Abstract
BackgroundTrophinin is an intrinsic membrane protein that forms a complex in the cytoplasm with bystin and tastin, linking it microtubule-associated motor dynein (ATPase) in some cell types. Previously, we found that human sperm tails contain trophinin, bystin and tastin proteins, and that trophinin-binding GWRQ (glycine, tryptophan, arginine, glutamine) peptide enhanced motility of human sperm.MethodsImmunohistochemistry was employed to determine trophinin protein in mouse spermatozoa from wild type mouse, by using spermatozoa from trophinin null mutant mice as a negative control. Multivalent 8-branched GWRQ (glycine, tryptophan, arginine, glutamine) peptide or GWRQ-MAPS, was chemically synthesized, purified by HPLC and its structure was confirmed by MALDI-TOF mass spectrometry. Effect of GWRQ-MAPS on mouse spermatozoa from wild type and trophinin null mutant was assessed by a computer-assisted semen analyzer (CASA).ResultsAnti-trophinin antibody stained the principal (central) piece of the tail of wild type mouse sperm, whereas the antibody showed no staining on trophinin null sperm. Phage particles displaying GWRQ bound to the principal piece of sperm tail from wild type but not trophinin null mice. GWRQ-MAPS enhanced motility of spermatozoa from wild type but not trophinin null mice. CASA showed that GWRQ-MAPS enhanced both progressive motility and rapid motility in wild type mouse sperm.ConclusionsPresent study established the expression of trophinin in the mouse sperm tail and trophinin-dependent effect of GWRQ-MAPS on sperm motility. GWRQ causes a significant increase in sperm motility.
Highlights
Trophinin is an intrinsic membrane protein that forms a complex in the cytoplasm with bystin and tastin, linking it microtubule-associated motor dynein (ATPase) in some cell types
Trophinin was identified as an apical cell adhesion molecule mediating adhesion between trophoblastic and endometrial epithelial cells at the time of human embryo implantation [1,2]
We found that GWRQ peptide bound to human sperm tail and promoted sperm motility [16]
Summary
Trophinin is an intrinsic membrane protein that forms a complex in the cytoplasm with bystin and tastin, linking it microtubule-associated motor dynein (ATPase) in some cell types. Trophinin exhibits an N-terminal cytoplasmic tail, The trophinin gene is found only in mammals. In both human and mouse, it gives rise to two distinct proteins, magphinin and trophinin [9,10]. A gene expression database analysis (http://www.ncbi.nih.gov/UniGene) indicates that magphinin/trophinin transcripts are expressed in the brain, testis, thymus, kidney, and parathyroid gland in mouse and human, suggesting yet undefined role of trophinin gene products in cells of these organs. Immunohistochemistry using trophinin-specific antibody detects strong signals for trophinin protein in distinct cell types of the germinal zone in adult rat brain [11] and in mature spermatozoa in the mouse testis [9]. Trophinin gene knockout mice do not show apparent neurological defects or male infertility [3], leaving trophinin’s role in neuronal or spermatogenic cells elusive
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