A differentiation-dependent splice variant of myosin light chain kinase, MLCK1, regulates epithelial tight junction permeability.

TitleA differentiation-dependent splice variant of myosin light chain kinase, MLCK1, regulates epithelial tight junction permeability.
Publication TypeJournal Article
Year of Publication2004
AuthorsClayburgh DR, Rosen S, Witkowski ED, Wang F, Blair S, Dudek S, Garcia JGN, Alverdy JC, Turner JR
JournalJ Biol Chem
Volume279
Issue53
Pagination55506-13
Date Published2004 Dec 31
ISSN Number0021-9258
KeywordsActins, Alternative Splicing, Caco-2 Cells, Cell Differentiation, DNA, Complementary, Electrophysiology, Enterocytes, Epithelial Cells, Humans, Immunoblotting, Jejunum, Lasers, Microdissection, Microscopy, Fluorescence, Myosin-Light-Chain Kinase, Phosphorylation, Protein Isoforms, Recombinant Proteins, Reverse Transcriptase Polymerase Chain Reaction, RNA, RNA Interference, RNA, Messenger, RNA, Small Interfering, Sodium, Tight Junctions, Time Factors
Abstract

<p>Activation of Na(+)-nutrient cotransport leads to increased tight junction permeability in intestinal absorptive (villus) enterocytes. This regulation requires myosin II regulatory light chain (MLC) phosphorylation mediated by MLC kinase (MLCK). We examined the spatiotemporal segregation of MLCK isoform function and expression along the crypt-villus axis and found that long MLCK, which is expressed as two alternatively spliced isoforms, accounts for 97 +/- 4% of MLC kinase activity in interphase intestinal epithelial cells. Expression of the MLCK1 isoform is limited to well differentiated enterocytes, both in vitro and in vivo, and this expression correlates closely with development of Na(+)-nutrient cotransport-dependent tight junction regulation. Consistent with this role, MLCK1 is localized to the perijunctional actomyosin ring. Furthermore, specific knockdown of MLCK1 using siRNA reduced tight junction permeability in monolayers with active Na(+)-glucose cotransport, confirming a functional role for MLCK1. These results demonstrate unique physiologically relevant patterns of expression and subcellular localization for long MLCK isoforms and show that MLCK1 is the isoform responsible for tight junction regulation in absorptive enterocytes.</p>

DOI10.1074/jbc.M408822200
Alternate JournalJ. Biol. Chem.
PubMed ID15507455
PubMed Central IDPMC1237105
Grant ListP30 DK042086 / DK / NIDDK NIH HHS / United States
P30 CA014599 / CA / NCI NIH HHS / United States
P30 DK 42086 / DK / NIDDK NIH HHS / United States
R01 DK061931 / DK / NIDDK NIH HHS / United States
T32 GM 07281 / GM / NIGMS NIH HHS / United States
R01 DK 61931 / DK / NIDDK NIH HHS / United States
P30 CA 14599 / CA / NCI NIH HHS / United States