Identification and evaluation of a novel sperm protamine abnormality in a population of infertile males.
BACKGROUND
A significant relationship exists between an abnormally high sperm protamine-1 (P1)/protamine-2 (P2) ratio and male infertility. In this study we investigate whether a decreased P1/P2 ratio is also linked to male infertility and we attempt to describe, at the protein expression level, the underlying cause of sperm P1/P2 deregulation.


METHODS
P1 and P2 protein concentrations were quantified in sperm from 272 infertility patients and 87 fertile donors. P1/P2 ratios and protamine quantity were correlated with fertility status using semen analysis, sperm penetration capacity, and IVF data.


RESULTS
We identified four distinct groups in the study: normal P1/P2 fertile donors, normal P1/P2 patients, low P1/P2 patients, and high P1/P2 patients. P1 and P2 were both under-expressed in patients with a normal P1/P2 ratio, but not in fertile donors. In patients with a low P1/P2 ratio, P1 was under-expressed while P2 was over-expressed; in patients with a high P1/P2 ratio, P1 was normally expressed and P2 was under-expressed. Patients with abnormal P1/P2 ratios displayed significantly reduced semen quality and sperm penetration ability.


CONCLUSIONS
We have identified a novel population of infertile males with a reduced P1/P2 ratio. Aberrant P1/P2 ratios arise from an abnormal concentration of P1 and/or P2, either of which is associated with male infertility.
Aoki
Vincent W
VW
Andrology and IVF Laboratories, University of Utah School of Medicine, Salt Lake City, 84108, USA.
Liu
Lihua
L
Carrell
Douglas T
DT
D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D006801:Humans; D007248:Infertility, Male / Q000378:metabolism* / Q000473:pathology; D008297:Male; D011247:Pregnancy; D011479:Protamines / Q000378:metabolism*; D012016:Reference Values; D012661:Semen; D013081:Sperm Motility; D013094:Spermatozoa / Q000378:metabolism* / Q000473:pathology
C082073:PRM1 protein, human; D011479:Protamines; C068621:protamine 2