| Project/Area Number |
18590271
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General medical chemistry
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| Research Institution | The University of Tokushima |
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Principal Investigator |
NISHIMURA Noriyuki The University of Tokushima, Institute of Health Biosciences, Graduate School, Associate Professor (00322719)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,920,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2006: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | Cell polarity / Tight junction / Adherens junction / Rab13 / Rab8 / JRAB / MICAL-L2 / 細胞接着 / オクルーディン |
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| Research Abstract |
Tight junction (TJ) and adherens junction (AJ) are located at the apical end of the basolateral membrane of polarized epithelial cells. During polarization, epithelial cells first form spot-like primordial AJ at the tips of the initial cell-cell contacts and develop belt-like mature AJ. In parallel with the maturation of AJ, TJ is formed at the apical side of AJ. Whereas epithelial polarization entails a complex interplay between the coordinated TJ and AJ assembly and several fundamental cellular processes, the transport of integral TJ and AJ proteins to and/or from the plasma membrane is essential for the control of TJ and AJ assembly. We previously reported that Rab 13 and a junctional Rab13-binding protein(JRAB)/molecule interacting with CasL-like 2 (MICAL-L2) mediated the endocytic recycling of an integral TJ protein occludin and the formation of functional TJ. In the present study, we examined the role of Rab13 and JRAB/MICAL-L2 in the transport of other integral TJ and AJ proteins claudin-1 and E-cadherin to the plasma membrane. Although knockdown of Rab13 specifically inhibited claudin-1 and occludin but not E-cadherin transport, knockdown of JRAB/MICAL-L2 and expression of its Rab13-binding domain(JRAB/MICAL-L2-C)retarded claudin-1, occludin, and E-cadherin transport. We then identified Rab8 as another JRAB/MICAL-L2-C-binding protein. Knockdown of Rab8 inhibited the Rab13-independent transport of E-cadherin to the plasma membrane. Rab13 and Rab8 competed with each other for the binding to JRAB/MICAL-L2 and functionally associated with JRAB/MICAL-L2 at the plasma membrane and recycling endosome, respectively. These results suggest that the interactions of JRAB/MICAL-L2 with Rab13 and Rab8 play a crucial role in establishing cell polarity.
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