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Modified receptor internalization upon coexpression of 5-HT1B receptor and 5-HT2B receptors

Agnes Janoshazi1, Maud Deraet, Jacques Callebert

  • 1Centre National de la Recherche Scientifique UMR7104, Illkirch, France.

Molecular Pharmacology
|February 28, 2007
PubMed

Insights

Co-expression of serotonin 5-HT(1B) and 5-HT(2B) receptors alters their internalization pathways and kinetics. This cross-talk influences receptor signaling and trafficking mechanisms, revealing new insights into serotonin receptor regulation.

Area of Science:

  • Pharmacology
  • Cell Biology
  • Neuroscience

Background:

  • Serotonin 5-HT(1B) and 5-HT(2B) receptors are frequently coexpressed.
  • Cross-talk between these receptors is known, but mechanistic details remain unclear.
  • Receptor trafficking is a key mechanism for regulating receptor signaling.

Purpose of the Study:

  • To investigate the hypothesis that 5-HT(1B) and 5-HT(2B) receptors modulate each other's signaling by affecting trafficking.
  • To examine the agonist-stimulated internalization kinetics of these receptors when expressed alone and together.

Main Methods:

  • Utilized fluorescent protein-tagged 5-HT(1B) and 5-HT(2B) receptors in LMTK(-) murine fibroblasts.
  • Employed time-lapse confocal microscopy and whole-cell radioligand binding assays.
  • Conducted antibody knockdown experiments to assess internalization pathways (clathrin and Caveolin1 dependence).

Main Results:

  • Coexpression significantly accelerated serotonin-induced 5-HT(2B) receptor internalization (5-fold) and made it 5-HT(1B) agonist-dependent.
  • 5-HT(1B) receptor internalization became Caveolin1-independent and protein kinase Cepsilon-dependent upon coexpression.
  • Distinct internalization pathways were observed for individual receptors (5-HT(1B): clathrin-independent, Caveolin1-dependent; 5-HT(2B): Caveolin1-independent, clathrin-dependent).

Conclusions:

  • Coexpression of 5-HT(1B) and 5-HT(2B) receptors significantly alters their individual internalization kinetics and pathways.
  • These findings highlight a novel mechanism of serotonin receptor cross-talk mediated by modulation of receptor trafficking.
  • The study provides crucial mechanistic insights into the regulation of serotonin receptor function.

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