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Rab11A and Rab11B distinctly regulate protease‐activated receptor‐1 recycling and constitutive degradation (802.10)
Author(s) -
Coronel Luisa,
Grimsey Neil,
Canto Isabel,
Stephens Bryan,
Phan Cattien,
Handel Tracy,
Trejo JoAnn
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.802.10
Subject(s) - microbiology and biotechnology , endosome , internalization , g protein coupled receptor , gene knockdown , intracellular , signal transduction , endocytosis , receptor , thrombin , chemistry , biology , cell culture , biochemistry , immunology , genetics , platelet
Protease‐activated receptor‐1 (PAR1) is a G protein‐coupled receptor (GPCR) expressed throughout the vasculature. Thrombin irreversibly activates PAR1, therefore receptor signaling and expression is tightly regulated. Upon activation, PAR1 is rapidly internalized and sorted to lysosomes for degradation, a process critical for signal termination. Whereas naïve PAR1 is constitutively internalized, generating an intracellular pool of PAR1 that recycles and repopulates the cell surface with uncleaved PAR1 after thrombin stimulation, a process critical for rapid recovery of thrombin signaling. The mechanisms that mediate recycling of naive PAR1 are not known. Using a siRNA library screen of 140 membrane trafficking proteins, we identified Rab11B as a key regulator of PAR1 trafficking. We confirmed that siRNA depletion of Rab11B, and not Rab11A reduced PAR1 surface expression, but did not affect expression of the thromboxane GPCRs, TPα and TPβ. Rab11B knockdown had no affect on PAR1 constitutive internalization, but blocked PAR1 recycling resulting in loss of surface expression and enhanced receptor degradation that was blocked by lysosomal protease inhibitors. In contrast to Rab11B, knockdown of Rab11A by siRNA disrupted PAR1 sorting from endosomes to lysosomes leading to accumulation, without affecting surface expression, suggesting that Rab11A and Rab11B distinctly regulate PAR1 trafficking. The mechanisms by which Rab11A and Rab11B distinctly regulate intracellular trafficking of PAR1 are not known and currently being investigated. Given that elevated PAR1 expression contributes to malignancy of certain cancers, understanding the mechanisms that control PAR1 surface expression could aid in the development of therapeutic approaches. Grant Funding Source : Supported by NIH R01 GM090689, Western States Affiliate AHA Postdoctoral Fellowship and the NIGMS In