus et al. 2001)-42

                                    3)  binds to COUP-TFII early on, and PPARg late in adipogenesis (Eubank, Duplus et al. 2001)

                                                a)  PPARg is induced during adipogenesis, while COUP-TF is decreased durng adipogenesis (Eubank, Duplus et al. 2001)

                                                b)  COUP-TFII mediates its inhibition of PPARg through this site (Eubank, Duplus et al. 2001)

                        b)  not regulated by PPARg

                                    1)  not regulated by PPARg thiazolidinedione RE (Eubank, Duplus et al. 2001)-29

UCP Protein Regulation

            1.  UCP-1

                        role

                        a)  mt proton transporter that uncouples respiration from oxidative phosphorylation (Teruel, Clapham et al. 1999)-1,2

                                    1)  functions in brown adipocytes, to thermogenesis

                        b)  activated by other hormones as well, including insulin, glucocorticoids, and IGF-1 (Teruel, Clapham et al. 1999)-3

                        a)  thiazolidinediones increases UCP-1 mRNA levels in rodent brown adipocytes (Teruel, Clapham et al. 1999)

                                    1)  can be blocked using Wy treatment (Teruel, Clapham et al. 1999)

                                    2)  2-4 fold induction in fetal brown adipocytes using 0.01-10mM roziglitazone

                                    3)  no induction is seen until six hours, and up to 72 hours were looked at with good induction

                                    4)  rosiglitazone induces an increase in UCP-1 mRNA, which can be countered by TNFa treatment and restored by cotreatment with PD98059 (Porras, Valladares et al. 2002)

                        b)  roziglitazone 1mM activates transcription from a 4.5kb 5’ flanking region upstream of UCP-1 promoter (Teruel, Clapham et al. 1999)

                                    1)  there are RARE and PPRE juxtaposed in the 5’ flanking region of the rat UCP-1 gene (Teruel, Clapham et al. 1999)-3-5

                                    2)  UCP-1 mRNA levels are activated also by all-trans-retinoic acid and 9-cis-retinoic acid by the RAR and RXR (Teruel, Clapham et al. 1999)-4,6

                                    3)  Wy has no effect on roziglitazone activation of this reporter at 10mM compared to 1mM rosiglitazone (Teruel, Clapham et al. 1999)

                        c)  UCP expression in BAT is regulated by PPARg (Braissant and Wahli 1998)-22

            2.  UCP-2

                        role

                        a)  in differentiated adipocytes, PPARg regulates this gene (Chevillotte, Rieusset et al. 2001)-19-21

                        b)  treatment with PPARg anonists increases UCP2 mRNA levels in vivo and in vitro (Medvedev, Snedden et al. 2001)-1,12

                                    1)  HIB-1B (brown preadipocyte) , D1 (white preadipocyte), C2C12 (myoblast), and C3H10T1/2 cells all show increased UCP2 mRNA levels upon BRL49653 treatment for 24 hours (1mM) (Medvedev, Snedden et al. 2001)

                        c)  reporter –7.3kb/+12

                                    1)  is responsive to BRL49653 (1mM, 24 hours) (Medvedev, Snedden et al. 2001)

                                    2)  cotransfection with PPARg also induces expression

                        d)  PPARg requires elements in the –71/-44 region (SRE and two E boxes) (Medvedev, Snedden et al. 2001)

                                    1)  possibly through USF1 and USF2

            3.  UCP-3

                        role

                        a)  PPARg agonists in mouse C2C12 cells induce this gene (Chevillotte, Rieusset et al. 2001)-22

                        b)  PPARg doesn’t regulate UCP-3 in rat L6 myotubes (Chevillotte, Rieusset et al. 2001)-23

                        c)  L6 cells, UCP-2 expression is induced by thiazolidine diones and PPARg activation (Chevillotte, Rieusset et al. 2001)-21

