Cell Surface β1,4 Galactosyltransferase on Primary Spermatocytes Facilitates their Initial Adhesion to Sertoli Cells in Vitro1

Pratt, Sana Abuhamad; Scully, Natalie F.; Shur, Barry D.

doi:10.1095/biolreprod49.3.470

Cited by 26 publications

(10 citation statements)

References 24 publications

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“…Consistent with the expected location of a zona receptor, GalT is found on the surface of mouse sperm overlying a discrete domain on the dorsal, anterior aspect of the sperm head, where it behaves as an integral membrane protein [Shur and Neely, 1988]. It is synthesized by pachytene spermatocytes, and on their surface it may function in their adhesion to Sertoli cells [Pratt et al, 1993]. As spermatogenic cells develop, GalT is redistributed to the anterior aspect of the sperm head, possibly by association with the actin cytoskeleton [Scully et al, 1987].…”

Section: Sperm Surface Galt Facilitates Binding To the Zpmentioning

confidence: 68%

Galactosyltransferase Function during Mammalian Fertilization

Nixon¹,

Lu²,

Wassler³

et al. 2000

Cells Tissues Organs

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Gamete recognition has been studied extensively in the mouse. In this system, it is generally believed that sperm bind to a class of O-linked oligosaccharides on the zona pellucida glycoprotein, ZP3. The best characterized sperm receptor for ZP3 is β1,4-galactosyltransferase (GalT), which functions in a lectin-like capacity by binding to N-terminal N-acetylglucosamine residues on ZP3 oligosaccharides. Multivalent oligosaccharides on ZP3, as well as synthetic polymers terminating in N-acetylglucosamine aggregate GalT, leading to activation of a heterotrimeric G protein cascade and culminating in the acrosome reaction. Following fertilization, cortical granules release N-acetylglucosaminidase, which removes the binding site for sperm GalT and facilitates the zona block to polyspermic binding. Genetic manipulation of GalT expression has confirmed its function as a ZP3 receptor. Overexpressing GalT on sperm leads to increased binding of ZP3, increased G protein activation, and precocious acrosome reactions. In contrast, sperm from mice made null for GalT by homologous recombination are refractory to ZP3, in that they are unable to bind soluble ZP3 and fail to undergo the acrosome reaction in response to zona glycoproteins. Surprisingly, GalT null sperm still bind to the zona and achieve low rates of fertilization in vitro. This then suggests that sperm-egg binding involves receptor-ligand interactions independent of GalT and ZP3. The current model suggests that GalT functions as the ZP3 receptor that is responsible for inducing the acrosome reaction, whereas initial sperm-zona binding is dictated by other sperm surface receptors. Consistent with this, at least three other zona pellucida monosaccharides have been implicated in sperm binding, and novel sperm surface glycoproteins have been suggested to function in gamete binding. A large scaffolding protein has been identified that associates with the GalT cytoplasmic domain and may be responsible for orchestrating its signal transduction capacities that lead to the acrosome reaction.

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Section: Sperm Surface Galt Facilitates Binding To the Zpmentioning

confidence: 68%

Galactosyltransferase Function during Mammalian Fertilization

Nixon¹,

Lu²,

Wassler³

et al. 2000

Cells Tissues Organs

Self Cite

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“…Much of this influence is thought to be mediated through direct Sertoli-germ cell contact, which is required for spermatogenesis [14]. Several molecules, including ␤1,4-galactosyltransferase [15], Ncadherin [16], and testis-specific protein 1 (Tpx-1) [17], have been identified as candidate adhesion proteins. Antibodies to all 3 proteins inhibit Sertoli-germ cell binding to various degrees in vitro.…”

Section: Introductionmentioning

confidence: 99%

Identification of Target Messenger RNA Substrates for the Murine Deleted in Azoospermia-Like RNA-Binding Protein1

