The role of Hsp27 and actin in the regulation of movement in human cancer cells responding to heat shock

Heat Shock Protein 27 Is Involved in the Bioactive Glass Induced Osteogenic Response of Human Mesenchymal Stem Cells

Bioactive glass (BaG) materials are increasingly used in clinics, but their regulatory mechanisms on osteogenic differentiation remain understudied. In this study, we elucidated the currently unknown role of the p38 MAPK downstream target heat shock protein 27 (HSP27), in the osteogenic commitment of human mesenchymal stem cells (hMSCs), derived from adipose tissue (hASCs) and bone marrow (hBMSCs). Osteogenesis was induced with ionic extract of an experimental BaG in osteogenic medium (OM). Our results showed that BaG OM induced fast osteogenesis of hASCs and hBMSCs, demonstrated by enhanced alkaline phosphatase (ALP) activity, production of extracellular matrix protein collagen type I, and matrix mineralization. BaG OM stimulated early and transient activation of p38/HSP27 signaling by phosphorylation in hMSCs. Inhibition of HSP27 phosphorylation with SB202190 reduced the ALP activity, mineralization, and collagen type I production induced by BaG OM. Furthermore, the reduced pHSP27 protein by SB202190 corresponded to a reduced F-actin intensity of hMSCs. The phosphorylation of HSP27 allowed its co-localization with the cytoskeleton. In terminally differentiated cells, however, pHSP27 was found diffusely in the cytoplasm. This study provides the first evidence that HSP27 is involved in hMSC osteogenesis induced with the ionic dissolution products of BaG. Our results indicate that HSP27 phosphorylation plays a role in the osteogenic commitment of hMSCs, possibly through the interaction with the cytoskeleton.

Integrity and wound healing of rainbow trout intestinal epithelial cell sheets at hypo-, normo-, and hyper-thermic temperatures

How temperature influences fish physiological systems, such as the intestinal barrier, is important for understanding and alleviating the impact of global warming on fish and aquaculture. Monolayers of the rainbow trout cell line, RTgutGC, with or without linear 500 μm wide gaps (wounds) were the in vitro models used to study the integrity and healing of intestinal epithelial sheets at different temperatures. Cultures at hypothermic (4 °C) or hyperthermic (≥ 26 °C) temperatures were compared to normothermic control cultures (18-22 °C). Monolayers remained intact for at least a week at temperatures from 4 to 28 °C, but had lost their integrity after 3 h at 32 °C as the cells pulled away from one another and from the plastic surface. F-actin appeared as prominent stress fibers in cells at 28 °C and as blobs in cells at 32 °C. At normothermia and at 26 °C, cells migrated as sheets into the gaps and closed (healed) the gaps within 5-6 days. By contrast, wounds took 14 days to heal at 4 °C. At 28 °C some cells migrated into the gap in the first few days but mainly as single cells rather than collectively and wounds never healed. When monolayers with wounds were challenged at 32 °C for 3 h and returned to 18-22 °C, cells lost their shape and actin organization and over the next 6 days detached and died. When monolayers were subjected to 26 °C for 24 h and challenged at 32 °C for 3 h prior to being placed at 18-22 °C, cell shape and actin cytoskeleton were maintained, and wounds were healed over 6 days. Thus, intestinal epithelial cells become thermostabilized for shape, cytoskeleton and migration by a prior heat exposure.

Mitogen-activated protein kinase-activated protein kinase-2 (MK2) and its role in cell survival, inflammatory signaling, and migration in promoting cancer

Cancer and the immune system share an intimate relationship. Chronic inflammation increases the risk of cancer occurrence and can also drive inflammatory mediators into the tumor microenvironment enhancing tumor growth and survival. The p38 MAPK pathway is activated both acutely and chronically by stress, inflammatory chemokines, chronic inflammatory conditions, and cancer. These properties have led to extensive efforts to find effective drugs targeting p38, which have been unsuccessful. The immediate downstream serine/threonine kinase and substrate of p38 MAPK, mitogen-activated-protein-kinase-activated-protein-kinase-2 (MK2) protects cells against stressors by regulating the DNA damage response, transcription, protein and messenger RNA stability, and motility. The phosphorylation of downstream substrates by MK2 increases inflammatory cytokine production, drives an immune response, and contributes to wound healing. By binding directly to p38 MAPK, MK2 is responsible for the export of p38 MAPK from the nucleus which gives MK2 properties that make it unique among the large number of p38 MAPK substrates. Many of the substrates of both p38 MAPK and MK2 are separated between the cytosol and nucleus and interfering with MK2 and altering this intracellular translocation has implications for the actions of both p38 MAPK and MK2. The inhibition of MK2 has shown promise in combination with both chemotherapy and radiotherapy as a method for controlling cancer growth and metastasis in a variety of cancers. Whereas the current data are encouraging the field requires the development of selective and well tolerated drugs to target MK2 and a better understanding of its effects for effective clinical use.

Extracellular heat shock proteins in cancer: From early diagnosis to new therapeutic approach

In cancer, human cells lose the ability to properly control the series of events that occur constantly during cell growth and division, including protein expression, stability, and dynamics. Heat shock proteins (Hsps) are key molecules in these events, constitutively expressed at high levels and could furthermore be induced by the response to cancer-induced stress. In tumor cells, Hsps have been shown to be implicated in the regulation of apoptosis, immune responses, angiogenesis and metastasis; in some cases, they can be overexpressed and dysregulated, representing important cancer hallmarks. In the past few years, it has been demonstrated that Hsps can be released by tumor cells through several secreting pathways, including the extracellular vesicles (EVs), thus modulating the tumor microenvironment as well as long-distance intercellular communication and metastatization. In this review, we discuss the role of extracellular Hsps in cancer, with a particular interest in Hsps in EVs. We would also like to highlight the importance of fully understanding of the role of extracellular Hsps released by EVs and encourage further research in this field the use of Hsps as early cancer biomarkers and therapeutic targets.

CHIP-dependent regulation of the actin cytoskeleton is linked to neuronal cell membrane integrity

CHIP is an E3-ubiquitin ligase that contributes to healthy aging and has been characterized as neuroprotective. To elucidate dominant CHIP-dependent changes in protein steady-state levels in a patient-derived human neuronal model, CHIP function was ablated using gene-editing and an unbiased proteomic analysis conducted to compare knock-out and wild-type isogenic induced pluripotent stem cell (iPSC)-derived cortical neurons. Rather than a broad effect on protein homeostasis, loss of CHIP function impacted on a focused cohort of proteins from actin cytoskeleton signaling and membrane integrity networks. In support of the proteomics, CHIP knockout cells had enhanced sensitivity to induced membrane damage. We conclude that the major readout of CHIP function in cortical neurons derived from iPSC of a patient with elevate α-synuclein, Parkinson's disease and dementia, is the modulation of substrates involved in maintaining cellular "health". Thus, regulation of the actin cytoskeletal and membrane integrity likely contributes to the neuroprotective function(s) of CHIP.

Responses and coping methods of different testicular cell types to heat stress: overview and perspectives

To facilitate temperature adjustments, the testicles are located outside the body cavity. In most mammals, the temperature of the testes is lower than the body temperature to ensure the normal progression of spermatogenesis. Rising temperatures affect spermatogenesis and eventually lead to a decline in male fertility or even infertility. However, the testes are composed of different cell types, including spermatogonial stem cells (SSCs), spermatocytes, spermatozoa, Leydig cells, and Sertoli cells, which have different cellular responses to heat stress. Recent studies have shown that using different drugs can relieve heat stress-induced reproductive damage by regulating different signaling pathways. Here, we review the mechanisms by which heat stress damages different cells in testes and possible treatments.

