Distinct Distribution and Localization of Rho-kinase in Mouse Epithelial, Muscle and Neural Tissues

Abstract

ABSTRACT. The small GTP-binding protein Rho plays a crucial role in a wide variety of cellular functions through various effector proteins. Rho-kinase is a key effector protein of Rho, which is composed of two isoforms, ROCK1 and ROCK2. To clarify the site of action of ROCK1 and ROCK2, we performed immunofluorescence and immunoelectron microscopic analyses using isoform-specific antibodies in mouse tissues. In the large and small intestines, ROCK1 immunoreactivity was predominantly identified in epithelial cells, and ROCK2 immunoreactivity was negligible. In these epithelial cells, ROCK1 immunoreactivity was distributed on plasma membranes, while ROCK1 immunogold signals were localized at cell-cell contacts and cell adhesion sites, especially at the adherens junctions at the ultrastructural level. In the bladder epithelium, however, ROCK1 and ROCK2 signals were identified at intermediate filaments, and ROCK2 signals were also observed in nuclei. In the three types of muscular cells-smooth, cardiac, and skeletal muscle cells-ROCK1 and ROCK2 also showed differential distribution. ROCK1 signals were localized at actin filaments, plasma membranes, and vesicles near plasma membranes in smooth muscle cells; at the lysosomes in skeletal muscle cells; and were undetectable in cardiac muscle cells. ROCK2 signals were localized at actin filaments and centrosomes in smooth muscle cells, at intercalated discs in cardiac muscle cells, and at Z-discs and sarcoplasmic reticulum in skeletal muscle cells. In the brain, ROCK1 immunoreactivity was distributed in glia, whereas ROCK2 immunoreactivity was observed in neurons. These results indicate that the two isoforms of Rho-kinase distribute differentially to accomplish their specific functions.

Selective inhibition of brain endothelial Rho-kinase-2 provides optimal protection of an in vitro blood-brain barrier from tissue-type plasminogen activator and plasmin

“…Two isoforms of ROCK have been described, ROCK-1 (p160ROCK; ROKβ) and ROCK-2 (ROKα) [10, 11]. ROCK-1 is ubiquitously expressed (with low levels in brain and muscle), while ROCK-2 is abundant in the brain [25, 26], particularly in neurons [25, 27] and in reactive astrocytes [27, 28]. The two isoforms share 65% overall amino-acid sequence identity and particularly high homology in the kinase domain (92%) [26, 29].…”

Abrogation of airway hyperresponsiveness but not inflammation by rho kinase insufficiency

“…There are tissue specific differences in ROCK1 and ROCK2 expression, as well as differences in the subcellular localization of ROCK1 and ROCK2 (10, 12, 13). In addition, accumulating evidence indicates differences in the regulation of ROCK1 and ROCK2 (14). Collectively, these data suggest that ROCK1 and ROCK2 may serve different functions depending on the cell type.…”

A FRET Biosensor for ROCK Based on a Consensus Substrate Sequence Identified by KISS Technology

“…The two ROCK homologs share 64% identity in their primary amino acid sequences, with the highest homology (92%) being within the kinase domains. Tissue-specific expressions of ROCK1 and ROCK2 were reported previously (Schmandke et al, 2007;Iizuka et al, 2012), but later analysis of ROCK1 and ROCK2 expressed sequence tag distribution revealed that the distribution patterns of ROCK1 and ROCK2 are similar and that there are few specific organs and/or tissues with dramatically higher expression levels than the others (Julian and Olson, 2014).…”

“…The control siRNA was purchased from Dharmacon (Lafayette, CO). siRNA sequences of ROCK1 and ROCK2 were obtained from previous reports (Vega et al, 2011;Iizuka et al, 2012).…”