RESUMEN
Proteostasis, the maintenance of proper protein folding, stability, and degradation within cells, is fundamental for cellular function. Two key players in this intricate cellular process are macroautophagy/autophagy and chaperoning of nascent proteins. Here, we explore the crosstalk between autophagy and the HSP90 chaperone in maintaining proteostasis, highlighting their interplay and significance in cellular homeostasis.Abbreviation: HSP90: heat shock protein 90; PTMs: post-translational modifications.
Asunto(s)
Autofagia , Proteínas HSP90 de Choque Térmico , Proteostasis , Animales , Humanos , Autofagia/fisiología , Proteínas HSP90 de Choque Térmico/metabolismo , Chaperonas Moleculares/metabolismo , Procesamiento Proteico-Postraduccional , Proteostasis/fisiologíaRESUMEN
Serine/threonine protein phosphatase-5 (PP5) is involved in tumor progression and survival, making it an attractive therapeutic target. Specific inhibition of protein phosphatases has remained challenging because of their conserved catalytic sites. PP5 contains its regulatory domains within a single polypeptide chain, making it a more desirable target. Here we used an in silico approach to screen and develop a selective inhibitor of PP5. Compound P053 is a competitive inhibitor of PP5 that binds to its catalytic domain and causes apoptosis in renal cancer. We further demonstrated that PP5 interacts with FADD, RIPK1, and caspase 8, components of the extrinsic apoptotic pathway complex II. Specifically, PP5 dephosphorylates and inactivates the death effector protein FADD, preserving complex II integrity and regulating extrinsic apoptosis. Our data suggests that PP5 promotes renal cancer survival by suppressing the extrinsic apoptotic pathway. Pharmacologic inhibition of PP5 activates this pathway, presenting a viable therapeutic strategy for renal cancer.
Asunto(s)
Neoplasias Renales , Fosfoproteínas Fosfatasas , Humanos , Proteínas Nucleares/metabolismo , Apoptosis , Neoplasias Renales/tratamiento farmacológicoRESUMEN
The molecular chaperone heat shock protein 90 (Hsp90) is essential in eukaryotes. Hsp90 chaperones proteins that are important determinants of multistep carcinogenesis. There are multiple Hsp90 isoforms including the cytosolic Hsp90α and Hsp90ß as well as GRP94 located in the endoplasmic reticulum and TRAP1 in the mitochondria. The chaperone function of Hsp90 is linked to its ability to bind and hydrolyze ATP. Co-chaperones and posttranslational modifications (such as phosphorylation, SUMOylation, and ubiquitination) are important for Hsp90 stability and regulation of its ATPase activity. Both mammalian and yeast cells can be used to express and purify Hsp90 and TRAP1 and also detect post-translational modifications by immunoblotting.
Asunto(s)
Proteínas HSP90 de Choque Térmico , Procesamiento Proteico-Postraduccional , Animales , Proteínas HSP90 de Choque Térmico/metabolismo , Chaperonas Moleculares/metabolismo , Fosforilación , Isoformas de Proteínas/metabolismo , Ubiquitinación , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Mamíferos/metabolismoRESUMEN
Cellular homeostasis relies on both the chaperoning of proteins and the intracellular degradation system that delivers cytoplasmic constituents to the lysosome, a process known as autophagy. The crosstalk between these processes and their underlying regulatory mechanisms is poorly understood. Here, we show that the molecular chaperone heat shock protein 90 (Hsp90) forms a complex with the autophagy-initiating kinase Atg1 (yeast)/Ulk1 (mammalian), which suppresses its kinase activity. Conversely, environmental cues lead to Atg1/Ulk1-mediated phosphorylation of a conserved serine in the amino domain of Hsp90, inhibiting its ATPase activity and altering the chaperone dynamics. These events impact a conformotypic peptide adjacent to the activation and catalytic loop of Atg1/Ulk1. Finally, Atg1/Ulk1-mediated phosphorylation of Hsp90 leads to dissociation of the Hsp90:Atg1/Ulk1 complex and activation of Atg1/Ulk1, which is essential for initiation of autophagy. Our work indicates a reciprocal regulatory mechanism between the chaperone Hsp90 and the autophagy kinase Atg1/Ulk1 and consequent maintenance of cellular proteostasis.
