title: Stable over-expression of PPARβ/δ and PPARγ to examine receptor signaling in human HaCaT keratinocytes.
abstract: Peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) function and receptor cross-talk with other nuclear receptors, including PPARγ and retinoic acid receptors (RARs), was examined using stable human HaCaT keratinocyte cell lines over-expressing PPARβ/δ or PPARγ. Enhanced ligand-induced expression of two known PPAR target genes, adipocyte differentiation-related protein (ADRP) and angiopoietin-like protein 4 (ANGPTL4), was found in HaCaT keratinocytes over-expressing PPARβ/δ or PPARγ. Over-expression of PPARβ/δ did not modulate the effect of a PPARγ agonist on up-regulation of ADRP or ANGPTL4 mRNA in HaCaT keratinocytes. All-trans retinoic acid (atRA) increased expression of a known RAR target gene, yet despite a high ratio of fatty acid binding protein 5 (FABP5) to cellular retinoic acid binding protein II, did not increase expression of ANGPTL4 or 3-phosphoinositide-dependent-protein kinase 1 (PDPK1), even in HaCaT keratinocytes expressing markedly higher levels of PPARβ/δ. While PPARβ/δ-dependent attenuation of staurosporine- or UVB-induced poly (ADP-ribose) polymerase (PARP) cleavage was not observed, PPARβ/δ- and PPARγ-dependent repression of UVB-induced expression and secretion of inflammatory cytokines was found in HaCaT keratinocytes over-expressing PPARβ/δ or PPARγ. These studies suggest that FABP5 does not transport atRA or GW0742 to PPARβ/δ and promote anti-apoptotic activity by increasing expression of PDPK1, or that PPARβ/δ interferes with PPARγ transcriptional activity. However, these studies demonstrate that stable over-expression of PPARβ/δ or PPARγ significantly increases the efficacy of ligand activation and represses UVB-induced expression of tumor necrosis factor α (TNFα), interleukin 6 (IL6), or IL8 in HaCaT keratinocytes, thereby establishing an excellent model to study the functional role of these receptors in human keratinocytes.
authors.affiliation: Department of Veterinary and Biomedical Sciences, The Center of Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Borland
authors.forename: Combiz
authors.initials: C
authors.lastname: Khozoie
authors.forename: Prajakta P
authors.initials: PP
authors.lastname: Albrecht
authors.forename: Bokai
authors.initials: B
authors.lastname: Zhu
authors.forename: Christina
authors.initials: C
authors.lastname: Lee
authors.forename: Tejas S
authors.initials: TS
authors.lastname: Lahoti
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Gonzalez
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Peters
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D000075803:Angiopoietin-Like Protein 4; D042682:Angiopoietins / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis; D002453:Cell Cycle; D002460:Cell Line; D049109:Cell Proliferation; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D050556:Fatty Acid-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005822:Genetic Vectors; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D047494:PPAR delta / Q000819:agonists / Q000378:metabolism*; D047495:PPAR gamma / Q000819:agonists / Q000378:metabolism*; D048068:PPAR-beta / Q000819:agonists / Q000378:metabolism*; D000070780:Perilipin-2; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D000072516:Retinoic Acid 4-Hydroxylase; D047490:Retinoid X Receptor alpha / Q000235:genetics / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D015398:Signal Transduction; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014212:Tretinoin / Q000494:pharmacology
chemical_list: C474772:ANGPTL4 protein, human; D000075803:Angiopoietin-Like Protein 4; D042682:Angiopoietins; C493412:FABP5 protein, human; D050556:Fatty Acid-Binding Proteins; D008565:Membrane Proteins; C000602982:PLIN2 protein, human; D047494:PPAR delta; D047495:PPAR gamma; D048068:PPAR-beta; D000070780:Perilipin-2; D018168:Receptors, Retinoic Acid; D011994:Recombinant Proteins; D047490:Retinoid X Receptor alpha; C082928:retinoic acid binding protein II, cellular; D014212:Tretinoin; D003577:Cytochrome P-450 Enzyme System; D000072516:Retinoic Acid 4-Hydroxylase; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D064413:3-Phosphoinositide-Dependent Protein Kinases; C578562:PDPK1 protein, human; D017346:Protein Serine-Threonine Kinases