Premium
N‐end‐rule‐mediated Degradation of the Proteolytically Activated Form of PKC‐theta Kinase attenuates its Pro‐Apoptotic Function
Author(s) -
Eldeeb Mohamed Ali,
Esmaili Mansoore,
Fahlman Richard
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.817.1
Subject(s) - jurkat cells , protein kinase c , staurosporine , microbiology and biotechnology , apoptosis , proteolysis , biology , programmed cell death , chemistry , kinase , biochemistry , t cell , genetics , enzyme , immune system
Cellular stresses and signalling that lead to the initiation of apoptotic pathways often result in the activation of caspases or calpains which in turn leads to the generation of proteolytically generated protein fragments with new or altered functions. Mounting number of studies reveal that the activity of these proteolytically activated protein fragments can be counteracted via their selective degradation by the N‐End Rule pathway. Here we investigate the proteolytically generated fragment of the PKC theta kinase, where we report the first study on the stability of this pro‐apoptotic protein fragment. We have determined that the pro‐apoptotic cleaved fragment of PKC‐theta is unstable in cells as its N‐terminal lysine targets it for proteasomal degradation via the N‐end rule pathway and this degradation is inhibited by mutating the destabilizing N‐Termini, knockdown of the UBR1 and UBR2 E3 ligases. Tellingly, we demonstrate that the metabolic stabilization of the cleaved fragment of PKC‐theta or inhibition of the N‐end rule augments the apoptosis‐inducing effect of staurosporine in Jurkat cells. Notably, we have demonstrated that the cleaved fragment of PKC theta, per se , can induce apoptotic cell death in Jurkat T‐cell leukemia. Our results expand the functional scope of N‐end rule pathway and support the notion that targeting N‐end rule machinery may have therapeutic implications. Support or Funding Information Mohamed Eldeeb is supported by Alberta‐Innovates Technology Futures (AITF) scholarship.