Disease relevance of Spam1

• RESULTS: Examination of the human, mouse and rat SPAM1 loci revealed that transcripts initiate within the pol gene of an endogenous retrovirus (ERV) element [1].

High impact information on Spam1

• Hyal5 was exclusively expressed in the testis and formed a 160-kbp gene cluster together with Hyalp1, Hyal4, and Ph-20 on mouse chromosome 6 [2].
• In this study with guinea pig gametes, we have asked if sperm can initiate binding to the zona before and after the acrosome reaction and if the sperm surface protein PH-20 is involved in the binding at these two stages [3].
• Sperm adhesion molecule 1 (SPAM1), is a glycosyl phoshatidylinositol-linked sperm membrane protein that is dually expressed in testis and epididymis [4].
• Epididymal SPAM1 is secreted in all three regions of the epididymis in all mammalian species studied, including humans [4].
• Epididymal SPAM1 Is a Marker for Sperm Maturation in the Mouse [4].

Biological context of Spam1

• Using two independent approaches, fluorescence in situ hybridization (FISH) and interspecific backcross analysis we show the Spam1 maps to proximal mouse Chromosome (Chr) 6 [5].
• The essential role of the Spam1 sperm antigen in mouse sperm-egg interactions and its gene location provide strong support for its candidacy as the gene involved in the dysfunction of mouse sperm bearing the Rb(6.16)24Lub or Rb(6.15)1Ald translocation [5].
• Caudal sperm from transgene carriers and caput sperm of null carriers showed a bimodal distribution of Spam1, indicating that the sperm in a male were biochemically different with respect to Spam1 quantities [6].
• In the present investigation, results of a reverse transcription polymerase chain reaction assay, an RNase-protection assay (RPA), and an in situ transcript hybridization assay revealed that the murine Spam1 gene is transcribed in the female genital tract [7].
• In the uterus, Spam1 expression fluctuated during the estrous cycle [7].

Anatomical context of Spam1

• In wild-type animals, EM studies of in situ transcript hybridization of testis sections and Northern analysis of biochemically fractionated testicular RNA were performed to localize Spam1 transcript [6].
• Our earlier studies on carriers of spontaneous mutations of mouse Sperm Adhesion Molecule 1 (Spam1) suggested that TRD results from biochemically different sperm, due to a lack of transcript sharing through the intercellular cytoplasmic bridges of spermatids [6].
• Spam1 RNA was absent from the bridges, associated exclusively with the ER, and was shown to be anchored to the cytoskeleton [6].
• RPA revealed that Spam1 transcripts are synthesized in a region-dependent manner, with the oviduct having lower transcript levels than the uterus and vagina [7].
• Here, we report Spam1 RNA and protein expression in the murine vas deferens and efferent ducts [8].

Associations of Spam1 with chemical compounds

• Mouse epididymal Spam1 (pH-20) is released in the luminal fluid with its lipid anchor [9].
• Six point mutations were shown to be clustered in the Spam1 hyaluronic acid-binding domain in Rb(6.15) [10].
• Ultracentrifugation of the luminal fluid reveals that epididymal Spam1 is secreted predominantly as insoluble particles, which when treated with phosphatidylinositol-specific phospholipase C or Triton X-100, reveal that the majority of epididymal Spam1 is released with its lipid anchor, a form in which it can bind to sperm [9].
• Two-dimensional polyacrylamide gel electrophoresis with immunoblotting reveals one to three isoforms for epididymal Spam1 with the isoelectric point (pl) ranging from 7.3 to 9.0, and four isoforms ranging from 6.6 to 9.0 pl for testicular Spam1 [9].
• Spam1 on the surface of caudal sperm was shown to mediate the increase in acrosome reactions induced by the synergistic effects of HA and progesterone, as confirmed in sperm from the Rb(6.16) translocation-bearing mice which are Spam1 mutants [11].

Other interactions of Spam1

• These sperm retained large cytoplasmic droplets engorged with overexpressed Spam1 or Hyal5 protein [6].
• Interestingly, transcripts for the testicular-type hyaluronidase PH-20 (Spam1, Hyal3) were also detected in normal and autoimmune kidneys as well as in tubular cells and macrophages [12].
• Using a dual environment culture chamber system in which corpus or cauda epithelial cells are cocultured with their corresponding epididymal fibroblasts in medium supplemented with androgens and epidermal growth factor, we show that in 2- to 6-day cultures Spam1 can be detected immunocytochemically in the epithelial cells [13].

Analytical, diagnostic and therapeutic context of Spam1

• METHODS: Carriers of Spam1-Hyal5 BAC transgenes were mated with wild-type female mice and the progeny analyzed for TRD by PCR genotyping [6].
• Sperm from transgene and Spam1 null carriers were analyzed using flow cytometry and immunocytochemistry to detect quantities of Spam1 and/or Hyal5 [6].
• Spam1 is uniformly distributed over the surface of the head of caput sperm while in caudal sperm, light and confocal microscopy demonstrate that it is localized to the anterior and posterior regions [14].
• Immunocytochemistry confirmed the location of Spam1 on the tail of testicular sperm and demonstrated that it is localized to both the principal piece and the midpiece [11].
• Light and electron microscopy were used to localize, by in situ hybridization, the cellular and subcellular sites of Spam1 mRNA in the murine testis [11].

References