Asunto(s)
Autofagia , Proteínas HSP90 de Choque Térmico , Animales , Fosforilación , Homólogo de la Proteína 1 Relacionada con la Autofagia/metabolismo , Autofagia/fisiología , Proteínas HSP90 de Choque Térmico/metabolismo , Saccharomyces cerevisiae/metabolismo , Serina/metabolismo , Mamíferos/metabolismoRESUMEN
c-Src tyrosine kinase is a renowned key intracellular signaling molecule and a potential target for cancer therapy. Secreted c-Src is a recent observation, but how it contributes to extracellular phosphorylation remains elusive. Using a series of domain deletion mutants, we show that the N-proximal region of c-Src is essential for its secretion. The tissue inhibitor of metalloproteinases 2 (TIMP2) is an extracellular substrate of c-Src. Limited proteolysis-coupled mass spectrometry and mutagenesis studies verify that the Src homology 3 (SH3) domain of c-Src and the P31VHP34 motif of TIMP2 are critical for their interaction. Comparative phosphoproteomic analyses identify an enrichment of PxxP motifs in phosY-containing secretomes from c-Src-expressing cells with cancer-promoting roles. Inhibition of extracellular c-Src using custom SH3-targeting antibodies disrupt kinase-substrate complexes and inhibit cancer cell proliferation. These findings point toward an intricate role for c-Src in generating phosphosecretomes, which will likely influence cell-cell communication, particularly in c-Src-overexpressing cancers.
Asunto(s)
Proteínas Tirosina Quinasas , Secretoma , Proteínas Tirosina Quinasas/metabolismo , Transducción de Señal , Fosfotransferasas , Fosforilación , Dominios Homologos src , Comunicación Celular , Familia-src QuinasasRESUMEN
Yeast is a valuable model organism for their ease of genetic manipulation, rapid growth rate, and relative similarity to higher eukaryotes. Historically, Saccharomyces cerevisiae has played a major role in discovering the function of complex proteins and pathways that are important for human health and disease. Heat shock protein 90 (Hsp90) is a molecular chaperone responsible for the stabilization and activation of hundreds of integral members of the cellular signaling network. Much important structural and functional work, including many seminal discoveries in Hsp90 biology are the direct result of work carried out in S. cerevisiae. Here, we have provided a brief overview of the S. cerevisiae model system and described how this eukaryotic model organism has been successfully applied to the study of Hsp90 chaperone function.
Asunto(s)
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Humanos , Saccharomyces cerevisiae/metabolismo , Chaperonas Moleculares/genética , Proteínas HSP90 de Choque Térmico/química , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMEN
The Second International Symposium on Cellular and Organismal Stress Responses took place virtually on September 8-9, 2022. This meeting was supported by the Cell Stress Society International (CSSI) and organized by Patricija Van Oosten-Hawle and Andrew Truman (University of North Carolina at Charlotte, USA) and Mehdi Mollapour (SUNY Upstate Medical University, USA). The goal of this symposium was to continue the theme from the initial meeting in 2020 by providing a platform for established researchers, new investigators, postdoctoral fellows, and students to present and exchange ideas on various topics on cellular stress and chaperones. We will summarize the highlights of the meeting here and recognize those that received recognition from the CSSI.
