Stress-induced release of Oct-1 from the nuclear envelope is mediated by JNK phosphorylation of lamin B1Report as inadecuate




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The nuclear lamina can bind and sequester transcription factors TFs, a function lost if the lamina is abnormal, with missing or mutant lamin proteins. We now show that TF sequestration is not all-or-nothing, but a dynamic physiological response to external signals. We show that the binding of the ubiquitous TF, Oct-1, to lamin B1 was reversed under conditions of cellular stress caused, inter alia, by the chemical methylating agent methylmethanesulfonate MMS. A search for lamin B1 post-translational modifications that might mediate changes in Oct-1 binding using kinase inhibitors uncovered a role for c-Jun N-terminal kinase JNK. Phosphoproteomic and site-directed mutagenesis analyses of lamin B1 isolated from control and MMS-treated nuclei identified T575 as a JNK site phosphorylated after stress. A new phospho-T575 specific anti-peptide antibody confirmed increased interphase cellular T575 phosphorylation after cell exposure to certain stress conditions, enabling us to conclude that lamin B1 acts as an interphase kinase target, releasing Oct-1 to execute a protective response to stress.



Author: Ivan I. Boubriak, Ashraf N. Malhas, Marek M. Drozdz, Lior Pytowski, David J. Vaux

Source: http://plos.srce.hr/



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