Search results for "chaperon"

Chaperones: General Characteristics and Classifications

2013

This chapter presents the classification of chaperones, their molecular properties among which that of forming functional complexes involving various molecules, and their distribution inside and outside the cell. The chaperone genes in the human genome are listed and briefly described, focusing on the small heat-shock proteins (sHsp), Hsp60, Hsp70, and Hsp90, and mentioning all others known. The chapter also introduces the concept of chaperoning system, i.e., the physiological system of an organism which is composed of all its chaperones, co-chaperones, and chaperone co-factors.

CtsR is the master regulator of stress response gene expression in Oenococcus oeni.

2005

ABSTRACT Although many stress response genes have been characterized in Oenococcus oeni , little is known about the regulation of stress response in this malolactic bacterium. The expression of eubacterial stress genes is controlled both positively and negatively at the transcriptional level. Overall, negative regulation of heat shock genes appears to be more widespread among gram-positive bacteria. We recently identified an ortholog of the ctsR gene in O. oeni . In Bacillus subtilis , CtsR negatively regulates expression of the clp genes, which belong to the class III family of heat shock genes. The ctsR gene of O. oeni is cotranscribed with the downstream clpC gene. Sequence analysis of t…

Human chaperonin disease-causing mutations: study with a prokaryotic model.

2012

Myelin pathology: Involvement of molecular chaperones and the promise of chaperonotherapy

2019

The process of axon myelination involves various proteins including molecular chaperones. Myelin alteration is a common feature in neurological diseases due to structural and functional abnormalities of one or more myelin proteins. Genetic proteinopathies may occur either in the presence of a normal chaperoning system, which is unable to assist the defective myelin protein in its folding and migration, or due to mutations in chaperone genes, leading to functional defects in assisting myelin maturation/migration. The latter are a subgroup of genetic chaperonopathies causing demyelination. In this brief review, we describe some paradigmatic examples pertaining to the chaperonins Hsp60 (HSPD1,…

Endoplasmic reticulum‐resident chaperones modulate the inflammatory and angiogenic responses of endothelial cells

2015

SummaryBackground Wound healing depends on a well-balanced regulation of inflammation and angiogenesis. In chronic wounds the healing process is disturbed and inflammation persists. Regulation of wound closure is controlled by transmembrane and extracellular proteins, the folding and maturation of which occur in the endoplasmic reticulum (ER) by ER-resident chaperone machinery. Objectives To study the role of the ER-resident chaperones BiP/Grp78, its cochaperone Mdg1/ERdJ4, and Grp94 in chronic, nonhealing wounds. Methods Immunohistochemical staining of these chaperones in individual human biopsies and investigation of the possible role of BiP and Mdg1 in endothelial cells, focusing on thei…

Hsp60 molecular anatomy and role in colorectal cancer diagnosis and treatment

2011

Quantitative changes in Hsp60 during the development of some tumors suggest that this chaperonin plays a role in carcinogenesis. A description of the specific role(s) of Hsp60 in tumor-cell growth and proliferation is still incomplete, but it is already evident that monitoring its levels and distribution in tissues and fluids has potential for diagnosis and staging, and for assessing prognosis and response to treatment. Although Hsp60 is considered an intramitochondrial protein, it has been demonstrated in the cytosol, cell membrane, vesicles, cell surface, extracellular space, and blood. The knowledge that Hsp60 occurs at all these locations opens new avenues for basic and applied research…

Mitochondrial compartment: a possible target of cadmium effects on breast epithelial cells.

2009

Cadmium–breast epithelial cell interactions were studied by analyzing some mitochondria-related aspects of stress response. We treated immortalized non-tumor breast cells with 5 or 50 μM CdCl2 for 24 or 96 h demonstrating that the exposure did not cause a significant mitochondrial proliferation, while it induced a significant increase in the respiratory activity and mitochondrial polarization. In addition, we found that hsp60 was up-regulated while hsp70 and COXII and COXIV were down-regulated. The mRNA for hsp70 remained constant and only the inducible form of the 70-kDa heat shock protein was over expressed. The mRNAs for COXII and COXIV remained constant after 24 h and increased after lo…

Reorganization of Nuclear Domain 10 Induced by Papillomavirus Capsid Protein L2

2002

AbstractNuclear domains (ND) 10 are associated with proteins implicated in transcriptional regulation, growth suppression, and apoptosis. We now show that the minor capsid protein L2 of human papillomavirus (HPV) type 33 induces a reorganization of ND10-associated proteins. Whereas the promyelocytic leukemia protein, the major structural component of ND10, was unaffected by L2, Sp100 was released from ND10 upon L2 expression. The total cellular amount of Sp100, but not of Sp100 mRNA, decreased significantly, suggesting degradation of Sp100. Proteasome inhibitors induced the dispersal of Sp100 and inhibited the nuclear translocation of L2. In contrast to Sp100, Daxx was recruited to ND10 by …

Heat shock and Cd2+ exposure regulate PML and Daxx release from ND10 by independent mechanisms that modify the induction of heat-shock proteins 70 an…

2003

Nuclear domains called ND10 or PML bodies might function as nuclear depots by recruiting or releasing certain proteins. Although recruitment of proteins through interferon-induced upregulation and SUMO-1 modification level of PML had been defined, it is not known whether release of proteins is regulated and has physiological consequences. Exposure to sublethal environmental stress revealed a sequential release of ND10-associated proteins. Upon heat shock Daxx and Sp100 were released but PML remained, whereas exposure to subtoxic concentrations of CdCl2 induced the release of ND10-associated proteins, including PML, with Sp100 remaining in a few sites. In both cases,recovery times were simil…

Decipher the mechanisms of protein conformational changes induced by nucleotide binding through free-energy landscape analysis: ATP binding to Hsp70.

2013

ATP regulates the function of many proteins in the cell by transducing its binding and hydrolysis energies into protein conformational changes by mechanisms which are challenging to identify at the atomic scale. Based on molecular dynamics (MD) simulations, a method is proposed to analyze the structural changes induced by ATP binding to a protein by computing the effective free-energy landscape (FEL) of a subset of its coordinates along its amino-acid sequence. The method is applied to characterize the mechanism by which the binding of ATP to the nucleotide-binding domain (NBD) of Hsp70 propagates a signal to its substrate-binding domain (SBD). Unbiased MD simulations were performed for Hsp…