Premium
Rab35 and Rab39 GTP‐ases as modulators of cannabinoid type 1 receptor signaling.
Author(s) -
Ghita Ioana,
Winsauer Peter J.,
Filipeanu Catalin M.
Publication year - 2018
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.2018.32.1_supplement.825.9
Subject(s) - g protein coupled receptor , microbiology and biotechnology , rab , endosome , receptor , gtp' , gtpase , g protein , cannabinoid receptor , cannabinoid , chemistry , internalization , small gtpase , agonist , intracellular , signal transduction , biology , biochemistry , enzyme
Cannabinoid type 1 receptor (CB1R) is distinct within G‐protein coupling receptors (GPCR) family, being able to trigger cellular signaling not only when present at the plasma membrane, but also within the endolysosomal system. Rab GTP‐ases are well characterized master regulators of intracellular protein trafficking, including GPCR. The classical controllers of bidirectional plasma membrane‐endosome shuttling Rab4 and Rab5 GTP‐ases were previously shown to profoundly change the subcellular distribution of CB1R, whereas Rab11 GTPase had no effect. However, the effects of recently described Rab35 and Rab39 GTPases, which are also modulating internalization/recycling process, in the regulation of GPCR trafficking are not yet characterized. In the present work, using a bioluminescent cAMP reporter, we found that overexpression of Rab35 wild‐type (Rab35wt) did not change the effects of CP55,940 at maximal concentration (10 −7 M), although slightly reduced its effects at lower concentrations (10 −9 M). In contrast, the dominant negative mutant Rab35S25N had opposite effects. However, the effects of non‐permeable peptide receptor agonist RVD‐Hpα (10 −6 M) which selectively activates plasma membrane CB1R were markedly potentiated by Rab35wt and reduced by Rab35S25N. Furthermore, overexpression of Rab35wt decreased the amount of CB1R internalized in presence of CP55,940 or RVD‐Hpα as determined by ELISA. Rab35S25N did not change the number of plasma membrane receptors in basal conditions, but reduced CB1R recycling after treatment with any of the two agonists. Overexpression of Rab39A or Rab39B GTP‐ases resulted in strong reduction of the effects of RVD‐Hpα on cAMP levels, but did not change the effects of CP55,940. These results correlated with the levels of CB1R at the plasma membrane, a decrease in CB1R internalization being observed after increasing the endogenous levels of Rab39A or Rab39B. These preliminary results indicate that multiple Rab GTP‐ases modulate CB1R signaling by interfering with the receptor shuttling between plasma membrane and endosomes. In addition, our data may have clinical significance on the use of cannabinoids in specific populations, considering that mutations affecting Rab39B functions were observed in people with intellectual disability, autism spectrum disorder, and macrocephaly. Support or Funding Information Supported by NIH DA037255 (PJW) and Bridge Grant from Howard University (CMF). This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .