Heat shock proteins Hsp70-1 and Hsp70-3 Are necessary and sufficient to prevent arsenite-induced dysmorphology in mouse embryos

Gene expression of Hsps in normal and abnormal embryonic development of mouse hindlimbs

Heat shock proteins (Hsps), which have important biological functions, are a class of highly conserved genetic molecules with the capacity of protecting and promoting cells to repair themselves from damage caused by various stimuli. Our previous studies found that Hsp25, HspB2, HspB3, HspB7, Hsp20, HspB9, HspB10, and Hsp40 may be related to all-trans retinoic acid (atRA)-induced phocomelic and other abnormalities, while HspA12B, HspA14, Trap1, and Hsp105 may be forelimb development-related genes; Grp78 may play an important role in forelimb development. In this study, the embryonic phocomelic, oligodactylic model of both forelimbs and hindlimbs was developed by atRA administered per os to the pregnant mice on gestational day 11, and the expression of 36 members of Hsps family in normal and abnormal development of embryonic hindlimbs was measured by real-time fluorescent quantitative polymerase chain reaction (qRT-PCR). It is found that HspA1L, Hsp22, Hsp10, Hsp60, Hsp47, HspB2, HspB10, HspA12A, Apg1, HspB4, Grp78, and HspB9 probably performs a major function in limb development, and HspA13, Grp94 and Hsp110 may be hindlimb development-related genes.

External and internal shell formation in the ramshorn snail Marisa cornuarietis are extremes in a continuum of gradual variation in development

BACKGROUND

Toxic substances like heavy metals can inhibit and disrupt the normal embryonic development of organisms. Exposure to platinum during embryogenesis has been shown to lead to a "one fell swoop" internalization of the shell in the ramshorn snail Marisa cornuarietis, an event which has been discussed to be possibly indicative of processes in evolution which may result in dramatic changes in body plans.

RESULTS

Whereas at usual cultivation temperature, 26°C, platinum inhibits the growth of both shell gland and mantle edge during embryogenesis leading to an internalization of the mantle and, thus, also of the shell, higher temperatures induce a re-start of the differential growth of the mantle edge and the shell gland after a period of inactivity. Here, developing embryos exhibit a broad spectrum of shell forms: in some individuals only the ventral part of the visceral sac is covered while others develop almost "normal" shells. Histological studies and scanning electron microscopy images revealed platinum to inhibit the differential growth of the shell gland and the mantle edge, and elevated temperature (28 - 30°C) to mitigate this platinum effect with varying efficiency.

CONCLUSION

We could show that the formation of internal, external, and intermediate shells is realized within the continuum of a developmental gradient defined by the degree of differential growth of the embryonic mantle edge and shell gland. The artificially induced internal and intermediate shells are first external and then partly internalized, similar to internal shells found in other molluscan groups.

Induction of Heat Shock Proteins and Antioxidant Enzymes in 2,3,7,8-TCDD-Induced Hepatotoxicity in Rats

2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) is an environmental toxicant with a polyhalogenated aromatic hydrocarbon structure and is one of the most toxic man-made chemicals. Exposure to 2,3,7,8-TCDD induces reproductive toxicity, immunotoxicity, and hepatotoxicity. In this study, we evaluated how 2,3,7,8-TCDD-induced hepatotoxicity affect the expression of heat shock proteins and antioxidant enzymes using the real-time polymerase chain reaction (PCR) in rat. 2,3,7,8-TCDD increased heat shock protein (Hsp27, α-B-crystallin, Mortalin, Hsp105, and Hsp90s) and antioxidant enzymes (SOD-3, GST and catalase) expression after a 1 day exposure in livers of rats, whereas heat shock protein (α-B-crystallin, Hsp90, and GRP78) and antioxidant enzymes (SOD-1, SOD-3, catalase, GST, and GPXs) expression decreased on day 2 and then slowly recovered back to control levels on day 8. These results suggest that heat shock proteins and antioxidant enzymes were induced as protective mechanisms against 2,3,7,8-TCDD induced hepatotoxicity, and that prolonged exposure depressed their levels, which recovered to control levels due to reduced 2,3,7,8-TCDD induced hepatotoxicity.

