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Selective decrease of membrane-associated PKC-alpha and PKC-epsilon in response to elevated intracellular O-GlcNAc
Jason A Matthews1, Mildred Acevedo-Duncan, Robert L Potter
1Department of Chemistry, University of South Florida, 4202 East Fowler Ave, SCA 400, Tampa, FL, 33620, USA.
Biochimica Et Biophysica Acta
|April 22, 2005
Summary
Increasing O-GlcNAc modification via HBP flux affects protein kinase C (PKC) isozyme translocation. This study shows how glucosamine, streptozotocin, and PUGNAc alter PKC-betaII, PKC-epsilon, and PKC-alpha membrane association in human astroglial cells.
Area of Science:
- Biochemistry
- Cell Biology
- Neuroscience
Background:
- Increased flux through the hexosamine biosynthetic pathway (HBP) influences protein kinase C (PKC) activity and localization.
- This modulation is hypothesized to be mediated by elevated beta-O-linked N-acetylglucosamine (O-GlcNAc) modification.
Purpose of the Study:
- To investigate the impact of enhanced O-GlcNAc modification on the translocation of specific PKC isozymes in a human astroglial cell line.
- To elucidate the differential effects of various compounds that increase O-GlcNAc levels on PKC isoform localization.
Main Methods:
- Human astroglial cells were treated with d-glucosamine (GlcN), streptozotocin (STZ), or PUGNAc to increase O-GlcNAc modification.
- Western blotting and subcellular fractionation techniques were employed to quantify O-GlcNAc levels and membrane-associated PKC isoforms (PKC-betaII, PKC-epsilon, PKC-alpha, PKC-iota).
Main Results:
- GlcN induced rapid, transient translocation of PKC-betaII and decreased membrane-associated PKC-epsilon.
- STZ and PUGNAc treatments also reduced membrane PKC-epsilon and PKC-alpha levels, with varying kinetics and magnitudes.
- Neither STZ nor PUGNAc affected PKC-betaII translocation, and none of the compounds altered membrane levels of PKC-iota.
Conclusions:
- Elevated O-GlcNAc modification levels significantly impact the membrane association of specific PKC isoforms, including PKC-betaII, PKC-epsilon, and PKC-alpha.
- The observed effects are isozyme-specific and compound-dependent, highlighting a novel regulatory mechanism for PKC localization.
- This research establishes a direct link between HBP flux, O-GlcNAc modification, and the spatial regulation of PKC signaling pathways in glial cells.