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1.
Transplantation ; 107(10): 2262-2270, 2023 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-37291709

RESUMO

BACKGROUND: Pulmonary blood flow can be assessed on ventilation-perfusion (VQ) scan with relative lung perfusion, with a 55% to 45% (or 10%) right-to-left differential considered normal. We hypothesized that wide perfusion differential on routine VQ studies at 3 mo posttransplant would be associated with an increased risk of death or retransplantation, chronic lung allograft (CLAD), and baseline lung allograft dysfunction. METHODS: We conducted a retrospective cohort study on all patients who underwent double-lung transplant in our program between 2005 and 2016, identifying patients with a wide perfusion differential of >10% on a 3-mo VQ scan. We used Kaplan-Meier estimates and proportional hazards models to assess the association between perfusion differential and time to death or retransplant and time to CLAD onset. We used correlation and linear regression to assess the relationship with lung function at time of scan and with baseline lung allograft dysfunction. RESULTS: Of 340 patients who met inclusion criteria, 169 (49%) had a relative perfusion differential of ≥ 10% on a 3-mo VQ scan. Patients with increased perfusion differential had increased risk of death or retransplantation ( P = 0.011) and CLAD onset ( P = 0.012) after adjustment for other radiographic/endoscopic abnormalities. Increased perfusion differential was associated with lower lung function at time of scan. CONCLUSIONS: Wide lung perfusion differential was common after lung transplant in our cohort and associated with increased risk of death, poor lung function, and CLAD onset. The nature of this abnormality and its use as a predictor of future risk warrant further investigation.


Assuntos
Transplante de Pulmão , Cintilografia de Ventilação/Perfusão , Humanos , Estudos Retrospectivos , Pulmão/diagnóstico por imagem , Transplante de Pulmão/efeitos adversos , Perfusão/efeitos adversos , Aloenxertos
2.
Niger J Clin Pract ; 23(8): 1039-1043, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32788478

RESUMO

AIM: The aim of this study was to investigate the relationship between the presence of Demodex on the face and within the eyelash follicles in patients with rosacea. SUBJECTS AND METHODS: This prospective cross-sectional study included 80 participants, 40 patients with rosacea and 40 individuals with no rosacea as controls. The presence of Demodex on the face was assessed by standard superficial skin biopsy. Sixteen eyelashes were epilated from each patient and control. RESULTS: The rate of Demodex infestation and severe infestation on the face in patients with rosacea was significantly higher than the control group. Demodex count within the eyelash follicle was significantly higher in patients with erythematotelangiectatic type rosacea than the control group. There was no increase in blepharitis in rosacea patients but when blepharitis was present, the rate of the presence of Demodex was higher in this group. There was a statistically significant relationship between the presence of Demodex within the eyelashes and itchy eyes in people without blepharitis. CONCLUSION: When at least one Demodex is found on the face in rosacea patients, the eyelashes should be examined for effective treatment of the mite. Itchy eyes may be an important sign of the presence of Demodex in people without blepharitis.


Assuntos
Infecções Oculares Parasitárias/parasitologia , Pestanas/parasitologia , Infestações por Ácaros/parasitologia , Rosácea/parasitologia , Pele/patologia , Adulto , Animais , Biópsia , Blefarite/diagnóstico , Blefarite/epidemiologia , Blefarite/parasitologia , Estudos de Casos e Controles , Conjuntivite , Estudos Transversais , Infecções Oculares Parasitárias/diagnóstico , Infecções Oculares Parasitárias/epidemiologia , Face , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infestações por Ácaros/diagnóstico , Infestações por Ácaros/epidemiologia , Ácaros , Estudos Prospectivos , Prurido , Rosácea/diagnóstico , Rosácea/epidemiologia
3.
Bioinformatics ; 34(17): i706-i714, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-30423092

