Regulation of heat shock protein synthesis by gonadotropins in cultured granulosa cells

Primary cultures of granulosa cells can be stimulated to produce large amounts of progesterone by gonadotropins. This stimulation is associated with significant changes in the expression of several major proteins, as revealed by two-dimensional gel electrophoresis. These changes include a decrease in the synthesis of actin cytoskeleton proteins and an increase in the synthesis of a few abundant proteins, one of which is a mammalian heat shock protein, hsp90. Under culture conditions that have previously been shown to bring about the maturation of granulosa cells into progesterone-producing cells (i.e. treatment with gonadotropins or cAMP or by disrupting the actin cytoskeleton with cytochalasin), an increased synthesis of hsp90 could be demonstrated. Freshly isolated granulosa cells isolated from PMSG-treated animals synthesize hsp90 at a much higher level than cells isolated from diethylstilbestrol-treated rats. Kinetic studies have shown that granulosa cells isolated from diethylstilbestrol- or PMSG-treated rats synthesize high levels of hsp90 if maintained in culture in the presence of gonadotropins, but rapidly decrease hsp90 synthesis in the absence of gonadotropins and increase the synthesis of actin cytoskeleton proteins. Furthermore, in cells cultured for 48 h in the presence of cytochalasin-B followed by incubation for 24 h in the absence of the drug, the synthesis of hsp90 and several other proteins characteristic of mature granulosa cells decreased, while that of the actin cytoskeleton increased. In vitro translation assays and Northern blot analyses suggest that hsp90 synthesis in gonadotropin-stimulated cells may be regulated by mRNA translational efficiency. Taken together with recent findings in which hsp90 was identified in complex with cytoplasmic steroid receptors and the hormonal regulation of hsp90 content in target tissues, the results support the notion that hsp90 plays a role in the control of steroid hormone action.     

Contrasting effects of triiodothyronine on heat shock protein 27 induction and vascular endothelial growth factor synthesis stimulated by TGF-beta in osteoblasts

In osteoblast-like MC3T3-E1 cells, we recently reported that transforming growth factor-beta (TGF-beta) stimulates the induction of heat shock protein 27 (HSP27). In the present study, we investigated the effects of triiodothyronine (T(3)) on the TGF-beta-stimulated induction of HSP27 and synthesis of vascular endothelial growth factor (VEGF) in these cells. T(3) by itself had little effect on the level of HSP27, however, it significantly reduced the TGF-beta-stimulated HSP27 accumulation in a dose-dependent manner in the range between 1 pM and 100 nM. The TGF-beta-stimulated increase in the level of mRNA for HSP27 was also attenuated by T(3). On the other hand, T(3), which alone stimulated the release of VEGF, more than additively stimulated the TGF-beta-induced VEGF release. T(3) enhanced the TGF-beta-induced increase in the levels of mRNA for VEGF. These results strongly suggest that T(3) has contrasting effects on HSP27 induction and VEGF synthesis induced by TGF-beta in osteoblasts.     

Involvement of stress-activated protein kinase/c-Jun N-terminal kinase in endothelin-1-induced heat shock protein 27 in osteoblasts

OBJECTIVE: We have reported that endothelin-1 (ET-1) activates p38 mitogen-activated protein (MAP) kinase through protein kinase C in osteoblast-like MC3T3-E1 cells, and that p38 MAP kinase plays a role in the ET-1-induced heat shock protein 27 (HSP27). Recently, we found that stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) is activated by ET-1 in these cells. In the present study, we have investigated the involvement of SAPK/JNK in ET-1-induced HSP27 in MC3T3-E1 cells. METHODS: The concentration of HSP27 in soluble extracts of the cells, the expression of mRNA for HSP27, and the phosphorylation of SAPK/JNK were determined by an enzyme immunoassay, Northern blot analysis, and Western blot analysis respectively. RESULTS: SP600125, a specific inhibitor of SAPK/JNK, markedly reduced ET-1-stimulated HSP27 accumulation. The inhibitory effect of SP600125 was dose dependent in the range between 1 and 50 microM. SP600125 reduced the ET-1-increased level of HSP27 mRNA. Calphostin C and Go 6976, inhibitors of protein kinase C, reduced the ET-1-induced phosphorylation of SAPK/JNK. 12-O-Tetradecanoylphorbol-13-acetate, a direct activator of protein kinase C, induced SAPK/JNK phosphorylation, which was suppressed by SP600125. A combination of SP600125 and p38 MAP kinase inhibitor such as SB203580 and PD169316 additively reduced the ET-1-stimulated accumulation of HSP27. CONCLUSIONS: These results strongly suggest that JNK plays a part in ET-1-induced HSP27 in addition to p38 MAP kinase in osteoblasts.     

