Impaired sperm maturation in RNASE9 knockout mice.
Ribonuclease, RNase A family, 9 (RNASE9) is a ribonuclease A superfamily member that is expressed only in the epididymis. It is a small, secreted polypeptide, it lacks ribonuclease activity, and its function(s) is unknown. However, epididymis-specific expression suggests a role in sperm maturation. We generated Rnase9(-/-) mice to study RNASE9 function in vivo. We confirm that RNASE9 expression is restricted to the epididymis. Within the epididymis, RNASE9 is first detected in midcaput, persists through the distal caput and corpus, and wanes in the cauda. Rnase9(-/-) mice are born at the expected Mendelian ratio, have normal postnatal growth and development, and have no outwardly apparent phenotype. Spermatogenesis is normal, and Rnase9-null sperm are morphologically normal. Rnase9(-/-) males have normal fertility in unrestricted mating trials, and fertilization rates in in vitro fertilization assays are indistinguishable from wild-type mice. Visual observations coupled with analyses of sperm velocities shortly after swim out from the corpus shows that motility of Rnase9-null sperm is significantly impaired. However, no differences between wild-type and Rnase9-null sperm are detected by computer-assisted sperm analysis 10-90 min after sperm isolation from the corpus or cauda. Assessment of capacitation-dependent signaling pathways in Rnase9-null sperm showed that, while levels of tyrosine phosphorylation of sperm proteins were normal, there was decreased phosphorylation of protein kinase A substrates upon capacitation compared to wild-type mice. In conclusion, RNASE9 is dispensable for fertility, but the absence of RNASE9 during epididymal transit results in impaired sperm maturation.
Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma.
Andrew D
AD
Westmuckett
Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.
Edward B
EB
Nguyen
Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma.
Oana M
OM
Herlea-Pana
Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, Massachusetts.
Antonio
A
Alvau
Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, Massachusetts.
Ana M
AM
Salicioni
Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma kevin-moore@omrf.org.
Kevin L
KL
Moore
D000818:Animals; D004822:Epididymis / Q000502:physiology; D005260:Female; D008297:Male; D057507:Mice, 129 Strain; D018345:Mice, Knockout; D011247:Pregnancy; D011506:Proteins / Q000235:genetics*; D016601:RNA-Binding Proteins; D012260:Ribonucleases / Q000235:genetics*; D013075:Sperm Capacitation / Q000235:genetics*; D013079:Sperm Maturation / Q000235:genetics*; D013081:Sperm Motility / Q000235:genetics; D013091:Spermatogenesis / Q000235:genetics; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*
D011506:Proteins; D016601:RNA-Binding Proteins; C000594647:RNASE9 protein, mouse; C543068:RNase9 protein, human; D012260:Ribonucleases
capacitation; epididymis; male reproductive tract; sperm; sperm maturation