The cell membrane-associated, polymorphic mucin, MUC1, has been proposed to hinder implantation by virtue of its anti-adhesive properties. Consistent with this proposal is the observation of a dramatic decrease in MUC1 protein and mRNA expression in the uterine epithelium of several species at the time of implantation. In contrast, little change in glandular epithelial expression of MUC1 protein or its mRNA during the peri-implantation period has been detected in humans. However, expression in the luminal epithelium, i.e. the epithelium involved in embryo attachment, has not been reported. Using tissue samples with a clearly defined luminal epithelium and antibodies directed against the cytoplasmic domain found in all cell-associated MUC1 species (CT-1) and against two MUC1 ectodomain epitopes, HMFG-1 and HMFG-2, we demonstrate that MUC1 expression in the luminal epithelium is maintained throughout the menstrual cycle. The staining observed with CT-1 correlates with that seen with HMFG-2, but not HMFG-1. HMFG-1 reactivity was high in all regions except basal glands in the mid proliferative endometrium and fell to very low levels throughout the tissue in the mid secretory phase. In all cases, HMFG-1 reactivity could be restored by predigestion with keratanase or neuraminidase which removes keratan sulphates and sialic acids, respectively. These observations suggest that regionally restricted glycosylation generates an altered external structure of MUC1. These alterations appear to decrease accessibility to the MUC1 protein core region and are maximal in luminal epithelium at the receptive phase. Due to their large highly extended structures, MUC1 ectodomains are very likely to be among the first cell surface components encountered during human blastocyst attachment to the luminal epithelium. Thus, MUC1 either must be locally removed during the attachment process or functions actually to promote the initial steps in embryo adhesion to the apical surface of the human uterine epithelium.

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Both the leukocyte numbers and cytokine expression profile were altered significantly in a well-defined group of women with implantation defects.

BackgroundThe ability of chemicals to disrupt neonatal development can be studied using embryonic stem cells (ESC). One such chemical is nicotine. Prenatal nicotine exposure is known to affect postnatal lung function, although the mechanisms by which it has this effect are not clear. Since fibroblasts are a critical component of the developing lung, providing structure and secreting paracrine factors that are essential to epithelialization, this study focuses on the differentiation of ESC into fibroblasts using a directed differentiation protocol.MethodsFibroblasts obtained from non-human primate ESC (nhpESC) differentiation were analyzed by immunohistochemistry, immunostaining, Affymetrix gene expression array, qPCR, and immunoblotting.ResultsResults of these analyses demonstrated that although nhpESCs differentiate into fibroblasts in the presence of nicotine and appear normal by some measures, including H&E and SMA staining, they have an altered gene expression profile. Network analysis of expression changes demonstrated an over-representation of cell-cycle related genes with downregulation of N-myc as a central regulator in the pathway. Further investigation demonstrated that cells differentiated in the presence of nicotine had decreased N-myc mRNA and protein expression and longer doubling times, a biological effect consistent with downregulation of N-myc.ConclusionsThis study is the first to use primate ESC to demonstrate that nicotine can affect cellular differentiation from pluripotency into fibroblasts, and in particular, mediate N-myc expression in differentiating ESCs. Given the crucial role of fibroblasts throughout the body, this has important implications for the effect of cigarette smoke exposure on human development not only in the lung, but in organogenesis in general.