Hsa_circ_0072309 inhibits proliferation and invasion of glioblastoma

Increasing literature reported that circRNAs play vital roles in the occurrence and progression of GBM and regulate GBM cell proliferation, metastases, and chemosensitivity. However, the expression pattern and function of circRNAs in GBM still need further studies. In our work, hsa_circ_0072309 was remarkably downregulated in GBM. Hsa_circ_0072309 inhibits proliferation and invasion of glioblastoma and affects cytoskeletal of GBM cells. Moreover, we found that the function of hsa_circ_0,072,309 in GBM was associated with HSP27, which was reported to be an important regulator of cell proliferation, invasion and cytoskeletal. Our study provides a novel view of hsa_circ_0072309 in GBM cell proliferation and invasion, indicating that hsa_circ_0072309 may act as a potential therapeutic target for GBM comprehensive treatment.

SteC and the intracellular Salmonella-induced F-actin meshwork

Salmonella enterica serovars infect a broad range of mammalian hosts including humans, causing both gastrointestinal and systemic diseases. Following uptake into host cells, bacteria replicate within vacuoles (Salmonella-containing vacuoles; SCVs). Clusters of SCVs are frequently associated with a meshwork of F-actin. This meshwork is dependent on the Salmonella pathogenicity island 2 encoded type III secretion system and its effector SteC. SteC contains a region with weak similarity to conserved subdomains of eukaryotic kinases and has kinase activity that is required for the formation of the F-actin meshwork. Several substrates of SteC have been identified. In this mini-review, we attempt to integrate these findings and propose a more unified model to explain SCV-associated F-actin: SteC (i) phosphorylates the actin sequestering protein Hsp27, which increases the local G-actin concentration (ii) binds to and phosphorylates formin family FMNL proteins, which enables actin polymerisation and (iii) phosphorylates MEK, resulting in activation of the MEK/ERK/MLCK/Myosin II pathway, leading to F-actin bundling. We also consider the possible physiological functions of SCV-associated F-actin and similar structures produced by other intracellular bacterial pathogens.

The Tudor-domain protein TDRD7, mutated in congenital cataract, controls the heat shock protein HSPB1 (HSP27) and lens fiber cell morphology

Mutations of the RNA granule component TDRD7 (OMIM: 611258) cause pediatric cataract. We applied an integrated approach to uncover the molecular pathology of cataract in Tdrd7-/- mice. Early postnatal Tdrd7-/- animals precipitously develop cataract suggesting a global-level breakdown/misregulation of key cellular processes. High-throughput RNA sequencing integrated with iSyTE-bioinformatics analysis identified the molecular chaperone and cytoskeletal modulator, HSPB1, among high-priority downregulated candidates in Tdrd7-/- lens. A protein fluorescence two-dimensional difference in-gel electrophoresis (2D-DIGE)-coupled mass spectrometry screen also identified HSPB1 downregulation, offering independent support for its importance to Tdrd7-/- cataractogenesis. Lens fiber cells normally undergo nuclear degradation for transparency, posing a challenge: how is their cell morphology, also critical for transparency, controlled post-nuclear degradation? HSPB1 functions in cytoskeletal maintenance, and its reduction in Tdrd7-/- lens precedes cataract, suggesting cytoskeletal defects may contribute to Tdrd7-/- cataract. In agreement, scanning electron microscopy (SEM) revealed abnormal fiber cell morphology in Tdrd7-/- lenses. Further, abnormal phalloidin and wheat germ agglutinin (WGA) staining of Tdrd7-/- fiber cells, particularly those exhibiting nuclear degradation, reveals distinct regulatory mechanisms control F-actin cytoskeletal and/or membrane maintenance in post-organelle degradation maturation stage fiber cells. Indeed, RNA immunoprecipitation identified Hspb1 mRNA in wild-type lens lysate TDRD7-pulldowns, and single-molecule RNA imaging showed co-localization of TDRD7 protein with cytoplasmic Hspb1 mRNA in differentiating fiber cells, suggesting that TDRD7-ribonucleoprotein complexes may be involved in optimal buildup of key factors. Finally, Hspb1 knockdown in Xenopus causes eye/lens defects. Together, these data uncover TDRD7's novel upstream role in elevation of stress-responsive chaperones for cytoskeletal maintenance in post-nuclear degradation lens fiber cells, perturbation of which causes early-onset cataracts.

The inflammatory markers sST2, HSP27 and hsCRP as a prognostic biomarker panel in chronic heart failure patients

BACKGROUND

The inflammatory markers sST2, HSP27 and hsCRP have already been identified as prognostic markers in chronic heart failure (HF). Though individual biomarkers have proven their value in mortality risk prediction, the role of a multimarker strategy needs further evaluation.

MATERIALS AND METHODS

This is an exploratory reanalysis in chronic HF patients. Plasma HSP27, sST2 and hsCRP in outpatients with chronic HF were analysed. Patients were followed for a minimum of twelve months for the endpoint cardiovascular mortality and unplanned HF associated hospitalisation (=event). 15 year overall mortality was assessed retrospectively. The prognostic impact was assessed using a Cox proportional hazard model.

RESULTS

113 chronic HF patients were included. Median follow up time was 614 days and 37 patients (32.7%) experienced an event. A Kaplan-Meier analysis revealed that patients with increased sST2, HSP27 and hsCRP levels have significantly worse prognosis (p < 0.001). The use of a three-biomarker combination was superior in an independent risk prediction of an event (one high vs. two high: HR = 4.5, 95% CI: 1.3-15.5, p = 0.018; and one high vs. all high: HR = 9.8, 95% CI: 2.8-34.3, p < 0.001) as shown in a multivariable cox proportional hazard model. However, the biomarker panel did not predict 15 year overall mortality, in contrast to elevated HSP27 levels (p = 0.012).

CONCLUSIONS

The combination of all three markers is an independent predictor of cardiovascular death and unplanned HF associated hospitalisation but not overall mortality. Our findings suggest that adding those markers in combination to well established risk assessment parameters may improve risk stratification.

Small heat shock protein genes are developmentally regulated during stress and non-stress conditions in Blastocladiella emersonii

Small heat shock proteins (sHsps) are molecular chaperones of low molecular weight involved in an early association with misfolded proteins. In response to heat shock, B. emersonii induces the synthesis of a number of proteins. As sHsps are still poorly studied in B. emersonii and in fungi overall, the aim of this work was to carry out a in-depth characterization of sHsps during B. emersonni life cycle, as well as in response to thermal stress. We verified a strong induction of the hsp17 gene in cells exposed to heat shock both in germination and sporulation stages, and that Hsp17 protein levels show the same pattern of variation of its mRNA. Unlike hsp17 and hsp30, hsp16 gene is not significantly induced during heat shock, in germination or sporulation cells. However, at normal temperatures, the hsp16 gene presents high mRNA levels in sporulation cells, whereas the hsp30 gene presents high mRNA levels in germination cells. Interestingly, heat shock mRNA levels for hsp17 and hsp30 genes are 10 times higher in germination cells than in sporulation cells. Thus, our data show that the expression of these sHsp genes is quite distinct, both under normal temperature as during heat shock.

A new role for heat shock factor 27 in the pathophysiology of Clostridium difficile toxin B

Clostridiumdifficile (CD) is a common pathogen that causes severe gastrointestinal inflammatory diarrhea in patients undergoing antibiotic therapy. Its virulence derives from two toxins, toxin CD, A and B (TcdA and TcdB) (Borriello et al. Rev Infect Dis 12, Suppl 2: S185-191, 1990). Among the prime candidates for CD colonization are patients with cystic fibrosis (CF), who are routinely treated with antibiotics and frequently hospitalized. Indeed, ~50% of patients with CF are colonized with virulent forms of CD but do not exhibit diarrhea (Bauer et al. Clin Microbiol Infect 20: O446-O449, 2014; Binkovitz et al. Am J Roentgenol 172: 517-521, 199; Zemljic et al. Anaerobe 16: 527-532, 2010). We found that TcdB has global effects on colonic cells, including reducing the steady-state levels of sodium-proton exchange regulatory factors, reducing the levels of heat shock protein (Hsp) 27, and increasing the fraction of total Hsp27 bound to the cystic fibrosis transmembrane conductance regulator (CFTR). Also, since some mutations in CFTR seem to be protective, we asked whether CFTR is a target of TcdB. We show here that TcdB increases the maturation of CFTR and transiently increases its function. These combined effects promote increased surface expression of CFTR, resulting in a transient increase in Cl^- secretion. This increase is followed by a precipitous decline in both CFTR-dependent Cl^- secretion and transepithelial resistance (TER), suggesting a breakdown in the epithelial cells' tight junctions. We also found that overexpressing Hsp27 reverses some of the deleterious effects of TcdB, in particular preserving TER and therefore likely the maintenance of barrier function. Thus, our data suggest that Hsp27 plays a role in the diarrhea generated by CD infection and is a potential therapeutic target for treating this diarrhea.NEW & NOTEWORTHYClostridium difficile (CD) is a common pathogen that causes severe gastrointestinal inflammatory diarrhea in patients undergoing antibiotic therapy. We provide new evidence that heat shock protein (Hsp) 27 is one of the key players in CD pathology and that increasing Hsp27 can prevent the decrease in transepithelial resistance induced by toxin CD B, pointing the way for pharmacologic therapies for patients with chronic CD infection that can increase Hsp27 as a means to mitigate the effects of CD on gastrointestinal pathology.

