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1.
Biomolecules ; 13(1)2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36671537

RESUMO

Apart from chaperoning, disulfide bond formation, and downstream processing, the molecular sequence of proinsulin folding is not completely understood. Proinsulin requires proline isomerization for correct folding. Since FK506-binding protein 2 (FKBP2) is an ER-resident proline isomerase, we hypothesized that FKBP2 contributes to proinsulin folding. We found that FKBP2 co-immunoprecipitated with proinsulin and its chaperone GRP94 and that inhibition of FKBP2 expression increased proinsulin turnover with reduced intracellular proinsulin and insulin levels. This phenotype was accompanied by an increased proinsulin secretion and the formation of proinsulin high-molecular-weight complexes, a sign of proinsulin misfolding. FKBP2 knockout in pancreatic ß-cells increased apoptosis without detectable up-regulation of ER stress response genes. Interestingly, FKBP2 mRNA was overexpressed in ß-cells from pancreatic islets of T2D patients. Based on molecular modeling and an in vitro enzymatic assay, we suggest that proline at position 28 of the proinsulin B-chain (P28) is the substrate of FKBP2's isomerization activity. We propose that this isomerization step catalyzed by FKBP2 is an essential sequence required for correct proinsulin folding.


Assuntos
Células Secretoras de Insulina , Proinsulina , Proinsulina/metabolismo , Dobramento de Proteína , Retículo Endoplasmático/metabolismo , Células Secretoras de Insulina/metabolismo , Chaperonas Moleculares/metabolismo , Prolina/metabolismo , Proteínas de Ligação a Tacrolimo/genética , Proteínas de Ligação a Tacrolimo/metabolismo , Insulina/metabolismo
2.
Cells ; 12(2)2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36672211

RESUMO

For decades, the undisputable definition of the cytosolic Hsp90α and hsp90ß proteins being evolutionarily conserved, ATP-driven chaperones has ruled basic research and clinical trials. The results of recent studies, however, have fundamentally challenged this paradigm, not to mention the spectacular failures of the paradigm-based clinical trials in cancer and beyond. We now know that Hsp90α and Hsp90ß are both ubiquitously expressed in all cell types but assigned for distinct and irreplaceable functions. Hsp90ß is essential during mouse development and Hsp90α only maintains male reproductivity in adult mice. Neither Hsp90ß nor Hsp90α could substitute each other under these biological processes. Hsp90ß alone maintains cell survival in culture and Hsp90α cannot substitute it. Hsp90α also has extracellular functions under stress and Hsp90ß does not. The dramatic difference in the steady-state expression of Hsp90 in different mouse organs is due to the variable expressions of Hsp90α. The lowest expression of Hsp90 is less than 2% and the highest expression of Hsp90 is 9% among non-transformed cell lines. The two linker regions only take up less than 5% of the Hsp90 proteins, but harbor 21% of the total amino acid substitutions, i.e., 40% in comparison to the 86% overall amino acid homology. A full understanding of the distinctions between Hsp90α and Hsp90ß could lead to new, safe and effective therapeutics targeting Hsp90 in human disorders such as cancer. This is the first comprehensive review of a comparison between the two cytosolic Hsp90 isoforms.


Assuntos
Proteínas de Choque Térmico HSP90 , Chaperonas Moleculares , Masculino , Camundongos , Humanos , Animais , Chaperonas Moleculares/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Isoformas de Proteínas/metabolismo , Substituição de Aminoácidos
3.
Theranostics ; 13(1): 339-354, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36593950

RESUMO

Rationale: Chemoresistance is a major challenge in the clinical management of patients with breast cancer. Mutant p53 proteins tend to form aggregates that promote tumorigenesis in cancers. We here aimed to explore the mechanism for the generation of mutant p53 aggregates in breast cancer and assess its role in inducing chemoresistance. Methods: Expression of BCL2-associated athanogene 2 (BAG2) was evaluated by qRT-PCR, western blotting, and immunohistochemistry in breast cancer patient specimens. The significance of BAG2 expression in prognosis was assessed by Kaplan-Meier survival analysis and the Cox regression model. The roles of BAG2 in facilitating the formation of mutant p53 aggregates were analyzed by co-immunoprecipitation, immunofluorescence, and semi-denaturing detergent-agarose gel electrophoresis assays. The effects of BAG2 on the chemoresistance of breast cancer were demonstrated by cell function assays and mice tumor models. Results: In the present study, we found that BAG2 was significantly upregulated in relapse breast cancer patient tissues and high BAG2 was associated with a worse prognosis. BAG2 localized in mutant p53 aggregates and interacted with misfolded p53 mutants. BAG2 exacerbated the formation of the aggregates and recruited HSP90 to promote the propagation and maintenance of the aggregates. Consequently, BAG2-mediated mutant p53 aggregation inhibited the mitochondrial apoptosis pathway, leading to chemoresistance in breast cancer. Importantly, silencing of BAG2 or pharmacological targeting of HSP90 substantially reduced the aggregates and increased the sensitivity of chemotherapy in breast cancer. Conclusion: These findings reveal a significant role of BAG2 in the chemoresistance of breast cancer via exacerbating mutant p53 aggregates and suggest that BAG2 may serve as a potential therapeutic target for breast cancer patients with drug resistance.


Assuntos
Neoplasias da Mama , Resistencia a Medicamentos Antineoplásicos , Chaperonas Moleculares , Proteína Supressora de Tumor p53 , Animais , Camundongos , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos/genética , Proteínas de Choque Térmico HSP90/metabolismo , Recidiva Local de Neoplasia , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Neoplasias da Mama/genética , Humanos , Feminino
4.
Nat Commun ; 14(1): 102, 2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36609656

RESUMO

The cell nucleus is a primary target for intracellular bacterial pathogens to counteract immune responses and hijack host signalling pathways to cause disease. Here we identify two Brucella abortus effectors, NyxA and NyxB, that interfere with host protease SENP3, and this facilitates intracellular replication of the pathogen. The translocated Nyx effectors directly interact with SENP3 via a defined acidic patch (identified from the crystal structure of NyxB), preventing nucleolar localisation of SENP3 at late stages of infection. By sequestering SENP3, the effectors promote cytoplasmic accumulation of nucleolar AAA-ATPase NVL and ribosomal protein L5 (RPL5) in effector-enriched structures in the vicinity of replicating bacteria. The shuttling of ribosomal biogenesis-associated nucleolar proteins is inhibited by SENP3 and requires the autophagy-initiation protein Beclin1 and the SUMO-E3 ligase PIAS3. Our results highlight a nucleomodulatory function of two Brucella effectors and reveal that SENP3 is a crucial regulator of the subcellular localisation of nucleolar proteins during Brucella infection, promoting intracellular replication of the pathogen.


Assuntos
Brucelose , Proteínas Nucleares , Humanos , Proteínas Nucleares/metabolismo , Núcleo Celular/metabolismo , Brucella abortus/metabolismo , Nucléolo Celular/metabolismo , Brucelose/microbiologia , Chaperonas Moleculares/metabolismo , Proteínas Inibidoras de STAT Ativados/metabolismo , Cisteína Endopeptidases/genética , Cisteína Endopeptidases/metabolismo
5.
J Cell Sci ; 136(1)2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36594787

RESUMO

Cdc28, the homolog of mammalian Cdk1, is a conserved key regulatory kinase for all major cell cycle transitions in yeast. We have found that defects in mitochondrial respiration (including deletion of ATP2, an ATP synthase subunit) inhibit growth of cells carrying a degron allele of Cdc28 (cdc28td) or Cdc28 temperature-sensitive mutations (cdc28-1 and cdc28-1N) at semi-permissive temperatures. Loss of cell proliferation in the atp2Δcdc28td double mutant is associated with aggravated cell cycle arrest and mitochondrial dysfunction, including mitochondrial hyperpolarization and fragmentation. Unexpectedly, in mutants defective in mitochondrial respiration, steady-state protein levels of mutant cdc28 are strongly reduced, accounting for the aggravated growth defects. Stability of Cdc28 is promoted by the Hsp90-Cdc37 chaperone complex. Our results show that atp2Δcdc28td double-mutant cells, but not single mutants, are sensitive to chemical inhibition of the Hsp90-Cdc37 complex, and exhibit reduced levels of additional Hsp90-Cdc37 client kinases, suggesting an inhibition of this complex. In agreement, overexpression of CDC37 improved atp2Δcdc28td cell growth and Cdc28 levels. Overall, our study shows that simultaneous disturbance of mitochondrial respiration and Cdc28 activity reduces the capacity of Cdc37 to chaperone client kinases, leading to growth arrest.


Assuntos
Proteínas de Ciclo Celular , Chaperonas Moleculares , Humanos , Animais , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Chaperonas Moleculares/metabolismo , Proteína Quinase CDC28 de Saccharomyces cerevisiae/genética , Proteína Quinase CDC28 de Saccharomyces cerevisiae/metabolismo , Proteínas de Choque Térmico HSP90/genética , Proteínas de Choque Térmico HSP90/metabolismo , Saccharomyces cerevisiae/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Ligação Proteica , Mamíferos/metabolismo , Chaperoninas/metabolismo , Proteína Quinase CDC2/genética , Proteína Quinase CDC2/metabolismo
6.
Int J Mol Sci ; 24(1)2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36614266

RESUMO

Modern pharmacotherapy of neurodegenerative diseases is predominantly symptomatic and does not allow vicious circles causing disease development to break. Protein misfolding is considered the most important pathogenetic factor of neurodegenerative diseases. Physiological mechanisms related to the function of chaperones, which contribute to the restoration of native conformation of functionally important proteins, evolved evolutionarily. These mechanisms can be considered promising for pharmacological regulation. Therefore, the aim of this review was to analyze the mechanisms of endoplasmic reticulum stress (ER stress) and unfolded protein response (UPR) in the pathogenesis of neurodegenerative diseases. Data on BiP and Sigma1R chaperones in clinical and experimental studies of Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease are presented. The possibility of neuroprotective effect dependent on Sigma1R ligand activation in these diseases is also demonstrated. The interaction between Sigma1R and BiP-associated signaling in the neuroprotection is discussed. The performed analysis suggests the feasibility of pharmacological regulation of chaperone function, possibility of ligand activation of Sigma1R in order to achieve a neuroprotective effect, and the need for further studies of the conjugation of cellular mechanisms controlled by Sigma1R and BiP chaperones.


Assuntos
Doenças Neurodegenerativas , Fármacos Neuroprotetores , Humanos , Neuroproteção , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Ligantes , Chaperonas Moleculares/metabolismo , Resposta a Proteínas não Dobradas , Estresse do Retículo Endoplasmático , Doenças Neurodegenerativas/tratamento farmacológico
7.
Proc Natl Acad Sci U S A ; 120(2): e2205199120, 2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36598941

RESUMO

Assembly of protein complexes is facilitated by assembly chaperones. Alpha and gamma adaptin-binding protein (AAGAB) is a chaperone governing the assembly of the heterotetrameric adaptor complexes 1 and 2 (AP1 and AP2) involved in clathrin-mediated membrane trafficking. Here, we found that before AP1/2 binding, AAGAB exists as a homodimer. AAGAB dimerization is mediated by its C-terminal domain (CTD), which is critical for AAGAB stability and is missing in mutant proteins found in patients with the skin disease punctate palmoplantar keratoderma type 1 (PPKP1). We solved the crystal structure of the dimerization-mediating CTD, revealing an antiparallel dimer of bent helices. Interestingly, AAGAB uses the same CTD to recognize and stabilize the γ subunit in the AP1 complex and the α subunit in the AP2 complex, forming binary complexes containing only one copy of AAGAB. These findings demonstrate a dual role of CTD in stabilizing resting AAGAB and binding to substrates, providing a molecular explanation for disease-causing AAGAB mutations. The oligomerization state transition mechanism may also underlie the functions of other assembly chaperones.


Assuntos
Proteínas Adaptadoras de Transporte Vesicular , Ceratodermia Palmar e Plantar , Humanos , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Proteínas de Transporte/genética , Ceratodermia Palmar e Plantar/genética , Ceratodermia Palmar e Plantar/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Clatrina/metabolismo , Complexo 2 de Proteínas Adaptadoras/genética , Complexo 2 de Proteínas Adaptadoras/metabolismo
8.
Int J Mol Sci ; 24(2)2023 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-36674442

RESUMO

Many neurodegenerative disorders are characterized by the abnormal aggregation of misfolded proteins that form amyloid deposits which possess prion-like behavior such as self-replication, intercellular transmission, and consequent induction of native forms of the same protein in surrounding cells. The distribution of the accumulated proteins and their correlated toxicity seem to be involved in the progression of nervous system degeneration. Molecular chaperones are known to maintain proteostasis, contribute to protein refolding to protect their function, and eliminate fatally misfolded proteins, prohibiting harmful effects. However, chaperone network efficiency declines during aging, prompting the onset and the development of neurological disorders. Extracellular vesicles (EVs) are tiny membranous structures produced by a wide range of cells under physiological and pathological conditions, suggesting their significant role in fundamental processes particularly in cellular communication. They modulate the behavior of nearby and distant cells through their biological cargo. In the pathological context, EVs transport disease-causing entities, including prions, α-syn, and tau, helping to spread damage to non-affected areas and accelerating the progression of neurodegeneration. However, EVs are considered effective for delivering therapeutic factors to the nervous system, since they are capable of crossing the blood-brain barrier (BBB) and are involved in the transportation of a variety of cellular entities. Here, we review the neurodegeneration process caused mainly by the inefficiency of chaperone systems as well as EV performance in neuropathies, their potential as diagnostic biomarkers and a promising EV-based therapeutic approach.


Assuntos
Vesículas Extracelulares , Doenças Neurodegenerativas , Príons , Humanos , Doenças Neurodegenerativas/metabolismo , Vesículas Extracelulares/metabolismo , Barreira Hematoencefálica/metabolismo , Príons/metabolismo , Chaperonas Moleculares/metabolismo
9.
Int J Mol Sci ; 24(2)2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36674565

RESUMO

The nucleosome is composed of histones and DNA. Prior to their deposition on chromatin, histones are shielded by specialized and diverse proteins known as histone chaperones. They escort histones during their entire cellular life and ensure their proper incorporation in chromatin. Physarum polycephalum is a Mycetozoan, a clade located at the crown of the eukaryotic tree. We previously found that histones, which are highly conserved between plants and animals, are also highly conserved in Physarum. However, histone chaperones differ significantly between animal and plant kingdoms, and this thus probed us to further study the conservation of histone chaperones in Physarum and their evolution relative to animal and plants. Most of the known histone chaperones and their functional domains are conserved as well as key residues required for histone and chaperone interactions. Physarum is divergent from yeast, plants and animals, but PpHIRA, PpCABIN1 and PpSPT6 are similar in structure to plant orthologues. PpFACT is closely related to the yeast complex, and the Physarum genome encodes the animal-specific APFL chaperone. Furthermore, we performed RNA sequencing to monitor chaperone expression during the cell cycle and uncovered two distinct patterns during S-phase. In summary, our study demonstrates the conserved role of histone chaperones in handling histones in an early-branching eukaryote.


Assuntos
Histonas , Physarum polycephalum , Animais , Histonas/metabolismo , Physarum polycephalum/genética , Physarum polycephalum/metabolismo , Chaperonas de Histonas/metabolismo , Saccharomyces cerevisiae/metabolismo , Cromatina/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo
10.
Int J Mol Sci ; 24(2)2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36674686

RESUMO

The Hsp70 family of molecular chaperones acts as a central 'hub' in the cell that interacts with numerous newly synthesized proteins to assist in their biogenesis. Apart from its central and well-established role in facilitating protein folding, Hsp70s also act as key decision points in the cellular chaperone network that direct client proteins to distinct biogenesis and quality control pathways. In this paper, we review accumulating data that illustrate a new branch in the Hsp70 network: the post-translational targeting of nascent membrane and organellar proteins to diverse cellular organelles. Work in multiple pathways suggests that Hsp70, via its ability to interact with components of protein targeting and translocation machineries, can initiate elaborate substrate relays in a sophisticated cascade of chaperones, cochaperones, and receptor proteins, and thus provide a mechanism to safeguard and deliver nascent membrane proteins to the correct cellular membrane. We discuss the mechanistic principles gleaned from better-studied Hsp70-dependent targeting pathways and outline the observations and outstanding questions in less well-studied systems.


Assuntos
Proteínas de Choque Térmico HSP70 , Proteínas de Membrana , Humanos , Proteínas de Membrana/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Chaperonas Moleculares/metabolismo , Dobramento de Proteína , Proteínas de Transporte/metabolismo
11.
Mol Cell ; 83(2): 252-265.e13, 2023 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-36630955

RESUMO

The conserved regulon of heat shock factor 1 in budding yeast contains chaperones for general protein folding as well as zinc-finger protein Zpr1, whose essential role in archaea and eukaryotes remains unknown. Here, we show that Zpr1 depletion causes acute proteotoxicity driven by biosynthesis of misfolded eukaryotic translation elongation factor 1A (eEF1A). Prolonged Zpr1 depletion leads to eEF1A insufficiency, thereby inducing the integrated stress response and inhibiting protein synthesis. Strikingly, we show by using two distinct biochemical reconstitution approaches that Zpr1 enables eEF1A to achieve a conformational state resistant to protease digestion. Lastly, we use a ColabFold model of the Zpr1-eEF1A complex to reveal a folding mechanism mediated by the Zpr1's zinc-finger and alpha-helical hairpin structures. Our work uncovers the long-sought-after function of Zpr1 as a bespoke chaperone tailored to the biogenesis of one of the most abundant proteins in the cell.


Assuntos
Proteínas de Transporte , Chaperonas Moleculares , Proteínas de Transporte/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Biossíntese de Proteínas , Dedos de Zinco , Zinco/metabolismo
12.
J Mol Biol ; 435(3): 167931, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36572238

RESUMO

The molecular chaperones Hsp90 and Hsp70 and their regulatory co-chaperone Hop play a key role at the crossroads of the folding pathways of numerous client proteins by forming fine-tuned multiprotein complexes. Alterations of the biomolecules involved may functionally impact the chaperone machinery: here, we integrate simulations and experiments to unveil how Hop conformational fitness and interactions can be controlled by the perturbation of just one residue. Specifically, we unveil how mechanisms mediated by Hop residue Y354 control Hop open and closed states, which affect binding of Hsp70/Hsp90. Phosphorylation or mutation of Hop-Y354 are shown to favor structural ensembles that are indeed not optimal for stable interactions with Hsp90 and Hsp70. This disfavors cellular accumulation of the stringent Hsp90 clients glucocorticoid receptor and the viral tyrosine kinase v-Src, with detrimental effects on v-Src activity. Our results show how the post-translational modification of a specific residue in Hop provides a regulation mechanism for the larger chaperone complex of which it is part. In this framework, the effects of one single alteration are amplified at the cellular level through the perturbation of protein-interaction networks.


Assuntos
Proteínas de Choque Térmico HSP90 , Chaperonas Moleculares , Humanos , Fosforilação , Chaperonas Moleculares/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas Tirosina Quinases/metabolismo , Ligação Proteica
13.
Subcell Biochem ; 101: 127-139, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36520305

RESUMO

Cellular homeostasis and stress survival requires maintenance of the proteome and suppression of proteotoxicity. Molecular chaperones promote cell survival through repair of misfolded proteins and cooperation with protein degradation machines to discard terminally damaged proteins. Hsp70 family members play an essential role in cellular protein metabolism by binding and releasing non-native proteins to facilitate protein folding, refolding, and degradation. Hsp40 (DnaJ-like proteins) family members are Hsp70 co-chaperones that determine the fate of Hsp70 clients by facilitating protein folding, assembly, and degradation. Hsp40s select substrates for Hsp70 via use of an intrinsic chaperone activity to bind non-native regions of proteins. During delivery of bound cargo Hsp40s employ a conserved J-domain to stimulate Hsp70 ATPase activity and thereby stabilize complexes between Hsp70 and non-native proteins. This review describes the mechanisms by which different Hsp40s use specialized sub-domains to direct clients of Hsp70 for triage between folding versus degradation.


Assuntos
Proteínas de Choque Térmico HSP40 , Proteínas de Choque Térmico HSP70 , Dobramento de Proteína , Proteólise , Humanos , Homeostase , Proteínas de Choque Térmico HSP40/genética , Proteínas de Choque Térmico HSP40/química , Proteínas de Choque Térmico HSP40/metabolismo , Proteínas de Choque Térmico HSP70/química , Proteínas de Choque Térmico HSP70/genética , Proteínas de Choque Térmico HSP70/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Ligação Proteica
14.
Proc Natl Acad Sci U S A ; 120(1): e2217476120, 2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36584296

RESUMO

HIV gene expression is modulated by the combinatorial activity of the HIV transcriptional activator, Tat, host transcription factors, and chromatin remodeling complexes. To identify host factors regulating HIV transcription, we used specific single-guide RNAs and endonuclease-deficient Cas9 to perform chromatin affinity purification of the integrated HIV promoter followed by mass spectrometry. The scaffold protein, p32, also called ASF/SF2 splicing factor-associated protein, was identified among the top enriched factors present in actively transcribing HIV promoters but absent in silenced ones. Chromatin immunoprecipitation analysis confirmed the presence of p32 on active HIV promoters and its enhanced recruitment by Tat. HIV uses Tat to efficiently recruit positive transcription elongation factor b (p-TEFb) (CDK9/CCNT1) to TAR, an RNA secondary structure that forms from the first 59 bp of HIV transcripts, to enhance RNAPII transcriptional elongation. The RNA interference of p32 significantly reduced HIV transcription in primary CD4+T cells and in HIV chronically infected cells, independently of either HIV splicing or p32 anti-splicing activity. Conversely, overexpression of p32 specifically increased Tat-dependent HIV transcription. p32 was found to directly interact with Tat's basic domain enhancing Tat stability and half-life. Conversely, p32 associates with Tat via N- and C-terminal domains. Likely due its scaffold properties, p32 also promoted Tat association with TAR, p-TEFb, and RNAPII enhancing Tat-dependent HIV transcription. In sum, we identified p32 as a host factor that interacts with and stabilizes Tat protein, promotes Tat-dependent transcriptional regulation, and may be explored for HIV-targeted transcriptional inhibition.


Assuntos
Infecções por HIV , HIV-1 , Humanos , Fator B de Elongação Transcricional Positiva/genética , Fator B de Elongação Transcricional Positiva/metabolismo , HIV-1/fisiologia , Produtos do Gene tat do Vírus da Imunodeficiência Humana/genética , Produtos do Gene tat do Vírus da Imunodeficiência Humana/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Chaperonas Moleculares/metabolismo , Infecções por HIV/genética , Transcrição Genética , Repetição Terminal Longa de HIV/genética
15.
Subcell Biochem ; 101: 189-211, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36520308

RESUMO

The UCS (UNC-45/CRO1/She4p) family of proteins has emerged as chaperones specific for the folding, assembly, and function of myosin. UCS proteins participate in various myosin-dependent cellular processes including myofibril organization and muscle functions, cell differentiation, striated muscle development, cytokinesis, and endocytosis. Mutations in the genes that code for UCS proteins cause serious defects in myosin-dependent cellular processes. UCS proteins that contain an N-terminal tetratricopeptide repeat (TPR) domain are called UNC-45. Vertebrates usually possess two variants of UNC-45, the ubiquitous general-cell UNC-45 (UNC-45A) and the striated muscle UNC-45 (UNC-45B), which is exclusively expressed in skeletal and cardiac muscles. Except for the TPR domain in UNC-45, UCS proteins comprise of several irregular armadillo (ARM) repeats that are organized into a central domain, a neck region, and the canonical C-terminal UCS domain that functions as the chaperoning module. With or without TPR, UCS proteins form linear oligomers that serve as scaffolds that mediate myosin folding, organization into myofibrils, repair, and motility. This chapter reviews emerging functions of these proteins with a focus on UNC-45 as a dedicated chaperone for folding, assembly, and function of myosin at protein and potentially gene levels. Recent experimental evidences strongly support UNC-45 as an absolute regulator of myosin, with each domain of the chaperone playing different but complementary roles during the folding, assembly, and function of myosin, as well as recruiting Hsp90 as a co-chaperone to optimize key steps. It is becoming increasingly clear that UNC-45 also regulates the transcription of several genes involved in myosin-dependent cellular processes.


Assuntos
Proteínas de Caenorhabditis elegans , Animais , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Chaperonas Moleculares/metabolismo , Miosinas/genética , Miosinas/química , Proteínas de Choque Térmico HSP90/genética , Proteínas de Choque Térmico HSP90/metabolismo
16.
Subcell Biochem ; 101: 141-158, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36520306

RESUMO

The co-chaperone p50/Cdc37 is an important partner for Hsp90, assisting in molecular chaperone activities, particularly with regard to the regulation of protein kinases. Analysis of the structure of Hsp90-Cdc37-kinase complexes demonstrates the way in which Cdc37 interacts with and controls the folding of a large proportion of intracellular protein kinases. This co-chaperone thus stands at the hub of a multitude of intracellular signaling networks. Indeed, the influence of Cdc37 reaches beyond the housekeeping pathways of protein folding into the regulation of a wide range of cellular processes. This co-chaperone has attracted attention as a potential intermediate in carcinogenesis. Cdc37 is an attractive potential target in cancer due to (1) high expression in a number of tumor types and (2) control of multiple signaling pathways. These properties indicate (3) a potential for selectivity due to its elevated expression in malignant cells and (4) robustness, as the co-chaperone may control multiple growth signaling pathways and thus be less prone to evolution of resistance than less versatile oncoproteins. Cdc37 may also be involved in other aspects of pathophysiology and has been shown to be secreted in exosomes. Protein aggregation disorders have been linked to age-related declines in molecular chaperones and co-chaperones. Cdc37 also appears to be a potential agent in longevity due to its links to protein folding and autophagy, and it will be informative to study the role of Cdc37 maintenance/decline in aging organisms.


Assuntos
Proteínas de Ciclo Celular , Chaperoninas , Chaperoninas/genética , Chaperoninas/química , Chaperoninas/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas de Choque Térmico HSP90/química , Proteínas de Choque Térmico HSP90/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Proteínas Quinases/metabolismo , Ligação Proteica
17.
Subcell Biochem ; 101: 1-39, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36520302

RESUMO

Molecular chaperones of the Hsp70 family are key components of the cellular protein-folding machinery. Substrate folding is accomplished by iterative cycles of ATP binding, hydrolysis, and release. The ATPase activity of Hsp70 is regulated by two main classes of cochaperones: J-domain proteins stimulate ATPase hydrolysis by Hsp70, while nucleotide exchange factors (NEFs) facilitate the conversion from the ADP-bound to the ATP-bound state, thus closing the chaperone folding cycle. NEF function can additionally be antagonized by ADP dissociation inhibitors. Beginning with the discovery of the prototypical bacterial NEF, GrpE, a large diversity of nucleotide exchange factors for Hsp70 have been identified, connecting it to a multitude of cellular processes in the eukaryotic cell. Here we review recent advances toward structure and function of nucleotide exchange factors from the Hsp110/Grp170, HspBP1/Sil1, and BAG domain protein families and discuss how these cochaperones connect protein folding with cellular quality control and degradation pathways.


Assuntos
Proteínas de Choque Térmico HSP70 , Chaperonas Moleculares , Proteínas de Choque Térmico HSP70/química , Proteínas de Choque Térmico HSP70/metabolismo , Chaperonas Moleculares/metabolismo , Dobramento de Proteína , Adenosina Trifosfatases/metabolismo , Difosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo
18.
Subcell Biochem ; 101: 247-291, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36520310

RESUMO

In mammalian cells, the rough endoplasmic reticulum (ER) plays central roles in the biogenesis of extracellular plus organellar proteins and in various signal transduction pathways. For these reasons, the ER comprises molecular chaperones, which are involved in import, folding, assembly, export, plus degradation of polypeptides, and signal transduction components, such as calcium channels, calcium pumps, and UPR transducers plus adenine nucleotide carriers/exchangers in the ER membrane. The calcium- and ATP-dependent ER lumenal Hsp70, termed immunoglobulin heavy-chain-binding protein or BiP, is the central player in all these activities and involves up to nine different Hsp40-type co-chaperones, i.e., ER membrane integrated as well as ER lumenal J-domain proteins, termed ERj or ERdj proteins, two nucleotide exchange factors or NEFs (Grp170 and Sil1), and NEF-antagonists, such as MANF. Here we summarize the current knowledge on the ER-resident BiP/ERj chaperone network and focus on the interaction of BiP with the polypeptide-conducting and calcium-permeable Sec61 channel of the ER membrane as an example for BiP action and how its functional cycle is linked to ER protein import and various calcium-dependent signal transduction pathways.


Assuntos
Cálcio , Retículo Endoplasmático , Animais , Humanos , Cálcio/metabolismo , Retículo Endoplasmático/metabolismo , Chaperonas Moleculares/metabolismo , Transporte Proteico , Chaperona BiP do Retículo Endoplasmático , Mamíferos/metabolismo , Fatores de Troca do Nucleotídeo Guanina/metabolismo
19.
Subcell Biochem ; 101: 293-318, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36520311

RESUMO

Mitochondrial J-domain protein (JDP) co-chaperones orchestrate the function of their Hsp70 chaperone partner(s) in critical organellar processes that are essential for cell function. These include folding, refolding, and import of mitochondrial proteins, maintenance of mitochondrial DNA, and biogenesis of iron-sulfur cluster(s) (FeS), prosthetic groups needed for function of mitochondrial and cytosolic proteins. Consistent with the organelle's endosymbiotic origin, mitochondrial Hsp70 and the JDPs' functioning in protein folding and FeS biogenesis clearly descended from bacteria, while the origin of the JDP involved in protein import is less evident. Regardless of their origin, all mitochondrial JDP/Hsp70 systems evolved unique features that allowed them to perform mitochondria-specific functions. Their modes of functional diversification and specialization illustrate the versatility of JDP/Hsp70 systems and inform our understanding of system functioning in other cellular compartments.


Assuntos
Proteínas de Saccharomyces cerevisiae , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Choque Térmico HSP70/genética , Proteínas de Choque Térmico HSP70/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo
20.
Neurosci Lett ; 792: 136971, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36414131

RESUMO

Despite the known importance of the endoplasmic reticulum (ER) in protein synthesis and vesicular transport, it is not clear whether neuropeptide and neuromodulator oxytocin can directly affect components of the ER in neuronal cells. Therefore, in the present study, we hypothesize that incubation of hippocampal neuronal cells in a presence of oxytocin 1) plays a role in the regulation of the expression of selected ER chaperone components and molecules involved in unfolded protein response pathway 2) affects distribution of the intracellular fluorescence signal highly selective for the ER. We found that oxytocin (1 µM) after 60 min significantly decreased the gene expression of oxidoreductase Ero1ß, chaperone glucose-regulated proteins (Grp) 78 and Grp94. A significant decrease in GRP78 protein levels in response to oxytocin treatment occurred after 30, 60 and 120 min. We also observed a time-dependent increase in calreticulin protein levels with a statistically significant increase observed after 360 min. We found that the dynamics of the ER network changes significantly within 2 h of incubation under the influence of oxytocin. In conclusion we have shown that ER chaperones, oxidoreductases and trafficking molecules in neuronal cells are changing in response to oxytocin treatment in a short-term scenario potentially relevant for growth of dendrites and axons.


Assuntos
Retículo Endoplasmático , Ocitocina , Ocitocina/farmacologia , Ocitocina/metabolismo , Retículo Endoplasmático/metabolismo , Neurônios/metabolismo , Hipocampo/metabolismo , Chaperonas Moleculares/metabolismo
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