TY - JOUR
T1 - Switch of PMCA4 splice variants in bovine epididymis results in altered isoform expression during functional sperm maturation
AU - Brandenburger, Timo
AU - Strehler, Emanuel E.
AU - Filoteo, Adelaida G.
AU - Caride, Ariel J.
AU - Aumüller, Gerhard
AU - Post, Heidi
AU - Schwarz, Anja
AU - Wilhelm, Beate
PY - 2011/3/11
Y1 - 2011/3/11
N2 - Ca2+ and Ca2+-dependent signals are essential for sperm maturation and fertilization. In mouse sperm the plasma membrane Ca 2+-ATPase (PMCA) isoform 4 plays a crucial role in Ca2+ transport. The two major splice variants of PMCA4 are PMCA4a and PMCA4b. PMCA4a differs from PMCA4b in the mechanism of calmodulin binding and activation. PMCA4a shows a much higher basal activity and is more effective than PMCA4b in returning Ca2+ to resting levels. Knock-out mice carrying a PMCA4-null mutation are infertile because their sperm cannot achieve a hyperactivated state of motility. As sperm reach functional maturity during their transit through the epididymis, the expression of PMCA4a and 4b was assessed in bull testis and epididymis. Quantitative PCR revealed that PMCA4b is the major splice variant in testis, caput, and corpus epididymidis. In contrast, PMCA4a is the major splice variant in cauda epididymidis, whereas sperm are transcriptionally silent. Immunohistochemical staining using a new antibody against bovine PMCA4a located the PMCA4a to the apical membrane of the epithelium of cauda epididymidis, whereas testis, caput, and corpus epididymidis were negative. Western blotting of testis, epididymis, and sperm isolated from caput and cauda epididymidis showed a much higher level of PMCA4a in cauda epididymidis and sperm from cauda epididymidis compared with testis membranes and sperm from caput epididymidis. These findings suggest that PMCA4a is transferred to bovine sperm membranes in cauda epididymidis. This isoform switch may facilitate a higher calcium turnover in sperm necessary to traverse the female genital tract.
AB - Ca2+ and Ca2+-dependent signals are essential for sperm maturation and fertilization. In mouse sperm the plasma membrane Ca 2+-ATPase (PMCA) isoform 4 plays a crucial role in Ca2+ transport. The two major splice variants of PMCA4 are PMCA4a and PMCA4b. PMCA4a differs from PMCA4b in the mechanism of calmodulin binding and activation. PMCA4a shows a much higher basal activity and is more effective than PMCA4b in returning Ca2+ to resting levels. Knock-out mice carrying a PMCA4-null mutation are infertile because their sperm cannot achieve a hyperactivated state of motility. As sperm reach functional maturity during their transit through the epididymis, the expression of PMCA4a and 4b was assessed in bull testis and epididymis. Quantitative PCR revealed that PMCA4b is the major splice variant in testis, caput, and corpus epididymidis. In contrast, PMCA4a is the major splice variant in cauda epididymidis, whereas sperm are transcriptionally silent. Immunohistochemical staining using a new antibody against bovine PMCA4a located the PMCA4a to the apical membrane of the epithelium of cauda epididymidis, whereas testis, caput, and corpus epididymidis were negative. Western blotting of testis, epididymis, and sperm isolated from caput and cauda epididymidis showed a much higher level of PMCA4a in cauda epididymidis and sperm from cauda epididymidis compared with testis membranes and sperm from caput epididymidis. These findings suggest that PMCA4a is transferred to bovine sperm membranes in cauda epididymidis. This isoform switch may facilitate a higher calcium turnover in sperm necessary to traverse the female genital tract.
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U2 - 10.1074/jbc.M110.142836
DO - 10.1074/jbc.M110.142836
M3 - Article
C2 - 21187283
AN - SCOPUS:79953139092
SN - 0021-9258
VL - 286
SP - 7938
EP - 7946
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 10
ER -