MAPKAP kinase 2-mediated phosphorylation of HspA1L protects male germ cells from heat stress-induced apoptosis

Developing male germ cells are extremely sensitive to heat stress; consequently, anatomic and physiologic adaptations have evolved to maintain proper thermoregulation during mammalian spermatogenesis. At the cellular level, increased expression and activity of HSP70 family members occur in response to heat stress in order to refold partially denatured proteins and restore function. In addition, several kinase-mediated signaling pathways are activated in the testis upon hyperthermia. The p38 MAP kinase (MAPK) pathway plays an important role in mitigating heat stress, and recent findings have implicated the downstream p38 substrate, MAPKAP kinase 2 (MK2), in this process. However, the precise function that this kinase plays in spermatogenesis is not completely understood. Using a proteomics-based screen, we identified and subsequently validated that the testis-enriched HSP70 family member, HspA1L, is a novel substrate of MK2. We demonstrate that MK2 phosphorylates HspA1L solely on Ser241, a residue within the N-terminal nucleotide-binding domain of the enzyme. This phosphorylation event enhances the chaperone activity of HspA1L in vitro and renders male germ cells more resistant to heat stress-induced apoptosis. Taken together, these findings illustrate a novel stress-induced signaling cascade that promotes the chaperone activity of HspA1L with implications for understanding male reproductive biology.

Endothelial Cell Mechano-Metabolomic Coupling to Disease States in the Lung Microvasculature

Lungs are the most vascular part of humans, accepting the totality of cardiac output in a volume much smaller than the body itself. Due to this cardiac output, the lung microvasculature is subject to mechanical forces including shear stress and cyclic stretch that vary with the cardiac and breathing cycle. Vessels are surrounded by extracellular matrix which dictates the stiffness which endothelial cells also sense and respond to. Shear stress, stiffness, and cyclic stretch are known to influence endothelial cell state. At high shear stress, endothelial cells exhibit cell quiescence marked by low inflammatory markers and high nitric oxide synthesis, whereas at low shear stress, endothelial cells are thought to "activate" into a pro-inflammatory state and have low nitric oxide. Shear stress' profound effect on vascular phenotype is most apparent in the arterial vasculature and in the pathophysiology of vascular inflammation. To conduct the flow of blood from the right heart, the lung microvasculature must be rigid yet compliant. It turns out that excessive substrate rigidity or stiffness is important in the development of pulmonary hypertension and chronic fibrosing lung diseases via excessive cell proliferation or the endothelial-mesenchymal transition. Recently, a new body of literature has evolved that couples mechanical sensing to endothelial phenotypic changes through metabolic signaling in clinically relevant contexts such as pulmonary hypertension, lung injury syndromes, as well as fibrosis, which is the focus of this review. Stretch, like flow, has profound effect on endothelial phenotype; metabolism studies due to stretch are in their infancy.

Neuropathy-causing mutations in HSPB1 impair autophagy by disturbing the formation of SQSTM1/p62 bodies

HSPB1 (heat shock protein family B [small] member 1) is a ubiquitously expressed molecular chaperone. Most mutations in HSPB1 cause axonal Charcot-Marie-Tooth neuropathy and/or distal hereditary motor neuropathy. In this study we show that mutations in HSPB1 lead to impairment of macroautophagic/autophagic flux. In HSPB1 knockout cells, we demonstrate that HSPB1 is necessary for autophagosome formation, which was rescued upon re-expression of HSPB1. Employing a label-free LC-MS/MS analysis on the various HSPB1 variants (wild type and mutants), we identified autophagy-specific interactors. We reveal that the wild-type HSPB1 protein binds to the autophagy receptor SQSTM1/p62 and that the PB1 domain of SQSTM1 is essential for this interaction. Mutations in HSPB1 lead to a decrease in the formation of SQSTM1/p62 bodies, and subsequent impairment of phagophore formation, suggesting a regulatory role for HSPB1 in autophagy via interaction with SQSTM1. Remarkably, autophagy deficits could also be confirmed in patient-derived motor neurons thereby indicating that the impairment of autophagy might be one of the pathomechanisms by which mutations in HSPB1 lead to peripheral neuropathy. Abbreviations: ACD: alpha-crystallin domain; ALS: amyotrophic lateral sclerosis; ATG14: autophagy related 14; BAG1/3: BCL2 associated athanogene 1/3; CMT: Charcot-Marie-Tooth; dHMN: distal hereditary motor neuropathy; GFP: green fluorescent protein; HSPA8: heat shock protein family A (Hsp70) member 8; HSPB1/6/8: heat shock protein family B (small) member 1/6/8; LIR: LC3-interacting region; LC3B: microtubule associated protein 1 light chain 3 beta; PB1: Phox and Bem1; SQSTM1: sequestosome 1; STUB1/CHIP: STIP1 homology and U-box containing protein 1; UBA: ubiquitin-associated; WIPI1: WD repeat domain, phosphoinositide interacting 1; WT: wild-type.

Stress-induced tunneling nanotubes support treatment adaptation in prostate cancer

Tunneling nanotubes (TNTs) are actin-based membranous structures bridging distant cells for intercellular communication. We define roles for TNTs in stress adaptation and treatment resistance in prostate cancer (PCa). Androgen receptor (AR) blockade and metabolic stress induce TNTs, but not in normal prostatic epithelial or osteoblast cells. Co-culture assays reveal enhanced TNT formation between stressed and unstressed PCa cells as well as from stressed PCa to osteoblasts. Stress-induced chaperones clusterin and YB-1 localize within TNTs, are transported bi-directionally via TNTs and facilitate TNT formation in PI3K/AKT and Eps8-dependent manner. AR variants, induced by AR antagonism to mediate resistance to AR pathway inhibition, also enhance TNT production and rescue loss of clusterin- or YB-1-repressed TNT formation. TNT disruption sensitizes PCa to treatment-induced cell death. These data define a mechanistic network involving stress induction of chaperone and AR variants, PI3K/AKT signaling, actin remodeling and TNT-mediated intercellular communication that confer stress adaptative cell survival.

MiR-214 sensitizes human colon cancer cells to 5-FU by targeting Hsp27

Overcoming chemorestistance to 5-fluorouracil (5-FU) could offer a new treatment option for highly malignant colon cancer. In our study, differential microRNA expression profiling revealed that miR-214 is downregulated in 5-FU-resistant colon cancer cells compared to normal cells. In vitro, miR-214 could sensitize non-resistant colon cancer cells and 5-FU-resistant colon cancer cellsto 5-FU. Functionally, miR-214 inhibited cell clone formation and cell growth and enhanced 5-FU-inducing cell apoptosis and caspase-3 levels. MiR-214 targeted heat shock protein 27 (Hsp27), as confirmed via dual luciferase reporter assays and western blots. Hsp27 also sensitized HT-29 and LoVo to 5-FU by enhancing cell apoptosis. Overexpression of Hsp27 could block miR-214 with an effect on the sensitivity of colon cancer cells to 5-FU. In conclusion, miR-214 sensitizes colon cancer cells to 5-FU by targeting Hsp27, indicating a significant role for this miRNA in colon cancer chemotherapy.

