MSK1 and MSK2 Are Required for the Mitogen- and Stress-Induced Phosphorylation of CREB and ATF1 in Fibroblasts

Abstract

AbstractUsing mouse knockouts for mitogen- and stress-activated protein kinase 1 (MSK1) and MSK2 and a double knockout of both MSK1 and MSK2, we show that these protein kinases are required for the stress-induced phosphorylation of transcription factors CREB and ATF1 in primary embryonic fibroblasts. In contrast mitogen-induced phosphorylation of CREB and ATF1 is greatly reduced but not totally abolished. The mitogen- and stress-induced phosphorylation of CREB at Ser133 has been linked to the transcription of several immediate early genes, including c-fos, junB, and egr1. The knockout of both MSK1 and MSK2 resulted in a 50% reduction in c-fos and junB gene transcription in response to anisomycin or UV-C radiation but only a small reduction in response to tetradecanoyl phorbol acetate or epidermal growth factor in fibroblasts. The transcription of egr1 in response to both mitogenic and stress stimuli, as well as stress-induced apoptosis, was unaffected in the MSK1/MSK2 double knockout. We thank Valeria Poli for help and advice on the generation of the mouse knockouts and Chris Armstrong and Jane Leitch for the production and purification of the antibodies used in this work. We thank The Sequencing Service (School of Life Sciences, University of Dundee, Scotland) for DNA sequencing.G.R.W. is the recipient of a postgraduate studentship from the United Kingdom Medical Research Council. This research was supported by grants from the Medical Research Council, Diabetes UK, The Royal Society, Astra-Zeneca, Boehringer-Ingelheim, GlaxoSmithKline, NovoNordisk, and Pfizer.