Junctional Rab13-binding protein (JRAB) regulates cell spreading via filamins.

Article Details


Sakane A, Alamir Mahmoud Abdallah A, Nakano K, Honda K, Kitamura T, Imoto I, Matsushita N, Sasaki T

Junctional Rab13-binding protein (JRAB) regulates cell spreading via filamins.

Genes Cells. 2013 Sep;18(9):810-22. doi: 10.1111/gtc.12078. Epub 2013 Jul 25.

PubMed ID
23890175 [ View in PubMed

We previously showed that Rab13 and its effector protein, junctional Rab13-binding protein (JRAB)/molecules interacting with CasL-like 2 (MICAL-L2), regulate junctional development by modulating cell adhesion molecule transport and actin cytoskeletal reorganization in epithelial cells. Here, we investigated how JRAB regulates reorganization of the actin cytoskeleton in NIH3T3 fibroblasts, in an attempt to obtain novel insights into the mechanism of JRAB action. To this end, we expressed mutant proteins that adopt a constitutively open or closed state and then examined effect on cellular morphology of the resulting actin cytoskeletal reorganization. Expression of the JRABDeltaCT mutant (constitutively 'closed' state) induced stress fibers, whereas expression of the JRABDeltaCC mutant (constitutively 'open' state) caused cell spreading with membrane ruffles. Next, we identified the proteins involved in JRAB-induced rearrangement of actin cytoskeleton leading to morphological changes. In NIH3T3 cells expressing HA-JRABDeltaCC, filamin, an actin cross-linking protein, coimmunoprecipitated with HA-JRABDeltaCC. Expression of ASB2 induced degradation of all three filamin isoforms and inhibited the JRABDeltaCC-induced cell spreading. Consistent with our previous results, actinin-1/-4 were also immunoprecipitated with HA-JRABDeltaCC. However, actinin-1/-4 have no effect on the cell spreading regulated by JRABDeltaCC. These data suggest that JRAB contributes to the rearrangement of the actin cytoskeleton during cell spreading via filamins.

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