Silencing Heat Shock Protein 27 Inhibits the Progression and Metastasis of Colorectal Cancer (CRC) by Maintaining the Stability of Stromal Interaction Molecule 1 (STIM1) Proteins

The incidence of colorectal cancer (CRC) has significantly increased in recent decades, and this disease has become an important health issue worldwide. Currently, there is no useful prognostic or diagnostic biomarker for CRC. Heat shock protein 27 (HSP27) is a chaperone that interacts with many proteins. HSP27 has been shown to be overexpressed in many cancers, including colon cancer, and its overexpression is related to poor disease outcome. Although the importance of HSP27 as a biomarker cannot be underrated, its detailed mechanisms in colon cancer are still unclear. In vitro studies have indicated that silencing HSP27 reduces the proliferation, migration and invasion of colon cancer cells, and xenograft models have shown that silencing HSP27 decreases tumor progression. Tissue array results showed that colon cancer patients with high expression of HSP27 exhibited poor prognosis. In addition, we found a reduction of calcium influx through a decrease in STIM1 protein after HSP27 was abolished. The formation of puncta was decreased in HSP27 knockdown (HSP27KD) cells after thapsigargin (TG) treatment. Finally, we confirmed that the reduction of STIM1 after HSP27 silencing may be due to a loss of STIM1 stability instead of transcription. HSP27 may interact with STIM1 but not Orai1, as shown by immunoprecipitation assays. HSP27 and STIM1 were co-expressed in CRC specimens. Our study showed that HSP27 is a key mediator in the progression and metastasis of CRC by regulating the store-operated calcium entry. This novel pathway may provide a new direction for development of therapeutic strategies for CRC.

Heat shock protein 27 influences the anti-cancer effect of curcumin in colon cancer cells through ROS production and autophagy activation

The problem of therapeutic resistance and chemotherapeutic efficacy is tricky and critical in the management of colorectal cancer (CRC). Curcumin is a promising anti-cancer agent. Heat shock protein 27 (HSP27) is correlated with CRC progression and is said to affect CRC response to different therapies. However, the role of HSP27 on the therapeutic efficacy of curcumin remains unknown. HSP27 was silenced using small hairpin RNA (shRNA) technique. The cytotoxic and apoptotic effects of curcumin were assessed by sulforhodamine B (SRB) colorimetric assay, flow cytometric cell cycle analysis, and annexin V/propidium iodide (PI) double-labeling assays. Total reactive oxygen species (ROS)/superoxide and autophagy detection were performed, and the levels of apoptosis-related proteins were examined by Western blotting. It was found that the silencing of HSP27 (HSP27-KD) resulted in increased treatment resistance to curcumin in CRC cells. In addition, cell cycle analysis showed that the curcumin treatment caused cell cycle arrest at the G2/M phase in the control group, and apoptosis was reduced in the HSP27-KD group. Curcumin treatment also resulted in a decrease in anti-apoptotic proteins, p-Akt, Akt, Bcl-2 and p-Bad, and increase in pro-apoptotic proteins Bad and c-PARP levels in the control cells but not in the HSP27-KD cells. This was also followed by low reactive oxygen/nitrogen species (ROS/RNS), superoxide and autophagy induction levels in the HSP27-KD cells as compared to the control cells. Therefore, as silencing of HSP27 increases curcumin resistance by reducing apoptosis and reactive oxidative stress production, HSP27 is a potential selective target for curcumin treatment in CRC.

A PRDX1-p38α heterodimer amplifies MET-driven invasion of IDH-wildtype and IDH-mutant gliomas

The Peroxiredoxin 1 (PRDX1) gene maps to chromosome arm 1p and is hemizygously deleted and epigenetically silenced in isocitrate dehydrogenase 1 or 2 (IDH)-mutant and 1p/19q-codeleted oligodendroglial tumors. In contrast, IDH-wildtype astrocytic gliomas including glioblastomas mostly lack epigenetic silencing and express PRDX1 protein. In our study, we investigated how PRDX1 contributes to the infiltrative growth of IDH-wildtype gliomas. Focusing on p38α-dependent pathways, we analyzed clinical data from 133 patients of the NOA-04 trial cohort to look for differences in the gene expression profiles of gliomas with wildtype or mutant IDH. Biochemical interaction studies as well as in vitro and ex vivo migration studies were used to establish a biological role of PRDX1 in maintaining pathway activity. Whole-brain high-resolution ultramicroscopy and survival analyses of pre-clinical mouse models for IDH-wildtype gliomas were then used for in vivo confirmation. Based on clinical data, we found that the absence of PRDX1 is associated with changes in the expression of MET/HGF signaling components. PRDX1 forms a heterodimer with p38α mitogen-activated protein kinase 14 (MAPK14), stabilizing phospho-p38α in glioma cells. This process amplifies hepatocyte growth factor (HGF)-mediated signaling and stimulates actin cytoskeleton dynamics that promote glioma cell migration. Whole-brain high-resolution ultramicroscopy confirms these findings, indicating that PRDX1 promotes glioma brain invasion in vivo. Finally, reduced expression of PRDX1 increased survival in mouse glioma models. Thus, our preclinical findings suggest that PRDX1 expression levels may serve as a molecular marker for patients who could benefit from targeted inhibition of MET/HGF signaling.

Platelet-Specific p38α Deficiency Improved Cardiac Function After Myocardial Infarction in Mice

OBJECTIVE

MAPKs (mitogen-activated protein kinases), especially p38, play detrimental roles in cardiac diseases and cardiac remodeling post-myocardial infarction. However, the activation and function of MAPKs in coronary thrombosis in vivo and its relationship with clinical outcomes remain poorly understood.

APPROACH AND RESULTS

Here, we showed that p38α was the major isoform expressed in human and mouse platelets. Platelet-specific p38α-deficient mice presented impaired thrombosis and hemostasis but had improved cardiac function, reduced infarct size, decreased inflammatory response, and microthrombus in a left anterior descending artery ligation model. Signaling analysis revealed that p38 activation was one of the earliest events in platelets after treatment with receptor agonists or reactive oxygen species. p38α/MAPK-activated protein kinase 2/heat shock protein 27 and p38α/cytosolic phospholipases A2 were the major pathways regulating receptor-mediated or hydrogen peroxide-induced platelet activation in an ischemic environment. Moreover, the distinct roles of ERK1/2 (extracellular signal-regulated kinase) in receptor- or reactive oxygen species-induced p38-mediated platelet activation reflected the complicated synergistic relationships among MAPKs. Analysis of clinical samples revealed that MAPKs were highly phosphorylated in platelets from preoperative patients with ST-segment-elevation myocardial infarction, and increased phosphorylation of p38 was associated with no-reflow outcomes.

CONCLUSIONS

We conclude that p38α serves as a critical regulator of platelet activation and potential indicator of highly thrombotic lesions and no-reflow, and inhibition of platelet p38α may improve clinical outcomes in subjects with ST-segment-elevation myocardial infarction.

The growing world of small heat shock proteins: from structure to functions

Small heat shock proteins (sHSPs) are present in all kingdoms of life and play fundamental roles in cell biology. sHSPs are key components of the cellular protein quality control system, acting as the first line of defense against conditions that affect protein homeostasis and proteome stability, from bacteria to plants to humans. sHSPs have the ability to bind to a large subset of substrates and to maintain them in a state competent for refolding or clearance with the assistance of the HSP70 machinery. sHSPs participate in a number of biological processes, from the cell cycle, to cell differentiation, from adaptation to stressful conditions, to apoptosis, and, even, to the transformation of a cell into a malignant state. As a consequence, sHSP malfunction has been implicated in abnormal placental development and preterm deliveries, in the prognosis of several types of cancer, and in the development of neurological diseases. Moreover, mutations in the genes encoding several mammalian sHSPs result in neurological, muscular, or cardiac age-related diseases in humans. Loss of protein homeostasis due to protein aggregation is typical of many age-related neurodegenerative and neuromuscular diseases. In light of the role of sHSPs in the clearance of un/misfolded aggregation-prone substrates, pharmacological modulation of sHSP expression or function and rescue of defective sHSPs represent possible routes to alleviate or cure protein conformation diseases. Here, we report the latest news and views on sHSPs discussed by many of the world's experts in the sHSP field during a dedicated workshop organized in Italy (Bertinoro, CEUB, October 12-15, 2016).