Asunto(s)
Chaperonas Moleculares , Estrés Fisiológico , Humanos , Proteínas HSP70 de Choque Térmico , Chaperonas Moleculares/fisiología , Estrés Fisiológico/fisiologíaRESUMEN
Posttranslational modifications (PTMs) regulate myriad cellular processes by modulating protein function and protein-protein interaction. Heat shock protein 90 (Hsp90) is an ATP-dependent molecular chaperone whose activity is responsible for the stabilization and maturation of more than 300 client proteins. Hsp90 is a substrate for numerous PTMs, which have diverse effects on Hsp90 function. Interestingly, many Hsp90 clients are enzymes that catalyze PTM, demonstrating one of the several modes of regulation of Hsp90 activity. Approximately 25 co-chaperone regulatory proteins of Hsp90 impact structural rearrangements, ATP hydrolysis, and client interaction, representing a second layer of influence on Hsp90 activity. A growing body of literature has also established that PTM of these co-chaperones fine-tune their activity toward Hsp90; however, many of the identified PTMs remain uncharacterized. Given the critical role of Hsp90 in supporting signaling in cancer, clinical evaluation of Hsp90 inhibitors is an area of great interest. Interestingly, differential PTM and co-chaperone interaction have been shown to impact Hsp90 binding to its inhibitors. Therefore, understanding these layers of Hsp90 regulation will provide a more complete understanding of the chaperone code, facilitating the development of new biomarkers and combination therapies.
Asunto(s)
Proteínas HSP90 de Choque Térmico , Neoplasias , Humanos , Proteínas HSP90 de Choque Térmico/genética , Proteínas HSP90 de Choque Térmico/metabolismo , Chaperonas Moleculares/metabolismo , Procesamiento Proteico-Postraduccional , Neoplasias/tratamiento farmacológico , Adenosina Trifosfato/metabolismoRESUMEN
The molecular chaperone Heat Shock Protein-90 (Hsp90) is known to interact with over 300 client proteins as well as regulatory factors (eg. nucleotide and proteins) that facilitate execution of its role as a chaperone and, ultimately, client protein activation. Hsp90 associates transiently with these molecular modulators during an eventful chaperone cycle, resulting in acquisition of flexible structural conformations, perfectly customized to the needs of each one of its client proteins. Due to the plethora and diverse nature of proteins it supports, the Hsp90 chaperone machinery is critical for normal cellular function particularly in response to stress. In diseases such as cancer, the Hsp90 chaperone machinery is hijacked for processes which encompass many of the hallmarks of cancer, including cell growth, survival, immune response evasion, migration, invasion, and angiogenesis. Elevated levels of extracellular Hsp90 (eHsp90) enhance tumorigenesis and the potential for metastasis. eHsp90 has been considered one of the new targets in the development of anti-cancer drugs as there are various stages of cancer progression where eHsp90 function could be targeted. Our limited understanding of the regulation of the eHsp90 chaperone machinery is a major drawback for designing successful Hsp90-targeted therapies, and more research is still warranted.
RESUMEN
The molecular chaperone TNF-receptor-associated protein-1 (TRAP1) controls mitochondrial respiration through regulation of Krebs cycle and electron transport chain activity. Post-translational modification (PTM) of TRAP1 regulates its activity, thereby controlling global metabolic flux. O-GlcNAcylation is one PTM that is known to impact mitochondrial metabolism, however the major effectors of this regulatory PTM remain inadequately resolved. Here we demonstrate that TRAP1-O-GlcNAcylation decreases TRAP1 ATPase activity, leading to increased mitochondrial metabolism. O-GlcNAcylation of TRAP1 occurs following mitochondrial import and provides critical regulatory feedback, as the impact of O-GlcNAcylation on mitochondrial metabolism shows TRAP1-dependence. Mechanistically, loss of TRAP1-O-GlcNAcylation decreased TRAP1 binding to ATP, and interaction with its client protein succinate dehydrogenase (SDHB). Taken together, TRAP1-O-GlcNAcylation serves to regulate mitochondrial metabolism by the reversible attenuation of TRAP1 chaperone activity.
