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Modulation of the chaperone heat shock cognate 70 by embryonic (pro)insulin correlates with prevention of apoptosis.

ABSTRACT: Insights have emerged concerning insulin function during development, from the finding that apoptosis during chicken embryo neurulation is prevented by prepancreatic (pro)insulin. While characterizing the molecules involved in this survival effect of insulin, we found insulin-dependent regulation of the molecular chaperone heat shock cognate 70 kDa (Hsc70), whose cloning in chicken is reported here. This chaperone, generally considered constitutively expressed, showed regulation of its mRNA and protein levels in unstressed embryos during early development. More important, Hsc70 levels were found to depend on endogenous (pro)insulin, as shown by using antisense oligodeoxynucleotides against (pro)insulin mRNA in cultured neurulating embryos. Further, in the cultured embryos, apoptosis affected mainly cells with the lowest level of Hsc70, as shown by simultaneous Hsc70 immunostaining and terminal deoxynucleotidyltransferase-mediated UTP nick end labeling. These results argue in favor of Hsc70 involvement, modulated by embryonic (pro)insulin, in the prevention of apoptosis during early development and suggest a role for a molecular chaperone in normal embryogenesis.

SUBMITTER: de la Rosa EJ

PROVIDER: S-EPMC21442 | biostudies-literature | 1998 Aug

REPOSITORIES: biostudies-literature

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Modulation of the chaperone heat shock cognate 70 by embryonic (pro)insulin correlates with prevention of apoptosis.

de la Rosa E J EJ Vega-Núñez E E Morales A V AV Serna J J Rubio E E de Pablo F F

Proceedings of the National Academy of Sciences of the United States of America 19980801 17

Insights have emerged concerning insulin function during development, from the finding that apoptosis during chicken embryo neurulation is prevented by prepancreatic (pro)insulin. While characterizing the molecules involved in this survival effect of insulin, we found insulin-dependent regulation of the molecular chaperone heat shock cognate 70 kDa (Hsc70), whose cloning in chicken is reported here. This chaperone, generally considered constitutively expressed, showed regulation of its mRNA and ...[more]

PMID: 9707581

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Project description:BackgroundHepatitis B virus (HBV) infection is a major health concern with more than two billion individuals currently infected worldwide. Because of the limited effectiveness of existing vaccines and drugs, development of novel antiviral strategies is urgently needed. Heat stress cognate 70 (Hsc70) is an ATP-binding protein of the heat stress protein 70 family. Hsc70 has been found to be required for HBV DNA replication. Here we report, for the first time, that combined siRNAs targeting viral gene and siHsc70 are highly effective in suppressing ongoing HBV expression and replication.MethodsWe constructed two plasmids (S1 and S2) expressing short hairpin RNAs (shRNAs) targeting surface open reading frame of HBV(HBVS) and one plasmid expressing shRNA targeting Hsc70 (siHsc70), and we used the EGFP-specific siRNA plasmid (siEGFP) as we had previously described. First, we evaluated the gene-silencing efficacy of both shRNAs using an enhanced green fluorescent protein (EGFP) reporter system and flow cytometry in HEK293 and T98G cells. Then, the antiviral potencies of HBV-specific siRNA (siHBV) in combination with siHsc70 in HepG2.2.15 cells were investigated. Moreover, type I IFN and TNF-α induction were measured by quantitative real-time PCR and ELISA.ResultsCotransfection of either S1 or S2 with an EGFP plasmid produced an 80%-90% reduction in EGFP signal relative to the control. This combinational RNAi effectively and specifically inhibited HBV protein, mRNA and HBV DNA, resulting in up to a 3.36 log10 reduction in HBV load in the HepG2.2.15 cell culture supernatants. The combined siRNAs were more potent than siHBV or siHsc70 used separately, and this approach can enhance potency in suppressing ongoing viral gene expression and replication in HepG2.2.15 cells while forestalling escape by mutant HBV. The antiviral synergy of siHBV used in combination with siHsc70 produced no cytotoxicity and induced no production of IFN-α, IFN-β and TNF-α in transfected cells.ConclusionsOur combinational RNAi was sequence-specific, effective against wild-type and mutant drug-resistant HBV strains, without triggering interferon response or producing any side effects. These findings indicate that combinational RNAi has tremendous promise for developing innovative therapy against viral infection.

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Modulation of the chaperone heat shock cognate 70 by embryonic (pro)insulin correlates with prevention of apoptosis.

Publications

Modulation of the chaperone heat shock cognate 70 by embryonic (pro)insulin correlates with prevention of apoptosis.

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