Gene expression of Hsp70, Hsp90 and Hsp110 families in normal palate and cleft palate during mouse embryogenesis

Most previous studies focused on a small number of heat shock proteins (Hsps) and their relationships with embryogenesis, and the actual roles of these Hsps in normal and abnormal embryonic development remain unclear. It was found in the present systemic study that except for Grp170, whose expression was not detectable at GD18, all 19 Hsps of Hsp70, Hsp90 and Hsp110 families were expressed in the normal development of embryonic palate tissue in mice, but their expression patterns varied with different Hsps, presenting as a correlation with the developmental phases. In the treatment group by all-trans retinoic acid (atRA), the messenger RNA (mRNA) abundance of HspA1A, HspA1L, HspA8, HspA9, HspA12A, HspA12B, HspA13, HspA14, Hsp90AA1, Hsp90AB1, Grp94, Trap1, Hsp105, Hsp110 and Grp170 was higher in the palates at GD11 (the beginning of palate development), the mRNA abundance of HspA1A, HspA12A and HspA12B was higher at GD18 (before birth) and an mRNA expression peak of HspA1L, HspA8, HspA9, Hsp90AA1, Grp94, Hsp110 and Grp170 was observed at GD17. The mRNA abundance of most genes in atRA-induced cleft palates of the treatment group was different from that of the control group. Grp78, HspA14 and Hsp105 were closely associated with the normal palate development and cleft palate in mouse embryo, possibly as palate development-related genes. Except Grp170, the other genes may be closely associated with the development of mouse palates through participating in the stress response process and/or the antiapoptosis process.

Expression pattern of testis-specific expressed gene 2 in cryptorchidism model and its role in apoptosis of spermatogenic cells

In our previous study, we identified a novel testis-specific expressed gene 2 (TSEG-2) from mouse testis. To further investigate its functions, 35 male Balb/c mice (8 weeks old) were divided into cryptorchidism group (n=20), sham group (n=10), and control group (n=5). In cryptorchidism group, the right testes were anchored to the inner lateral abdominal wall. In situ hybridization (ISH) was applied to measure the localization of TSEG-2 in mouse testis. Real-time quantitative PCR was performed to detect the expression of TSEG-2 gene. Meanwhile, under the mediation of polyethylenimine (PEI), the recombinant vector pEGFP-TSEG-2 (n=5) or empty vector (mock, n=5) was transfected into the testis of male mice. The transfection efficiencies were measured under a fluorescence microscope. The apoptosis of spermatogenic cells was detected by terminal deoxynuleotidyl-mediated nick end labeling (TUNEL). The results showed that TSEG-2 was expressed in convoluted seminiferous tubules, more precisely, in spermatogonia and spermatocytes. As compared with sham and control groups, the TSEG-2 transcription was significantly enhanced (P<0.05) and was correlated with apoptosis of spermatogenic cells in cryptorchid testes (P<0.05). PEI was efficient in mediating transfection of TSEG-2 into seminiferous tubules of testis. One week post-transfection, intratesticular injection of TSEG-2 resulted in increased apoptosis of spermatogenic cells in vivo (P<0.05). These results indicate that TSEG-2 may participate in the apoptosis of spermatogenic cells and the pathogenesis of cryptorchidism.

Inducible 70 kDa heat shock protein does not protect spermatogenic cells from damage induced by cryptorchidism

Accumulation of inducible heat shock proteins (e.g. Hsp70i) during cellular stress confers thermotolerance, reduces the consequences of damage and facilitates cellular recovery, while abrogation of Hsp70i expression renders sensitivity to apoptosis. Testis translocation into abdominal cavity, which results in temperature elevation, does not induce expression of the Hsp70i proteins. Despite constitutive expression of testis-specific Hsp70 proteins, spermatocytes are very sensitive to damage at elevated temperatures. To test whether Hsp70i protein could protect testes from heat-induced damage, we have engineered transgenic mice that over-express this protein selectively in spermatocytes and spermatids. We demonstrate that the testes of cryptorchid transgenic mice, like those of wild-type mice, exhibit reduced weight and smaller sizes of their seminiferous tubules, disorganization of their germinal epithelium structures, appearance of multinucleated giant cells, and reduced populations of germ cells. The data show that constitutive expression of Hsp70i does not protect the seminiferous epithelium against cryptorchidism-induced damage.

