Changes in cytosolic Ca2+ levels regulate Bcl-xS and Bcl-xL expression in spermatogenic cells during apoptotic death.
Bcl-x exists in two isoforms, the anti-apoptotic form Bcl-xL and the proapoptotic form Bcl-xS. The critical balance between the two forms appears to be important for cell survival; however, it is still not clear exactly how the vital balance is maintained. Using an in vitro spermatogenic cell apoptosis model, this study provides a new insight into the possible role of Ca2+ in regulating the Bcl-xS and Bcl-xL expression. 2,5-Hexanedione, a metabolite of the common industrial solvent n-hexane, caused a significant increase in reactive oxygen species followed by an enhancement of intracellular Ca2+ through the T-type Ca2+ channels. Consequent to the above changes, expression of Bcl-xS increased with a concomitant drop in Bcl-xL expression, thus altering the ratio of the two proteins. Impediment of Ca2+ influx by using a T-type Ca2+ channel blocker pimozide resulted in a decrease in Bcl-xS and an increase in Bcl-xL expression. This caused prevention of mitochondrial potential loss, reduction of caspase-3 activity, inhibition of DNA fragmentation, and increase in cell survival. Alternatively, Ca2+ ionophores caused an increase of Bcl-xS encoding isoform over the Bcl-xL-encoding isoform. Therefore, this study proposes a role for Ca2+ in regulation of Bcl-xS and Bcl-xL expression and ultimately cell fate.
Mishra
Durga Prasad
DP
National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067 India.
Pal
Rajarshi
R
Shaha
Chandrima
C
D000255:Adenosine Triphosphate / Q000737:chemistry; D017398:Alternative Splicing; D000818:Animals; D017304:Annexin A5 / Q000737:chemistry; D017209:Apoptosis; D015153:Blotting, Western; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D015220:Calcium Channels / Q000737:chemistry; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival; D003600:Cytosol / Q000378:metabolism*; D053938:DNA Fragmentation; D004591:Electrophoresis, Polyacrylamide Gel; D005434:Flow Cytometry; D006586:Hexanes / Q000737:chemistry; D006588:Hexanones / Q000737:chemistry / Q000494:pharmacology; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007476:Ionophores / Q000737:chemistry; D008297:Male; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism; D010718:Phosphatidylserines / Q000737:chemistry; D010868:Pimozide / Q000494:pharmacology; D020033:Protein Isoforms; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species; D012997:Solvents / Q000737:chemistry; D013091:Spermatogenesis; D013094:Spermatozoa / Q000378:metabolism*; D013997:Time Factors; D051020:bcl-X Protein / Q000737:chemistry* / Q000378:metabolism
D017304:Annexin A5; D015220:Calcium Channels; D006586:Hexanes; D006588:Hexanones; D007476:Ionophores; D010718:Phosphatidylserines; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D012997:Solvents; D051020:bcl-X Protein; D010868:Pimozide; D000255:Adenosine Triphosphate; C011269:2,5-hexanedione; C505410:Casp3 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; D002118:Calcium