Group Of Heat Shock Proteins Research Articles

Genome-wide analysis and characterization of HSP gene families (HSP20, HSP40, HSP60, HSP70, HSP90) in the yellow fever mosquito (Aedes aegypti) (Diptera: Culicidae)

Abstract The heat shock protein (HSP) gene families, present across prokaryotes to eukaryotes, play vital roles in growth, development, and heat resistance processes. While HSP proteins have been identified and characterized in various species, this study achieved the first genome-wide identification and characterization of HSP proteins in the Aedes aegypti genome. This study identified and assessed 80 potential HSP genes in Ae. aegypti. The phylogenetic relationships of HSP genes were investigated in Ae. aegypti, Anopheles stephensi, and Drosophila melanogaster. Additionally, the structural features, chromosomal locations, protein characteristics, 3D structure, protein–protein interactions, and microsatellites associated with HSP proteins were examined in Ae. aegypti. The phylogenetic analysis of HSP gene families revealed distinct intra-group relationships for each HSP group. Each family exhibited relatively conserved genetic structures and motif components. In the expression analysis of growth and development, high expression was observed in certain HSP20 and HSP70 genes, while others exhibited low expression. Notably, sex-dependent expression differences were observed, particularly in HSP20 genes. These findings, the relationships, evolution, and modification of HSP gene families are illuminated by these comprehensive findings, and a better understanding of the mechanisms underlying growth, development, and heat resistance in vector organisms is facilitated.

Omics analyses in citrus reveal a possible role of RNA translation pathways and Unfolded Protein Response regulators in the tolerance to combined drought, high irradiance, and heat stress.

Environmental changes derived from global warming and human activities increase the intensity and frequency of stressful conditions for plants. Multiple abiotic factors acting simultaneously enhance stress pressure and drastically reduce plant growth, yield, and survival. Stress combination causes a specific stress situation that induces a particular plant response different to the sum of responses to the individual stresses. Here, by comparing transcriptomic and proteomic profiles to different abiotic stress combinations in two citrus genotypes, Carrizo citrange (Citrus sinensis×Poncirus trifoliata) and Cleopatra mandarin (Citrus reshni), with contrasting tolerance to different abiotic stresses, we revealed key responses to the triple combination of heat stress, high irradiance and drought. The specific transcriptomic response to this stress combination in Carrizo was directed to regulate RNA metabolic pathways and translation processes, potentially conferring an advantage with respect to Cleopatra. In addition, we found endoplasmic reticulum stress response as common to all individual and combined stress conditions in both genotypes and identified the accumulation of specific groups of heat shock proteins (HSPs), such as small HSPs and HSP70s, and regulators of the unfolded protein response, BiP2 and PDIL2-2, as possible factors involved in citrus tolerance to triple stress combination. Taken together, our findings provide new insights into the acclimation process of citrus plants to multiple stress combination, necessary for increasing crop tolerance to the changing climatic conditions.

Proteomic analysis reveals that the heat shock proteins 70-17 and BiP5 enhance cotton male fertility under high-temperature stress by reducing the accumulation of ROS in anthers

Cotton (Gossypium hirsutum) is a typical tropical and subtropical commercial crop. During the reproductive development period of cotton, high temperature (HT) weather frequently occurs, which leads to male abortion and yield loss. Identifying proteins that experience coordinated metabolism in anthers during HT stress could provide information regarding protein dynamics under HT stress and assist in developing HT-tolerant cotton varieties. In the current study, two-dimensional electrophoresis (2-DE) of the anthers of an HT-sensitive line (H05) and an HT-tolerant line (84021) was performed. In total, 307 differentially expressed protein spots were identified in the anthers of the H05 and 84021 lines. The Gene Ontology analysis revealed that protein processing in the endoplasmic reticulum pathway plays a major role in the anther response to HT stress conditions involving a group of heat shock proteins (HSPs). Among these HSPs, HSP70-17 and binding protein 5 (BiP5) play vital roles under HT stress conditions in cotton. Furthermore, HSP70-17 and BiP5 proteins were expressed and verified through a prokaryotic expression system and western blot analysis, respectively. Exogenous applications of HSP70-17 and BiP5 proteins reduced ROS accumulation in pollen grains under HT stress conditions. These results suggest that HSP70-17 and BiP5 are the key proteins in Gossypium hirsutum anthers responding to HT stress and provide a genetic resource for the development of novel cotton HT-tolerant cultivars.

