| IntroductionThe embryonic phase is very important for the development of multicellular organisms. At that time embryos are affected by various harmful environment easily. Important stressful events occur in embryonic development. Heat shock proteins that are highly conserved proteins play important roles in repair of damages and in protection of cell from stresses. In addition, most HSPs are also present in the unstressed cell. So the effect of heat shock proteins in the development of embryo was concerned . Marie - Therese. Loones, Sandra M. have investigated the developmental expression of heat shock proteins in the nervous system of the unstressed mouse embryo. The results suggested the biological importance of HSPs in neuronal differentiation and migration, as well as in cell signaling, protein transport.The glucose - regulated proteins ( GRPs) are a group of highly conserved stress proteins. GRP78 and GRP94 share high homology with the 70 - KD and 90 - KD heat shock protein families. Both of them are localized within the endoplasmic reticulum(ER) and possess ATP-binding sites. Envidence has shown that GRPs function as molecular chaperones by assisting in the proper folding and assembly of proteins within the ER. The development of a multicellular organism results from the selective expression of genes and the maturation of proteins is dependent on molecular chaperons. Some studies have investigated the expression of GRPs during normal mammalian development. In mouse embryos, GRP78 has been identified as early as the 2 - cell stage, and high levels were i-dentified at the blastocyst stage. The current study suggested that GRP78 and GRP94 may play a significant role in the normal development and differentiationof mouse cadiac tissues. However, the functions of molecular chaperones, especially endoplasmic reticulum chaperones, on brain development are unclear. In this article we examined the distribution and level of GRF78 and GRP94 in mouse brain during early development to find the relationship between brain development and molecular chaperones ( GRF78 and GRP94).Methods1. RT - PCR analysis was used to determine the levels of GRP78 and GRP94 mRNA during the different phase of mouse development2. Northern - blot analysis was used to determine the levels of GRP78 mRNA in mouse brain at El6. 53. Western blot analysis was used to determine the levels of GRP78 and GRP94 proteins during the different phase of mouse development4. S - P immunohistochemsrry techniques was used to investigate the histo-logical distribution of GRP78 and GRP94 proteins within brain tissues during mouse development.5. Mouse brain tissues on El6. 5 culture and treat with tunicamycin to induce UPR. RT-PCR, Western blotting to detect the expression of mRNA and proteinsResult1. The results demonstrated that the expression of GRP78 and GRP94 was in a time specific pattern. High levels of GRP78 were present in early embryo stage, and were decreased during the fetal period, increased gradually during postnatal development, and reached adult mouse after one week. But the expression of GRP94 was initially observed in low levels, and raised gradually along with the development process until the later stage. Moreover, the level of GRP94 during postnatal development was invariable. The diverse expression of GRPs is suggestive of the different action on mouse brain development, and the difference between the expression levels of different GRPs at the same developmental period shown that there was some mechanism in vivo to regulate distinctmolecular chaperones expression within the given time.2. In addition, the results demonstrated that the dimensional expressions of GRPs were also different. The expression of GRP78 was in a space specific pattern but the expression of GRP94 was not. The expression of GPR78 displayed the levels in tendency to decrease from telencephalon to metencephalon during embryonic period. This suggested GRP78 play an important role in the early morphogenesis of brain. I...
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