The regulation of sperm motility by a novel hyaluronan receptor.

OBJECTIVE

To determine if a novel receptor for hyaluronan, termed RHAMM, is responsible for the previously observed increase in sperm locomotion in response to hyaluronan and to assess whether expression of the RHAMM protein is involved in sperm motility.

DESIGN

The RHAMM protein was localized on human sperm by immunofluorescence of fixed cells, fluorescence-activated cell sorter (FACS) of cell surface phenotype, and Western transblot analysis of cell proteins. The effect of monospecific antibodies on sperm motility was examined using computer-assisted image analysis. Results of motility studies were assessed statistically with analysis of variance.

SETTING

Samples were collected from donors from the University of Manitoba donor insemination program.

SUBJECTS

Semen was collected twice from four participants and a total of 10,000 sperm per sample were evaluated.

RESULTS

A hyaluronan receptor, RHAMM, was localized by immunofluorescence along the tail, the midpiece, and the head of sperm. Positive staining obtained with FACS analysis indicated that RHAMM occurred on the surface of sperm, whereas immunoblot analysis of sperm cell lysates revealed RHAMM proteins of MWE 58 and 64 kd, consistent with the size of RHAMM localized from fibroblasts. A polyclonal antibody specific to a peptide encoded in the fibroblast RHAMM complementary DNA significantly decreased the motility of sperm. Analysis of this inhibition is consistent with an effect of the antibody on flagellar function.

CONCLUSIONS

The presence of RHAMM on sperm surfaces and the ability of monospecific antibodies to inhibit sperm motility suggest an important role for this novel glycoprotein in sperm motility.