The Role of Taste Receptor mTAS1R3 in Chemical Communication of Gametes

Abstract

Fertilization is a multiple step process leading to the fusion of female and male gametes and the formation of a zygote. Besides direct gamete membrane interaction via binding receptors localized on both oocyte and sperm surface, fertilization also involves gamete communication via chemical molecules triggering various signaling pathways. This work focuses on a mouse taste receptor, mTAS1R3, encoded by the Tas1r3 gene, as a potential receptor mediating chemical communication between gametes using the C57BL/6J lab mouse strain. In order to specify the role of mTAS1R3, we aimed to characterize its precise localization in testis and sperm using super resolution microscopy. The testis cryo-section, acrosome-intact sperm released from cauda epididymis and sperm which underwent the acrosome reaction (AR) were evaluated. The mTAS1R3 receptor was detected in late spermatids where the acrosome was being formed and in the acrosomal cap of acrosome intact sperm. AR is triggered in mice during sperm maturation in the female reproductive tract and by passing through the egg surroundings such as cumulus oophorus cells. This AR onset is independent of the extracellular matrix of the oocyte called zona pellucida. After AR, the relocation of mTAS1R3 to the equatorial segment was observed and the receptor remained exposed to the outer surroundings of the female reproductive tract, where its physiological ligand, the amino acid L-glutamate, naturally occurs. Therefore, we targeted the possible interaction in vitro between the mTAS1R3 and L-glutamate as a part of chemical communication between sperm and egg and used an anti-mTAS1R3-specific antibody to block it. We detected that the acrosome reacted spermatozoa showed a chemotactic response in the presence of L-glutamate during and after the AR, and it is likely that mTAS1R3 acted as its mediator.

Longitudinal Expression of Testicular TAS1R3 from Prepuberty to Sexual Maturity in Congjiang Xiang Pigs

“…The observed T1R3 expression pattern was consistent with the results of our previous study of mice [11]. The expression pattern of T1R3 and its related taste signaling components in germ cells and their potential functions have mainly been reported in mice [6,9,10,12,27,28]. The components of sweet/umami taste-related signaling cascades, such as T1R1, T1R2, T1R3, G αgust , G γ13gust , PLCβ2, and TRMP5, have been detected in spermatogenic cells of mice, in some cases, these molecules have been observed in the testicular basal layer, Leydig cells and epididymal spermatozoa [7,8].…”

Taste receptors affect male reproduction by influencing steroid synthesis

“…Besides, T2Rs has ectopic expression during spermatogenesis in human ( Governini et al, 2020 ). Besides, T1r1 and T1r3 are present in the spermatozoa during the immotile to motile phases when spermatozoa are transported to the epididymis for maturation and storage ( Frolikova et al, 2020 ). Moreover, T2Rs are expressed in cumulus and granulosa cells, essential for oocyte development and fertilization ( Semplici et al, 2021 ).…”

“…The acrosome response of spermatozoa occurs in the female reproductive tract, where l -glutamate is present as a physiological ligand for T1r3. In vitro chemotaxis experiments showed that acrosome responsive spermatozoa are significantly attracted to l -glutamate, which provides a new perspective to resolve the complex fertilization process ( Frolikova et al, 2020 ).…”

N-Formyl-L-aspartate mediates chemotaxis in sperm via the beta-2-adrenergic receptor

“…Sperm may have chemosensory receptors which likely get activated on encountering their cognate ligands. In mammalian species, olfactory receptors (Flegel et al, 2016) and taste receptors (Frolikova et al, 2020) have been of interest as molecular sensors for sperm-egg communication; however, their physiologically relevant ligands have not been identified yet. In general, receptor-ligand interaction in the ampulla of the oviduct leads to rapid downstream signal transduction resulting in sperm flagellar motor activation and regulation of motility to modulate its swimming path (Inaba, 2003).…”