Mitigation of Heat Stress in Broiler Chickens with Heat Shock Protein 70 Gene Expression as its Indicator

<p class="awabstrak2"><span lang="EN-US">Heat stress is an important issue in broiler chicken farms in tropical countries, such as Indonesia. Heat stress is very detrimental to broiler chickens because reducing production performance, health, and causing mortality. In the condition of heat stress, broilers synthesize Heat Shock Protein (HSP) quickly as the body's response to heat stress. HSP 70 is the most studied HSP group related to heat stress. The objective of this study was to review the nutritional approach that has been done to mitigate heat stress in broiler chickens with the HSP70 gene expression as its indicator. Based on some studies, nutritional approaches that can be taken are through the management of feed availability, supplementation of vitamin C, vitamin E, plant bioactives, amino acids (taurine and glutamine), probiotics, prebiotics, synbiotics, manan oligo saccharide (MOS) and minerals (selenium, zinc, manganese, chromium). By these approaches, HSP70 gene expression decreased indicating that the heat stress level of broiler chicken also reduced. It can be concluded that the nutritional approach can be used as a method for heat stress mitigation in broilers with the HSP70 gene expression indicator. </span></p>

Consequences of Atrial or Ventricular Tachypacing on the Heat Shock Proteins (HSP) level of Expression and Phosphorylation

Uncontrolled atrial fibrillation (AF) results in complex changes in the cardiomyocyte electrical and contractile functioning that promote atrial remodeling and the continuation of AF. Recently there has been a growing interest in understanding the role of heat shock proteins (HSPs), which are cytoprotective molecular chaperones, in the pathophysiology of AF. Several groups have examined HSP expression in patients with AF but have yielded mixed results. To allow for better consistency and reproducibility between subjects, we utilized canine models to reproduce AFpromoting conditions to better investigate the role of HSPs in the pathophysiology of AF. AF promoting conditions were simulated in canine models with fifteen adult mongrel dogs (20.6 to 36.0 kg) divided into three groups: (1) Control (n=5), (2) two week ventricular tachypacing (VTP) induced congestive heart failure (CHF) (n=5), and (3) one week atrial tachypacying (ATP) (n=5). Quick frozen right atrial free wall tissue samples were used for protein isolation and were analyzed via Western blotting with data was expressed as a relative ratio and were analyzed using a two-tailed, unpaired ttest and significance was set at p < 0.05. The expression levels of HSP 90, 70, and 25 were studied along with the phosphorylation status of HSP27 at serine-78. We first examined the effects of the ATP and CHF heart models on the expression of a select group of HSPs via Western Blot. We found that there was no significant difference in levels of expression of HSP 90, 70, or 25 when either ATP or CHF models were compared to control canines. The phosphorylation status of HSP27 was significantly decreased in the CHF canine model when compared to control (p < 0.0111) and it tended towards a decrease in the ATP canine model when compared to control (p=0.0923). This study showed that even though the expression levels of HSPs may remain constant, there are protein phosphorylation and dephosphorylation events that occur in AF that may have important consequences in its pathophysiology. It is therefore necessary to investigate the full scale of HSP modifications during AF and AF-promoting conditions.

Trypanosoma brucei J-Protein 2 Functionally Co-Operates with the Cytosolic Hsp70 and Hsp70.4 Proteins.

The etiological agent of African trypanosomiasis, Trypanosoma brucei (Tb), has been identified to possess an expanded and diverse group of heat shock proteins, which have been implicated in cytoprotection, differentiation, and subsequently progression and transmission of the disease. Heat shock protein 70 (Hsp70) is a highly conserved and ubiquitous molecular chaperone that is important in maintaining protein homeostasis in the cell. Its function is regulated by a wide range of co-chaperones, and inhibition of these functions and interactions with co-chaperones are emerging as potential therapeutic targets for numerous diseases. This study sought to biochemically characterize the cytosolic TbHsp70 and TbHsp70.4 proteins and to investigate if they functionally co-operate with the Type I J-protein, Tbj2. Expression of TbHsp70 was shown to be heat inducible, while TbHsp70.4 was constitutively expressed. The basal ATPase activities of TbHsp70.4 and TbHsp70 were stimulated by Tbj2. It was further determined that Tbj2 functionally co-operated with TbHsp70 and TbHsp70.4 as the J-protein was shown to stimulate the ability of both proteins to mediate the refolding of chemically denatured β-galactosidase. This study provides further insight into this important class of proteins, which may contribute to the development of new therapeutic strategies to combat African Trypanosomiasis.

