Melatonin‐related genes expressed in the mouse uterus during early gestation promote embryo implantation

Melatonin, a superior antioxidant, is an important molecule which regulates female reproduction due to its receptor‐mediated and receptor‐independent antioxidant actions. In this study, we investigated the effect of melatonin on early gestation in a mouse model. During early gestation, the expression of the melatonin's rate‐limiting enzyme, AANAT, gradually increased – in the uterus while the MT2 melatonin receptor was only expressed at day 2 of gestation and no MT1 was detected. Based on these findings, we conducted a melatonin injection experiment which demonstrated that 15 mg/kg melatonin significantly improved the number of implantation sites and the litter size. Also, the blastocyst and uterus were collected to identify the local action of melatonin. In the melatonin‐treated mice, the endometrium was thicker than in the control mice; melatonin also caused an increase in density of uterine glands, and the uterine gland index (UGI) was significantly elevated over that of the control. Serum steroid hormone measurements revealed that at day 6 of gestation (postimplantation), melatonin significantly downregulated the E₂ level, with no obvious effects on progesterone. Gene expression assay revealed that melatonin significantly upregulated expression of HB‐EGF, a crucial gene involved in implantation as well as its receptor ErbB1 in the blastocyst. In addition, PRA, an important gene which influences the decidual response and luminal cell differentiation, p53, which regulates uterine through leukaemia inhibitory factor (LIF), were both increased after melatonin treatment. These data suggest that melatonin and its MT2 receptor influence early gestation. Exogenous melatonin treatment can improve mouse embryo implantation and litter size, which may have important applications in human reproductive health and animal husbandry.     

Membrane-associated mucins of the ocular surface: New genes,new protein functions and new biological roles in human and mouse

The mucosal glycocalyx of the ocular surface constitutes the point of interaction between the tear film and the apical epithelial cells. Membrane-associated mucins (MAMs) are the defining molecules of the glycocalyx in all mucosal epithelia. Long recognized for their biophysical properties of hydration, lubrication, anti-adhesion and repulsion, MAMs maintain the wet ocular surface, lubricate the blink, stabilize the tear film and create a physical barrier to the outside world. However, it is increasingly appreciated that MAMs also function as cell surface receptors that transduce information from the outside to the inside of the cell. A number of excellent review articles have provided perspective on the field as it has progressed since 1987, when molecular cloning of the first MAM was reported. The current article provides an update for the ocular surface, placing it into the broad context of findings made in other organ systems, and including new genes, new protein functions and new biological roles. We discuss the epithelial tissue-equivalent with mucosal differentiation, the key model system making these advances possible. In addition, we make the first systematic comparison of MAMs in human and mouse, establishing the basis for using knockout mice for investigations with the complexity of an in vivo system. Lastly, we discuss findings from human genetics/genomics, which are providing clues to new MAM roles previously unimagined. Taken together, this information allows us to generate hypotheses for the next stage of investigation to expand our knowledge of MAM function in intracellular signaling and roles unique to the ocular surface.