Receptor type protein tyrosine phosphatase-kappa mediates cross-talk between transforming growth factor-beta and epidermal growth factor receptor signaling pathways in human keratinocytes.
Epidermal growth factor receptor (EGFR) signaling pathways promote human keratinocyte survival and proliferation. In contrast, transforming growth factor-beta (TGF-beta) signaling pathways are strongly anti-proliferative. Receptor type protein tyrosine phosphatase-kappa (RPTP-kappa) specifically dephosphorylates EGFR, thereby blocking EGFR-dependent signaling, and inhibiting proliferation. We report here that RPTP-kappa mediates functional integration of EGFR and TGF-beta signaling pathways in human keratinocytes. TGF-beta up-regulates RPTP-kappa mRNA and protein, in a dose and time dependent manner. Induction of RPTP-kappa by TGF-beta significantly decreases basal and EGF-stimulated EGFR tyrosine phosphorylation. shRNA-mediated reduction of TGF-beta-induced RPTP-kappa significantly attenuates the ability of TGF-beta to inhibit proliferation. RPTP-kappa induction is dependent on activation of transcription factors Smad3 and Smad4. Inhibition of TGF-beta receptor kinase completely prevents induction of RPTP-kappa. Chromatin immunoprecipitation assays reveal that TGF-beta stimulates Smad3 and Smad4 binding to RPTP-kappa gene promoter. Smad3/4 binding is localized to an 186-base pair region, which contains a consensus Smad3-binding element. These data describe a novel mechanism of cross-talk between EGFR and TGF-beta pathways, in which RPTP-kappa functions to integrate growth-promoting and growth-inhibiting signaling pathways.
Xu
Yiru
Y
Department of Dermatology, University of Michigan, Ann Arbor, MI 48109-5609, USA.
Baker
Dustin
D
Quan
TaiHao
T
Baldassare
Joseph J
JJ
Voorhees
John J
JJ
Fisher
Gary J
GJ
D000328:Adult; D049109:Cell Proliferation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D019000:Phosphotyrosine / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020239:Receptor Cross-Talk / Q000187:drug effects; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051785:Smad Proteins / Q000378:metabolism; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000494:pharmacology
D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D051785:Smad Proteins; D016212:Transforming Growth Factor beta; D019000:Phosphotyrosine; D066246:ErbB Receptors; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2