RESUMO

Motivation: Segmental duplications (SDs) or low-copy repeats, are segments of DNA > 1 Kbp with high sequence identity that are copied to other regions of the genome. SDs are among the most important sources of evolution, a common cause of genomic structural variation and several are associated with diseases of genomic origin including schizophrenia and autism. Despite their functional importance, SDs present one of the major hurdles for de novo genome assembly due to the ambiguity they cause in building and traversing both state-of-the-art overlap-layout-consensus and de Bruijn graphs. This causes SD regions to be misassembled, collapsed into a unique representation, or completely missing from assembled reference genomes for various organisms. In turn, this missing or incorrect information limits our ability to fully understand the evolution and the architecture of the genomes. Despite the essential need to accurately characterize SDs in assemblies, there has been only one tool that was developed for this purpose, called Whole-Genome Assembly Comparison (WGAC); its primary goal is SD detection. WGAC is comprised of several steps that employ different tools and custom scripts, which makes this strategy difficult and time consuming to use. Thus there is still a need for algorithms to characterize within-assembly SDs quickly, accurately, and in a user friendly manner. Results: Here we introduce SEgmental Duplication Evaluation Framework (SEDEF) to rapidly detect SDs through sophisticated filtering strategies based on Jaccard similarity and local chaining. We show that SEDEF accurately detects SDs while maintaining substantial speed up over WGAC that translates into practical run times of minutes instead of weeks. Notably, our algorithm captures up to 25% 'pairwise error' between segments, whereas previous studies focused on only 10%, allowing us to more deeply track the evolutionary history of the genome. Availability and implementation: SEDEF is available at https://github.com/vpc-ccg/sedef.


Assuntos
Genoma , Duplicações Segmentares Genômicas , Algoritmos , Genômica , Humanos
4.
Int J Biochem Cell Biol ; 45(2): 344-6, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23183002

RESUMO

The recently published paper by Wettstein et al. (2012) reviews the data of literature dealing with participation of small heat shock proteins (sHsp) in cytoskeleton regulation. Analyzing the effect of sHsp on microfilaments, the authors come to conclusion that depending on phosphorylation HspB1 can function as barbed-end-capping protein and can prevent aggregation of F-actin under stress conditions. The modern data do not confirm all these suggestions. We propose that stabilization effect of HspB1 on microfilaments is due to HspB1 interaction with partially unfolded actin or with genuine actin-binding proteins. In addition, HspB1 can exert its stabilizing effect on F-actin by modulating other elements of the cytoskeleton (intermediate filaments and microtubules) or by controlling homeostasis (for instance, redox state). Without being genuine actin-binding proteins, HspB1 and HspB6 predominantly protect microfilaments via an indirect mechanism that is yet to be characterized.


Assuntos
Fibrose/metabolismo , Proteínas de Choque Térmico Pequenas/metabolismo , Filamentos Intermediários/metabolismo , Neoplasias/metabolismo , Animais , Humanos
5.
Arch Biochem Biophys ; 521(1-2): 62-70, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22450169

RESUMO

It has been previously reported that phosphorylated cofilin interacted with 14-3-3ζ protein to generate a sub-micromolar K(d) binary complex. Here we challenge this hypothesis by analyzing the direct association of recombinant cofilin with 14-3-3ζ using different in vitro biochemical methods. Phosphorylated cofilin at high concentration binds to 14-3-3 immobilized on nitrocellulose, however no complex formation was detected by means of native gel electrophoresis or chemical crosslinking. Intact dimeric or mutant monomeric 14-3-3 was unable to form stable complexes with phosphorylated or unphosphorylated cofilin detected by size-exclusion chromatography. In co-sedimentation assay 14-3-3 did not affect interaction of cofilin with F-actin. The data of native gel electrophoresis indicate that 14-3-3 did not affect interaction of cofilin with G-actin. Thus, cofilin only weakly interacts with 14-3-3 and therefore cannot directly compete with phosphorylated small heat shock protein HspB6 for its binding to 14-3-3. It is hypothesized that phosphorylated HspB6 might affect interaction of 14-3-3 with protein phosphatases (and/or protein kinases) involved in dephosphorylation (or phosphorylation) of cofilin and by this means regulate cofilin-dependent reorganization of cytoskeleton.


Assuntos
Proteínas 14-3-3/metabolismo , Cofilina 1/metabolismo , Cofilina 2/metabolismo , Proteínas de Choque Térmico HSP20/metabolismo , Proteínas 14-3-3/química , Proteínas 14-3-3/genética , Actinas/metabolismo , Substituição de Aminoácidos , Animais , Sequência de Bases , Movimento Celular/fisiologia , Cofilina 1/química , Cofilina 1/genética , Cofilina 2/química , Cofilina 2/genética , Primers do DNA/genética , Humanos , Técnicas In Vitro , Fosforilação , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Coelhos , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
6.
Cell Stress Chaperones ; 17(2): 157-69, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22002549

RESUMO

Oligomeric association of human small heat shock proteins HspB1, HspB5, HspB6 and HspB8 was analyzed by means of size-exclusion chromatography, analytical ultracentrifugation and chemical cross-linking. Wild-type HspB1 and Cys mutants of HspB5, HspB6 and HspB8 containing a single Cys residue in position homologous to that of Cys137 of human HspB1 were able to generate heterodimers cross-linked by disulfide bond. Cross-linked heterodimers between HspB1/HspB5, HspB1/HspB6 and HspB5/HspB6 were easily produced upon mixing, whereas formation of any heterodimers with participation of HspB8 was significantly less efficient. The size of heterooligomers formed by HspB1/HspB6 and HspB5/HspB6 was different from the size of the corresponding homooligomers. Disulfide cross-linked homodimers of small heat shock proteins were unable to participate in heterooligomer formation. Thus, monomers can be involved in subunit exchange leading to heterooligomer formation and restriction of flexibility induced by disulfide cross-linking prevents subunit exchange.


