Mouse testicular hyaluronidase-like proteins SPAM1 and Hyal5 but not HyalP1 degrade hyaluronan

Stephan Reitinger , Gerhard T Laschober , Christine Fehrer , Brigitte Greiderer , Günter Lepperdinger , Günter Lepperdinger (1)

1 Inst. Biomed Aging Res

Besides SPAM1 (formerly named PH-20), further hyaluronidase-like proteins, HYAL5 and HYALP1 are also expressed in murine testicular tissue. As they share a high degree of sequence similarity with known hyaluronidases, all three polypeptides could potentially exhibit hyaluronidase activity, a function that is beneficial for sperm in order to penetrate the hyaluronan-rich cumulus, which surrounds the oocyte. Recently, it was reported that SPAM1-deficient mice are fertile and sperm derived from mutant mice still exhibits hyaluronidase activity (Baba et al., (2002) J. Biol. Chem. 277, 30310-30314). We have now recombinantly expressed mouse SPAM1, HYAL5 and HYALP1 in Xenopus laevis oocytes and determined their respective expression pattern in testis. Transcripts of all three genes are expressed in seminiferous tubules in regions, where maturing spermatogenic cells reside. SPAM1 and HYAL5 but not HYALP1 proteins exhibit hyaluronidase activity at neutral pH. The two active hyaluronidases are both bound to the cell surface via a glycosylphosphatidylinositol anchor. Furthermore, structural characteristics are discussed that are necessary for hyaluronidases in order to exhibit hyaluronan cleavage.

Mots clés: Life Sciences

Stephan Reitinger, Gerhard T Laschober, Christine Fehrer, Brigitte Greiderer, Günter Lepperdinger, et al.. Mouse testicular hyaluronidase-like proteins SPAM1 and Hyal5 but not HyalP1 degrade hyaluronan. Biochemical Journal, 2006, 401 (1), pp.79-85. ⟨10.1042/BJ20060598⟩. ⟨hal-00478581⟩