Regulation of 130-kDa smooth muscle myosin light chain kinase expression by an intronic CArG element

Meng Chen, Wenwu Zhang, Xiao Lu, April M. Hoggatt, Susan J. Gunst, Ghassan S. Kassab, Johnathan D. Tune, B. Paul Herring

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The mylk1 gene encodes a 220-kDa nonmuscle myosin light chain kinase (MLCK), a 130-kDa smooth muscle MLCK (smMLCK), as well as the non-catalytic product telokin. Together, these proteins play critical roles in regulating smooth muscle contractility. Changes in their expression are associated with many pathological conditions; thus, it is important to understand the mechanisms regulating expression of mylk1 gene transcripts. Previously, we reported a highly conserved CArG box, which binds serum response factor, in intron 15 of mylk1. Because this CArG element is near the promoter that drives transcription of the 130- kDasmMLCK,weexaminedits role in regulating expression of this transcript. Results show that deletion of the intronic CArG region from a β-galactosidase reporter gene abolished transgene expression in mice in vivo. Deletion of the CArG region from the endogenous mylk1 gene, specifically in smooth muscle cells, decreased expression of the 130-kDa smMLCK by 40% without affecting expression of the220-kDaMLCKor telokin. This reduction in 130- kDa smMLCK expression resulted in decreased phosphorylation of myosin light chains, attenuated smooth muscle contractility, and a 24% decrease in small intestine length that was associated with a significant reduction of Ki67-positive smooth muscle cells. Overall, these data show that the CArG element in intron 15 of the mylk1 gene is necessary for maximal expression of the 130-kDa smMLCK and that the 130-kDa smMLCK isoform is specifically required to regulate smooth muscle contractility and small intestine smooth muscle cell proliferation.

Original languageEnglish
Pages (from-to)34647-34657
Number of pages11
JournalJournal of Biological Chemistry
Issue number48
StatePublished - 29 Nov 2013


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