Mouse testicular hyaluronidase-like proteins SPAM1 and HYAL5 but not HYALP1 degrade hyaluronan

Abstract

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.

Sperm penetration through cumulus mass and zona pellucida

“…It should be noted that a research group has reported that Hyalp1, in addition to Ph-20 and Hyal5, is enzymatically functional in sperm penetration of the cumulus in the mouse (Zhang et al, 2005;Miller et al, 2007), although other workers (Reitinger et al, 2007) provide evidence that recombinant Hyalp1 is incapable of hydrolyzing hyaluronan.…”

Regulation and roles of the hyaluronan system in mammalian reproduction

“…HYAL3 and HYAL4 lack hyaluronidase activity and seem to play a non-significant role in constitutive HA degradation (Harada & Takahashi 2007, Kaneiwa et al 2012. Similarly, HYALP1 that is present in mouse testis does not degrade HA (Reitinger et al 2007). The role of SPAM1 is discribed later in fertilisation paragraph.…”

Active Hyaluronidase 2 Expression in the Granulation Tissue Formed in the Healing Process of Equine Superficial Digital Flexor Tendonitis

“…Recently, it was reported that platelet-derived HYAL2 cleaves HA into fragments that are specific for inflammatory and angiogenic signaling [5]. Additionally, HYALP1 is recognized as a pseudogene in the human, but the degrading activity for HA was found in the mouse [21]. Presence of all HAase except for HYALP1 in the horse has been predicted from corresponding genomic sequences, but there is no report concerning the analysis of these activities.…”

“…Among these, HYAL1 and HYAL2 usually found in serum are considered as major somatic HAase [4], while SPAM1 is well known as testicular HAase [21]. HYAL1 has acidic pH optima, and its upregulation is found in several metastatic carcinomas, suggesting a potential prognostic marker and therapeutic target [10,11,23].…”

“…It is known that matrix-related polysaccharides are degraded by hyaluronidase (HAase), and there are at least eight different forms of HAase, hyaluronidase 1 (HYAL1), HYAL2, HYAL3, HYAL4, HYAL5, hyaluronoglucosaminidase pseudogene 1 (HYALP1), sperm adhesion molecule 1 (SPAM1, also known as PH-20) and meningioma expressed antigen 5 (MGEA5) [3,4,8,21]. Among these, HYAL1 and HYAL2 usually found in serum are considered as major somatic HAase [4], while SPAM1 is well known as testicular HAase [21].…”