Other Targets

            1.  phosphoenolpyruvate carboxykinase (reviewed in either (Kersten 2001)-(Kersten 2000b or Yoon 2000)

            2.  SHP (small heterodimer partner)

                        a) suppressed by oxLDL and 13-hydroxyoctadecadienoic acid (Kim, Han et al. 2001)

            3.  PPARg binding site

                        a)  human PPARg binds in vitro to DNA elements containing direct repeats of TGACCT (Lambe and Tugwood 1996)

                                    1)  can bind DR1 or DR2 of the same sequence

            4.  b-catenin is induced in C57BL/6J-APCMin/+ mice (Lefebvre, Chen et al. 1998)

                        a)  this is probably not due to PPARg, because PPARg heterozygotes have more expression of b-catenin, at least in the colon (Girnun, Smith et al. 2002)

            5.  RegIA – regeneration gene IA

                        negative target

                        a)  role

                                    1)  expression

                                                a)  strongly expressed in the regenerating crypt epithelial cells of patients with ulcerative colitis (Gupta, Brockman et al. 2001)-61

                                    1)  secreted protein that induces the proliferation of pancreatic b and acinar cells (Gupta, Brockman et al. 2001)-42

                                    2)  rapidly induced in islets of Langerhans cells forced to regenerate following depancreatization (Gupta, Brockman et al. 2001)-57

                                    3)  binds to a cell surface receptor, stimulates the proliferation of both pancreatic b-cells and ductal cells (Gupta, Brockman et al. 2001)-58

                                    4)  overexpression

                                                a)  transgenic mice expressing RegIA in islet cells have multiple tumors including cervical lymphoma, ovarian adenocarcinoma, and hepatocellular carcinoma (Gupta, Brockman et al. 2001)-59

                                    5)  cancer

                                                a)  overexpressed in a large percentage of colorectal tumors (Gupta, Brockman et al. 2001)-60

                                                b)  negative correlation of expression and the differentiation status of colon cancer cells (Gupta, Brockman et al. 2001)-63

                                    6)  diabetes

                                                a)  overexpression in pancreatic islet cells induces diabetes (through stimulation of excess islet cell regeneration) (Gupta, Brockman et al. 2001)-59

                                                b)  perhaps PPARg ligands down-regulate RegIA expression in the pancreas, limiting pancreatic b-cell injury and depletion in rats predisposed to insulin resistance (Gupta, Brockman et al. 2001)-65

                        b)  structure

                                    1)  166 aa secreted protein

                        b)  repressed by PPARg ligand in colon carcinoma using array (Gupta, Brockman et al. 2001)

                                    1)  repressed most strogly after 24 hours of ligand treatment (Gupta, Brockman et al. 2001)

            6.  Gob-4 / hAG-2

                        negative target

                        a)  role

                                    1)  secreted protein whose expression is associated with mature goblet cells in the intestine (Gupta, Brockman et al. 2001)-44

                        b)  structure

                        c)  repressed by PPARg ligand in colon carcinoma using array [Gupta,2001 #1057

                                    1)  repressed most strogly after 24 hours of ligand treatment [Gupta, 2001 #1057]

            7.  keratin 20

                        not a direct PPARg target

                        a)  role\

                                    1)  expressied in the most differentiated cell types within the mucosal epithelium of the intestine (Gupta, Brockman et al. 2001)-45,46

                        b)  structure

                                    1)  intermediate sized filament protein

                        b)  activated by PPARg ligand in colon carcinoma using array (Gupta, Brockman et al. 2001)

                                    1)  activated most strogly after 20 days of ligand treatment (Gupta, Brockman et al. 2001)

            8.  CEA gene family members – carcinoembryonic antigen

                        not a direct PPARg target

                        a)  roles

                                    2)  microbial receptors and regulators of cellular differentiation and adhesion (Gupta, Brockman et al. 2001)-47

