ISSN:0192-253X    

DOI:10.1002/dvg.1020140202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractAfter fertilization in the mouse, the zygotic genome is activated in two‐cell embryos by the spontaneous expression, among other genes, of the major inducible heat shock gene, hsp68, in the absence of heat‐inducibility of heat shock genes. To obtain information on this phenomenon, we have probed one‐ and two‐cell embryo's ability to express microinjected reporter DNA constructs, containing theEscherichia coli lacZgene driven by promoters from early SV40 genes, the human ß‐actin gene, and the normal or HSE‐deleted mouse hsp68 gene. Activity of these promoters was also tested in mouse granulosa cells and dictyate oocytes, as a function of circular/linear construct configuration and occurrence of heat shock. The hsp68 promoter was heat‐inducible in both granulosa cells and oocytes. Its heat activation required the presence of HSEs and, in the oocytes, of construct linear configuration. In the embryos however, this promoter was expressed in dependently of the presence of HSEs and of construct configuration, and its activity was not affected by heat shock. When constructs with early SV40 and ß‐actin promoters were injected into one‐cell embryos, they appeared to be inactivated with the first embryonic cleavage, in agreement with previous observations [Wiekowskiet ai., 1992]. By contrast, both normal and HSE‐deleted hsp68 promoters maintained their activity through the first cleavage, providing the first evidence of a gene escaping such transcriptional repression. Present results confirm previous findings on hsp68 expression during early mouse development, and suggest that this activation is mediated by a factor(s) other than HSF.

ISSN:0192-253X    

DOI:10.1002/dvg.1020140203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractWe have investigated the developmental and tissue‐specific distribution of the mouse small hsp25 by immunohistology using an antibody that specifically identifies hsp25. Our analysis shows that the relative amount of hsp25 increases during embryogenesis. Through days 13–20 of embryogenesis, hsp25 accumulation is predominant in the various muscle tissues, including the heart, the bladder, and the back muscles. hsp25 is detectable also in neurons of the spinal cord and the purkinje cells. Furthermore analysis of the closely related α, B‐crystallin shows that in several tissues, including the bladder, the notochordal sheath and the eye lens both proteins are coexpressed. Our studies demonstrate that mammalian hsp25 accumulation is developmentally regulated during mouse embryogenesis and support the view of an important functional role of small heat shock proteins in normal cell metabolism. © 1993Wiley‐

ISSN:0192-253X    

DOI:10.1002/dvg.1020140204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe steady‐state levels of four members of the heat shock proteins families (HSP84, HSC73, HSP71, and HSP25) were examined by immunoblot analysis of several different tissues of young and adult mice in the absence of stress. These hsps were detected in all tissues but their level was variable. The levels of HSC73 and HSP84 varied only slightly between different tissues in either young or adult mice, with the exception of skin where these hsps were found in reduced amounts. In contrast, the stress‐inducible member of the HSP70 family, HSP71, was found to be expressed in all tissues but in amounts which differed by as much as two orders of magnitude between tissues. In general, the levels of both HSP71 and HSP25 were found to be tissue dependent, with higher levels found in tissues such as stomach, intestine, colon and bladder, tissues which are exposed to toxic environmental or metabolic products, and which may concentrate these substances by water resorption and/or be exposed to them for longer periods. The levels of HSP71 and HSP25 were generally positively correlated both in young and adult mice although this correlation was not found in certain tissues such as kidney, testes, and bone. Tissues of young mice contained lower amounts of HSP25 and HSP71 than were found in the same tissues from adults. We conclude that hsps are expressed in all tissues of the mouse in the absence of stress and that some organs, particularly those exposed to potentially toxic metabolites, show a higher level of expression of HSP71 and HSP25. © 1993Wiley‐Lis

ISSN:0192-253X    

DOI:10.1002/dvg.1020140205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis study extends to the protein level our previous observations, which had established the stage and cellular specificity of expression ofhsp86andhsp84in the murine testis in the absence of exogenous stress. Immunoblot analysis was used to demonstrate that HSP86 protein was present throughout testicular development and that its levels increased with the appearance of differentiating germ cells. HSP86 was most abundant in the germ cell population and was present at significantly lower levels in the somatic cells. By contrast, the HSP84 protein was detected in the somatic cells of the testis rather than in germ cells. The steady‐state levels of HSP86 and HSP84 paralleled the pattern of the expression of their respective mRNAs, suggesting that regulation at the level of translation was not a major mechanism controllinghsp90gene expression in testicular cells. Immunoprecipitation analysis revealed that a 70‐kDa protein coprecipitated with the HSP86/HSP84 proteins in testicular homogenates. This protein was identified as an HSP70 family member by immunoblot analysis, suggesting that HSP70 and HSP90 family members interact in testicular cells. © 1993Wiley‐Lis

