TY - JOUR

T1 - Expression of the O-Glycosylation Enzyme GalNAc-T3 in the Equatorial Segment Correlates with the Quality of Spermatozoa

AU - Nygaard, Marie B.

AU - Herlihy, Amy S.

AU - Jeanneau, Charlotte

AU - Nielsen, John E.

AU - Bennett, Eric Paul

AU - Jørgensen, Niels

AU - Clausen, Henrik

AU - Mandel, Ulla

AU - Rajpert-De Meyts, Ewa

AU - Almstrup, Kristian

PY - 2018

Y1 - 2018

N2 - We question whether the expression of GalNAc-T3, the only known O-GalNAc-transferase present in germ cells, is correlated with qualitative and functional parameters of spermatozoa. We investigated the expression of GalNAc-T3 in ejaculated spermatozoa with immunocytochemistry in swim-up purified and acrosome-reacted spermatozoa from quality-control semen donors and in semen samples from 206 randomly selected men representing a broad spectrum of semen quality. Using donor ejaculates and immunofluorescence detection we found that expression of GalNAc-T3 and the presence of the immature O-glycans Tn and T localized to the equatorial segment of spermatozoa. The proportion of GalNAc-T3-positive spermatozoa in the ejaculate increased after swim-up and appeared unaffected by induction of acrosomal exocytosis. The fraction of spermatozoa with equatorial expression of GalNAc-T3 correlated with classical semen parameters (concentration p = 9 × 10−6, morphology p = 7 × 10−8, and motility p = 1.8 × 10−5) and was significantly lower in men with oligoteratoasthenozoospermia (p = 0.0048). In conclusion, GalNAc-T3 was highly expressed by motile spermatozoa and the expression correlated positively with the classical semen parameters. Therefore, GalNAc-T3 expression seems related to the quality of the spermatozoa, and we propose that reduced expression of GalNAc-T3 may lead to impaired O-glycosylation of proteins and thereby abnormal maturation and reduced functionality of the spermatozoa.

AB - We question whether the expression of GalNAc-T3, the only known O-GalNAc-transferase present in germ cells, is correlated with qualitative and functional parameters of spermatozoa. We investigated the expression of GalNAc-T3 in ejaculated spermatozoa with immunocytochemistry in swim-up purified and acrosome-reacted spermatozoa from quality-control semen donors and in semen samples from 206 randomly selected men representing a broad spectrum of semen quality. Using donor ejaculates and immunofluorescence detection we found that expression of GalNAc-T3 and the presence of the immature O-glycans Tn and T localized to the equatorial segment of spermatozoa. The proportion of GalNAc-T3-positive spermatozoa in the ejaculate increased after swim-up and appeared unaffected by induction of acrosomal exocytosis. The fraction of spermatozoa with equatorial expression of GalNAc-T3 correlated with classical semen parameters (concentration p = 9 × 10−6, morphology p = 7 × 10−8, and motility p = 1.8 × 10−5) and was significantly lower in men with oligoteratoasthenozoospermia (p = 0.0048). In conclusion, GalNAc-T3 was highly expressed by motile spermatozoa and the expression correlated positively with the classical semen parameters. Therefore, GalNAc-T3 expression seems related to the quality of the spermatozoa, and we propose that reduced expression of GalNAc-T3 may lead to impaired O-glycosylation of proteins and thereby abnormal maturation and reduced functionality of the spermatozoa.

KW - GalNAc-T3

KW - GALNT3

KW - Male fertility

KW - Semen quality

KW - Mucin-type O-linked glycosylation

KW - Spermatozoa

U2 - 10.3390/ijms19102949

DO - 10.3390/ijms19102949

M3 - Journal article

C2 - 30262754

VL - 19

SP - 1

EP - 13

JO - International Journal of Molecular Sciences (Online)

JF - International Journal of Molecular Sciences (Online)

SN - 1661-6596

IS - 10

M1 - 2949

ER -