Comparative co-expression network analysis extracts the SlHSP70 gene affecting to shoot elongation of tomato.

Tomato is one of vegetables crops that has the highest value in the world. Thus, researchers are continually improving the agronomical traits of tomato fruits. Auxins and gibberellins regulate plant growth and development. Aux/indole-3-acetic acid 9 (SlIAA9) and the gene encoding the DELLA protein (SlDELLA) are well-known genes that regulate plant growth and development, including fruit set and enlargement by cell division and cell expansion. The absence of tomato SlIAA9 and SlDELLA results in abnormal shoot growth and leaf shape and giving rise to parthenocarpy. To investigate the key regulators that exist up- or downstream of SlIAA9 and SlDELLA signaling pathways for tomato growth and development, we performed gene co-expression network analysis by using publicly available microarray data to extract genes that are directly connected to the SlIAA9 and SlDELLA nodes, respectively. Consequently, we chose a gene in the group of heat-shock protein (HSP)70s that was connected with the SlIAA9 node and SlDELLA node in each co-expression network. To validate the extent of effect of SlHSP70-1 on tomato growth and development, overexpressing lines of the target gene were generated. We found that overexpression of the targeted SlHSP70-1 resulted in internode elongation, but the overexpressing lines did not show abnormal leaf shape, fruit set, or fruit size when compared with that of the wild type. Our study suggests that the targeted SlHSP70-1 is likely to function in shoot growth, like SlIAA9 and SlDELLA, but it does not contribute to parthenocarpy as well as fruit set. Our study also shows that only a single SlHSP70 out of 25 homologous genes could change the shoot length.

Expression of thermal tolerance genes in two Drosophila species with different acclimation capacities.

Heat tolerance increases at higher acclimation temperatures in D. melanogaster, but not in D. subobscura. The two species represent separate lineages of the subgenus Sophophora of Drosophila with contrasting tropical African and temperate Palearctic evolutionary histories. D. melanogaster has five copies of the inducible hsp70 gene distributed in two clusters, named A (with two copies) and B (three copies), while D. subobscura has only two copies arranged similarly to cluster A of D. melanogaster. The hsp70s of the two species also differ in their cis-regulatory regions, with D. melanogaster exhibiting features of a faster and more productive promoter. We predicted that the interspecific variation in acclimation capacity of heat tolerance is explained by evolved variation in expression of the major group of heat shock proteins. To test this prediction, we compared basal levels of gene expression at different developmental temperatures within each of the two species. Furthermore, we explored the heat hardening dynamics by measuring the induction of gene expression during a ramping assay. The prediction of a stronger heat shock protein response in D. melanogaster as compared to D. subobscura was confirmed for both long-term acclimation and short-term hardening. For D. melanogaster the upregulation with temperature ramping ranged from less than two fold (hsp26) to 2500 fold (hsp70A) increase. In all cases induction in D. melanogaster exceeded that of D. subobscura homologs. These differences correlate with structural differences in the regulatory regions of hsp70, and might explain differences in acclimation capacity among species. Finally, in D. melanogaster we found an indication of an inverse relationship between basal and induced levels of hsp70A and hsp83 expression, suggesting a divergent role for thermal adaptation of these genes at benign and stressful temperatures, respectively.

MAIN STAGES OF PLANT CELLULAR RESPONSE TO HEAT STRESS

The article provides a recapitulation of published data on plant cellular response to high temperature stress. We have reviewed the main stages of this response: heat sensing and signal transduction and synthesis of heat shock proteins (HSP). Some structures and components of plant cells, which are the most probable participants of heat sensing, are described. An emphasis is placed on plasmalemma, calcium channels and calcium ions. The hypothesis of the participation of cytoskeleton, phytochrome B, HSP70 and HSP90 is also considered. Another idea of the article is possible participation of secondary stress, for example ER-stress, in heat sensing and signaling. It is shown that calcium ions and reactive oxygen species (ROS) are components of the heat sigaling pathway. Additionally, calcium-binding proteins, lipid signaling molecules, phytohormones and transcription factors (HSF, MBF1, DREB, C2H2 ZF) can participate in signal transduction pathways induced by high temperature. The article stresses a particular role of heat shock proteins (HSPs) in plant response to heat stress. Five major groups of HSP (HSP100, HSP90, HSP70, HSP60, sHSP) are taken into consideration. Sensing of heat, heat signal transduction pathways and synthesis of HSP are the main events in the process of plant cellular response to high temperature stress. The final result of these events and other temperature-dependent changes in plants is enhanced thermotolerance of plant cells and whole plants that lead to higher plant survival under high temperature stress.

