Mouse testicular hyaluronidase-like proteins SPAM1 and HYAL5 but not HYALP1 degrade hyaluronan.
Besides SPAM1 (sperm adhesion molecule 1; formerly named PH-20), further hyaluronidase-like proteins, HYAL5 (hyaluronoglucosaminidase 5) and HYALP1 (hyaluronoglucosaminidase pseudogene 1) 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 spermatozoa in order to penetrate the hyaluronan-rich cumulus, which surrounds the oocyte. Recently, it was reported that SPAM1-deficient mice are fertile and spermatozoa derived from mutant mice still exhibit hyaluronidase activity [Baba, Kashiwabara, Honda, Yamagata, Wu, Ikawa, Okabe and Baba (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.
Reitinger
Stephan
S
The Extracellular Matrix Research Group, Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria.
Laschober
Gerhard Thomas
GT
Fehrer
Christine
C
Greiderer
Brigitte
B
Lepperdinger
Günter
G
D000818:Animals; D001483:Base Sequence; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D005260:Female; D005786:Gene Expression Regulation; D006820:Hyaluronic Acid / Q000378:metabolism*; D006821:Hyaluronoglucosaminidase / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051379:Mice; D009865:Oocytes; D016133:Polymerase Chain Reaction; D011544:Pseudogenes / Q000235:genetics*; D013737:Testis / Q000201:enzymology; D014982:Xenopus laevis
D015815:Cell Adhesion Molecules; D017931:DNA Primers; D006820:Hyaluronic Acid; C510449:Hyal5 protein, mouse; D006821:Hyaluronoglucosaminidase; C066852:hyaluronidase PH-20