Activation of p38 mitogen-activated protein kinase mediates thyroid hormone-stimulated osteocalcin synthesis in osteoblasts

It is well known that thyroid hormone modulates osteoblast cell function. We have previously shown that triiodothyronine (T(3)) activates p44/p42 mitogen-activated protein (MAP) kinase, which limits T(3)-induced alkaline phosphatase activity in osteoblast-like MC3T3-E1 cells. In the present study, we investigated whether p44/p42 MAP kinase or p38 MAP kinase is involved in the thyroid hormone-stimulated osteocalcin synthesis in these cells. T(3) markedly induced the phosphorylation of p38 MAP kinase in addition to p44/p42 MAP kinase. PD98059 and U0126, inhibitors of the upstream kinase that activates p44/p42 MAP kinase, had little effect on the T(3)-induced synthesis of osteocalcin. On the contrary, the T(3)-induced osteocalcin synthesis was significantly reduced by SB203580 and PD169316, inhibitors of p38 MAP kinase. SB203580, PD169316 or PD98059 suppressed the T(3)-phosphorylation of myelin basic protein. T(3)-induced osteocalcin synthesis was significantly reduced by SB203580 or PD169316 also in primary cultured mouse osteoblasts. These results strongly suggest that p38 MAP kinase but not p44/p42 MAP kinase takes part in the thyroid hormone-stimulated osteocalcin synthesis in osteoblasts.     

Adenylyl cyclase-cAMP system inhibits thyroid hormone-stimulated osteocalcin synthesis in osteoblasts

It is generally recognized that thyroid hormone modulates osteoblast cell function. We have previously shown that triiodothyronine (T(3)) activates p38 mitogen-activated protein (MAP) kinase, resulting in the synthesis of osteocalcin in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effect of the adenylyl cyclase-cAMP system on thyroid hormone-stimulated osteocalcin synthesis in these cells. Dibutyryl-cAMP (DBcAMP) reduced the osteocalcin synthesis stimulated by T(3). Forskolin and cholera toxin suppressed the osteocalcin synthesis while dideoxyforskolin, a forskolin derivative that does not activate adenylyl cyclase, had little effect on the synthesis. KT5720, a selective inhibitor of protein kinase A, reversed the inhibitory effect of forskolin or DBcAMP. DBcAMP and forskolin markedly reduced the phosphorylation of p38 MAP stimulated by T(3). Pituitary adenylate cyclase-activating polypeptide (PACAP) significantly inhibited the T(3)-stimulated osteocalcin synthesis. These results strongly suggest that the adenylyl cyclase-cAMP system has an inhibitory role in thyroid hormone-stimulated osteocalcin synthesis via suppression of p38 MAP kinase activation in osteoblasts.     

Erythrophagocytosis induces heat shock protein synthesis by human monocytes-macrophages.

Exposure of cells to elevated temperatures and other environmental stresses results in the expression of specific genes encoding the so-called heat shock proteins (HSPs). Since exogenous H2O2 induces in human monocytes the synthesis of HSPs, and previous induction of HSPs protects these cells from oxidative injury, we investigated whether HSP synthesis was also induced during generation of reactive oxygen species by the phagocyte itself during phagocytosis. As a model system, we analyzed the effects of erythrophagocytosis on protein synthesis by the human premonocytic line U937, in which phagocytosis is induced during differentiation with 1,25-dihydroxyvitamin D3. Exposure to whole erythrocytes, but not to erythrocyte ghosts, induced in the phagocytic cells only the synthesis of the 70- and 83- to 90-kDa HSPs and a 32-kDa oxidation-related stress protein identical by partial peptide mapping to heme oxygenase. The radioprotective aminothiol N-(2'-mercaptoethyl)-1,3-propanediamine (WR-1065), which can substitute for glutathione as hydrogen donor, prevented this induction. These results suggest that oxygen free radicals generated in the presence of hemoglobin-derived iron and consecutive glutathione depletion are involved in induction of stress protein synthesis during erythrophagocytosis. HSPs synthesized during phagocytosis may play a role in the phagocyte's defense mechanisms and in protective immunity.     

Inhibition of heat shock protein synthesis by heat-inducible antisense RNA.