Characterisation and expression analysis of trophozoite and cyst proteins of Acanthamoeba spp. isolated from Acanthamoeba keratitis (AK) patient

The study was carried out to characterise and analyze the expression pattern of proteins of infective trophozoite and cyst forms of Acanthamoeba spp. isolated from an amoebic keratitis patient. Protein was isolated from the trophozoites and cysts of Acanthamoeba spp. isolates and subjected to SDS PAGE, 2D PAGE analysis where a large number of protein bands and protein spots were observed. Four prominent protein spots i.e. 2 from trophozoites and 2 from cysts that appeared more intense compared to the corresponding spots in other corresponding gel were excised from the 2D PAGE gels and analysed by MALDI-TOF/TOF MS assay and Mascot search software. Protein spots from trophozoites were identified as “hypothetical protein ACA1” and “eukaryotic porin protein” and those from cysts were identified as “chaperone protein DnaK” and “chaperonin protein” respectively. Proteomic results of 4 proteins were further validated by reverse genomics using quantitative real time PCR assay which showed a 1388 fold and 4.35 fold increase in expression of “hypothetical protein ACA1” gene and “eukaryotic porin protein” gene respectively in trophozoites compared to cysts and a 15 fold and 12.36 fold increase in expression of “chaperone protein DnaK” gene and “chaperonin protein” gene respectively in cysts compared to trophozoites. “Hypothetical protein ACA1” of trophozoites, whose function is unknown might have some important role in the parasite division and pathogenicty of Acanthamoeba spp. which needs further study. As trophozoites are the active and feeding form of Acanthamoeba spp., “eukaryotic porin” proteins may have some important role in efflux of toxic metabolites and exudates from interior of cell to outside along with some role in pathogenicity. Similarly proteins such as “chaperone protein DnaK” and “chaperonin protein” which belongs to group of heat shock proteins may have a role in folding of cyst specific proteins in cyst which needs further study.

Hsp90·Cdc37 Complexes with Protein Kinases Form Cooperatively with Multiple Distinct Interaction Sites

Protein kinases are the most prominent group of heat shock protein 90 (Hsp90) clients and are recruited to the molecular chaperone by the kinase-specific cochaperone cell division cycle 37 (Cdc37). The interaction between Hsp90 and nematode Cdc37 is mediated by binding of the Hsp90 middle domain to an N-terminal region of Caenorhabditis elegans Cdc37 (CeCdc37). Here we map the binding site by NMR spectroscopy and define amino acids relevant for the interaction between CeCdc37 and the middle domain of Hsp90. Apart from these distinct Cdc37/Hsp90 interfaces, binding of the B-Raf protein kinase to the cochaperone is conserved between mammals and nematodes. In both cases, the C-terminal part of Cdc37 is relevant for kinase binding, whereas the N-terminal domain displaces the nucleotide from the kinase. This interaction leads to a cooperative formation of the ternary complex of Cdc37 and kinase with Hsp90. For the mitogen-activated protein kinase extracellular signal-regulated kinase 2 (Erk2), we observe that certain features of the interaction with Cdc37·Hsp90 are conserved, but the contribution of Cdc37 domains varies slightly, implying that different kinases may utilize distinct variations of this binding mode to interact with the Hsp90 chaperone machinery.

