ERK Kinases Phosphorylate Lin28a to Modulate P19 Cell Proliferation and Differentiation [Cell Biology]

Lin28a, originally discovered in the nematode Caenorhabditis elegans and highly conserved across species, is a well characterized regulator of let-7 miRNAs and is implicated in cell proliferation and pluripotency control. However, little is known about how Lin28a function is modulated at post-translational level and thereby responds to major signaling pathways. Here we show that Lin28a is directly phosphorylated by ERK1/2 kinases at Ser200. By editing lin28a gene with Crispr/Cas9 based method, we generated P19 mouse embryonic carcinoma (EC) stem cells expressing Lin28a-S200A (phospho-deficient) and Lin28a-S200D (phospho-mimetic) mutants respectively to study the functional impact of S200 phosphorylation. Lin28a-S200D expressing cells, but not Lin28a-S200A expressing or control P19 EC cells, displayed impaired inhibition of let-7 miRNA and resulted in decreased Cyclin D1, while Lin28a-S200A knock-in cells express less let-7s miRNA, proliferate faster, and exhibit differentiation defect upon Retinoic Acid induction. Therefore our results support that ERK kinases mediated-Lin28a phosphorylation may be an important mechanism for pluripotent cells to facilitate the escape from self-renewal cycle and start differentiation process.

from #AlexandrosSfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/2kQf1Xw
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