Pregnancy-specific {beta}-1-glycoprotein 1 and human leukocyte antigen-E mRNA in human sperm: differential expression in fertile and infertile men and evidence of a possible functional role during early development.
BACKGROUND
Mature spermatozoa contain thousands of mRNA transcripts. It has been recently shown that human sperm can deliver RNA into the oocyte, suggesting that mRNAs might have a role before or after fertilization. Human embryos express PSG1 (pregnancy-specific beta-1-glycoprotein 1) and HLA-E (human leukocyte antigen-E), molecules playing a role in implantation and early development. We compared PSG1 and HLA-E sperm mRNA levels in fertile and infertile men and we tested the hypothesis that these transcripts are selectively retained in the newly formed zygote.


METHODS
Real-time RT-PCR was used to analyze sperm mRNA levels (n = 11 fertile, n = 31 infertile patients) of PSG1, HLA-E and PRM2 (protamine 2). The presence of PSG1 and HLA-E proteins was evaluated by western blot in sperm protein extracts (n = 3). Using ICSI of human sperm into hamster oocytes we evaluated the permanence of these mRNAs at different time points (n = 10 for each time) after fertilization.


RESULTS
PSG1, HLA-E and PRM2 transcripts were demonstrated in ejaculated sperm. The fertile group showed significantly higher levels of PSG1 and HLA-E mRNA (both P < 0.05) than the infertile group, whereas PRM2 levels were not significantly different. However, PSG1 and HLA-E proteins were not found in ejaculated sperm. Following ICSI, PRM2 was undetectable after fertilization; conversely, PSG1 and HLA-E transcripts remained detectable for at least 24 h of zygotic development.


CONCLUSIONS
We provide new evidence that indicates that human sperm deliver transcripts that may have a role in early embryo development and decreased levels of these transcripts may be associated with infertility.
Avendaño
Conrado
C
Department of Obstetrics and Gynecology, The Jones Institute for Reproductive Medicine, Eastern Virginia Medical School, 601 Colley Avenue, Norfolk, Virginia 23507, USA.
Franchi
Anahí
A
Jones
Estella
E
Oehninger
Sergio
S
D000818:Animals; D015153:Blotting, Western; D006224:Cricetinae; D047108:Embryonic Development / Q000235:genetics*; D005306:Fertilization; D006680:HLA Antigens / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007248:Infertility, Male / Q000378:metabolism*; D008297:Male; D009865:Oocytes / Q000378:metabolism; D011268:Pregnancy-Specific beta 1-Glycoproteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011479:Protamines / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D012661:Semen / Q000166:cytology / Q000378:metabolism; D013075:Sperm Capacitation; D013094:Spermatozoa / Q000378:metabolism*; D000097625:HLA-E Antigens
D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; D011268:Pregnancy-Specific beta 1-Glycoproteins; D011479:Protamines; D012333:RNA, Messenger; D000097625:HLA-E Antigens; C068621:protamine 2