Assuntos
Proteínas de Choque Térmico HSP27/metabolismo , Proteínas de Choque Térmico Pequenas/metabolismo , Proteínas Recombinantes/metabolismo , Reagentes de Ligações Cruzadas/química , Eletroforese em Gel Bidimensional , Proteínas de Choque Térmico HSP27/química , Proteínas de Choque Térmico HSP27/genética , Proteínas de Choque Térmico , Proteínas de Choque Térmico Pequenas/química , Proteínas de Choque Térmico Pequenas/genética , Humanos , Modelos Biológicos , Chaperonas Moleculares , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Oxirredução , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Ultracentrifugação
7.
Curr Protein Pept Sci ; 13(1): 76-85, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22044147

RESUMO

Small heat shock proteins (sHsp) form a large ubiquitous family of proteins expressed in all phyla of living organisms. The members of this family have low molecular masses (13-43 kDa) and contain a conservative α-crystallin domain. This domain (about 90 residues) consists of several ß-strands forming two ß-sheets packed in immunoglobulinlike manner. The α-crystallin domain plays an important role in formation of stable sHsp dimers, which are the building blocks of the large sHsp oligomers. A large N-terminal domain and a short C-terminal extension flank the α-crystallin domain. Both the N-terminal domain and the C-terminal extension are flexible, susceptible to proteolysis, prone to posttranslational modifications, and are predominantly intrinsically disordered. Differently oriented N-terminal domains interact with each other, with the core α-crystallin domain of the same or neighboring dimers and play important role in formation of large sHsp oligomers. Phosphorylation of certain sites in the N-terminal domain affects the sHsp quaternary structure, the sHsp interaction with target proteins and the sHsp chaperone-like activity. The C-terminal extension often carrying the conservative tripeptide (I/V/L)-X-(I/V/L) is capable of binding to a hydrophobic groove on the surface of the core α-crystallin domain of neighboring dimer, thus affecting the plasticity and the overall structure of sHsp oligomers. The Cterminal extension interacts with target proteins and affects their interaction with the α-crystallin domain increasing solubility of the complexes formed by sHsp and their targets. Thus, disordered N- and C-terminal sequences play important role in the structure, regulation and functioning of sHsp.


Assuntos
Proteínas de Choque Térmico Pequenas/química , Proteínas de Choque Térmico Pequenas/metabolismo , Estrutura Terciária de Proteína , Relação Estrutura-Atividade , alfa-Cristalinas
8.
Biochemistry ; 50(45): 9797-808, 2011 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-21978388

RESUMO

Dimers formed by seven isoforms of the human 14-3-3 protein participate in multiple cellular processes. The dimeric form has been extensively characterized; however, little is known about the structure and properties of the monomeric form of 14-3-3. The monomeric form is involved in the assembly of homo- and heterodimers, which could partially dissociate back into monomers in response to phosphorylation at Ser58. To obtain monomeric forms of human 14-3-3ζ, we produced four protein constructs with different combinations of mutated (M) or wild-type (W) segments E(5), (12)LAE(14), and (82)YREKIE(87). Under a wide range of expression conditions in Escherichia coli, the MMM and WMM mutants were insoluble, whereas WMW and MMW mutants were soluble, highly expressed, and purified to homogeneity. WMW and MMW mutants remained monomeric over a wide range of concentrations while retaining the α-helical structure characteristic of wild-type 14-3-3. However, WMW and MMW mutants were highly susceptible to proteolysis and had much lower thermal stabilities than the wild-type protein. Using WMW and MMW mutants, we show that the monomeric form interacts with the tau protein and with the HspB6 protein, in both cases forming complexes with a 1:1 stoichiometry, in contrast to the 2:1 and/or 2:2 complexes formed by wild-type 14-3-3. Significantly, this interaction requires phosphorylation of tau protein and HspB6. Because of minimal changes in structure, MMW and especially WMW mutant proteins are promising candidates for analyzing the effect of monomerization on the physiologically important properties of 14-3-3ζ.


