Increased MKK4 abundance with replicative senescence is linked to the joint reduction of multiple microRNAs.
MKK4 (mitogen-activated protein kinase kinase 4) is a pivotal upstream activator of c-Jun N-terminal kinase and p38. Here, we report that the abundance of MKK4 increases in senescent human diploid fibroblasts through enhanced translation. We identified four microRNAs (miR-15b, miR-24, miR-25, and miR-141) that target the MKK4 messenger RNA (mRNA); the abundance of these microRNAs decreased during replicative senescence. Individually modulating the amount of each microRNA did not modify MKK4 abundance, but their concomitant overexpression decreased and their joint reduction increased MKK4 abundance. Reporter analyses indicated that these microRNAs acted through the MKK4 5' and 3' untranslated regions. Elevated MKK4 abundance inhibited cell proliferation and increased the phosphorylation and activity of p38 and PRAK (p38-regulated/activated protein kinase). Thus, multiple microRNAs acting on a single target, the MKK4 mRNA, collectively influence MKK4 abundance during replicative senescence.
Laboratory of Cellular and Molecular Biology, National Institute on Aging-Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA.
Bernard S
BS
Marasa
Subramanya
S
Srikantan
Kiyoshi
K
Masuda
Kotb
K
Abdelmohsen
Yuki
Y
Kuwano
Xiaoling
X
Yang
Jennifer L
JL
Martindale
Carrie W
CW
Rinker-Schaeffer
Myriam
M
Gorospe
D020413:3' Untranslated Regions; D001483:Base Sequence; D049109:Cell Proliferation; D002478:Cells, Cultured; D016922:Cellular Senescence; D017931:DNA Primers; D006801:Humans; D007150:Immunohistochemistry; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism*; D035683:MicroRNAs / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
D020413:3' Untranslated Regions; D017931:DNA Primers; D035683:MicroRNAs; D012333:RNA, Messenger; D048670:MAP Kinase Kinase 4; C482559:MAP2K4 protein, human