Jiao

Trifillis

Kiledjian

2002

Biology of Reproduction

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The murine autosomal deleted in azoospermia-like protein (mDAZL) is a germ cell-restricted RNA-binding protein essential for sperm production. Homozygous disruption of the mDAZL gene results in the absence of germ cells beyond the spermatogonial stage. Progress into the function of DAZL in spermatogenesis has been hampered without identification of the cognate mRNA substrates that it binds to and regulates. Using the isolation of specific nucleic acids associated with proteins (SNAAP) technique recently developed in our lab, we identified mRNAs from testis that were specifically bound by mDAZL. One mRNA encoded the Tpx-1 protein, a testicular cell adhesion protein essential for the progression of spermatogenesis. A 26-nucleotide region necessary and sufficient to bind mDAZL was found within additional mRNAs isolated by the screen. These included mRNA encoding Pam, a protein associated with myc; GRSF1, an mRNA-binding protein involved in translation activation, and TRF2, a TATA box-binding protein-like protein involved in transcriptional regulation. Each mRNA containing the mDAZL binding site was specifically bound by mDAZL. A similar sequence is also present in the Cdc25A mRNA, a threonine/tyrosine phosphatase involved in cell cycle progression. The mDAZL and Cdc25A homologues are functionally linked in Drosophila and are necessary for spermatogenesis. Our demonstration that Tpx-1 and Cdc25A mRNAs are bound by mDAZL suggests that mDAZL regulates a subset of mRNAs necessary for germ cell development and cell cycle progression. Understanding how mDAZL regulates the target mRNAs will provide new insights into spermatogenesis, strategies for therapeutic intervention in azoospermic patients, and novel approaches for male contraception.

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“…It binds to glycoside chains on the egg coat glycoprotein, ZP3. During spermatogenesis, surface B4GALT1 is expressed as early as pachytene spermatocytes (Scully et al, 1987), where it may facilitate adhesion of germ cells to Sertoli cells (Pratt et al, 1993). During spermiogenesis, B4GALT1 is redistributed to the anterior aspect of the sperm head possibly by the actin cytoskeleton.…”

mentioning

confidence: 99%

Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 3: Developmental changes in spermatid flagellum and cytoplasmic droplet and interaction of sperm with the zona pellucida and egg plasma membrane

Hermo¹,

Pelletier²,

Cyr³

et al. 2009

Microscopy Res & Technique

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Spermiogenesis constitutes the steps involved in the metamorphosis of spermatids into spermatozoa. It involves modification of several organelles in addition to the formation of several structures including the flagellum and cytoplasmic droplet. The flagellum is composed of a neck region and middle, principal, and end pieces. The axoneme composed of nine outer microtubular doublets circularly arranged to form a cylinder around a central pair of microtubules is present throughout the flagellum. The middle and principal pieces each contain specific components such as the mitochondrial sheath and fibrous sheath, respectively, while outer dense fibers are common to both. A plethora of proteins are constituents of each of these structures, with each playing key roles in functions related to the fertility of spermatozoa. At the end of spermiogenesis, a portion of spermatid cytoplasm remains associated with the released spermatozoa, referred to as the cytoplasmic droplet. The latter has as its main feature Golgi saccules, which appear to modify the plasma membrane of spermatozoa as they move down the epididymal duct and hence may be partly involved in male gamete maturation. The end product of spermatogenesis is highly streamlined and motile spermatozoa having a condensed nucleus equipped with an acrosome. Spermatozoa move through the female reproductive tract and eventually penetrate the zona pellucida and bind to the egg plasma membrane. Many proteins have been implicated in the process of fertilization as well as a plethora of proteins involved in the development of spermatids and sperm, and these are high lighted in this review.

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Cell Surface β1,4 Galactosyltransferase on Primary Spermatocytes Facilitates their Initial Adhesion to Sertoli Cells in Vitro1

Cited by 26 publications

References 24 publications

Galactosyltransferase Function during Mammalian Fertilization

Galactosyltransferase Function during Mammalian Fertilization

Identification of Target Messenger RNA Substrates for the Murine Deleted in Azoospermia-Like RNA-Binding Protein1

Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 3: Developmental changes in spermatid flagellum and cytoplasmic droplet and interaction of sperm with the zona pellucida and egg plasma membrane

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