Protamine 2 precursors, protamine 1/protamine 2 ratio, DNA integrity and other sperm parameters in infertile patients.
BACKGROUND
The protamine 1-to-protamine 2 ratio (P1/P2) is altered in the sperm cells of some infertile patients. Also, evidence for increased protamine 2 precursors (pre-P2) in a few patients has been reported. But so far, there have been no studies measuring simultaneously these two variables in a large number of patients.


METHODS
We measured the P1/P2 ratio and the presence of pre-P2 using, for the first time, an antibody specific to the precursor pre-P2, together with other sperm parameters in 224 infertile patients. Additionally, the DNA integrity was assessed by terminal transferase dUTP nick-end labelling (TUNEL) in a subset of the samples.


RESULTS
Pre-P2 levels show a significant positive correlation with the P1/P2 ratio, with the presence of other proteins and, at low pre-P2 levels, with TUNEL-positive sperm. An inverse correlation with sperm count, normal morphology and motility was detected.


CONCLUSIONS
The levels of pre-P2 may provide clues into the pathogenic mechanisms of infertility. The increased proportion of pre-P2 in some patients with increased P1/P2 ratio suggests an involvement of pre-P2 processing. The positive correlation between TUNEL-positive sperm and pre-P2 at low pre-P2/P2 ratios also suggests a link between deficient protamine processing and decreased DNA integrity.
Torregrosa
Nuria
N
Human Genetics Research Group, IDIBAPS, University of Barcelona, Barcelona, Spain.
Domínguez-Fandos
David
D
Camejo
Maria Isabel
MI
Shirley
Cynthia R
CR
Meistrich
Marvin L
ML
Ballescà
José Luis
JL
Oliva
Rafael
R
D053938:DNA Fragmentation; D006801:Humans; D020287:In Situ Nick-End Labeling; D007248:Infertility, Male / Q000378:metabolism*; D008297:Male; D011479:Protamines / Q000276:immunology / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism*
C082073:PRM1 protein, human; D011479:Protamines; D011498:Protein Precursors; C068621:protamine 2