Lanlan Yin

A sperm GPI-anchored protein elicits sperm-cumulus cross-talk leading to the acrosome reaction.

Abstract.The acrosome reaction has long been thought to be induced by the zona pellucida. Here we report the identification and function of a novel human sperm glycosylphosphatidylinositol (GPI)-anchored membrane protein, NYD-SP8. The release of the protein during sperm-egg interaction and its binding to the cumulus, the first layer of egg investment, elicits cross-talk between the gametes and produces calcium dependant release of progesterone, which lead to the acrosome reaction. An in vivo mouse model of NYD-SP8 immunization is also established showing a reduced fertility rate. Thus, contrary to accepted dogma, our study demonstrates for the first time that, prior to reaching the zona pellucida, sperm may release a surface protein that acts on the cumulus cells leading to the acrosome reaction, which may be important for determining the outcome of fertilization.

A Gene Encoding Sialic-Acid-Specific 9-O-Acetylesterase Found in Human Adult Testis

Using differential display RT-PCR, we identified a gene of 2750 bp from human adult testis, named H-Lse, which encoded a putative protein of 523 amino acids and molecular weight of 58 kd with structural characteristics similar to that of mouse lysosome sialic-acid-specific 9-O-acetylesterase. Northern blot analysis showed a widespread distribution of H-Lse in various human tissues with high expression in the testis, prostate, and colon. In situ hybridization results showed that while H-Lse was not detected in embryonic testis, positive signals were found in spermatocytes but not spermatogonia in adult testis of human. The subcellular localization of H-Lse was visualized by green fluorescent protein (GFP) fused to the amino terminus of H-Lse, showing compartmentalization of H-Lse in large dense-core vesicles, presumably lysosomes, in the cytoplasm. The developmentally regulated and spermatogenic stage-specific expression of H-Lse suggests its possible involvement in the development of the testis and/or differentiation of germ cells.

Identification and characterization of a gene coding a novel isoform of DEAD-box protein

A gene coding a novel isoform of DEAD-box protein named testicular DEAD-box protein (tDbp), presumably involved in testicular function, was identified and characterized. Testicular DEAD-box protein was cloned from a human testis cDNA library. The cDNA microarray hybridization showed that it was expressed at a higher level in adult testis than in embryo testis. Reverse transcription-polymerase chain reaction indicated that tDbp was specifically expressed in testis, but not in some other tissues.