Penicillinase-resistant antibiotics induce non-immune-mediated cholestasis through HSP27 activation associated with PKC/P38 and PI3K/AKT signaling pathways

The penicillinase-resistant antibiotics (PRAs), especially the highly prescribed flucloxacillin, caused frequent liver injury via mechanisms that remain largely non-elucidated. We first showed that flucloxacillin, independently of cytotoxicity, could exhibit cholestatic effects in human hepatocytes in the absence of an immune reaction, that were typified by dilatation of bile canaliculi associated with impairment of the Rho-kinase signaling pathway and reduced bile acid efflux. Then, we analyzed the sequential molecular events involved in flucloxacillin-induced cholestasis. A crucial role of HSP27 by inhibiting Rho-kinase activity was demonstrated using siRNA and the specific inhibitor KRIBB3. HSP27 activation was dependent on the PKC/P38 pathway, and led downstream to activation of the PI3K/AKT pathway. Other PRAs induced similar cholestatic effects while non PRAs were ineffective. Our results demonstrate that PRAs can induce cholestatic features in human hepatocytes through HSP27 activation associated with PKC/P38 and PI3K/AKT signaling pathways and consequently support the conclusion that in clinic they can cause a non-immune-mediated cholestasis that is not restricted to patients possessing certain genetic determinants.

Heat Shock Protein HSP27 Secretion by Ovarian Cancer Cells Is Linked to Intracellular Expression Levels, Occurs Independently of the Endoplasmic Reticulum Pathway and HSP27's Phosphorylation Status, and Is Mediated by Exosome Liberation

The heat shock protein HSP27 has been correlated in ovarian cancer (OC) patients with aggressiveness and chemoresistance and, therefore, represents a promising potential biomarker for OC diagnosis, prognosis, and treatment response. Notably, secretion of soluble HSP27 has been described by a few cell types and may take place as well in OC cells. Therefore, we studied HSP27 secretion mechanisms under diverse cellular conditions in an OC cell model system. Secretion of HSP27 was characterized after overexpression of HSP27 by transfected plasmids and after heat shock. Intra- and extracellular HSP27 amounts were assessed by Western blotting and ELISA. Protein secretion was blocked by brefeldin A and the impact of the HSP27 phosphorylation status was analyzed overexpressing HSP27 phosphomutants. The present study demonstrated that HSP27 secretion by OVCAR-3 and SK-OV-3 cells depends on intracellular HSP27 concentrations. Moreover, HSP27 secretion is independent of the endoplasmic reticulum secretory pathway and HSP27 phosphorylation. Notably, analysis of OC cell-born exosomes not only confirmed the concentration-dependent correlation of HSP27 expression and secretion but also demonstrated a concentration-dependent incorporation of HSP27 protein into exosomes. Thus, secreted HSP27 may become more important as an extracellular factor which controls the tumor microenvironment and might be a noninvasive biomarker.

Stage and cell-specific expression and intracellular localization of the small heat shock protein Hsp27 during oogenesis and spermatogenesis in the Mediterranean fruit fly, Ceratitis capitata

The cell-specific expression and intracellular distribution of the small heat protein Hsp27 was investigated in the ovaries and testes of the Mediterranean fruit fly, Ceratitis capitata (medfly), under both normal and heat shock conditions. For this study, a gfp-hsp27 strain was used to detect the chimeric protein by confocal microscopy. In unstressed ovaries, the protein was expressed throughout egg development in a stage and cell-specific pattern. In germarium, the protein was detected in the cytoplasm of the somatic cells in both unstressed and heat-shocked ovaries. In the early stages of oogenesis of unstressed ovaries, the protein was mainly located in the perinuclear region of the germ cells and in the cytoplasm of the follicle cells, while in later stages (9-10) it was distributed in the cytoplasm of the germ cells. In late stages (12-14), the protein changed localization pattern and was exclusively associated with the nuclei of the somatic cells. In heat shocked ovaries, the protein was mainly located in the nuclei of the somatic cells throughout egg chamber's development. In unstressed testes, the chimeric protein was detected in the nuclei of primary spermatocytes and in the filamentous structures of spermatid bundles, called actin cones. Interestingly, after a heat shock, the protein presented the same cell-specific localization pattern as in unstressed testes. Furthermore, the protein was also detected in the nuclei of the epithelial cells of the deferent duct, the accessory glands and the ejaculatory bulb. Our data suggest that medfly Hsp27 may have cell-specific functions, especially in the nucleus. Moreover, the association of this protein to actin cones during spermatid individualization, suggests a possible role of the protein in the formation and stabilization of actin cones.

Bradykinin stimulates protein kinase D-mediated colonic myofibroblast migration via cyclooxygenase-2 and heat shock protein 27

BACKGROUND

Inflammatory bowel disease is characterized by episodic intestinal injury and repair. Myofibroblasts are gastrointestinal tract stromal cells that regulate the reparative process and are known targets of inflammatory mediators including bradykinin (BK). However, the mechanisms through which inflammation regulates myofibroblast-induced wound healing remain incompletely understood. Here, we demonstrate, for the first time, that BK stimulates myofibroblast migration through protein kinase D (PKD)-mediated activation of the cyclooxygenase-2 (COX-2) and heat shock protein 27 (Hsp27) pathways.

MATERIALS AND METHODS

CCD-18Co is a human colonic myofibroblast cell line used from passages 8 to 14. An in vitro scratch assay assessed the effect of BK (100 nM) on myofibroblast migration over 24 h in the presence or absence of several inhibitors (CID755673 [10 μM] and NS398 [10 μM]). Hsp27 small interfering RNA evaluated the effect of Hsp27 on colonic myofibroblast migration. Antibodies to pPKD, pHsp27, and COX-2 evaluated expression levels by Western blot.

RESULTS

BK stimulated myofibroblast migration over 24 h. BK also led to rapid and sustained phosphorylation of PKD at Ser-916, rapid phosphorylation of Hsp27 at Ser-82, and increased COX-2 expression over 4 h. BK-mediated COX-2 expression and Hsp27 phosphorylation were both inhibited by the PKD inhibitor CID755673. Similarly, BK-induced myofibroblast migration was significantly inhibited by CID755673 (P < 0.05), by the direct COX-2 inhibitor NS398 (P < 0.05), and by Hsp27 small interfering RNA (P < 0.05).

CONCLUSIONS

BK stimulates myofibroblast migration through PKD-mediated activation of COX-2 and Hsp27. PKD, COX-2, and Hsp27 all appear to regulate myofibroblast cell migration, a stromal population that may play an important role in mucosal healing in the setting of inflammation.

HSPB1 Inhibits the Endothelial-to-Mesenchymal Transition to Suppress Pulmonary Fibrosis and Lung Tumorigenesis

The endothelial-to-mesenchymal transition (EndMT) contributes to cancer, fibrosis, and other pathologic processes. However, the underlying mechanisms are poorly understood. Endothelial HSP1 (HSPB1) protects against cellular stress and has been implicated in cancer progression and pulmonary fibrosis. In this study, we investigated the role of HSPB1 in mediating the EndMT during the development of pulmonary fibrosis and lung cancer. HSPB1 silencing in human pulmonary endothelial cells accelerated emergence of the fibrotic phenotype after treatment with TGFβ or other cytokines linked to pulmonary fibrosis, suggesting that HSPB1 maintains endothelial cell identity. In mice, endothelial-specific overexpression of HSPB1 was sufficient to inhibit pulmonary fibrosis by blocking the EndMT. Conversely, HSPB1 depletion in a mouse model of lung tumorigenesis induced the EndMT. In clinical specimens of non-small cell lung cancer, HSPB1 expression was absent from tumor endothelial cells undergoing the EndMT. Our results showed that HSPB1 regulated the EndMT in lung fibrosis and cancer, suggesting that HSPB1-targeted therapeutic strategies may be applicable for treating an array of fibrotic diseases.

