MERTK signaling in the retinal pigment epithelium regulates the tyrosine phosphorylation of GDP dissociation inhibitor alpha from the GDI/CHM family of RAB GTPase effectors

Autor: Debra A. Thompson, Kecia L. Feathers, Jason Miller, Anna M. Ganios, Shameka J. Shelby, Lin Jia
Rok vydání: 2015
Předmět:
Blotting
Western
Cell Culture Techniques
Retinal Pigment Epithelium
Biology
Transfection
Peptide Mapping
Rats
Mutant Strains
Article
Cellular and Molecular Neuroscience
chemistry.chemical_compound
Mice
Phagocytosis
Proto-Oncogene Proteins
Retinal Dystrophies
medicine
Animals
Phosphorylation
Fluorescent Antibody Technique
Indirect
Adaptor Proteins
Signal Transducing
Guanine Nucleotide Dissociation Inhibitors
Mice
Inbred BALB C
Retinal pigment epithelium
c-Mer Tyrosine Kinase
GAS6
Receptor Protein-Tyrosine Kinases
Tyrosine phosphorylation
MERTK
Apical membrane
Molecular biology
Sensory Systems
eye diseases
Rats
Mice
Inbred C57BL
Ophthalmology
medicine.anatomical_structure
chemistry
rab GTP-Binding Proteins
Spectrometry
Mass
Matrix-Assisted Laser Desorption-Ionization
Tyrosine
Rab
sense organs
Proto-oncogene tyrosine-protein kinase Src
Signal Transduction
Zdroj: Experimental eye research. 140
ISSN: 1096-0007
Popis: Photoreceptor outer segments (OS) in the vertebrate retina undergo a process of continual renewal involving shedding of disc membranes that are cleared by phagocytic uptake into the retinal pigment epithelium (RPE). In dystrophic Royal College of Surgeons (RCS) rats, OS phagocytosis is blocked by a mutation in the gene encoding the receptor tyrosine kinase MERTK. To identify proteins tyrosine-phosphorylated downstream of MERTK in the RPE, MALDI-mass spectrometry with peptide-mass fingerprinting was used in comparative studies of RCS congenic and dystrophic rats. At times corresponding to peak phagocytic activity, the RAB GTPase effector GDP dissociation inhibitor alpha (GDI1) was found to undergo tyrosine phosphorylation only in congenic rats. In cryosections of native RPE/choroid, GDI1 colocalized with MERTK and the intracellular tyrosine-kinase SRC. In cultured RPE-J cells, and in transfected heterologous cells, MERTK stimulated SRC-mediated tyrosine phosphorylation of GDI1. In OS-fed RPE-J cells, GDI1 colocalized with MERTK and SRC on apparent phagosomes located near the apical membrane. In addition, both GDI1 and RAB5, a regulator of vesicular transport, colocalized with ingested OS, but exhibited labeling patterns that were coincident in some areas and mutually exclusive in others. Taken together, these findings identify a novel role of MERTK signaling in membrane trafficking in the RPE that is likely to subserve mechanisms of phagosome formation.
Databáze: OpenAIRE
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