Detection of autoantibodies against heat shock proteins and collapsin response mediator proteins in autoimmune retinopathy

BackgroundAutoimmune retinopathy (AR) and Cancer-Associated Retinopathy (CAR) are associated with a diverse repertoire of anti-retinal autoantibodies (AAbs) but not all antigenic targets have been characterized. Identification of new AAbs may help with clinical diagnosis and prognosis of retinal dysfunction in AR. The goal was to identify frequently targeted retinal autoantigens within the 60-70-kDa molecular weight range.MethodsHuman retinal proteins were separated by SDS-PAGE and 2D gel electrophoresis (2-DE) and sera from AR patients with and without cancer were used to identify immunoreactive proteins by Western blotting. Proteins were identified following separation by electrophoresis, Coomassie staining using in-gel trypsin digestion and mass spectrometric analysis. Circulating serum hsp60 and anti-hsp60 antibody levels were determined by quantitative ELISA.ResultsRetrospective evaluation of 819 patients with anti-retinal AAbs showed that 29% patients had AAbs targeted proteins between 60-70-kDa. Shotgun mass spectrometry of human retinal proteins present in 1D-gel found 66 species within this range. To identify the immunoreactive proteins, we performed Western blots of 2-DE gels and showed a group of heat shock proteins (hsps), including hsp60 and CRMP proteins that were frequently recognized by AR patient AAbs, irrespective of cancer status. These results were validated by immunostaining of purified hsp60 and CRMP2 proteins. ELISA results revealed that patients with AR and CAR had significantly increased levels of serum anti-hsp60 antibodies compared to control healthy subjects (p < 0.0001). However, circulating hsp60 protein was not significantly elevated in sera of either patient group.ConclusionsDifferent anti-retinal antibodies frequently co-exist in a single patient, creating antibody-arrays related to the syndrome. Hsps and CRMP-2 are newly identified autoantigens in AR. A frequent co-association of anti-hsp antibodies with other anti-retinal AAbs may augment pathogenic processes, leading to retinal degeneration.

Heat Shock Protein 70 Acts as a Potential Biomarker for Early Diagnosis of Heart Failure

Early identification for heart failure (HF) may be useful for disease modifying treatment in order to reduce heart disease progression or even to reverse it. In our previous studies, we have revealed a group of heat shock proteins (HSPs) which might be related to neonatal rat cardiomyocyte hypertrophy by proteomic approach. Here, we confirm that HSPs, including HSP27 and HSP70, altered in the early stage of cardiac remodeling in vivo animal model. Furthermore, plasma concentrations of those HSPs and their potential screening value were evaluated at different stages in 222 patient subjects. Plasma HSP27, HSP70 and HSP90 were measured using enzyme-linked immunosorbent assay. Results indicate that HSP70 was positively correlated to the severity (progression) of HF (r = 0.456, p<0.001). The area under the rate of change (ROC) curve was 0.601 (p = 0.017) in patients with stage B HF and 0.835 (p<0.001) in those with stage C HF. However, HSP27 and HSP90 did not display significant changes in any stage of HF in this study. Taken together, plasma concentrations of HSP70 elevated with the progression of HF and might act as a potential screening biomarker for early diagnosis of HF.

STK31(TDRD8) is dynamically regulated throughout mouse spermatogenesis and interacts with MIWI protein

Tudor-domain-containing proteins (TDRDs) are suggested to be critical regulators of germinal granules assembly involved in Piwi-interacting RNAs (piRNAs)-mediated pathways, of which associated components and the underlying functional mechanisms, however, remain to be elucidated. We herein characterized the expression pattern of STK31, a member of TDRDs subfamily (also termed as TDRD8), throughout spermatogenesis during mouse postnatal development. RT-PCR and Western blot verified its preferential expression in testis, but not in any other somatic tissues, in addition to embryonic stem cells. Immunofluorescent staining demonstrated that STK31 was confined to granules-like structures in mid-to-late spermatocyte cytoplasm and to acrosomal cap starting at steps 7-8 of spermatids. Furthermore, STK31 retained its localization to equatorial segment of acrosome during epididymal maturation, capacitation, and acrosome reaction. Co-immunoprecipitation assay in vivo and in vitro confirmed MIWI is a bona fide partner of STK31 in mice testes, in combination with LC/MS identification. We also discovered a group of heat shock proteins specifically associated with STK31 in vivo. Our findings suggest mouse STK31 could be a potential nuage-associated protein in the cytoplasm of mid-to-late spermatocytes and play pivotal roles related to fertilization.

Quantitative transcription dynamic analysis reveals candidate genes and key regulators for ethanol tolerance in Saccharomyces cerevisiae.

