Failure of the Expression of Phospholipid Hydroperoxide Glutathione Peroxidase in the Spermatozoa of Human Infertile Males1

Abstract

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) was intensely expressed in mitochondria in the midpiece of human spermatozoa by immunostaining with anti-PHGPx monoclonal antibodies. The PHGPx not only reduced phospholipid hydroperoxide but also scavenged hydrogen peroxide in human spermatozoa. We found a dramatic decrease in the level of expression of PHGPx in the spermatozoa of some infertile males by immunoblotting with anti-PHGPx monoclonal antibodies. These individuals accounted for about 10% of the group of 73 infertile males that we examined. All seven patients with PHGPx-defective spermatozoa were classified as suffering from oligoasthenozoospermia, a defect in which both the number and the motility of spermatozoa are significantly below normal. Males with PHGPx-defective spermatozoa accounted for 26% of the 27 infertile males with oligoasthenozoospermia. No defects in expression of PHGPx in spermatozoa were observed in 31 fertile volunteers. After a 3-h incubation, the relative number of motile spermatozoa with low-level expression of PHGPx was significantly lower than that of spermatozoa with normal expression of PHGPx. The PHGPx-defective spermatozoa failed to incorporate rhodamine 123, revealing a loss of mitochondrial membrane potential. Ultrastructual analysis of mitochondria by electron microscopy demonstrated that the morphology of mitochondria in PHGPx-defective spermatozoa was abnormal. The results suggest that failure of the expression of mitochondrial PHGPx in spermatozoa might be one of the causes of oligoasthenozoospermia in infertile men.

Essential Role of the Apolipoprotein E Receptor-2 in Sperm Development

“…This capsule is a keratin-like matrix that surrounds the mitochondria wrapped in a helical arrangement around the flagellum in the sperm mid-piece. The capsule stabilizes the mitochondrial helix, and impaired PHGPx expression results in mid-piece irregularities and in mitochondria irregularly wrapped around the flagellum (26). As demonstrated by two-dimensional SDS-PAGE (Fig.…”

“…When expression of the protein was assessed in spermatozoa from infertile men, more than 10% of the individuals suffered from a dramatic decrease of PHGPx expression. As a consequence, their sperm were immotile and exhibited irregularly sized mitochondria, a phenotype that closely resembles features of sperm in apoER2-deficient mice (26). Loss of the sperm tail, as frequently observed in sperm from selenium-deficient mice, has also been attributed to inadequate levels of PHGPx in the mitochondrial membrane (36).…”

“…The crucial role of PHGPx in fertility has been appreciated in numerous studies (26,35). Thus, PHGPx levels in human sperm are correlated positively with morphological integrity and forward motility (35).…”

“…Lack of peroxidase activity in the sperm may result in the accumulation of reactive oxygen species and in oxidative damage to the mitochondria (26,(37)(38)(39). Alternatively, absence of the protein may affect formation of the sperm mitochondrial capsule that is essential for forming the mitochondrial helix in the sperm mid-piece.…”

Distinct Promoters Determine Alternative Transcription of gpx-4 into Phospholipid-Hydroperoxide Glutathione Peroxidase Variants

“…See "Experimental Procedures" for other details. (20) and clinical sperm samples of infertile patients (21,37), are best explained by the role of PHGPx as a structural protein of the mitochondrial capsule in sperm. Although only cPHGPx were detected in the capsule material (16), both mPHGPx and cPHGPx may be considered to provide the raw material for the capsule formation, because these two forms can no longer be distinguished after processing.…”