The MKK(3/6)-p38-signaling cascade alters the subcellular distribution of hnRNP A1 and modulates alternative splicing regulation.
Individual members of the serine-arginine (SR) and heterogeneous nuclear ribonucleoprotein (hnRNP) A/B families of proteins have antagonistic effects in regulating alternative splicing. Although hnRNP A1 accumulates predominantly in the nucleus, it shuttles continuously between the nucleus and the cytoplasm. Some but not all SR proteins also undergo nucleo-cytoplasmic shuttling, which is affected by phosphorylation of their serine/arginine (RS)-rich domain. The signaling mechanisms that control the subcellular localization of these proteins are unknown. We show that exposure of NIH-3T3 and SV-40 transformed green monkey kidney (COS) cells to stress stimuli such as osmotic shock or UVC irradiation, but not to mitogenic activators such as PDGF or EGF, results in a marked cytoplasmic accumulation of hnRNP A1, concomitant with an increase in its phosphorylation. These effects are mediated by the MKK(3/6)-p38 pathway, and moreover, p38 activation is necessary and sufficient for the induction of hnRNP A1 cytoplasmic accumulation. The stress-induced increase in the cytoplasmic levels of hnRNP A/B proteins and the concomitant decrease in their nuclear abundance are paralleled by changes in the alternative splicing pattern of an adenovirus E1A pre-mRNA splicing reporter. These results suggest the intriguing possibility that signaling mechanisms regulate pre-mRNA splicing in vivo by influencing the subcellular distribution of splicing factors.
van der Houven van Oordt
W
W
MRC Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, Scotland, United Kingdom.
Diaz-Meco
M T
MT
Lozano
J
J
Krainer
A R
AR
Moscat
J
J
Cáceres
J F
JF
D016475:3T3 Cells; D017398:Alternative Splicing; D000818:Animals; D019556:COS Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002461:Cell Line, Transformed; D005786:Gene Expression Regulation; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D048371:MAP Kinase Kinase 3; D048669:MAP Kinase Kinase 6; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D009994:Osmolar Concentration; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis; D012261:Ribonucleoproteins / Q000378:metabolism*; D015398:Signal Transduction; D013539:Simian virus 40; D014162:Transfection; D014466:Ultraviolet Rays
D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048371:MAP Kinase Kinase 3; D048669:MAP Kinase Kinase 6; C482531:Map2k3 protein, mouse; C482567:Map2k6 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases