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Modulation of a 190-kD microtubule-associated protein in pigment epithelium by VIP
1Department of Ophthalmology, University of Maryland, Baltimore 21201.
Abstract:
Vasoactive intestinal peptide stimulates phosphorylation of six high molecular weight cytosolic proteins in the cultured retinal pigment epithelium (RPE). Of these, the 190-kD phosphoprotein is associated with the microtubules assembled by taxol/GTP and is immunologically related to the brain microtubule-associated protein 2 (mol.wt. = 280 kD). VIP is also shown here to stimulate secretion in the cultured RPE. VIP-stimulated phosphorylation of a 190-kD microtubule-associated protein is also demonstrated here in the retinal glia.
Insights
Vasoactive intestinal peptide (VIP) triggers the phosphorylation of key proteins, including a 190-kD microtubule-associated protein, in retinal pigment epithelium and glia. This peptide also enhances secretion in cultured RPE cells.
Area of Science:
- Neuroscience
- Cell Biology
- Ophthalmology
Background:
- Vasoactive intestinal peptide (VIP) is a neuropeptide with diverse physiological roles.
- The retinal pigment epithelium (RPE) and retinal glia are crucial for retinal function and homeostasis.
- Microtubule-associated proteins play vital roles in cellular structure and function.
Purpose of the Study:
- To investigate the effects of VIP on protein phosphorylation in cultured RPE cells.
- To identify specific phosphoproteins modulated by VIP in the RPE.
- To examine the association of VIP-stimulated phosphoproteins with microtubules and their relation to known microtubule-associated proteins.
Main Methods:
- Cultured RPE cells and retinal glia were treated with VIP.
- Phosphorylation of cytosolic proteins was analyzed using biochemical assays.
- Immunological methods were employed to characterize phosphoproteins and their relation to microtubule-associated protein 2 (MAP2).
Main Results:
- VIP stimulated the phosphorylation of six high molecular weight cytosolic proteins in cultured RPE.
- A 190-kD phosphoprotein was identified, associated with taxol/GTP-assembled microtubules and immunologically related to brain MAP2.
- VIP also stimulated secretion in cultured RPE and induced phosphorylation of a 190-kD microtubule-associated protein in retinal glia.
Conclusions:
- VIP modulates protein phosphorylation in RPE and retinal glia, impacting microtubule-associated proteins.
- The 190-kD phosphoprotein is a key target of VIP signaling in the retina.
- VIP's effects on phosphorylation and secretion suggest a role in regulating retinal function.