ISSN:0192-253X    

DOI:10.1002/dvg.1020140206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSynchronized regulation of cell division during gastrulation is essential for the regional proliferation of cells and pattern formation of the early CNS. The neural plate and neuroectoderm cells are a rapidly dividing and differentiating population of cells with a unique and rapid heat‐shock response. Heat shock and the heat‐shock genes were studied during neural plate development in a whole rat embryo culture system at 9.5‐11.5 days. A lethal heat shock can cause cell death and severe developmental defects to the forebrain and eye during organogenesis. Heat shock can also result in acquired thermotolerance whereby cell progression is delayed at the G1/S and S/G2 boundaries of the cell cycle. This delay in cell cycle progression caused an overall lengthening of the cell cycle time of at least 2 hr. The heat shock genes may therefore function as cell cycle regulators in neuroectoderm induction and differentiation. The kinetics and expression of the hsp genes were examined in neuroectodermal cells by flow cytometry and Northern analysis. The levels of hsp mRNA 27, 71, 73, and 88 were identified following exposure at 42°C (nonlethal), 43deg;C (lethal) and 42deg;/43deg;C (thermotolerant) heat shock. Examination of hsp gene expression in the neural plate showed tight regulation in the cell cycle phases. Hsp 88 expression was enhanced at Go and hsp71 induction at G2 + M of the cell cycle. Cells exposed to a thermotolerant heat shock of 42deg;C induced hsp71 mRNA expression in all phases of the cell cycle with the mRNA levels of hsp27, 73, and 88 increased but relatively constant. Following a lethal heat shock, dramatic changes in hsp expression were seen especially enhanced hsp71 induction in late S phase. The regulated expression of hsps during the cell cycle at various phases could play a unique and important role in the fate and recovery of neuroectoderm cells during early mammalian embryo development. © 1993Wiley‐

ISSN:0192-253X    

DOI:10.1002/dvg.1020140207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe present study was undertaken to examine the role of heat shock response in the development of tolerance and cross‐tolerance in an in vivo murine model of teratogen‐induced neural tube defects. The experimental paradigm designed to address this question was to utilize inbred mouse strains that differed in their sensitivity to hyperthermia and valproic acid induced neural tube defects, subjecting the dams to subteratogenic pretreatments with either heat or valproic acid at two different timepoints during development prior to the administration of the teratogenic insult. A statistically significant reduction in the frequency of neural tube defects and/or embryolethality following a pretreatment in dams subsequently exposed to a teratogenic treatment was considered evidence for the induction of tolerance. This was observed in the SWV embryos exposed to the 38°C pretreatment at 8:06 and to embryos exposed to either pretreatment temperature at 8:10 priorto a teratogenic heat shock at 8:12. In the LM/Bc embryos, only the 41°C pretreatment at 8:06 induced thermotolerance. There was no evidence of tolerance induced in either mouse strain using valproic acid. On the other hand, cross‐tolerance was clearly demonstrated in this study, with a low temperature (41°C) pretreatment successfully protecting SWV fetuses from a subsequent teratogenic treatment with valproic acid, while valproic acid (200 mg/kg) was effective in reducing the risk of hyperthermia‐induced neural tube defects in the LM/Bc fetuses. In all instances, tolerance was induced in the absence of significant induction of hsp synthesis. The lack ofconcordance between hsps and thermotolerance suggests that some other factor(s) is involved in conferring thermotolerance on developing murine embryos. © 1993 Wile

ISSN:0192-253X    

DOI:10.1002/dvg.1020140208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractHeat shock protein synthesis was examined in mouse thymocytes at three stages of development: early embryonic thymocytes, which are CD4−CD8−, adult thymocytes, which are primarily CD4+CD8+, and mature spleen T cells, which are CD4+CD8−or CD4−CD8+. After either a 41°C or 42°C heat shock, the synthesis of the maior heat‐inducible protein (hsp68) was elevated during the first hour of recovery but then decreased abruptly in thymocytes from adult mice. In contrast, the synthesis of hsp68 continued for up to 4 h after heating embryonic mouse thymocytes or mature spleen T cells. The more rapid termination ofthe heat shock response in the adult thymocytes was not the result of eitherless heat damage or more rapid repair since the recovery of general protein synthesis was more severely delayed in these cells. As well, the double positive CD4+CD8+cells were more sensitive to hyperthermia than either the double negative CD4−CD8−or single positive CD4+CD8−or CD4−CD8+cells. Exposure of fetal thymus organ cultures to elevated temperature revealed that the double negative thymocytes were able to survive and differentiate normally following a heat shock treatment that was lethal for the double positive thymocytes. Exposure of thymocytes from adult mice to elevated temperatures induced apoptotic cell death. This was evident by the cleavage of DNA into oligonucleosome‐sized fragments. Quantitation of the extent of DNA fragmentation and the number of apoptotic cells by flow cytometry demonstrated that the extent of apoptotic cell death was related to the severity of the heat stress. Double positive (CD4+CD8+) thymocytes are selected on the basis of their T‐cell antigen receptor (TCR). Most of these cells are negatively selected and die within the thymus by an active process of cell deletion known as apoptosis. Restricting hsp synthesis in response to stress might be essential during developmental processes in which cell maturation is likely to result in death rather than functional differentiation

ISSN:0192-253X    

DOI:10.1002/dvg.1020140209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020140201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY