The pathology of cellular anti-stress mechanisms: a new frontier

Microwave Spectroscopic Detection of Human Hsp70 Protein on Annealed Gold Nanostructures on ITO Glass Strips

Conductive indium-tin oxide (ITO) and non-conductive glass substrates were successfully modified with embedded gold nanoparticles (AuNPs) formed by controlled thermal annealing at 550 °C for 8 h in a preselected oven. The authors characterized the formation of AuNPs using two microscopic techniques: scanning electron microscopy (SEM) and atomic force microscopy (AFM). The analytical performances of the nanostructured-glasses were compared regarding biosensing of Hsp70, an ATP-driven molecular chaperone. In this work, the human heat-shock protein (Hsp70), was chosen as a model biomarker of body stress disorders for microwave spectroscopic investigations. It was found that microwave screening at 4 GHz allowed for the first time the detection of 12 ng/µL/cm² of Hsp70.

Immunohistochemistry of Human Hsp60 in Health and Disease: From Autoimmunity to Cancer

Hsp60 (also called Cpn60) is a chaperonin with essential functions for cell physiology and survival. Additionally, its involvement in the pathogenesis of a variety of diseases (e.g., some autoimmune disorders and cancer) is becoming evident with new research. For example, the distribution and levels of Hsp60 in cells and tissues have been found altered in many pathologic conditions, and the significance of these alterations is being investigated in a number of laboratories. The aim of this ongoing research is to determine the meaning of these Hsp60 alterations with regard to pathogenetic mechanisms, diagnosis, classification of lesions, and assessing prognosis and response to treatment.Hsp60 occurs in the mitochondria, i.e., its typical residence according to classic knowledge, and also in other locales, such as the cytosol, the cell membrane, the intercellular space, and biological fluids (e.g., blood and cerebrospinal fluid). Detection and quantitative determinations in all these locations are becoming essential components of laboratory pathology in clinics and research. Consequently, immunohistochemistry targeting Hsp60 is also becoming essential for pathologists and researchers interested in disorders involving this chaperonin.In this chapter, we summarize some recent discoveries on the participation of Hsp60 in the pathogenesis of human diseases, and describe in detail how to perform immunohistochemical reactions for detecting the chaperonin, determining its location, and measuring its quantitative levels.

Multifactorial level of extremostability of proteins: can they be exploited for protein engineering?

Research on extremostable proteins has seen immense growth in the past decade owing to their industrial importance. Basic research of attributes related to extreme-stability requires further exploration. Modern mechanistic approaches to engineer such proteins in vitro will have more impact in industrial biotechnology economy. Developing a priori knowledge about the mechanism behind extreme-stability will nurture better understanding of pathways leading to protein molecular evolution and folding. This review is a vivid compilation about all classes of extremostable proteins and the attributes that lead to myriad of adaptations divulged after an extensive study of 6495 articles belonging to extremostable proteins. Along with detailing on the rationale behind extreme-stability of proteins, emphasis has been put on modern approaches that have been utilized to render proteins extremostable by protein engineering. It was understood that each protein shows different approaches to extreme-stability governed by minute differences in their biophysical properties and the milieu in which they exist. Any general rule has not yet been drawn regarding adaptive mechanisms in extreme environments. This review was further instrumental to understand the drawback of the available 14 stabilizing mutation prediction algorithms. Thus, this review lays the foundation to further explore the biophysical pleiotropy of extreme-stable proteins to deduce a global prediction model for predicting the effect of mutations on protein stability.

Patterns of gene expression associated with recovery and injury in heat-stressed rats

Background

The in vivo gene response associated with hyperthermia is poorly understood. Here, we perform a global, multiorgan characterization of the gene response to heat stress using an in vivo conscious rat model.

Results

We heated rats until implanted thermal probes indicated a maximal core temperature of 41.8°C (T_c,Max). We then compared transcriptomic profiles of liver, lung, kidney, and heart tissues harvested from groups of experimental animals at T_c,Max, 24 hours, and 48 hours after heat stress to time-matched controls kept at an ambient temperature. Cardiac histopathology at 48 hours supported persistent cardiac injury in three out of six animals. Microarray analysis identified 78 differentially expressed genes common to all four organs at T_c,Max. Self-organizing maps identified gene-specific signatures corresponding to protein-folding disorders in heat-stressed rats with histopathological evidence of cardiac injury at 48 hours. Quantitative proteomics analysis by iTRAQ (isobaric tag for relative and absolute quantitation) demonstrated that differential protein expression most closely matched the transcriptomic profile in heat-injured animals at 48 hours. Calculation of protein supersaturation scores supported an increased propensity of proteins to aggregate for proteins that were found to be changing in abundance at 24 hours and in animals with cardiac injury at 48 hours, suggesting a mechanistic association between protein misfolding and the heat-stress response.

Conclusions

Pathway analyses at both the transcript and protein levels supported catastrophic deficits in energetics and cellular metabolism and activation of the unfolded protein response in heat-stressed rats with histopathological evidence of persistent heat injury, providing the basis for a systems-level physiological model of heat illness and recovery.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-1058) contains supplementary material, which is available to authorized users.

Heat shock proteins in hematopoietic malignancies

Inducible heat shock proteins are molecular chaperones whose expression is increased after many different types of stress. They have a protective function helping the cell to cope with lethal conditions. Their basal expression is low in nonstressed, normal and nontransformed cells. However, in cancer cells and particularly in hematological malignancies, they are surprisingly abundant. Malignant cells have to rewire their metabolic requirements and therefore have a higher need for chaperones. This cancer cell addiction for HSPs is the basis for the use of HSP inhibitors in cancer therapy. HSPs have been shown to interact with different key apoptotic proteins. As a result, HSPs can essentially block the apoptotic pathways at several steps, most of them involving the activation of cystein proteases called caspases. Apoptosis and differentiation are physiological processes that share many common features, for instance, a controlled caspase activation and chromatin condensation are frequently observed. It is, therefore, not surprising that HSPs may be implicated in the differentiation process. HSPs may determine the fate of the cells by orchestrating the decision of apoptosis versus differentiation. This review will focus on the role of HSPs in hematological malignancies and the emerging therapeutic options that are being either proposed or used to target these protective proteins.

Heat shock proteins as danger signals for cancer detection

First discovered in 1962, heat shock proteins (HSPs) are highly studied with about 35,500 publications on the subject to date. HSPs are highly conserved, function as molecular chaperones for a large panel of “client” proteins and have strong cytoprotective properties. Induced by many different stress signals, they promote cell survival in adverse conditions. Therefore, their roles have been investigated in several conditions and pathologies where HSPs accumulate, such as in cancer. Among the diverse mammalian HSPs, some members share several features that may qualify them as cancer biomarkers. This review focuses mainly on three inducible HSPs: HSP27, HPS70, and HSP90. Our survey of recent literature highlights some recurring weaknesses in studies of the HSPs, but also identifies findings that indicate that some HSPs have potential as cancer biomarkers for successful clinical applications.

Immunohistochemistry of human Hsp60 in health and disease: from autoimmunity to cancer

Hsp60 (also called Cpn60) is a chaperonin with essential functions for cell physiology and survival. Additionally, its involvement in the pathogenesis of a number of diseases (e.g., some autoimmune disorders and cancer) is becoming evident with new research. For example, the distribution and levels of Hsp60 in cells and tissues have been found altered in many pathologic conditions, and the significance of these alterations is being investigated in a number of laboratories. The aim of this ongoing research is to determine the meaning of these Hsp60 alterations with regard to pathogenetic mechanisms, diagnosis, classification of lesions, and assessing of prognosis and response to treatment. Hsp60 occurs in the mitochondria, i.e., its typical residence according to classic knowledge, and also in other locales, such as the cytosol, the cell membrane, the intercellular space, and biological fluids (e.g., blood and cerebrospinal fluid). Detection and quantitative determinations in all these locations are becoming essential components of laboratory pathology in clinics and research. Consequently, immunohistochemistry targeting Hsp60 is also becoming essential for pathologists and researchers interested in disorders involving this chaperonin. In this chapter, we briefly summarize some recent discoveries on the participation of Hsp60 in the pathogenesis of human diseases and describe in detail how to perform immunohistochemical reactions for detecting the chaperonin, determining its location, and measuring its levels of expression.