Asunto(s)
Chaperonas Moleculares , Succinato Deshidrogenasa , Adenosina Trifosfatasas/metabolismo , Adenosina Trifosfato/metabolismo , Proteínas HSP90 de Choque Térmico/metabolismo , Humanos , Chaperonas Moleculares/metabolismo , Procesamiento Proteico-Postraduccional , Respiración , Succinato Deshidrogenasa/metabolismo , Factor 1 Asociado a Receptor de TNF/química , Factor 1 Asociado a Receptor de TNF/metabolismoRESUMEN
Heat shock protein-90 (Hsp90) is an ATP-dependent molecular chaperone that is tightly regulated by a group of proteins termed co-chaperones. This chaperone system is essential for the stabilization and activation of many key signaling proteins. Recent identification of the co-chaperones FNIP1, FNIP2, and Tsc1 has broadened the spectrum of Hsp90 regulators. These new co-chaperones mediate the stability of critical tumor suppressors FLCN and Tsc2 as well as the various classes of Hsp90 kinase and non-kinase clients. Many early observations of the roles of FNIP1, FNIP2, and Tsc1 suggested functions independent of FLCN and Tsc2 but have not been fully delineated. Given the broad cellular impact of Hsp90-dependent signaling, it is possible to explain the cellular activities of these new co-chaperones by their influence on Hsp90 function. Here, we review the literature on FNIP1, FNIP2, and Tsc1 as co-chaperones and discuss the potential downstream impact of this regulation on normal cellular function and in human diseases.
Asunto(s)
Proteína 1 del Complejo de la Esclerosis Tuberosa/metabolismo , Esclerosis Tuberosa , Proteínas Supresoras de Tumor , Proteínas HSP90 de Choque Térmico/metabolismo , Humanos , Chaperonas Moleculares , Esclerosis Tuberosa/metabolismo , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismoRESUMEN
Heat shock protein-90 (Hsp90) chaperone machinery is involved in the stability and activity of its client proteins. The chaperone function of Hsp90 is regulated by co-chaperones and post-translational modifications. Although structural evidence exists for Hsp90 interaction with clients, our understanding of the impact of Hsp90 chaperone function toward client activity in cells remains elusive. Here, we dissect the impact of recently identified higher eukaryotic co-chaperones, FNIP1/2 (FNIPs) and Tsc1, toward Hsp90 client activity. Our data show that Tsc1 and FNIP2 form mutually exclusive complexes with FNIP1, and that unlike Tsc1, FNIP1/2 interact with the catalytic residue of Hsp90. Functionally, these co-chaperone complexes increase the affinity of the steroid hormone receptors glucocorticoid receptor and estrogen receptor to their ligands in vivo. We provide a model for the responsiveness of the steroid hormone receptor activation upon ligand binding as a consequence of their association with specific Hsp90:co-chaperone subpopulations.
Asunto(s)
Proteínas HSP90 de Choque Térmico , Chaperonas Moleculares , Proteínas HSP90 de Choque Térmico/metabolismo , Hormonas/metabolismo , Humanos , Ligandos , Chaperonas Moleculares/metabolismo , Unión Proteica , Esteroides/metabolismoRESUMEN
Mitochondrial function is dependent on molecular chaperones, primarily due to their necessity in the formation of respiratory complexes and clearance of misfolded proteins. Heat shock proteins (Hsps) are a subset of molecular chaperones that function in all subcellular compartments, both constitutively and in response to stress. The Hsp90 chaperone TNF-receptor-associated protein-1 (TRAP1) is primarily localized to the mitochondria and controls both cellular metabolic reprogramming and mitochondrial apoptosis. TRAP1 upregulation facilitates the growth and progression of many cancers by promoting glycolytic metabolism and antagonizing the mitochondrial permeability transition that precedes multiple cell death pathways. TRAP1 attenuation induces apoptosis in cellular models of cancer, identifying TRAP1 as a potential therapeutic target in cancer. Similar to cytosolic Hsp90 proteins, TRAP1 is also subject to post-translational modifications (PTM) that regulate its function and mediate its impact on downstream effectors, or 'clients'. However, few effectors have been identified to date. Here, we will discuss the consequence of TRAP1 deregulation in cancer and the impact of post-translational modification on the known functions of TRAP1.
Asunto(s)
Proteínas HSP90 de Choque Térmico , Neoplasias , Factor 1 Asociado a Receptor de TNF , Glucólisis , Proteínas HSP90 de Choque Térmico/metabolismo , Humanos , Mitocondrias/metabolismo , Chaperonas Moleculares/metabolismo , Neoplasias/metabolismo , Factor 1 Asociado a Receptor de TNF/metabolismoRESUMEN
The treatment of advanced and metastatic kidney cancer has entered a golden era with the addition of more therapeutic options, improved survival and new targeted therapies. Tyrosine kinase inhibitors, mammalian target of rapamycin (mTOR) inhibitors and immune checkpoint blockade have all been shown to be promising strategies in the treatment of renal cell carcinoma (RCC). However, little is known about the best therapeutic approach for individual patients with RCC and how to combat therapeutic resistance. Cancers, including RCC, rely on sustained replicative potential. The cyclin-dependent kinases CDK4 and CDK6 are involved in cell-cycle regulation with additional roles in metabolism, immunogenicity and antitumour immune response. Inhibitors of CDK4 and CDK6 are now commonly used as approved and investigative treatments in breast cancer, as well as several other tumours. Furthermore, CDK4/6 inhibitors have been shown to work synergistically with other kinase inhibitors, including mTOR inhibitors, as well as with immune checkpoint inhibitors in preclinical cancer models. The effect of CDK4/6 inhibitors in kidney cancer is relatively understudied compared with other cancers, but the preclinical studies available are promising. Collectively, growing evidence suggests that targeting CDK4 and CDK6 in kidney cancer, alone and in combination with current therapeutics including mTOR and immune checkpoint inhibitors, might have therapeutic benefit and should be further explored.
Asunto(s)
Carcinoma de Células Renales , Neoplasias Renales , Carcinoma de Células Renales/tratamiento farmacológico , Quinasa 4 Dependiente de la Ciclina/metabolismo , Quinasa 4 Dependiente de la Ciclina/uso terapéutico , Femenino , Humanos , Inhibidores de Puntos de Control Inmunológico , Neoplasias Renales/tratamiento farmacológico , Masculino , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéutico , Serina-Treonina Quinasas TOR/uso terapéuticoRESUMEN
Heat shock protein-90 (Hsp90) is an essential molecular chaperone in eukaryotes that plays a vital role in protecting and maintaining the functional integrity of deregulated signaling proteins in tumors. We have previously reported that the stability and activity of the mitotic checkpoint kinase Mps1 depend on Hsp90. In turn, Mps1-mediated phosphorylation Hsp90 regulates its chaperone function and is essential for the mitotic arrest. Cdc14-assisted dephosphorylation of Hsp90 is vital for the mitotic exit. Post-translational regulation of Hsp90 function is also known as the Hsp90 "Chaperone Code." Here, we demonstrate that only the active Mps1 is ubiquitinated on K86, K827, and K848 by the tumor suppressor von Hippel-Lindau (VHL) containing E3 enzyme, in a prolyl hydroxylation-independent manner and degraded in the proteasome. Furthermore, we show that this process regulates cell exit from the mitotic checkpoint. Collectively, our data demonstrates an interplay between the Hsp90 chaperone and VHL degradation machinery in regulating mitosis.