Hepatic artery bridging lessens temporary ischemic injury to bile canaliculi

AIM: To study whether transfer of blood between the right gastroepiploic artery and gastroduodenal artery could lessens the damage to bile canaliculi.

METHODS: Forty male Bama miniature pigs were divided into four groups as follows: a control group, two hepatic artery ischemia groups (1 h and 2 h), and a hepatic artery bridging group. The hemodynamics of the hepatic artery in the hepatic artery bridging group was measured using color Doppler ultrasound. Morphological changes in the bile canaliculus were observed by transmission electron microscopy. Cofilin, heat shock protein 27 and F-actin expression was detected by immunohistochemistry, Western blot, and real-time polymerase chain reaction. Terminal deoxynucleotidyl transferase-mediated nick end-labeling method was used to evaluate liver injury.

RESULTS: The hemodynamics was not changed in the hepatic artery bridging group. The microvilli in the bile canaliculus were impaired in the two hepatic artery ischemia groups. The down-regulation of cofilin and F-actin and up-regulation of heat shock protein 27 were observed in the two hepatic artery ischemia groups, while there were no significant differences between the control group and hepatic artery bridging group.

CONCLUSION: Hepatic artery ischemia aggravates damage to bile canaliculi, and this damage can be diminished by a hepatic artery bridging duct.

Canine heat shock protein 27 promotes proliferation, migration, and doxorubicin resistance in the canine cell line DTK-F

Canine mammary tumors (CMTs) are the most common type of tumors in female dogs. Heat shock proteins are highly expressed in many cancers and are involved in tumor progression and chemoresistance in CMTs; however, the biological role of canine heat shock protein 27 (cHSP27) in CMTs has not been thoroughly characterized. This study investigated the roles of cHSP27 in cell growth, migration, anchorage, and resistance to doxorubicin (DOX) using DTK-F cells, a CMT cell line that does not express cHSP27. DTK-F cells were transfected with cHSP27 and stable overexpression was established. A mouse monoclonal antibody against cHSP27 was also produced. The biological functions of cHSP27 in DTK-F cells were then evaluated using a variety of assays. Overexpression of cHSP27 was associated with increased cell proliferation, clone formation, migration, and decreased DOX sensitivity. In conclusion, these data provide evidence that cHSP27 overexpression can promote anchorage-independent growth, migration, and increased DOX resistance in CMT cells.

Small heat shock proteins: big folding machines

The workshop was entitled "The Small HSP World" and had the mission to bring together investigators studying small heat shock proteins (sHSPs). It was held at Le Bonne Entente in Quebec City (Quebec, Canada) from October 2 to October 5 2014. Forty-four scientists from 14 different countries attended this workshop of the Cell Stress Society International (CSSI). The small number of participants stimulated interesting discussions, and the resulting informal atmosphere was appreciated by everybody. This article provides highlights from talks and discussions of the workshop, giving an overview of the latest work on sHSPs.

HSF-1-mediated cytoskeletal integrity determines thermotolerance and life span

The conserved heat shock transcription factor-1 (HSF-1) is essential to cellular stress resistance and life-span determination. The canonical function of HSF-1 is to regulate a network of genes encoding molecular chaperones that protect proteins from damage caused by extrinsic environmental stress or intrinsic age-related deterioration. In Caenorhabditis elegans, we engineered a modified HSF-1 strain that increased stress resistance and longevity without enhanced chaperone induction. This health assurance acted through the regulation of the calcium-binding protein PAT-10. Loss of pat-10 caused a collapse of the actin cytoskeleton, stress resistance, and life span. Furthermore, overexpression of pat-10 increased actin filament stability, thermotolerance, and longevity, indicating that in addition to chaperone regulation, HSF-1 has a prominent role in cytoskeletal integrity, ensuring cellular function during stress and aging.

Heat shock proteins HSP70 and MRJ cooperatively regulate cell adhesion and migration through urokinase receptor

Background

The urokinase-type plasminogen activator receptor (uPAR) is an important regulator of ECM proteolysis, cell-ECM interactions and cell signaling. uPAR and heat shock proteins HSP70 and MRJ (DNAJB6) have been implicated in tumor growth and metastasis. We have reported recently that MRJ (DNAJB6, a heat shock protein) can interact with uPAR and enhance cell adhesion. Here, we identified another heat shock protein HSP70 as a novel uPAR-interacting protein.

Methods

We performed co-immunoprecipitation in human embryonic kidney (HEK) 293 and colon cancer HCT116 cells as well as immunofluorence assays in HEK293 cells stably transfected with uPAR to investigate the association of suPAR with HSP70/MRJ. To understand the biological functions of the triple complex of suPAR/HSP70/MRJ, we determined whether HSP70 and/or MRJ regulated uPAR-mediated cell invasion, migration, adhesion to vitronectin and MAPK pathway in two pair of human tumor cells (uPAR negative HEK293 cells vs HEK293 cells stably transfected with uPAR and HCT116 cells stably transfected with antisense-uPAR vs HCT116 mock cells transfected with vector only) using transwell assay, wound healing assay, quantitative RT-PCR analyzing mmp2 and mmp9 transcription levels, cell adhesion assay and Western blotting assay.

Results

HSP70 and MRJ formed a triple complex with uPAR and over-expression of MRJ enhanced the interaction between HSP70 and uPAR, while knockdown of MRJ decreased soluble uPAR in HCT116 cells (P < 0.05) and reduced the formation of the triple complex, suggesting that MRJ may act as an uPAR-specific adaptor protein to link uPAR to HSP70. Further experiments showed that knockdown of HSP70 and/or MRJ by siRNA inhibited uPAR-mediated cell adhesion to vitronectin as well as suppressed cell invasion and migration. Knockdown of HSP70 and/or MRJ inhibited expression of invasion related genes mmp2 and mmp9. Finally, HSP70 and/or MRJ up-regulated phosphorylation levels of ERK1/2 and FAK suggesting MAPK pathway was involved. All the biological function experiments in cell level showed an additive effect when HSP70 and MRJ were regulated simultaneously indicating their collaborated regulation effects on uPAR.

Conclusions

These findings may offer a novel insight into the interactions between uPAR and HSP70/MRJ and their functions in cell adhesion and migration may provide more understanding of the roles in regulating cancer metastasis.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-639) contains supplementary material, which is available to authorized users.

Structure and properties of chimeric small heat shock proteins containing yellow fluorescent protein attached to their C-terminal ends

Recombinant chimeras of small heat shock proteins (sHsp) HspB1, HspB5, and HspB6 containing enhanced yellow fluorescent protein (EYFP) attached to their C-terminal ends were constructed and purified. Some properties of these chimeras were compared with the corresponding properties of the same chimeras containing EYFP attached to the N-terminal end of sHsp. The C-terminal fluorescent chimeras of HspB1 and HspB5 tend to aggregate and form a heterogeneous mixture of oligomers. The apparent molecular weight of the largest C-terminal chimeric oligomers was higher than that of the corresponding N-terminal chimeras or of the wild-type proteins; however, both homooligomers of N-terminal chimeras and homooligomers of C-terminal chimeras contained fewer subunits than the wild-type HspB1 or HspB5. Both N-terminal and C-terminal chimeras of HspB6 form small oligomers with an apparent molecular weight of 73-84 kDa. The C-terminal chimeras exchange their subunits with homologous wild-type proteins. Heterooligomers formed by the wild-type HspB1 (or HspB5) and the C-terminal chimeras of HspB6 differ in size and composition from heterooligomers formed by the corresponding wild-type proteins. As a rule, the N-terminal chimeras possess similar or slightly higher chaperone-like activity than the corresponding wild-type proteins, whereas the C-terminal chimeras always have a lower chaperone-like activity than the wild-type proteins. It is concluded that attachment of EYFP to either N-terminal or C-terminal ends of sHsp affects their oligomeric structure, their ability to form heterooligomers, and their chaperone-like activity. Therefore, the data obtained with fluorescent chimeras of sHsp expressed in the cell should be interpreted with caution.

