Our genetic material is very breakable and needs appropriate checkpoints to make certain the integrity of the same. Hence our cells have developed mechanisms to shield the integrity of DNA. Various cellular processes including cell integrity are mediated by protein kinase C superfamily. PKC (EC 220.127.116.11) has also some essential roles like differentiation, proliferation regulation etc. Eukaryotes carry a variety of different PKC isoforms which have been divided into conventional PKCs, Novel PKCs, atypical PKCs etc. However, Saccharomyces cerevisiae carries a single PKC, called as Pkc 1. The main function of Pkc 1 is the protection of cell wall integrity.
Authors in this manuscript have claimed that PKC is implicated in a control mechanism that is conserved from yeast to humans. Since there are many isoforms of PKC, only the delta PKC isoform is able to commence the checkpoint for DNA integrity.
Authors from the same paper had earlier established that there is a possible involvement of Pkc1 in DNA metabolism. Infact it was shown that the Pkc1 mutants have high recombination rate and hence defect in genome integrity. The authors emphasize that:
‘’we have established a clear direct connection of PKC with DNA metabolism: Pkc1 activity is required in yeast cells to activate the DNA integrity checkpoint. We have checked this effect in different independent backgrounds and, moreover, checkpoint activation was restored when a PKC1 gene was re-introduced into pkc1 mutant cells, demonstrating that the lack of checkpoint function is caused by Pkc1 inactivation.’’
Under genotoxic stress especially replicative and DSB stress, electrophoretic band shift was observed for Pkc1, suggestive of genotoxic stress regulating Pkc1 activity. But, at what cellular level is DNA integrity checkpoint controlled by Pkc1 had to be determined?
Some observations has led authors to complete the proposed model by adding that there possibly could be a feedback loop between Pkc1 and Tel1 and that PKC checkpoint control must be a general trait of eukaryotes. However establishing such fact needs more research and digging into the phenomenon. For complete study please refer to citation below:
Source: María Soriano-Carot, Inma Quilis, M. Carmen Bañó, and J. Carlos Igual
Protein kinase C controls activation of the DNA integrity checkpoint
Nucleic Acids Res. 2014 : gku373v1-gku373.