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Proteínas de Ciclo Celular/genética , Chaperoninas/genética , Proteínas HSP90 de Choque Térmico/genética , Proteínas Serina-Treonina Quinasas/genética , Proteínas Tirosina Quinasas/genética , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/genética , Humanos , Puntos de Control de la Fase M del Ciclo Celular/genética , Mitosis/genética , Chaperonas Moleculares/genética , Fosforilación , Unión Proteica , Proteolisis , Transducción de Señal/genéticaRESUMEN
Aerobic glycolysis in cancer cells, also known as the 'Warburg effect', is driven by hyperactivity of lactate dehydrogenase A (LDHA). LDHA is thought to be a substrate-regulated enzyme, but it is unclear whether a dedicated intracellular protein also regulates its activity. Here, we identify the human tumor suppressor folliculin (FLCN) as a binding partner and uncompetitive inhibitor of LDHA. A flexible loop within the amino terminus of FLCN controls movement of the LDHA active-site loop, tightly regulating its enzyme activity and, consequently, metabolic homeostasis in normal cells. Cancer cells that experience the Warburg effect show FLCN dissociation from LDHA. Treatment of these cells with a decapeptide derived from the FLCN loop region causes cell death. Our data suggest that the glycolytic shift of cancer cells is the result of FLCN inactivation or dissociation from LDHA. Together, FLCN-mediated inhibition of LDHA provides a new paradigm for the regulation of glycolysis.
Asunto(s)
Glucólisis/fisiología , Lactato Deshidrogenasa 5/antagonistas & inhibidores , Neoplasias/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Supresoras de Tumor/metabolismo , Dominio Catalítico/fisiología , Línea Celular Tumoral , Proliferación Celular , Regulación Neoplásica de la Expresión Génica/genética , Células HEK293 , Humanos , Lactato Deshidrogenasa 5/metabolismo , Transducción de SeñalRESUMEN
Birt-Hogg-Dubé (BHD) and tuberous sclerosis (TS) syndromes share many clinical features. These two diseases display distinct histologic subtypes of renal tumors: chromophobe renal cell carcinoma and renal angiomyolipoma, respectively. Early work suggested a role for mTOR dysregulation in the pathogenesis of these two diseases, however their detailed molecular link remains elusive. Interestingly, a growing number of case reports describe renal angiomyolipoma in BHD patients, suggesting a common molecular origin. The BHD-associated proteins FNIP1/2 and the TS protein Tsc1 were recently identified as regulators of the molecular chaperone Hsp90. Dysregulation of Hsp90 activity has previously been reported to support tumorigenesis, providing a potential explanation for the overlapping phenotypic manifestations in these two hereditary syndromes.
Asunto(s)
Síndrome de Birt-Hogg-Dubé/etiología , Proteínas HSP90 de Choque Térmico/fisiología , Esclerosis Tuberosa/etiología , Angiomiolipoma/etiología , Carcinoma de Células Renales/etiología , Humanos , Neoplasias Renales/etiologíaRESUMEN
Cells have a remarkable ability to synthesize large amounts of protein in a very short period of time. Under these conditions, many hydrophobic surfaces on proteins may be transiently exposed, and the likelihood of deleterious interactions is quite high. To counter this threat to cell viability, molecular chaperones have evolved to help nascent polypeptides fold correctly and multimeric protein complexes assemble productively, while minimizing the danger of protein aggregation. Heat shock protein 90 (Hsp90) is an evolutionarily conserved molecular chaperone that is involved in the stability and activation of at least 300 proteins, also known as clients, under normal cellular conditions. The Hsp90 clients participate in the full breadth of cellular processes, including cell growth and cell cycle control, signal transduction, DNA repair, transcription, and many others. Hsp90 chaperone function is coupled to its ability to bind and hydrolyze ATP, which is tightly regulated both by co-chaperone proteins and post-translational modifications (PTMs). Many reported PTMs of Hsp90 alter chaperone function and consequently affect myriad cellular processes. Here, we review the contributions of PTMs, such as phosphorylation, acetylation, SUMOylation, methylation, O-GlcNAcylation, ubiquitination, and others, toward regulation of Hsp90 function. We also discuss how the Hsp90 modification state affects cellular sensitivity to Hsp90-targeted therapeutics that specifically bind and inhibit its chaperone activity. The ultimate challenge is to decipher the comprehensive and combinatorial array of PTMs that modulate Hsp90 chaperone function, a phenomenon termed the "chaperone code."