Functional Characterization of Phosphorylation of Decapping Protein 1a (Dcp1a)
Date Issued
2008
Date
2008
Author(s)
Kao, Ching-Han
Abstract
Regulation of mRNA decay is a critical step in gene expression. Decapping plays a major role in mRNA turnover as it removes the 5’ cap of target mRNA after deadenylation to generate m7GDP and a 5’ monophosphate substrate that is susceptible for 5’ to 3’exonucleolytic degradation by Xrn1. Dcp1p and Dcp2p were noted to form a decapping complex and associate with other mRNA decay regulators such as Tristetraprolin (TTP). TTP is an immediate early gene stimulated upon induction in 3T3-L1 preadipocytes, and was reported to precipitate with hDcp1a and the complex functioned in the ARE-mediated decay pathway. The potential role of mouse Dcp1a during mitotic clonal expansion in preadipocyte differentiation was thus studied. Dcp1a was phosphorylated during the early differentiation of 3T3-L1 cells, and was possibly regulated by the ERK signaling pathway. Mouse Dcp1a was localized mostly in the cytoplasm, and its position was not affected by its phosphorylation status. The colocalization of overexpressed Dcp1a and Dcp2 was also observed in cytoplasmic processing bodies. In the in vitro decapping assay, mouse Dcp2 displayed strong decapping activity while Dcp1a expressed partial decapping activity. In addition, highly phosphorylated Dcp1a appeared to enhance the catalytic activity of Dcp2 in a dosage dependent manner. Further analysis would be required to reveal the effect of phosphorylation on Dcp1a’s role in decapping and enhancing the activity of Dcp2 during early differentiation of 3T3-L1 cells.
Subjects
decapping
mRNA decay
Dcp1a
processing bodies
preadipocyte
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