We show that antisense RNAs transcribed from genes that are stably integrated into the genome can be used to inhibit the expression of an endogenous cellular gene. Drosophila tissue culture cells were stably transformed with a gene encoding a heat-inducible RNA complementary to the message for hsp26, one of the small heat shock proteins. These cells produced much less hsp26 after heat shock than did untransformed cells. The inhibition was highly specific: expression of the closely related heat shock proteins hsp22, hsp23, and hsp28 was unaffected. By varying the copy number of the antisense gene, the degree of inhibition was varied over a broad range. Reducing the rate of hsp26 synthesis did not appear to affect the synthesis of any other protein during either heat shock or recovery.     

热休克蛋白27在脑缺血耐受中的作用

热休克蛋白27( heat shock protein 27,HSP27)是小分子热休克蛋白家族成员之一,其分子伴侣功能以及与细胞死亡通路的相互作用介导了应激状态下的细胞存活.脑缺血时,缺血灶以及远隔区域HSP27表达量及其磷酸化水平变化与神经元对缺血的耐受性有关.然而,HSP27在脑缺血耐受中的神经保护机制至今尚不完...     

AP-1 and heat shock protein 27 expression in human astrocytomas

PURPOSE: In previous work we have shown that the expression of heat shock protein 27 (Hsp27) is associated with anaplastic potential of astrocytomas (Anticancer Res 1997, 17:2677-2682). Heat shock protein-coding genes have been found to have a putative AP-1 (activator protein-1)-binding site in their promoter region and the synthesis of these proteins is induced by the same extracellular stimuli that also activate AP-1 (a homo/heterodimer of members of the Jun and Fos families). In order to detect the putative relation of Hsp27 with AP-1 activation in human astrocytomas we examined eighty astrocytic tumors with different grades of malignancy for c-Jun, c-Fos, and Hsp27 expression. METHODS: Six pilocytic astrocytomas (WHO grade I), 15 diffuse fibrillary astrocytomas (WHO grade II), 19 anaplastic astrocytomas (WHO grade III), and 40 glioblastomas multiforme (WHO grade IV), were studied by immunohistochemistry using monoclonal and polyclonal antibodies directed against human Hsp27, c-Fos, and active (phosphorylated) forms of c-Jun (p-c-Jun). Monoclonal antibodies against the phosphorylated forms of the over-expressed MAP kinases JNK (c-Jun N-terminal kinase) (p-JNK) and p38 (p-p38) were also used. RESULTS: Overexpression of p-c-Jun, c-Fos and p-JNK was observed in the majority of glioblastomas (grade IV) whereas only minimal expression was noted in diffuse fibrillary astrocytomas (grade II). Hsp27 expression was observed only in the tumor specimens where c-Jun and c-Fos were co-expressed. AP-1/Hsp27 co-expression was associated with ascending grading of malignancy and it was independent of the proliferation index of the tumors. CONCLUSIONS: Our findings suggest that during malignant progression of astrocytomas there is activation of signal transduction cascade(s) culminating in AP-1 induction.     

Identification of heat shock protein 27 as a radioresistance-related protein in nasopharyngeal carcinoma cells

Purpose

To identify the proteins involved in radioresistance in nasopharyngeal cancer (NPC) cells.

Methods

Sublethal ionizing radiation was applied to establish a radioresistant NPC cell line from its parental NPC cell line CNE1. Clonogenic survival assay, cell growth assay and flow cytometry analysis were used to examine the difference of radiosensitivity in the radioresistant CNE1 cells (CNE1-IR) and control CNE1 cells. Comparative proteomics was performed to identify the differential proteins in the two cell lines. Association of HSP27, one of upregulated proteins in CNE1-IR cells, with NPC cell radioresistance was selected for further investigation using antisense oligonucleotides (ASOs), clonogenic survival assay, Hoechst 33258 staining of apoptotic cells and MTT assay of cell viability.

Results

Radioresistant NPC cell line CNE1-IR derived from its parental cell line CNE1 was established. Thirteen differential proteins in the CNE1-IR and CNE1 cells were identified by proteomics, and differential expression of HSP27, one of identified proteins, was selectively confirmed by western blot. Inhibition of HSP27 expression by HSP27 ASOs decreased clonogenic survival and cell viability and increased cell apoptosis of CNE1-IR cells after irradiation, that is, enhanced radiosensitivity of CNE1-IR cells.

Conclusion

The data suggest that HSP27 is a radioresistant protein in NPC cells, and its upregulation may be involved in the NPC radioresistance.     

