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Endonuclease G modulates the alternative splicing of deoxyribonuclease 1 mRNA in human CD4+ T lymphocytes and prevents the progression of apoptosis

Author:
Zhdanov, Dmitry D., Gladilina, Yulia A., Pokrovsky, Vadim S., Grishin, Dmitry V., Grachev, Vladimir A., Orlova, Valentina S., Pokrovskaya, Marina V., Alexandrova, Svetlana S., Plyasova, Anna A., Sokolov, Nikolay N.
Source:
Biochimie 2019 v.157 pp. 158-176
ISSN:
0300-9084
Subject:
CD4-positive T-lymphocytes, alternative splicing, antisense DNA, apoptosis, cell nucleus, deoxyribonuclease I, enzyme activity, exons, gene overexpression, humans, introns, messenger RNA, mitochondria, oligonucleotides
Abstract:
Apoptotic endonucleases act cooperatively to fragment DNA and ensure the irreversibility of apoptosis. However, very little is known regarding the potential regulatory links between endonucleases. Deoxyribonuclease 1 (DNase I) inactivation is caused by alternative splicing (AS) of DNase I pre-mRNA skipping exon 4, which occurs in response to EndoG overexpression in cells. The current study aimed to determine the role of EndoG in the regulation of DNase I mRNA AS and the modulation of its enzymatic activity. A strong correlation was identified between the EndoG expression levels and DNase I splice variants in human lymphocytes. EndoG overexpression in CD4+ T cells down-regulated the mRNA levels of the active full-length DNase I variant and up-regulated the levels of the non-active spliced variant, which acts in a dominant-negative fashion. DNase I AS was induced by the translocation of EndoG from mitochondria into nuclei during the development of apoptosis. The DNase I spliced variant was induced by recombinant EndoG or by incubation with EndoG-digested cellular RNA in an in vitro system with isolated cell nuclei. Using antisense DNA oligonucleotides, we identified a 72-base segment that spans the adjacent segments of exon 4 and intron 4 and appears to be responsible for the AS. DNase I-positive CD4+ T cells overexpressing EndoG demonstrated decreased progression towards bleomycin-induced apoptosis. Therefore, EndoG is an endonuclease with the unique ability to inactivate another endonuclease, DNase I, and to modulate the development of apoptosis.
Agid:
6251767