Cell-type specific effects of endocytosis inhibitors on 5-hydroxytryptamine2A receptor desensitization and resensitization reveal an arrestin-, GRK2-, and GRK5-independent mode of regulation in human embryonic kidney 293 cells

John Gray, Douglas J. Sheffler, Anushree Bhatnagar, Jason A. Woods, Sandra J. Hufeisen, Jeffrey L. Benovic, Bryan L. Roth

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The effect of endocytosis inhibitors on 5-hydroxytryptamine2A (5-HT2A) receptor desensitization and resensitization was examined in transiently transfected human embryonic kidney (HEK) 293 cells and in C6 glioma cells that endogenously express 5-HT2A receptors. In HEK-293 cells, 5-HT2A receptor desensitization was unaffected by cotransfection with a dominant-negative mutant of dynamin (DynK44A), a truncation mutant of arrestin-2 [Arr2(319-418)], or by two well-characterized chemical inhibitors of endocytosis: concanavalin A (conA) and phenylarsine oxide (PAO). In contrast, β2-adrenergic receptor desensitization was significantly potentiated by each of these treatments in HEK-293 cells. In C6 glioma cells, however, DynK44A, Arr2(319- 418), conA, and PAO each resulted in the potentiation of 5-HT2A and β-adrenergic receptor desensitization. The cell-type-specific effect of Arr2(319-418) on 5-HT2A receptor desensitization was not related to the level of GRK2 or GRK5 expression. Interestingly, although β2-adrenergic receptor resensitization was potently blocked by cotransfection with DynK44A, 5-HT2A receptor resensitization was enhanced, suggesting the existence of a novel cell-surface mechanism for 5-HT2A receptor resensitization in HEK-293 cells. In addition, Arr2(319-418) had no effect on 5-HT2A receptor resensitization in HEK-293 cells, although it attenuated the resensitization of the β2-adrenergic receptor. However, in C6 glioma cells, both DynK44A and Arr2(319-418) significantly reduced 5-HT2A receptor resensitization. Taken together, these results provide the first convincing evidence of cell-type-specific roles for endocytosis inhibitors in regulating GPCR activity. Additionally, these results imply that novel GRK and arrestin-independent mechanisms of 5-HT2A receptor desensitization and resensitization exist in HEK-293 cells.

Original languageEnglish (US)
Pages (from-to)1020-1030
Number of pages11
JournalMolecular Pharmacology
Issue number5
StatePublished - 2001
Externally publishedYes


ASJC Scopus subject areas

  • Pharmacology

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