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Diabetic osteoporosis is a severe public health concern in the world. Puerarin (PU) is extensively attractive due to its superior bioactivities. In the study, we found that PU protected against streptozotocin (STZ)-induced osteoporotic changes in rats. PU treatment improved STZ-induced diabetes in rats, as evidenced by the reduced serum glucose and insulin levels. PU administration markedly attenuated bone loss and tartarate-resistant acid phosphatase (TRAP) activity in STZ-induced rats. Bone mineral density (BMD) was significantly decreased in diabetic rats, while being prevented by PU. STZ-induced impairments in microarchitecture of femoral tissues were markedly alleviated by PU treatment. In addition, bone-specific alkaline phosphatase (BALP), osteoprotegerin (OPG) and Runt-related transcription factor 2 (Runx2) levels in serum or tibia were improved by PU in STZ-injected rats; however, TRACP isoform 5b (TRACP-5b), carboxy-terminal collagen cross-links (β-CTX) and receptor activator of nuclear factor-κB ligand (RANKL) levels were decreased. Further, PU treatment inhibited inflammation and apoptosis in STZ-treated rats. Additionally, STZ injection increased histone deacetylase (HDAC)-1 and -3 expressions in femoral heads of rats, which were relieved by PU treatment. Notably, both HDAC1 and HDAC3 could enhance osteoporosis in vitro, as proved by the decreased ALP and Runx2 levels and the increased TRAP expression. Inflammation and apoptosis were exacerbated by HDAC1/3 over-expression, which were markedly diminished by PU treatment. In contrast, suppressing HDAC1/3 significantly abrogated fructose (Fru)-elicited inflammation and apoptosis in cells. Collectively, our data illustrated that PU is a potential therapeutic option to prevent diabetic osteoporosis by inhibiting HDAC1/HDAC3 signaling. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the anti-cancer effect and mechanism of mimic of manganese superoxide dismutase (MnSODm) in gastric carcinoma cells in vitro and in vivo. The MTT was used to measure cytotoxicity of the MnSODm. The appearance of apoptotic BGC-823 cells was detected by flow cytometry analysis. Apoptosis proteins, caspase family and Bcl-2 family were viewed by Western blotting. The phosphoinositide 3 kinase (PI3K)/Akt signaling pathway and the NF-κB pathway were also examined. PI3K inhibitor LY294002 was used to examine the involvement of the PI3K/Akt signaling pathway in this apoptosis-inducing effect. BGC-823 cell xenograft serious combined immunodeficiency disease mice were used for the in vivo study. The result showed that MnSODm could induce growth arrest and apoptosis of BGC-823 cells in vitro and in vivo. Further analysis demonstrated the involvement of activation of caspase cascade in MnSODm induced apoptosis. The expression of anti-apoptotic Bcl-2 was decreased, whereas the expression of pro-apoptotic Bax protein was increased. The main mechanisms on MnSODm-induced apoptosis were related to the inhibition of PI3K expression, which inactivated the phosphorylation of Akt involving the prevention of NF-κB phosphorylation and nuclear translocation. This phenomenon could be inhibited by the PI3K inhibitor LY294002. We demonstrated that the mechanisms of MnSODm inhibited the BGC-823 cell proliferation in vitro primarily are related to the induced apoptosis, which appears to be regulated by the PI3K/Akt pathway involving the prevention of NF-κB nuclear translocation, and then triggering the activation of the caspase cascades. Moreover, the anticancer effect in vivo on BGC-823 cells xenografted mice was also due to MnSODm-mediated apoptosis. [ABSTRACT FROM AUTHOR]

Both calpain activation and endoplasmic reticulum (ER) stress are implicated in ischemic heart injury. However, the role of calpain in ER stress remains largely elusive. This study investigated whether calpain activation causes ER stress, thereby mediating cardiomyocyte apoptosis in an in vitro model of hypoxia/re-oxygenation (H/R). In neonatal mouse cardiomyocytes and rat cardiomyocyte-like H9c2 cells, up-regulation of calpain-1 sufficiently induced ER stress, c-Jun N-terminal protein kinase1/2 (JNK1/2) activation and apoptosis. Inhibition of ER stress or JNK1/2 prevented apoptosis induced by calpain-1. In an in vitro model of H/R-induced injury in cardiomyocytes, H/R was induced by a 24-hour hypoxia followed by a 24-hour re-oxygenation. H/R activated calpain-1, induced ER stress and JNK1/2 activation, and triggered apoptosis. Inhibition of calpain and ER stress blocked JNK1/2 activation and prevented H/R-induced apoptosis. Furthermore, blockade of JNK1/2 signaling inhibited apoptosis following H/R. The role of calpain in ER stress was also demonstrated in an in vivo model of ischemia/reperfusion using transgenic mice over-expressing calpastatin. In summary, calpain-1 induces ER stress and JNK1/2 activation, thereby mediating apoptosis in cardiomyocytes. Accordingly, inhibition of calpain prevents ER stress, JNK1/2 activation and apoptosis in H/R-induced cardiomyocytes. Thus, ER stress/JNK1/2 activation may represent an important mechanism linking calpain-1 to ischemic injury. [ABSTRACT FROM AUTHOR]

The small heat shock protein Hsp20 protects cardiomyocytes against apoptosis, and phosphorylation at its Ser16 site enhances its cardioprotection. To determine whether genetic variants exist in human Hsp20, which may modify these beneficial effects, we sequenced the coding region of the Hsp20 gene in 1347 patients suffering from dilated cardiomyopathy and 744 subjects with no heart disease. We identified a C59T substitution in the human Hsp20 gene in one patient and three individuals without heart disease. All subjects were heterozygous for this mutation, which changes a fully conserved proline residue into leucine at position 20 (P20L), resulting in secondary structural alterations. To examine the potential functional significance of the P20L-Hsp20 human variant, adult rat cardiomyocytes were infected with Ad.GFP (where Ad is adenovirus and GFP is green fluorescent protein), Ad.WTHsp20 (where WT is wild-type), and Ad.P20L-Hsp20 and subjected to simulated ischemia/reperfusion injury. Expression of WT-Hsp20 resulted in significant attenuation of apoptosis compared with the GFP control. However, the P20LHsp20 mutant showed no protection against apoptosis, assessed by Hoechst staining and DNA fragmentation. The loss of cardioprotection by the mutant Hsp20 was associated with its diminished phosphorylation at Ser16 compared with WT-Hsp20. Furthermore, maximal stimulation of cardiomyocytes with isoproterenol or protein kinase A-mediated phosphorylation in vitro confirmed the impaired ability of the mutant Hsp20 to become phosphorylated at Ser16. In conclusion, we have identified a P20L substitution in human Hsp20, which is associated with diminished phosphorylation at Ser16 and complete abrogation of the Hsp20 cardioprotective effects which may adversely affect the ability of human carriers to cope with cellular stress. [ABSTRACT FROM AUTHOR]