Molecular cloning of a novel rat gene Tsarg1, a member of the DnaJ/HSP40 protein family

Beginning with a mouse gene mTSARG3, which was related to apoptosis of spermatogenic cells, bioinformatics was applied and a predicted novel rat gene full-length cDNA sequence was attained. Gene-specific primers were designed for PCR in rat testis cDNA library. A new gene Tsarg1 (GenBank Accession No. AY380804) was cloned, which is related to apoptosis in rat spermatogenic cells. The gene whose full cDNA length is 1176 bp containing 8 exons and 7 introns is located in rat chromosome 1q32-1q33, which encoded a protein containing 316 amino acid residues and being a new member of HSP40 protein family since the sequence contains the highly conserved J domain, which is present in all DnaJ-like proteins and is supported to have a critical role in DnaJ-DnaK protein-protein interactions. The results of RT-PCR and Northern blot analysis showed that Tsarg1 was specifically expressed in rat testis, which probably inhibits rat testis spermatogenic cell apoptosis.

Gene Expression and Developmental Competence of Bovine Embryos Produced In Vitro with Different Serum Concentrations

The objective of this study was to determine the developmental rates and relative abundance of Hsp 70.1 and Glut-1 transcripts in in vivo- and in vitro-produced (IVP) bovine embryos in media supplemented with bovine serum albumin (BSA) or different oestrous cow serum concentrations. In experiment 1, in vitro maturation and culture media were supplemented with 0.4% BSA or 1, 5, 10 or 20% of oestrous cow serum (ECS). The analysis of the expression of Hsp 70.1 and Glut-1 was carried out in individual days 7 and 8 embryos by a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay. In experiment 2, in vivo-produced morulae were collected on day 7 of the oestrous cycle and employed for the comparison of the relative abundances of Hsp 70.1 and Glut-1 transcripts with IVP morulae produced using two protein sources (10% ECS or 0.4% BSA). No differences were observed in cleavage rate among groups, but blastocyst formation (27%) and hatching rates (78%) were significantly higher in IVP embryos produced with 20% ECS than the other groups (p<0.05). No significant differences were observed in the relative abundances of Hsp 70.1 and Glut-1 mRNA in days 7 and 8 blastocysts expanded blastocysts between groups. The abundances of mRNA for those genes were similar between IVP and in vivo-produced morulae. In spite of the alterations observed in embryonic development, the presence of serum at distinct concentrations did not appear to alter the relative abundance profiles of Hsp 70.1 and Glut-1 compared with controls or the BSA supplementation to the IVP media.

Gene expression and developmental competence of bovine embryos produced in vitro under varying embryo density conditions

The objective of this study was to determine the effects of oocyte/embryo density (embryo number:medium volume ratio) on developmental competence and relative transcription of developmentally important genes in in vitro-produced bovine embryos. Using standard procedures, bovine oocytes were matured, fertilized and cultured in vitro in groups of 5, 10, 20 or 30 oocytes/embryos per 100 microL medium drop (embryo number/medium volume ratios of 1:20, 1:10, 1:5 and 1:3.3, respectively). A semi-quantitative RT-PCR assay was used to determine the relative abundance of Hsp 70.1 and Glut-1 transcripts in Day-6 morulae, and in Day-7 and Day-8 blastocysts and expanded blastocysts. Cleavage rates (55.9, 49.1, 47.1 and 34.6%, respectively) and blastocyst developmental rates (24.1, 18.9, 20.4 and 12.6%, respectively) were higher in groups containing 5, 10 and 20 embryos versus 30 embryos per drop, but there were no significant differences among groups in hatching rates. The relative abundance of Hsp 70.1 transcripts in Day-7 blastocysts was higher in embryos produced in the 20-embryo than in the 5-embryo groups. There were no differences among embryos from all groups in the amount of Glut-1 mRNA (regardless of embryonic stage). However, there were differences in the pattern of Hsp 70.1 gene expression between distinct stages of embryo development and embryo density; these dissimilarities appeared to be associated with compromised development at higher embryo densities. In conclusion, the increase in embryo density during IVM, IVF, and IVC phases of in vitro embryo production might negatively affect embryo development and the pattern of gene expression of in vitro-produced bovine embryos.

