Maternally derived FILIA-MATER complex localizes asymmetrically in cleavage-stage mouse embryos

Abstract

Initial cell lineages that presage the inner cell mass and extra-embryonic trophectoderm are established when eight blastomeres compact to form polarized morulae in preimplantation mouse development. FILIA has been identified as a binding partner to MATER (maternal antigen that embryos require; also known as NLRP5), which is encoded by a maternal effect gene. Products of each gene are detected in growing oocytes and, although transcripts are degraded before fertilization, the cognate proteins persist in early blastocysts. The two proteins co-localize to the cytocortex of ovulated eggs, where the stability of FILIA is dependent on the presence of MATER. After fertilization, FILIA-MATER complexes become asymmetrically restricted in the apical cytocortex of twocell embryos due to their absence in regions of cell-cell contact. This asymmetry is reversible upon disaggregation of blastomeres of the two-and four-cell embryo. Each protein persists in cells of the preimplantation embryo, but the continuous cell-cell contact of 'inner' cells of the morulae seemingly precludes formation of the subcortical FILIA-MATER complex and results in cell populations that are marked by its presence ('outer') or absence ('inner'). Thus, the FILIA-MATER complex provides a molecular marker of embryonic cell lineages, but it remains to be determined if the molecular asymmetry established after the first cell division plays a role in cell fate determinations in the early mouse embryo. If so, the plasticity of the FILIA-MATER complex localization may reflect the regulative nature of preimplantation mouse development.

The subcortical maternal complex: multiple functions for one biological structure?

“…The subcortical maternal complex (SCMC) is a multiprotein complex uniquely expressed in mammalian oocytes and early embryos [10] The SCMC shows a peculiar localization: it is situated in the subcortex of murine and human eggs and preimplantation embryos and is excluded from regions of cell-cell contact in the cleavage-stage embryo [10,12]; it segregates to the outer cells of morulae and blastocysts, being therefore completely absent in the embryo inner cell mass [13]. Despite being essential for murine zygote progression beyond the first embryonic cell divisions [10,11], its structure, composition, and specific functions are yet to be completely clarified.…”

“…The genes encoding the four SCMC components are expressed during oogenesis, and the transcripts are rapidly degraded after EGA; their proteins accumulate already in growing oocytes and persist in cleavage-stage embryos up to the blastocyst stage [10,13,16,17]. Mater, Floped, and Tle6 expression was observed in oocytes as early as the primary follicle stage [10,17,18].…”

Efectos de los RNAm maternos sobre la maduración del ovocito y el desarrollo embrionario temprano en mamíferos

“…Posterior a esto, la membrana nuclear se rompe dando oportunidad para que los microtúbulos del huso mitótico se unan al and, at least in mice, are related to the progression of the zygote to 2-cell embryos. The proteins that make up this group are MATER (131) , FLOPED (10) , TLE6 (10) , FILIA (132) and PADI6 (133) . The absence of any of these proteins does not affect the ovarian follicle development or the development of germ cells; however, the absence of any of them, produces seemingly normal but infertile individuals, females produce eggs capable of being fertilized, but during embryonic development does not occur the maternal subcortical complex formation, and the phenotypes observed in embryos deficient of the genes that encode for some of these proteins, present arrests in 2-cell embryos (10,131,134,135) .…”

“…Las proteínas que componen este grupo son MATER (131) , FLOPED (10) , TLE6 (10) , FILIA (132) y PADI6 (133) . La ausencia de cualquiera de estas proteínas no afecta el desarrollo del folículo ovárico ni el desarrollo de células germinales; sin embargo, la ausencia de cualquiera de ellas, produce individuos aparentemente normales pero estériles, las hembras producen ovocitos capaces de ser fertilizados, pero durante el desarrollo embrionario no sucede la formación del complejo subcortical materno, y los fenotipos observados en embriones deficientes de los genes que codifican para algunas de estas proteínas, presentan arrestos en embriones de dos células (10,131,134,135) .…”

Expression patterns of Nlrp9a, Nlrp9b and Nlrp9c during mouse development

“…Hence, the first cleavages depend on maternal factors, while compaction and blastocyst formation depends on both maternal and embryonic factors. Over the past few years, some researchers focused on oocyte-restricted maternal effect gene because of their specific expression profiles (Dean 2002;Dharma et al 2009;Evsikov et al 2006;Paillisson et al 2005;Yoon et al 2006), which are mainly expressed in oocytes, remained present in zygotes and downregulated sharply after broad zygotic genome activation Ma et al 2006;Ohsugi et al 2008;Wu et al 2003).…”