The role of protein kinase C δ activation and STAT3 Ser727 phosphorylation in insulin-induced keratinocyte proliferation

Marina Gartsbein, Addy Alt, Koji Hashimoto, Koichi Nakajima, Toshio Kuroki, Tamar Tennenbaum

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Activation of the STAT family of transcription factors is regulated by cytokines and growth factors. STAT tyrosine and serine phosphorylation are linked to the transcriptional activation and function of STAT. We have previously described a unique pathway inducing keratinocyte proliferation, which is mediated by insulin stimulation and depends on protein kinase C δ (PKCδ). In this study, we assessed STAT3 activation downstream of this pathway and characterized the role of PKCδ activation in STAT3 tyrosine and serine phosphorylation and keratinocyte proliferation. Following insulin stimulation, STAT3 interacted with PKCδ but not with any other PKC isoform expressed in skin. Activated forms of PKCδ and STAT3 were essential for insulin-induced PKCδ-STAT3 activation in keratinocyte proliferation. Abrogation of PKCδ activity inhibited insulin-induced STAT3 phosphorylation, PKCδ-STAT3 association and nuclear translocation. In addition, overexpression of STAT3 tyrosine mutant eliminated insulin-induced PKCδ activation and keratinocyte proliferation. Finally, overexpression of a STAT3 serine mutant abrogated insulin-induced STAT3 serine phosphorylation and STAT3-induced keratinocyte proliferation, whereas STAT3 tyrosine phosphorylation was induced and nuclear localization remained intact. This study indicates that PKCδ activation is a primary regulator of STAT3 serine phosphorylation and that PKCδ is essential in directing insulin-induced signaling in keratinocyte proliferation.

Original languageEnglish
Pages (from-to)470-481
Number of pages12
JournalJournal of Cell Science
Issue number3
StatePublished - 1 Feb 2006


  • Keratinocyte
  • PKCδ
  • Proliferation
  • STAT3
  • Serine phosphorylation
  • Tyrosine phosphorylation


Dive into the research topics of 'The role of protein kinase C δ activation and STAT3 Ser727 phosphorylation in insulin-induced keratinocyte proliferation'. Together they form a unique fingerprint.

Cite this