Assuntos
Proteínas 14-3-3/química , Proteínas 14-3-3/metabolismo , Proteínas de Choque Térmico HSP20/química , Proteínas de Choque Térmico HSP20/metabolismo , Proteínas tau/química , Proteínas tau/metabolismo , Proteínas 14-3-3/genética , Sequência de Aminoácidos , Sequência de Bases , Primers do DNA/genética , Dimerização , Transferência Ressonante de Energia de Fluorescência , Proteínas de Choque Térmico HSP20/genética , Humanos , Técnicas In Vitro , Modelos Moleculares , Mutagênese Sítio-Dirigida , Engenharia de Proteínas , Domínios e Motivos de Interação entre Proteínas , Multimerização Proteica , Estabilidade Proteica , Estrutura Quaternária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas tau/genética
9.
Physiol Rev ; 91(4): 1123-59, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22013208

RESUMO

Modern classification of the family of human small heat shock proteins (the so-called HSPB) is presented, and the structure and properties of three members of this family are analyzed in detail. Ubiquitously expressed HSPB1 (HSP27) is involved in the control of protein folding and, when mutated, plays a significant role in the development of certain neurodegenerative disorders. HSPB1 directly or indirectly participates in the regulation of apoptosis, protects the cell against oxidative stress, and is involved in the regulation of the cytoskeleton. HSPB6 (HSP20) also possesses chaperone-like activity, is involved in regulation of smooth muscle contraction, has pronounced cardioprotective activity, and seems to participate in insulin-dependent regulation of muscle metabolism. HSPB8 (HSP22) prevents accumulation of aggregated proteins in the cell and participates in the regulation of proteolysis of unfolded proteins. HSPB8 also seems to be directly or indirectly involved in regulation of apoptosis and carcinogenesis, contributes to cardiac cell hypertrophy and survival and, when mutated, might be involved in development of neurodegenerative diseases. All small heat shock proteins play important "housekeeping" roles and regulate many vital processes; therefore, they are considered as attractive therapeutic targets.


Assuntos
Proteínas de Choque Térmico Pequenas/química , Proteínas de Choque Térmico Pequenas/fisiologia , Apoptose/fisiologia , Citoesqueleto/fisiologia , Proteínas de Choque Térmico Pequenas/classificação , Humanos , Contração Muscular/fisiologia , Doenças Neurodegenerativas/fisiopatologia , Dobramento de Proteína
10.
Mol Cell Biochem ; 355(1-2): 47-55, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21526341

RESUMO

A number of phosphomimicking mutants (replacement of Ser/Thr residues by Asp) of human small heat shock protein HspB8 were obtained and phosphorylation of the wild type HspB8 and its mutants by ERK1 kinase was analyzed in vitro. Mutation S159D does not affect phosphorylation, whereas mutations S24D and S27D equally moderately inhibited and mutation T87D strongly inhibited phosphorylation of HspB8. The double mutations S24D/T87D and S27D/T87D induced very strong inhibitory effect and the triple mutations S24D/S27D/T87D completely prevented phosphorylation catalyzed by ERK1. Thus, Ser24 and Thr87, found to be phosphorylated in vivo, are among the sites phosphorylated by ERK1 in HspB8 in vitro. Mutations S24D and T87D affect intrinsic tryptophan fluorescence and susceptibility to chymotrypsinolysis of HspB8. Phosphomimicking mutations and phosphorylation promote concentration-dependent association of HspB8 subunits. Mutations S24D and S27D decrease, whereas mutation T87D increases the chaperone-like activity of HspB8. It is concluded that phosphorylation catalyzed by ERK1 might affect the structure and chaperone-like activity of HspB8 and therefore can be important for regulation of interaction of HspB8 with different target proteins.


Assuntos
Proteínas de Choque Térmico/química , Proteína Quinase 3 Ativada por Mitógeno/química , Proteínas Serina-Treonina Quinases/química , Cromatografia em Gel , Dicroísmo Circular , Eletroforese em Gel de Poliacrilamida , Ensaios Enzimáticos , Humanos , Chaperonas Moleculares , Fragmentos de Peptídeos/química , Fosforilação , Espectrometria de Fluorescência
11.
Arch Biochem Biophys ; 506(1): 24-34, 2011 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-21081103

