The N-terminal fragment from caspase-cleaved serine/arginine protein-specific kinase2 (SRPK2) translocates into the nucleus and promotes apoptosis.
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Hong Y, Jang SW, Ye K
The N-terminal fragment from caspase-cleaved serine/arginine protein-specific kinase2 (SRPK2) translocates into the nucleus and promotes apoptosis.
J Biol Chem. 2011 Jan 7;286(1):777-86. doi: 10.1074/jbc.M110.193441. Epub 2010 Nov 5.
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- 21056976 [ View in PubMed]
- Abstract
SRPK2 belongs to a family of serine/arginine (SR) protein-specific kinases (SRPKs), which phosphorylate SR domain-containing proteins in the nuclear speckles and mediate the pre-mRNA splicing. Previous studies have shown that SRPK2 plays a pivotal role in cell proliferation and apoptosis. However, how SRPK2 is regulated during the apoptosis is unclear. Here, we show that SRPK2 is cleaved by caspases at Asp-139 and -403 residues. Its N terminus cleaved product translocates into the nucleus and promotes VP16-induced apoptosis. Akt phosphorylation of SRPK2 prevents its apoptotic cleavage by caspases. 14-3-3beta, the binding partner of Akt-phosphorylated SRPK2, further protects it from degradation. Hence, our results suggest that the N-terminal domain of SRPK2 cleaved by caspases translocates into the nucleus, where it promotes chromatin condensation and apoptotic cell death.