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Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes
15:43

Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes

Published on: January 7, 2013

Novel protein kinase C delta isoform insensitive to caspase-3

Y Sakurai1, Y Onishi, Y Tanimoto

  • 1Department of Biochemistry, Tokyo Dental College, Chiba, Japan.

Biological & Pharmaceutical Bulletin
|September 18, 2001
PubMed

Insights

A novel protein kinase C delta isoform (PKC deltaII) is expressed upon H-7 treatment, showing altered cleavage compared to PKC deltaI. This PKC deltaII isoform is insensitive to caspase-3 and exhibits distinct tissue distribution, suggesting unique functions.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Biochemistry

Background:

  • Protein kinase C delta (PKC delta) regulates critical cellular processes like apoptosis, growth, and differentiation.
  • Previous research indicated that the PKC inhibitor H-7 induces apoptosis in mouse thymocytes.

Purpose of the Study:

  • To investigate the molecular mechanisms underlying H-7-induced apoptosis in thymocytes.
  • To identify and characterize novel isoforms of PKC delta.

Main Methods:

  • Treatment of mouse thymocytes with H-7.
  • cDNA analysis to identify novel PKC delta isoforms.
  • Expression and characterization of PKC delta isoforms in COS-1 cells.
  • In vivo and in vitro cleavage assays using caspase-3 inhibitors.

Main Results:

  • A novel PKC delta isoform, PKC deltaII, was transiently expressed in H-7-treated thymocytes.
  • PKC deltaII contains a 78 bp insertion in the caspase-3 sensitive site compared to PKC deltaI.
  • PKC deltaII (81 kDa) exhibited similar kinase activity to PKC deltaI but was insensitive to caspase-3 mediated cleavage.
  • PKC deltaI (78 kDa) was partially cleaved into a 38 kDa fragment, while PKC deltaII was not.
  • PKC deltaII showed high expression in testis and ovary, with lower levels in thymocytes, brain, and kidney, unlike PKC deltaI found in most tissues.

Conclusions:

  • The novel PKC deltaII isoform is generated by alternative splicing and is resistant to caspase-3 cleavage.
  • The distinct tissue distribution and cleavage resistance suggest specialized roles for PKC deltaII compared to PKC deltaI.

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