Changes in the distribution of a spectrin-like protein during development of the preimplantation mouse embryo.

Abstract

The mouse blastocyst expresses a 240,000-mol-wt polypeptide that cross-reacts with antibody to avian erythrocyte c~-spectrin. Immunofluorescence localization showed striking changes in the distribution of the putative embryonic spectrin during preimplantation and early postimplantation development. There was no detectable spectrin in either the unfertilized or fertilized egg. The first positive reaction was observed in the early 2-cell stage when a bright band of fluorescence delimited the region of cell-cell contact. The blastomeres subsequently developed continuous cortical layers of spectrin and this distribution was maintained throughout the cleavage stages. A significant reduction in fluorescence intensity occurred before implantation in the apical region of the mural trophoblast and the trophoblast outgrowths developed linear arrays of spectrin spots that were oriented in the direction of spreading. In contrast to the alterations that take place in the periphery of the embryo, spectrin was consistently present in the cortical cytoplasm underlying regions of contact between the blastomeres and between cells of the inner cell mass. The results suggest a possible role for spectrin in cell-cell interactions during early development.The cortical cytoskeleton of the preimplantation mouse embryo contains actin microfilaments and microtubules (7), intermediate filaments of the cytokeratin type (15), myosin (31), and a-actinin (20). A developmental function for these components has been inferred from the changes in cortical organization and from the effects of cytoskeletal disrupting agents on major developmental transitions during preimplantation development (7,27,35,36). Essentially nothing is known, however, about the actual mechanisms whereby the cytoskeleton influences cell shape and polarization, locomotion, and contact interaction between the cells.The recent discovery of spectrin-like proteins in many nonerythroid cells and the possibility that nonerythroid spectrin may function in a manner analogous to erythroid spectrin (for reviews see references 6,8,12,18) is of potential significance for an understanding of developmental processes because spectrin, in association with actin and other components of the membrane cytoskeleton, is a major determinant of cell shape, deformability and fusogenicity, and the mobility of membrane proteins (1,3,23,25). The present study was undertaken to see when spectrin appears during embryonic development. Using immunoblotting procedures, a 240,000-mol-wt polypeptide was identified in the mouse blastocyst that cross-reacts with antibody to avian erythrocyte a-spectrin.Immunofluorescence localization, moreover, shows changes in the distribution of the putative embryonic spectrin that suggest a role for spectrin in cell-cell interactions during preimplantation development. MATERIALS AND METHODS Collection of Embryos:Preimplantation mouse embryos were obtained from 5-7-wk-old Institute for Cancer Research (ICR) females (West Seneca Breeding Facility, Roswell Park Memori...

Brain spectrin(240/235) and brain spectrin(240/235E): differential expression during mouse brain development

“…Therefore, chicken brain spectrin(240/230) expression is both temporally and spatially related to mammalian brain spectrin(240/235E), although these proteins are structurally distinct. Mammalian brain spectrin(240/235E) is also associated with the cytoplasmic surface of organelle membranes in addition to the plasma membrane , while avian brain spectrin(240/230) has been suggested to be exclusively associated with the plasma membrane (Lazarides and Nelson, 1983a Significance of brain spectrin subtype expression Although this is the first report of spectrin subtype expression during mammalian brain development, Sobel and Alliegro (1985) have found a 240 kDa polypeptide that cross-reacts with antibody to avian erythrocyte ol-spectrin in mouse embryo, as early as the 2-cell stage. Given the present observations showing a spectrin subtype in germinal cells of the mouse brain, it would appear that spectrin may be expressed in all developing cells and tissues.…”

Cell surface localisation and stability of uvomorulin during early mouse development

“…However, in both oocytes and the compact 8-cell stage microfilaments and uvomorulin appear to show reciprocal patterns of distribution. Of the known microfilament-associated proteins examined in early mouse embryos, the distribution of fodrin/spectrin most closely resembles that of uvomorulin, being localised at intercellular contacts from the early 2-cell stage (Schatten et al, 1986;Sobel & Alliegro, 1985;Sobel & Goldstein, 1988). At the transition from 4-to 8-cell stages, microfilaments are redistributed from a uniform distribution to become concentrated, in association with microvilli, at the apical poles of the compacted blastomeres, whilst uvomorulin becomes localised preferentially at apposed basolateral regions Fleming & Johnson, 1988).…”

From Egg to Epithelium

“…Little biochemical work has yet been undertaken on the actin-associated proteins. The suggestion that alpha-spectrin was totally lacking in the oocyte and appeared fi rst at the 2-cell stage (Sobel & Alliegro 1985) has not been substantiated (Reima & Lehtonen 1985;Damjanov et aI1986).…”