ISSN:
1573-4919
Keywords:
acylphosphatase
;
free calcium
;
cell cycle
;
SH-SY5Y cells
;
neuroblastoma
;
calcium ATPase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Abstract Ca2+ transport by sarco/endoplasmic reticulum, tightly coupled with the enzymatic activity of Ca2+-dependent ATPase, controls the cell cycle through the regulation of genes operating in the critical G1 to S checkpoint. Experimental studies demonstrated that acylphosphatase actively hydrolyses the phosphorylated intermediate of sarco/endoplasmic reticulum calcium ATPase (SERCA) and therefore enhances the activity of Ca2+ pump. In this study we found that SH-SY5Y neuroblastoma cell division was blocked by entry into a quiescent G0-like state by thapsigargin, a high specific SERCA inhibitor, highlighting the regulatory role of SERCA in cell cycle progression. Addition of physiological amounts of acylphosphatase to SY5Y membranes resulted in a significant increase in the rate of ATP hydrolysis of SERCA. In synchronized cells a concomitant variation of the level of acylphosphatase isoenzymes opposite to that of intracellular free calcium during the G1 and S phases occurs. Particularly, during G1 phase progression the isoenzymes content declined steadily and hit the lowest level after 6 h from G0 to G1 transition with a concomitant significant increase of calcium levels. No changes in free calcium and acylphosphatase levels upon thapsigargin inhibition were observed. Moreover, a specific binding between acylphosphatase and SERCA was demonstrated. No significant change in SERCA-2 expression was found. These findings suggest that the hydrolytic activity of acylphosphatase increase the turnover of the phosphoenzyme intermediate with the consequences of an enhanced efficiency of calcium transport across endoplasmic reticulum and a subsequent decrease in cytoplasmic calcium levels. A hypothesis about the modulation of SERCA activity by acylphosphatase during cell cycle in SY5Y cells in discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1007162717292
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