BackgroundDerived from our lignocellulosic conversion inhibitor-tolerant yeast, we generated an ethanol-tolerant strain Saccharomyces cerevisiae NRRL Y-50316 by enforced evolutionary adaptation. Using a newly developed robust mRNA reference and a master equation unifying gene expression data analyses, we investigated comparative quantitative transcription dynamics of 175 genes selected from previous studies for an ethanol-tolerant yeast and its closely related parental strain.ResultsA highly fitted master equation was established and applied for quantitative gene expression analyses using pathway-based qRT-PCR array assays. The ethanol-tolerant Y-50316 displayed significantly enriched background of mRNA abundance for at least 35 genes without ethanol challenge compared with its parental strain Y-50049. Under the ethanol challenge, the tolerant Y-50316 responded in consistent expressions over time for numerous genes belonging to groups of heat shock proteins, trehalose metabolism, glycolysis, pentose phosphate pathway, fatty acid metabolism, amino acid biosynthesis, pleiotropic drug resistance gene family and transcription factors. The parental strain showed repressed expressions for many genes and was unable to withstand the ethanol stress and establish a viable culture and fermentation. The distinct expression dynamics between the two strains and their close association with cell growth, viability and ethanol fermentation profiles distinguished the tolerance-response from the stress-response in yeast under the ethanol challenge. At least 82 genes were identified as candidate and key genes for ethanol-tolerance and subsequent fermentation under the stress. Among which, 36 genes were newly recognized by the present study. Most of the ethanol-tolerance candidate genes were found to share protein binding motifs of transcription factors Msn4p/Msn2p, Yap1p, Hsf1p and Pdr1p/Pdr3p.ConclusionEnriched background of transcription abundance and enhanced expressions of ethanol-tolerance genes associated with heat shock proteins, trehalose-glycolysis-pentose phosphate pathways and PDR gene family are accountable for the tolerant yeast to withstand the ethanol stress, maintain active metabolisms, and complete ethanol fermentation under the ethanol stress. Transcription factor Msn4p appeared to be a key regulator of gene interactions for ethanol-tolerance in the tolerant yeast Y-50316.

The Small Heat Shock Protein HSP25/27 (HspB1) Is Abundant in Cultured Astrocytes and Associated with Astrocytic Pathology in Progressive Supranuclear Palsy and Corticobasal Degeneration

Filamentous tau-positive protein inclusions in neurons and glia are prominent features of a number of neurodegenerative disorders termed tauopathies. These inclusions are further characterized by the presence of heat shock proteins (HSPs). The group of small HSPs, namely, HSP27 and αB-crystallin, interact with the cytoskeleton, bind to nonnative proteins, and prevent their aggregation after stress. To further investigate their contribution to neurodegenerative diseases, we have analyzed the association of HSP27 with pathological lesions of tauopathies. Microarray and immunoblot analysis revealed that HSP27 is enhanced at the mRNA and protein levels in affected brains, and that it is associated with astrocytic pathology. The upregulation of HSP27 in tauopathies with gial pathology implies distinct mechanisms for glial and neuronal cells. This was sustained by cell culture studies, demonstrating that the small HSPs are specifically and prominently expressed in unstressed astrocytes and not in neurons and in neurons remained at a rather low level even after stress situations.

HspB8 Chaperone Activity toward Poly(Q)-containing Proteins Depends on Its Association with Bag3, a Stimulator of Macroautophagy

Mutations in HspB8, a member of the B group of heat shock proteins (Hsp), have been associated with human neuromuscular disorders. However, the exact function of HspB8 is not yet clear. We previously demonstrated that overexpression of HspB8 in cultured cells prevents the accumulation of aggregation-prone proteins such as the polyglutamine protein Htt43Q. Here we report that HspB8 forms a stable complex with Bag3 in cells and that the formation of this complex is essential for the activity of HspB8. Bag3 overexpression resulted in the accelerated degradation of Htt43Q, whereas Bag3 knockdown prevented HspB8-induced Htt43Q degradation. Additionally, depleting Bag3 caused a reduction in the endogenous levels of LC3-II, a key molecule involved in macroautophagy, whereas overexpressing Bag3 or HspB8 stimulated the formation LC3-II. These results suggested that the HspB8-Bag3 complex might stimulate the degradation of Htt43Q by macroautophagy. This was confirmed by the observation that treatments with macroautophagy inhibitors significantly decreased HspB8- and Bag3-induced degradation of Htt43Q. We conclude that the HspB8 activity is intrinsically dependent on Bag3, a protein that may facilitate the disposal of doomed proteins by stimulating macroautophagy.

