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PKCdelta survival signaling in cells containing an activated p21Ras protein requires PDK1

Shuhua Xia1, Zhihong Chen, Lora W Forman

  • 1Cancer Research Center, Boston University School of Medicine, Boston, Massachusetts 02118, USA.

Cellular Signalling
|January 17, 2009
PubMed

Insights

Activated p21(Ras) promotes cell survival by activating protein kinase C delta (PKCdelta) via phosphoinositide-dependent kinase 1 (PDK1). This pathway is crucial for preventing apoptosis in cells with mutated p21(Ras).

Area of Science:

  • Cellular signaling pathways
  • Apoptosis regulation
  • Oncogene-induced signaling

Background:

  • Protein kinase C delta (PKCdelta) plays a role in cell survival and apoptosis.
  • PKCdelta acts as an anti-apoptotic signal transducer in cells with activated p21(Ras), promoting survival via AKT activation.
  • The precise mechanism of PKCdelta regulation by p21(Ras) requires further elucidation.

Purpose of the Study:

  • To investigate the regulatory mechanism of PKCdelta by p21(Ras) in cellular survival.
  • To determine the role of phosphoinositide 3-kinase/phosphoinositide-dependent kinase 1 (PI(3)K-PDK1) in mediating p21(Ras)-induced anti-apoptotic signaling.
  • To elucidate how PDK1 regulates PKCdelta activity and influences cell fate in the context of activated p21(Ras).

Main Methods:

  • Investigated the activation of PKCdelta by PI(3)K-PDK1 in cells with activated p21(Ras).
  • Utilized knock-down experiments for PDK1, PKCdelta, and AKT to assess their roles in cell survival.
  • Examined the effect of PDK1 expression levels (constitutive and dominant-negative) on PKCdelta activity.

Main Results:

  • PKCdelta is activated by PI(3)K-PDK1, delivering survival signals to AKT in the presence of activated p21(Ras).
  • PDK1 is upregulated in cells with activated p21(Ras); its knock-down, along with PKCdelta or AKT, induces apoptosis.
  • PDK1 directly regulates PKCdelta activity, with increased PDK1 enhancing and dominant-negative PDK1 suppressing PKCdelta activity.

Conclusions:

  • p21(Ras)-mediated survival signaling relies on the PI(3)K-AKT pathway, dependent on both PDK1 and PKCdelta.
  • PDK1 activates and regulates PKCdelta, thereby determining the survival or apoptotic fate of cells with mutated, activated p21(Ras).
  • This study clarifies a critical signaling axis involving PDK1 and PKCdelta in oncogenic Ras-driven cell survival.

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