Heat shock modulates neutrophil motility in zebrafish

Heat shock is a routine method used for inducible gene expression in animal models including zebrafish. Environmental temperature plays an important role in the immune system and infection progression of ectotherms. In this study, we analyzed the impact of short-term heat shock on neutrophil function using zebrafish (Danio rerio) as an animal model. Short-term heat shock decreased neutrophil recruitment to localized Streptococcus iniae infection and tail fin wounding. Heat shock also increased random neutrophil motility transiently and increased the number of circulating neutrophils. With the use of the translating ribosome affinity purification (TRAP) method for RNA isolation from specific cell types such as neutrophils, macrophages and epithelial cells, we found that heat shock induced the immediate expression of heat shock protein 70 (hsp70) and a prolonged expression of heat shock protein 27 (hsp27). Heat shock also induced cell stress as detected by the splicing of X-box binding protein 1 (xbp1) mRNA, a marker for endoplasmic reticulum (ER) stress. Exogenous expression of Hsp70, Hsp27 and spliced Xbp1 in neutrophils or epithelial cells did not reproduce the heat shock induced effects on neutrophil recruitment. The effect of heat shock on neutrophils is likely due to a combination of complex changes, including, but not limited to changes in gene expression. Our results indicate that routine heat shock can alter neutrophil function in zebrafish. The findings suggest that caution should be taken when employing a heat shock-dependent inducible system to study the innate immune response.

Cell stress promotes the association of phosphorylated HspB1 with F-actin

Previous studies have suggested that the small heat shock protein, HspB1, has a direct influence on the dynamics of cytoskeletal elements, in particular, filamentous actin (F-actin) polymerization. In this study we have assessed the influence of HspB1 phosphorylation on its interaction(s) with F-actin. We first determined the distribution of endogenous non-phosphorylated HspB1, phosphorylated HspB1 and F-actin in neuroendocrine PC12 cells by immunocytochemistry and confocal microscopy. We then investigated a potential direct interaction between HspB1 with F-actin by precipitating F-actin directly with biotinylated phalloidin followed by Western analyses; the reverse immunoprecipitation of HspB1 was also carried out. The phosphorylation influence of HspB1 in this interaction was investigated by using pharmacologic inhibition of p38 MAPK. In control cells, HspB1 interacts with F-actin as a predominantly non-phosphorylated protein, but subsequent to stress there is a redistribution of HspB1 to the cytoskeletal fraction and a significantly increased association of pHspB1 with F-actin. Our data demonstrate HspB1 is found in a complex with F-actin both in phosphorylated and non-phosphorylated forms, with an increased association of pHspB1 with F-actin after heat stress. Overall, our study combines both cellular and biochemical approaches to show cellular localization and direct demonstration of an interaction between endogenous HspB1 and F-actin using methodolgy that specifically isolates F-actin.

Upregulation of heat shock protein 32 in Sertoli cells alleviates the impairments caused by heat shock-induced apoptosis in mouse testis

Heat stress results in apoptosis in testicular germ cells. A small heat shock protein (hsp), hsp32, is induced by heat stress in the testis, but little is known about its definitive function in physiological processes. To clarify the underlying role of hsp32, hsp32 expression and related signals in the heat shock pathway were analysed in mouse testes and Sertoli cells after heat stress in vivo and in vitro; meanwhile, expression of hsp32 was silenced only in the Sertoli cells using three different small interfering RNAs (siRNAs) to further verify the functional role of hsp32 in Sertoli cells, and hsp32-derived carbon monoxide (CO) contents in cultured media were analysed to clarify whether hsp32-derived CO involve in the apoptosis regulation mechanisms. The results from the in vivo experiment showed that the high expression levels of hsp32 (P < 0.05) were observed whether chronic, moderate or acute, transient heat exposure. The in vitro experiment showed that acute, transient heat exposure resulted in increases in Sertoli cells apoptosis (P < 0.01), the expression of hsp32 and caspase-3 activity; hsp32-siRNA knockdown of hsp32 expression resulted in upregulated apoptosis (P < 0.01) and caspase-3 activity (P < 0.01) in the Sertoli cells and hyperthermia increases CO (P < 0.01) release by Sertoli cells. The results suggested that upregulating hsp32 in Sertoli cells inhibits caspase-3 activity and alleviates heat-induced impairments in mouse testis; hsp32-derived CO may involve in the regulation mechanism.

Expression of heat shock protein 27 and proliferating cell nuclear antigen in human retinoblastoma

AIM OF THE STUDY

This study aimed to observe the expressions of heat shock protein 27 (HSP27) and proliferating cell nuclear antigen (PCNA) in retinoblastoma (Rb) cells and to explore the relationships of the expression with Rb differentiation and optic nerve infiltration.

MATERIAL AND METHODS

Heat shock protein 27 and PCNA expressions in 36 routine Rb paraffin specimens were observed using PV9000 two-stage immunohistochemical staining. The correlations of the HSP27 and PCNA expressions with Rb differentiation and optic nerve infiltration were analyzed.

RESULTS

Heat shock protein 27 was weakly expressed in the normal retina, specifically in the ganglion cell layer. It was extensively expressed in Rb tissues at a positive rate of 69.4%, and the positive substances were primarily located in the cytoplasm. Proliferating cell nuclear antigen was expressed weakly or not at all expressed in the normal retina and was extensively expressed in Rb tissues at a positive rate of 83.3%, and the positive substances were primarily located in the nucleus. The positive expression rates of HSP27 and PCNA in the differentiated group were significantly higher than in the undifferentiated group (p < 0.05). The positive expression rates of HSP27 and PCNA in the optic nerve-infiltrated group were significantly higher than in the non-infiltrated group (p < 0.05). Heat shock protein 27 expression was positively correlated with PCNA expression in Rb (p < 0.01).

CONCLUSIONS

Heat shock protein 27 and PCNA expressions are markedly correlated with cell differentiation and optic nerve infiltration in Rb.

Hyperthermic intraperitoneal chemotherapy in patients with peritoneal carcinomatosis: role of heat shock proteins and dissecting effects of hyperthermia

BACKGROUND

In patients with isolated peritoneal carcinomatosis (PC) of gastrointestinal cancer, hyperthermic intraperitoneal chemotherapy (HIPEC) represents a promising treatment option integrated into multimodal concepts. Heat shock proteins (HSP) seem to play a major role in cellular stress during HIPEC therapy. We analyzed differentially hyperthermic conditions and HSPs responsible for cell stress-mediated repair mechanisms in tumor tissues from patients who underwent HIPEC therapy and in an in vitro hyperthermic model.

METHODS

Tumor tissues from our patient cohort with isolated PC were selected for further analysis when representative material was available before and after HIPEC therapy. To further dissect the role of HSPs under conditions of hyperthermia, gene and protein expression was additionally determined, together with cellular apoptosis and proliferation in human HT-29 colon cancer cells.

RESULTS

Differently up-regulated HSP70/72 and HSP90 gene and protein expression was found in all investigated patient tumors. In vitro studies confirmed observations from clinical tumor analysis as underlying HSP-mediated cell stress mechanisms. Moreover, results from proliferation and apoptosis assays combined with differentiated HSP expression analysis demonstrated the relevance of preselecting specific target temperatures to achieve optimal toxic effects on remaining tumor cells in vivo.

CONCLUSIONS

Therapeutic approaches like HIPEC to achieve antiproliferative and apoptosis-inducing cellular effects in patients with PC are negatively influenced by highly conserved HSP mechanisms in tumor cells. This study shows for the first time that specific hyperthermic conditions are necessary to be established to achieve optimal toxic effects on tumor cells during HIPEC therapy, a finding that opens potentially new therapeutic strategies.