Arsenic trioxide therapy in acute promyelocytic leukemia and beyond: from bench to bedside

Arsenic trioxide (As2O3) has a long history of use in medicine. However, it was almost forgotten in Western medicine in the recent centuries. Prompted by reports from China about successful treatment of acute promyelocytic leukemia (APL) with As2O3, there was again increasing interest in this drug in the 1990s. This review summarizes the considerable knowledge about the mechanisms of action of As2O3 that was gained during the last 5-10 years. It is focused in particular on the effects of As2O3 in non-APL cells. Since As2O3 seems to induce apoptosis and inhibits growth in a large variety of cellular targets, it might become an alternative or adjunct drug to conventional chemotherapy. As2O3 can even be effective in cells resistant to conventional cytostatic agents. Insight into the cellular mechanisms, in particular the impact of the redox state on sensitivity towards As2O3 opens the possibility to enhance As2O3 effects by appropriate combination therapies.

Mercury, cadmium, and arsenite enhance heat shock protein synthesis in chick embryos prior to embryotoxicity

BACKGROUND

Cells respond to adverse environmental stimuli by enhancing the expression of specific genes, the products of which include a suite of proteins known as heat shock proteins (hsps), a response often attributed to cellular protection.

METHODS

In this study, we characterized alterations in hsp expression in chick embryos (Hamburger-Hamilton stage 17, 72 h) exposed in ovo to arsenite (As), mercury (Hg), and cadmium (Cd), known developmental toxicants. Embryos were incubated for 2 h following exposure to 3, 10, 30, or 100 nmol metal, or for 2, 4, 12, or 24 h following treatment with 10 nmol metal.

RESULTS

An enhanced de novo synthesis of 24-, 70-, and 90-kD, 70- and 90-kD, and 70-kD proteins was observed with As, Hg, and Cd treatments, respectively. These responses were transient; apparent rates of protein synthesis were maximal 2-4 h after exposure and returned to control rates by 24 h. Actinomycin D experiments demonstrated that arsenite-induced expression of these proteins is transcriptionally regulated. Immunoblotting experiments identified the 24-, 70-, and 90-kD proteins as the heat shock proteins hsp24, hsp70, and hsp90, respectively. Exposure duration-related abnormalities were noted in the neural tube with all metals and in the ganglia and somites with Cd and As. Retina, allantois, and limb defects were specific to Cd-treated embryos, and branchial arch defects were specific to As-treated embryos.

CONCLUSIONS

The data support metal-induced developmental abnormalities, which are preceded by synthesis of stress proteins.

Effects of heat shock protein 70 (Hsp70) on arsenite-induced genotoxicity

Arsenic, a human carcinogen, is genotoxic, although its mechanism(s) of action for tumorigenesis is not well understood. Among the toxicity-related properties of this chemical are its clastogenic and aneugenic activities, as well as its capacity for inducing stress-response in the form of elevated heat shock protein (HSP) expression. In the present study, we evaluated the effects of Hsp70 expression on arsenite (As)-induced structural and numerical chromosome anomalies in human cells. Human MCF-7 Tet-off cells stably transfected with a pTRE/Hsp70-1 transgene construct were used to regulate Hsp70 levels prior to in vitro As exposures. Separate cultures of relatively high vs. low Hsp70-expressing cells were established. A cytokinesis block micronucleus assay with kinetochore immunostaining was used to detect micronuclei (MN) derived from chromosome breakage (K-MN) or loss (K+MN). These studies demonstrated significant increases in micronucleus frequencies in response to As following either a long exposure (5 or 10 microM for 46 hr), or short exposure (10 or 40 microM for 8 hr) protocol. Overall, the long protocol was more efficient in producing K+MN and cells with multiple MN. Overexpressing Hsp70 resulted in significant reductions in the percent of cells positive for MN for both the long and short As exposure protocols. Both K+ and K- types of As-induced MN were lower in cells with elevated Hsp70 as compared to cells without overexpression of Hsp70. We conclude that the dose and duration of As exposure influence the type as well as amount of chromosomal alteration produced and that inducible Hsp70 protects against both the clastogenic and aneugenic effects of this chemical.