Over-expression of heat shock protein 27 attenuates doxorubicin-induced cardiac dysfunction in mice

BACKGROUND: Oxidative stress and myocyte apoptosis are thought to play an important role in the pathogenesis, progression and prognosis of heart failure (HF). Heat shock protein 27 (Hsp27) has been found to confer resistance to oxidative stress in cultured cells; however, the role of Hsp27 in in-vivo hearts remains to be determined. AIM: To investigate the effects of Hsp27 over-expression on doxorubicin-induced HF. METHODS AND RESULTS: Transgenic mice (TG) with cardiac specific over-expression of Hsp27 and their wild type littermates (WT) were challenged with doxorubicin (25 mg/kg, IP) to induce HF. At day 5, TG mice had significantly improved cardiac function and viability and decreased loss of heart weight following doxorubicin exposure compared with WT. In another parallel experiment, doxorubicin-induced increased levels of reactive oxygen species, protein carbonylation, apoptosis and morphologic changes were detected in the mitochondria in WT hearts, whereas these effects were markedly attenuated in TG hearts. In addition, upregulation of heat shock protein 70 and heme oxygenase-1 was present in the TG hearts after doxorubicin stimulation in comparison to WT hearts. CONCLUSION: These findings indicate that Hsp27 may play a key role in resistance to doxorubicin-induced cardiac dysfunction.     

Overexpression of heat shock protein Hsp27 protects against cerulein-induced pancreatitis

BACKGROUND & AIMS: Heat shock protein (Hsp) 27 regulates actin cytoskeletal dynamics, and overexpression of Hsp27 in fibroblasts protects against stress in a phosphorylation-dependent manner. Induction of Hsps occurs in acute pancreatitis, but Hsp27 has not been ascribed a specific role. To examine whether Hsp27 would ameliorate acute pancreatitis, we generated transgenic mice overexpressing human Hsp27 (huHsp27) or Hsp27 with the phosphorylatable residues Ser(15,78,82) mutated to aspartic acid (huHsp27-3D) to mimic phosphorylation or to alanine (huHsp27-3A), which is nonphosphorylatable. METHODS: huHsp27 was expressed at high levels in the exocrine pancreas by use of a cytomegalovirus promoter. Protein expression was analyzed by Western blotting and immunofluorescence. Acute pancreatitis was induced with 6 or 12 hourly cerulein injections (50 microg/kg intraperitoneally) and its severity assessed by measuring serum amylase and lipase levels, pancreatic trypsin activity, edema, and morphologic changes by quantitative scoring of multiple histologic sections and visualization of filamentous actin. Systemic inflammatory effects were monitored by measuring lung myeloperoxidase activity (a marker of neutrophil infiltration). RESULTS: huHsp27 protein was overexpressed in the pancreas and localized to pancreatic acini. Acute pancreatitis was ameliorated by overexpression of huHsp27 and the huHsp27-3D mutant, which were associated with suppression of pancreatic trypsin activity and acinar cell injury and preservation of the actin cytoskeleton. In contrast, these changes were unaffected by overexpression of the nonphosphorylatable huHsp27-3A mutant. CONCLUSIONS: Pancreatic overexpression of huHsp27 protects against cerulein-induced acute pancreatitis in a specific phosphorylation-dependent manner and is associated with preservation of the actin cytoskeleton.     

HSP27在慢性阻塞性肺疾病中的研究进展

热休克蛋白27是小分子热休克蛋白亚家族的重要一员,在保护细胞免受各种应激损伤的过程中发挥着重要的作用.本文就HSP27在慢性阻塞性肺疾病巾的研究进展进行简要综述.     