Comparison of gene expression profile between human chondrons and chondrocytes: a cDNA microarray study

The chondron is a basic unit of articular cartilage that includes the chondrocyte and its pericellular matrix (PCM). This current study was designed to investigate the effects of the chondron PCM on the gene expression profile of chondrocytes. Chondrons and chondrocytes were enzymatically isolated from human articular cartilage, and maintained in pellet culture. Pellets of chondrons or chondrocytes were collected at days 1, 3 and 5 for cDNA microarray analysis. In comparison with chondrocytes alone, chondrons had 258 genes, in a broad range of functional categories, either up- or downregulated at the three time points tested. At day 1, 26 genes were significantly upregulated in chondrons and four downregulated in comparison to chondrocytes. At day 3, the number of upregulated chondron genes was 97 and the number downregulated was 43. By day 5, there were more downregulated genes (56) than upregulated genes (32) in chondrons. Upregulation of a group of heat shock proteins (HSPA1A, HSPA2 and HSPA8) in chondrons was validated by real time reverse transcription polymerase chain reaction (RT-PCR). Genes related to chondrocyte hypertrophy and dedifferentiation such as SSP1 and DCN were downregulated in chondrons as compared to the expression in chondrocytes. The presence of the PCM in chondrons has a profound influence on chondrocyte gene expression. Upregulation of the heat shock protein 70 may contribute to the robustness and active matrix production of chondrons. The intact PCM may further stabilize the phenotype of chondrocytes within chondrons.

Overexpression of heat shock factor 1 inhibits butyrate-induced differentiation in colon cancer cells

Produced by dietary fiber, butyrate is a potential chemopreventive agent against colon cancer. It stimulates proliferation of normal colonic epithelial cells but induces growth inhibition, differentiation, apoptosis, or a combination of effects in colon carcinoma cells. In this study, we used cDNA membrane arrays and real-time reverse transcriptase-polymerase chain reaction to identify stress genes that were differentially regulated by sodium butyrate (NaB) in HT 29 human colon carcinoma cells. The results indicated that a group of heat shock protein (hsp) genes were upregulated by 3 mM NaB within the first 24 hours of exposure. Because the transcription of hsp genes is under the control of heat shock factors (HSFs), we measured the effects of overexpressed HSF-1 on the responses of HT 29 cells to NaB. Overexpression of HSF-1 inhibited NaB-induced differentiation as measured by alkaline phosphatase activity and carcinoembryonic antigen expression. These results suggest that increased expression of HSFs and Hsps might render colon carcinoma cells resistant to the chemopreventive effects of butyrate.

Heat shock protein 70 negatively regulates the heat-shock-induced suppression of the IκB/NF-κB cascade by facilitating IκB kinase renaturation and blocking its further denaturation

Heat shock (HS) treatment has been previously shown to suppress the IκB/nuclear factor-κB (NF-κB) cascade by denaturing, and thus inactivating IκB kinase (IKK). HS is characterized by the induction of a group of heat shock proteins (HSPs). However, their role in the HS-induced suppression of the IκB/NF-κB cascade is unclear. Adenovirus-mediated HSP70 overexpression was found not to suppress the TNF-α-induced activation of the IκB/NF-κB pathway, thus suggesting that HSP70 is unlikely to suppress this pathway. When TNF-α-induced activation of the IκB/NF-κB pathway was regained 24 h after HS, HSP70 was found to be highly up-regulated. Moreover, blocking HSP70 induction delayed TNF-α-induced IκBα degradation and the resolubilization of IKK. In addition, HSP70 associated physically with IKK, suggesting that HSP70 is involved in the recovery process via molecular chaperone effect. Adenovirus-mediated HSP70 overexpression prior to HS blocked the IκBα stabilizing effect of HS by suppressing IKK insolubilization. Moreover, the up-regulation of endogenous HSP70 by preheating, suppressed this subsequent HS-induced IKK insolubilization, and this effect was abrogated by blocking HSP70 induction. These findings indicate that HSP70 accumulates during HS and negatively regulates the HS-induced suppression of the IκB/NF-κB cascade by facilitating the renaturation of IKK and blocking its further denaturation.