High-resolution fractionation of signaling endosomes containing different receptors.
Receptor endocytosis is regulated by ligand binding, and receptors may signal after endocytosis in signaling endosomes. We hypothesized that signaling endosomes containing different types of receptors may be distinct from one another and have different physical characteristics. To test this hypothesis, we developed a high-resolution organelle fractionation method based on mass and density, optimized to resolve endosomes from other organelles. Three different types of receptors undergoing ligand-induced endocytosis were localized predominately in endosomes that were resolved from one another using this method. Endosomes containing activated receptor tyrosine kinases (RTKs), TrkA and EGFR, were similar to one another. Endosomes containing p75(NTR) (in the tumor necrosis receptor superfamily) and PAC1 (a G-protein-coupled receptor) were distinct from each other and from RTK endosomes. Receptor-specific endosomes may direct the intracellular location and duration of signal transduction pathways to dictate response to signals and determine cell fate.
Division of Biological Sciences, University of Montana, Missoula, Montana, USA.
Gretchen
G
McCaffrey
Jonathan
J
Welker
Jessica
J
Scott
Louise van
Lv
der Salm
Mark L
ML
Grimes
D000818:Animals; D002458:Cell Fractionation / Q000379:methods*; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D066246:ErbB Receptors / Q000378:metabolism; D006801:Humans; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D016716:PC12 Cells; D051381:Rats; D020800:Receptor, Nerve Growth Factor / Q000378:metabolism; D020917:Receptor, trkA / Q000378:metabolism; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
D020800:Receptor, Nerve Growth Factor; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D066246:ErbB Receptors; D020917:Receptor, trkA