Influence of inositol 1,4,5-trisphosphate and guanine nucleotides on intracellular calcium release within the N1E-115 neuronal cell line.

The inositol 1,4,5-trisphosphate receptor (InsP3R), an intracellular calcium channel, has three isoforms with >65% sequence homology, yet the isoforms differ in their function and regulation by post-translational modifications. We showed previously that InsP3R-1 is functionally modified by O-linked β-N-acetylglucosamine glycosylation (O-GlcNAcylation) (Rengifo, J., Gibson, C. J., Winkler, E., Collin, T., and Ehrlich, B. E. (2007) J. Neurosci. 27, 13813–13821). We now report the effect of O-GlcNAcylation on InsP3R-2 and InsP3R-3. Analysis of AR4-2J cells, a rat pancreatoma cell line expressing predominantly InsP3R-2, showed no detectable O-GlcNAcylation of InsP3R-2 and no significant functional changes despite the presence of the enzymes for addition (O-β-N-acetylglucosaminyltransferase) and removal (O-β-N-acetylglucosaminidase) of the monosaccharide. In contrast, InsP3R-3 in Mz-ChA-1 cells, a human cholangiocarcinoma cell line expressing predominantly InsP3R-3, was functionally modified by O-GlcNAcylation. Interestingly, the functional impact of O-GlcNAcylation on the InsP3R-3 channel was opposite the effect measured with InsP3R-1. Addition of O-GlcNAc by O-β-N-acetylglucosaminyltransferase increased InsP3R-3 single channel open probability. Incubation of Mz-ChA-1 cells in hyperglycemic medium caused an increase in the InsP3-dependent calcium release from the endoplasmic reticulum. The dynamic and inducible nature of O-GlcNAcylation and the InsP3R isoform specificity suggest that this form of modification of InsP3R and subsequent changes in intracellular calcium transients are important in physiological and pathophysiological processes.

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T cells deficient in inositol 1,4,5-trisphosphate receptor are resistant to apoptosis.

Molecular and Cellular Biology ◽

10.1128/mcb.17.6.3005 ◽

1997 ◽

Vol 17 (6) ◽

pp. 3005-3012 ◽

Cited By ~ 196

Author(s):

T Jayaraman ◽

A R Marks

Keyword(s):

T Cells ◽

Intracellular Calcium ◽

Calcium Release ◽

Calcium Influx ◽

Cell Receptor ◽

Calcium Release Channel ◽

Release Channel ◽

Inositol 1,4,5 Trisphosphate ◽

Intracellular Calcium Release ◽

Trisphosphate Receptor

The type 1 inositol 1,4,5-trisphosphate receptor (IP3R1) calcium release channel is present on the endoplasmic reticulum of most cell types. T lymphocytes which have been made deficient in IP3R1 lack detectable IP3-induced intracellular calcium release and exhibit defective signaling via the T-cell receptor (TCR) (T. Jayaraman, E. Ondriasova, K. Ondrias, D. Harnick, and A. R. Marks, Proc. Natl. Acad. Sci. USA 92:6007-6011, 1995). We now show that IP3R1-deficient T cells are resistant to apoptosis induced by dexamethasone, TCR stimulation, ionizing radiation, and Fas. Resistance to TCR-mediated apoptosis in IP3R1-deficient cells is reversed by pharmacologically raising cytoplasmic calcium levels. TCR-mediated apoptosis can be induced in calcium-free media, indicating that extracellular calcium influx is not required. These findings suggest that intracellular calcium release via the IP3R1 is a critical mediator of apoptosis.

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