内毒素预适应减轻急性肝功能衰竭中热休克蛋白27的作用

目的研究热休克蛋白27（HSP27）介导内毒素（LPS）预适应减轻急性肝功能衰竭（ALF）的作用机制。方法实验动物为雄性C57BL/6小鼠。将小鼠分为5组,对照组为正常C57BL/6小鼠;肝功能衰竭组小鼠以LPS10μg/kg＋D-半乳糖胺700 mg/kg,用1 mL0.9%氯化钠溶液溶解后腹腔内注射,建立急性肝功能衰竭的模型;LPS预处理组小鼠经LPS预适应24 h后,建立急性肝功能衰竭的模型;HSP27干扰组小鼠和转染对照组小鼠分别以尾静脉注射包装有干扰HSP27表达的短发夹RNA的重组腺病毒以及对照空病毒,成功干扰HSP27表达后,经LPS预处理,建立急性肝功能衰竭模型。通过比较各组ALT和AST水平,评价肝组织病理损伤程度,以及检测肝组织内TNF-α、IL-6mRNA水平,观察HSP27对LPS预适应减轻急性肝功能衰竭的影响。结果 LPS预适应可明显减轻Galn/LPS所致的肝损伤,干扰HSP27的表达后,小鼠血清ALT和AST明显升高,肝组织病理损伤和炎性反应加重（P〈0.05）。下调HSP27的表达水平后,LPS预适应的保护作用几乎完全消失。结论 LPS预适应可以减轻小鼠的急性肝损伤,HSP27在这一效应中发挥重要作用。     

超速起搏预适应的延迟保护与热休克蛋白27的表达

目的：观察超速心室起搏（VOP）预适应延迟保护阶段热休克蛋白27（HSP27）的表达水平。方法：新西兰兔24只,随机分为3组,缺血再灌注（I/R）空白对照组,起搏组,起搏＋放线菌素D组。制作I/R和超速起搏预适应的动物模型,检测肌酸激酶（CK）和肌酸激酶-同工酶（CK-MB）水平的变化,动态描记再灌注时心电图,以免疫组织化染色法检测HSP27抗原表达水平。结果：I/R后起搏组心肌酶的水平均明显低于I/R空白对照组和起搏＋放线菌素D组（P〈0.01）;I/R空白对照组在再灌注过程中共有5只（62.5%）发生心律失常,起搏＋放线菌素D组有4只（50.0%）,而起搏组无心律失常发生。起搏组心律失常发生率明显低于I/R空白对照组和起搏＋放线菌素D组（P〈0.05）。起搏组HSP27阳性表达＋＋者（37.5%）明显高于I/R空白对照组和起搏＋放线菌素D组（0,12.5%,P〈0.05）。结论：心室超速起搏预适应有心脏保护作用,其机制可能与热休克蛋白27表达增加密切相关。     

热休克蛋白27/60在胃癌中的表达及意义

目的研究热休克蛋白27和60(HSP27/60)在胃癌组织中的表达及与胃癌生物学行为关系。方法采用免疫组化SABC法检测48例胃癌组织中热休克蛋白27和60的蛋白表达。结果胃癌组织中HSP27和HSP60蛋白表达阳性率分别为64.6%、81.3%;HSP27在胃癌中表达与肿瘤有无远处转移、淋巴结转移个数及浸润深度有关;HSP60表达与肿瘤细胞分化程度及Ki-67增殖指数有关;HSP27/60的表达存在相关性。结论 HSP27/60表达与胃癌生物学行为有相关性,在胃癌的发生、发展过程中发挥着重要的作用。     

Suppression of heat shock protein 27 induces long-term dormancy in human breast cancer

The mechanisms underlying tumor dormancy have been elusive and not well characterized. We recently published an experimental model for the study of human tumor dormancy and the role of angiogenesis, and reported that the angiogenic switch was preceded by a local increase in VEGF-A and basic fibroblast growth factor. In this breast cancer xenograft model (MDA-MB-436 cells), analysis of differentially expressed genes revealed that heat shock protein 27 (HSP27) was significantly up-regulated in angiogenic cells compared with nonangiogenic cells. The effect of HSP27 down-regulation was further evaluated in cell lines, mouse models, and clinical datasets of human patients with breast cancer and melanoma. Stable down-regulation of HSP27 in angiogenic tumor cells was followed by long-term tumor dormancy in vivo. Strikingly, only 4 of 30 HSP27 knockdown xenograft tumors initiated rapid growth after day 70, in correlation with a regain of HSP27 protein expression. Significantly, no tumors escaped from dormancy without HSP27 expression. Down-regulation of HSP27 was associated with reduced endothelial cell proliferation and decreased secretion of VEGF-A, VEGF-C, and basic fibroblast growth factor. Conversely, overexpression of HSP27 in nonangiogenic cells resulted in expansive tumor growth in vivo. By clinical validation, strong HSP27 protein expression was associated with markers of aggressive tumors and decreased survival in patients with breast cancer and melanoma. An HSP27-associated gene expression signature was related to molecular subgroups and survival in breast cancer. Our findings suggest a role for HSP27 in the balance between tumor dormancy and tumor progression, mediated by tumor-vascular interactions. Targeting HSP27 might offer a useful strategy in cancer treatment.