Withaferin A induces proteasome inhibition, endoplasmic reticulum stress, the heat shock response and acquisition of thermotolerance

In the present study, withaferin A (WA), a steroidal lactone with anti-inflammatory and anti-tumor properties, inhibited proteasome activity and induced endoplasmic reticulum (ER) and cytoplasmic HSP accumulation in Xenopus laevis A6 kidney epithelial cells. Proteasomal inhibition by WA was indicated by an accumulation of ubiquitinated protein and a decrease in chymotrypsin-like activity. Additionally, immunoblot analysis revealed that treatment of cells with WA induced the accumulation of HSPs including ER chaperones, BiP and GRP94, as well as cytoplasmic/nuclear HSPs, HSP70 and HSP30. Furthermore, WA-induced an increase in the relative levels of the protein kinase, Akt, while the levels of actin were unchanged compared to control. Northern blot experiments determined that WA induced an accumulation in bip, hsp70 and hsp30 mRNA but not eIF-1α mRNA. Interestingly, WA acted synergistically with mild heat shock to enhance HSP70 and HSP30 accumulation to a greater extent than the sum of both stressors individually. This latter phenomenon was not observed with BiP or GRP94. Immunocytochemical analysis indicated that WA-induced BiP accumulation occurred mainly in the perinuclear region in a punctate pattern, while HSP30 accumulation occurred primarily in a granular pattern in the cytoplasm with some staining in the nucleus. Prolonged exposure to WA resulted in disorganization of the F-actin cytoskeleton as well as the production of relatively large HSP30 staining structures that co-localized with F-actin. Finally, prior exposure of cells to WA treatment, which induced the accumulation of HSPs conferred a state of thermal protection since it protected the F-actin cytoskeleton against a subsequent cytotoxic thermal challenge.

Utilization of fluorescent chimeras for investigation of heterooligomeric complexes formed by human small heat shock proteins

Fluorescent chimeras composed of enhanced cyan (or enhanced yellow) fluorescent proteins (ECFP or EYFP) and one of the four human small heat shock proteins (HspB1, HspB5, HspB6 or HspB8) were expressed in E. coli and purified. Fluorescent chimeras were used for investigation of heterooligomeric complexes formed by different small heat shock proteins (sHsp) and for analysis of their subunit exchange. EYFP-HspB1 and ECFP-HspB6 form heterooligomeric complex with apparent molecular weight of ∼280 kDa containing equimolar quantities of both sHsp. EYFP-HspB5 and ECFP-HspB6 formed heterogeneous oligomeric complexes. Fluorescent proteins inside heterooligomeric complexes formed by HspB1/HspB6 and HspB5/HspB6 chimeras are closely located, making possible effective fluorescence resonance energy transfer (FRET). Neither the wild type HspB8 nor its fluorescent chimeras were able to form stable heterooligomeric complexes with the wild type HspB1 and HspB5. Homo- and hetero-FRET was used for analysis of subunit exchange of small heat shock proteins. The apparent rate constant of subunit exchange was temperature-dependent and was higher for HspB6 forming small oligomers than for HspB1 forming large oligomers. Replacement induced by homologous subunits was more rapid than the replacement induced by heterologous subunits of small heat shock proteins. Fusion of fluorescent proteins might affect oligomeric structure of small heat shock proteins, however fluorescent chimeras can be useful for investigation of heterooligomeric complexes formed by sHsp and for analysis of kinetics of their subunit exchange.

A Study of the Wound Healing Mechanism of a Traditional Chinese Medicine, Angelica sinensis, Using a Proteomic Approach

Angelica sinensis (AS) is a traditional Chinese herbal medicine that has been formulated clinically to treat various form of skin trauma and to help wound healing. However, the mechanism by which it works remains a mystery. In this study we have established a new platform to evaluate the pharmacological effects of total AS herbal extracts as well as its major active component, ferulic acid (FA), using proteomic and biochemical analysis. Cytotoxic and proliferation-promoting concentrations of AS ethanol extracts (AS extract) and FA were tested, and then the cell extracts were subject to 2D PAGE analysis. We found 51 differentially expressed protein spots, and these were identified by mass spectrometry. Furthermore, biomolecular assays, involving collagen secretion, migration, and ROS measurements, gave results that are consistent with the proteomic analysis. In this work, we have demonstrated a whole range of pharmacological effects associated with Angelica sinensis that might be beneficial when developing a wound healing pharmaceutical formulation for the herbal medicine.

Charcot-Marie-Tooth disease and intracellular traffic

Mutations of genes whose primary function is the regulation of membrane traffic are increasingly being identified as the underlying causes of various important human disorders. Intriguingly, mutations in ubiquitously expressed membrane traffic genes often lead to cell type- or organ-specific disorders. This is particularly true for neuronal diseases, identifying the nervous system as the most sensitive tissue to alterations of membrane traffic. Charcot-Marie-Tooth (CMT) disease is one of the most common inherited peripheral neuropathies. It is also known as hereditary motor and sensory neuropathy (HMSN), which comprises a group of disorders specifically affecting peripheral nerves. This peripheral neuropathy, highly heterogeneous both clinically and genetically, is characterized by a slowly progressive degeneration of the muscle of the foot, lower leg, hand and forearm, accompanied by sensory loss in the toes, fingers and limbs. More than 30 genes have been identified as targets of mutations that cause CMT neuropathy. A number of these genes encode proteins directly or indirectly involved in the regulation of intracellular traffic. Indeed, the list of genes linked to CMT disease includes genes important for vesicle formation, phosphoinositide metabolism, lysosomal degradation, mitochondrial fission and fusion, and also genes encoding endosomal and cytoskeletal proteins. This review focuses on the link between intracellular transport and CMT disease, highlighting the molecular mechanisms that underlie the different forms of this peripheral neuropathy and discussing the pathophysiological impact of membrane transport genetic defects as well as possible future ways to counteract these defects.

Application of SELDI-TOF-MS and LCM to screen protein markers for early diagnosis of liver metastasis of colorectal carcinoma

AIM: To screen protein markers for liver metastases of colorectal cancer using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry protein chip (SELDI-TOF-MS) in combination with laser capture microdissection (LCM) technology.

METHODS: Normal colorectal cells, primary tumor cells and liver metastatic cells were obtained from 24 colorectal cancer patients with liver metastases using the LCM technology. Protein profiling was performed using SELDI-TOF-MS technology. Differentially expressed proteins were analyzed using Biomarker Wizard software and identified by querying the database.

RESULTS: Fifteen differentially expressed proteins were found between primary tumor cells and normal colorectal cells, of which 12 were up-regulated and 3 down-regulated. Nine differentially expressed proteins were found between liver metastatic cells and primary tumor cells, of which 5 were up-regulated and 4 down-regulated. Twenty differentially expressed proteins were identified by querying ExPasy protein database, including integral membrane protein 2C, DNA repair protein RAD51 homolog 4, cell cycle checkpoint protein RAD1, human epididymis protein 4, centromere protein R, and pleckstrin homology domain family member 3. Apoptosis regulator Bax-γ, S100A11, Raf kinase inhibitor protein (RKIP) and heat shock protein 27 (HSP-27) displayed most obvious differential expression among normal colorectal cells, primary tumor cells and liver metastatic cells (all P < 0. 01).

CONCLUSION: SELDI-TOF-MS technology combined with LCM may allow to screen highly sensitive and specific protein markers for colorectal cancer and liver metastases of colorectal cancer.

Knock down of heat shock protein 27 (HspB1) induces degradation of several putative client proteins

Hsp27 belongs to the heat shock protein family and displays chaperone properties in stress conditions by holding unfolded polypeptides, hence avoiding their inclination to aggregate. Hsp27 is often referenced as an anti-cancer therapeutic target, but apart from its well-described ability to interfere with different stresses and apoptotic processes, its role in non-stressed conditions is still not well defined. In the present study we report that three polypeptides (histone deacetylase HDAC6, transcription factor STAT2 and procaspase-3) were degraded in human cancerous cells displaying genetically decreased levels of Hsp27. In addition, these proteins interacted with Hsp27 complexes of different native size. Altogether, these findings suggest that HDAC6, STAT2 and procaspase-3 are client proteins of Hsp27. Hence, in non stressed cancerous cells, the structural organization of Hsp27 appears to be a key parameter in the regulation by this chaperone of the level of specific polypeptides through client-chaperone type of interactions.