Chlamydia trachomatis infection and anti-Hsp60 immunity: the two sides of the coin

Chlamydia trachomatis (CT) infection is one of the most common causes of reproductive tract diseases and infertility. CT-Hsp60 is synthesized during infection and is released in the bloodstream. As a consequence, immune cells will produce anti-CT-Hsp60 antibodies. Hsp60, a ubiquitous and evolutionarily conserved chaperonin, is normally sequestered inside the cell, particularly into mitochondria. However, upon cell stress, as well as during carcinogenesis, the chaperonin becomes exposed on the cell surface (sf-Hsp60) and/or is secreted from cells into the extracellular space and circulation. Reports in the literature on circulating Hsp and anti-Hsp antibodies are in many cases short on details about Hsp60 concentrations, and about the specificity spectra of the antibodies, their titers, and their true, direct, pathogenetic effects. Thus, more studies are still needed to obtain a definitive picture on these matters. Nevertheless, the information already available indicates that the concurrence of persistent CT infection and appearance of sf-Hsp60 can promote an autoimmune aggression towards stressed cells and the development of diseases such as autoimmune arthritis, multiple sclerosis, atherosclerosis, vasculitis, diabetes, and thyroiditis, among others. At the same time, immunocomplexes composed of anti-CT-Hsp60 antibodies and circulating Hsp60 (both CT and human) may form deposits in several anatomical locations, e.g., at the glomerular basal membrane. The opposite side of the coin is that pre-tumor and tumor cells with sf-Hsp60 can be destroyed with participation of the anti-Hsp60 antibody, thus stopping cancer progression before it is even noticed by the patient or physician.

Chaperonopathies and chaperonotherapy

The study of molecular chaperones (genetics, structure, location, physiology, pathology, and therapeutics) has developed into a science with specific objectives, methods, and hypotheses, a discipline we called chaperonology. Subdisciplines of chaperonology include the study of pathological chaperones (chaperonopathies) and the analysis of their genes in sequenced genomes (chaperonomics). Chaperonopathies are pathological conditions in which one type of chaperone is deficient due to a genetic or acquired defect that modifies the chaperone's structure and/or makes the chaperone unavailable for functioning when needed. Experimental and clinical data show that chaperones and their genes can be used for treating various pathological conditions, thus justifying the development of chaperonotherapy. We discuss recent work showing that chaperonotherapy is on solid foundations: the data demonstrate that molecular chaperones counteract pathogenetic mechanisms in disease and during stress.

Chaperonomics, a new tool to study ageing and associated diseases

The participation of molecular chaperones in the process of senescence and in the mechanisms of age-related diseases is currently under investigation in many laboratories. However, accurate, complete information about the number and diversity of chaperone genes in any given genome is scarce. Consequently, the results of efforts aimed at elucidating the role of chaperones in ageing and disease are often confusing and contradictory. To remedy this situation, we have developed chaperonomics, including means to identify and characterize chaperone genes and their families applicable to humans and model organisms. The problem is difficult because in eukaryotic organisms chaperones have evolved into complex multi-gene families. For instance, the occurrence of multiple paralogs in a single genome makes it difficult to interpret results if consideration is not given to the fact that similar but distinct chaperone genes can be differentially expressed in separate cellular compartments, tissues, and developmental stages. The availability of complete genome sequences allows implementation of chaperonomics with the purpose of understanding the composition of chaperone families in all cell compartments, their evolutionary and functional relations and, ultimately, their role in pathogenesis. Here, we present a series of concatenated, complementary procedures for identifying, characterizing, and classifying chaperone genes in genomes and for elucidating evolutionary relations and structural features useful in predicting functional properties. We illustrate the procedures with applications to the complex family of hsp70 genes and show that the kind of data obtained can provide a solid basis for future research.

Steroid receptor coregulator diversity: What can it mean for the stressed brain?

Glucocorticoid hormones modulate brain function and as such are crucial for responding and adjusting to physical and psychological stressors. Their effects are mediated via mineralo- and glucocorticoid receptors, which in large measure act as transcription factors to modulate transcription of target genes, in a receptor-, cell-, and state-specific manner. The nature and magnitude of these transcriptional effects depend on the presence and activity of downstream proteins, such as steroid receptor coactivators and corepressors (together: coregulators), many of which are expressed in the brain. We address the role of coregulators for mineralo- and glucocorticoid receptor-mediated modulation of gene transcription. We first address evidence from cell lines for the importance of coregulator stoichiometry for steroid signaling. The in vivo importance of coregulators-when possible specifically for glucocorticoid signaling in the brain-is discussed based on knockout mice, transient knockdown of steroid receptor coactivators, and distribution and regulation of coactivator expression in the brain. We conclude that for a better understanding of modulation of brain function by glucocorticoids, it is necessary to take into account the role of coregulators, and to assess their importance relative to changes in hormone levels and receptor expression.