                                                a)  might mediate rapid adhesive interactions between microvilli

                                    3)  implicated in Ca2+-independent homophilic binding to molecules on adjacent cells (Gupta, Brockman et al. 2001)-50,51,52

                                    4)  cancer

                                                a)  can induce homotypic aggregation of colon cancer cells, possible role in regulating intercellular adhesion during intestinal development or in adult intestinal epithelium (Gupta, Brockman et al. 2001)-50

                        b)  expression

                                    1)  the most differentiated epithelial cells exposed to the lumen (Gupta, Brockman et al. 2001)-68

                                    2)  overexpression of CEA blocks the differentiation program of rat myoblasts (Gupta, Brockman et al. 2001)-69

                        a)  CEA – carcinoembryonic antigen

                        b)  NCA

                        c)  BGP – biliary glycoprotein

                        b)  activated by PPARg ligand in colon carcinoma using array (Gupta, Brockman et al. 2001)

                                    1)  activated most strogly after 20 days of ligand treatment (Gupta, Brockman et al. 2001)

                                    2)  activation causes clumping/aggregation of the cells (Gupta, Brockman et al. 2001)

            9.  ABCA1 – ATP-binding cassette subuamily A

                        a)  role

                                    1)  cholesterol export to apolipoprotein acceptors such as apoA-I and apoE

                                    2)  knockout has reduced cellular cholesterol efflux, and HDL levels drop to 0 (Moore, Fitzgerald et al. 2001)-33

                        b)  PPARg agonists stimulate mRNA levels of ABCA1 and cellular cholesterol efflux in response to apoA-1 (Moore, Fitzgerald et al. 2001)-31,32

                                    1)  indirect stimulation through activation of LXR (Moore, Fitzgerald et al. 2001)-31

            10.  subtractive hybridization and other massive searching genes

                        a)  NIH 3T3 cells, infected with PPARg, treated with BRL (Okuno, Arimoto et al. 2002)

                                    1)  aldehyde dehydrogenase Ahd-2-like             Ahd-2-like

                                                a)  induced in differentiating 3T3-L1 adipocyte differenciation at day 4

                                    alpha-soluble NSF attachment protein

                                    calmodulin-dependent protein kinase II-delta

                                    CGI-67 protein

                                    electron transfer flavoprotein alpha-subunit

                                    isocitrate dehydrogenase

                                    KIAA 0196

                                    osteoblast specific factors 1 and 2

                                    type VI collagen alpha 3 subunit

                                                a)  induced at days 4 through 8

                                    unknown

                                    2)  downregulated

                                    activating transcription factor 4

                                    CRABP1

                                                1)  retinoid binding proteins

                                    lanosterol 14-alpha-demethylase

                                    monocarboxylate transporter 1

                                    sarcoma amplified sequence

                                    thrombospondin 1 (TSP1)

                                    vascuolar adenosine triphosphatase subunit A

            11.  UDP-glucuronosyltransferase 1A9

                        a)  role

                                    1)  adds the nucleotide sugar (UDP-glucuronic acid (UDPGA)) to targets (Barbier, Villeneuve et al. 2003)-15

                                                a)  targets include androgens, estrogens, progestins, bile acids, fatty acids, retinoids, and bilirubin (Barbier, Villeneuve et al. 2003)-16

                                    2)  expressed in liver, intestine, kidney, mammary gland, and ovary (Barbier, Villeneuve et al. 2003)-21

                        b)  PPARg regulation

                                    1)  regulated by a DR1 at –719 to –706 in the promoter region (Barbier, Villeneuve et al. 2003)

                                    2)  upregulated in 3T3-L1 adipocytes by rosiglitazone treatment (Barbier, Villeneuve et al. 2003)

                                    3)  glucuronidation also increases after treatment with gemfibrozil (Barbier, Villeneuve et al. 2003)

                                    4)  dependent on a DR1 element upstream of 1A9 (Barbier, Villeneuve et al. 2003)

 


 


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