RESUMO

Effect of phosphomimicking mutations of 14-3-3ζ on its interaction with phosphorylated shortest isoform of human tau protein and phosphorylated human small heat shock protein HspB6 (Hsp20) was analyzed. Chemical crosslinking and native gel electrophoresis indicate that mutations S184E and T232E weakly affect interaction of 14-3-3 with phosphorylated tau protein, whereas mutations S58E and S58E/S184E/T232E significantly impair interaction of 14-3-3 and tau. Size-exclusion chromatography, chemical crosslinking and immunoprecipitation revealed that phosphomimicking mutations S58E and S58E/S184E/T232E strongly decrease, mutation T232E weakly affects and mutation S184E improves interaction of 14-3-3 with phosphorylated HspB6. Thus, mutation mimicking phosphorylation of Ser58 dramatically decreases interaction of 14-3-3 with two target proteins and this effect might be due to destabilization of the dimeric structure of 14-3-3 and/or conformational changes of the target-binding site. The mutation mimicking phosphorylation of Thr232 weakly affects interaction of 14-3-3 with both proteins. The mutation mimicking phosphorylation of Ser184 does not markedly affect interaction with tau protein and improves the interaction of 14-3-3 with HspB6. Thus, effect of 14-3-3 phosphorylation depends on the nature of the target protein and therefore, phosphorylation of 14-3-3 might affect its target specificity.


Assuntos
Proteínas 14-3-3/genética , Proteínas 14-3-3/metabolismo , Proteínas de Choque Térmico HSP20/metabolismo , Proteínas tau/metabolismo , Proteínas 14-3-3/química , Substituição de Aminoácidos , Sítios de Ligação/genética , Proteínas de Choque Térmico HSP20/química , Proteínas de Choque Térmico HSP20/genética , Humanos , Técnicas In Vitro , Cinética , Modelos Moleculares , Mimetismo Molecular , Complexos Multiproteicos , Mutagênese Sítio-Dirigida , Fosforilação , Conformação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas tau/química , Proteínas tau/genética
12.
Cell Stress Chaperones ; 15(3): 233-6, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-19777375

RESUMO

The recently published review by Dreiza et al. (Cell Stress and Chaperones DOI 10.1007/s12192-0090127-8 ) dealing with the functional role of HSPB6 in muscle regulation is critically analyzed. Published data indicate that the chaperone-like activity of HSPB6 is comparable with that of HSPB5 and that phosphorylation of HSPB6 does not affect its oligomeric structure. Different hypotheses concerning the molecular mechanisms of HSPB6 action on smooth muscle contraction and on the reorganization of the cytoskeleton are compared, and it is concluded that although HSPB6 is not a genuine actin-binding protein, it can affect the actin cytoskeleton indirectly. Phosphorylated HSPB6 interacts with 14-3-3 and thereby displaces other binding partners of 14-3-3; among them, certain phosphatases, protein kinases, and various actin-binding proteins, which can participate in the reorganization of the actin cytoskeleton. In addition, HSPB6 seems to regulate the activity of certain protein kinases. All of these processes are dependent on HSPB6 phosphorylation which in turn might be regulated by the formation of heterooligomeric complexes of HSPB6 with other small heat shock proteins.


Assuntos
Proteínas de Choque Térmico HSP20/metabolismo , Contração Muscular/fisiologia , Músculos/fisiologia , Proteínas 14-3-3/metabolismo , Actinas/metabolismo , Proteínas de Choque Térmico HSP20/genética , Relaxamento Muscular/fisiologia , Fosforilação
13.
Cell Stress Chaperones ; 15(4): 365-77, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19856132

RESUMO

Human alpha B-crystallin and small heat shock proteins HspB6 and HspB8 were mutated so that all endogenous Cys residues were replaced by Ser and the single Cys residue was inserted in a position homologous to that of Cys137 of human HspB1, i.e. in a position presumably located in the central part of beta 7 strand of the alpha-crystallin domain. The secondary, tertiary, and quaternary structures of thus obtained Cys-mutants as well as their chaperone-like activity were similar to those of their wild-type counterparts. Mild oxidation of Cys-mutants leads to formation of disulfide bond crosslinking neighboring monomers thus indicating participation of the beta 7 strand in intersubunit interaction. Oxidation weakly affects the secondary and tertiary structure, does not affect the quaternary structure of alpha B-crystallin and HspB6, and shifts equilibrium between monomer and dimer of HspB8 towards dimer formation. It is concluded that the beta 7 strand participates in the intersubunit interaction of four human small heat shock proteins (alpha B-crystallin, HspB1, HspB6, HspB8) having different structure of beta2 strand of alpha-crystallin domain and different length and composition of variable N- and C-terminal tails.


Assuntos
Proteínas de Choque Térmico Pequenas/química , Substituição de Aminoácidos , Dicroísmo Circular , Cisteína/química , Proteínas de Choque Térmico HSP20/química , Proteínas de Choque Térmico HSP27/química , Proteínas de Choque Térmico/química , Proteínas de Choque Térmico Pequenas/genética , Proteínas de Choque Térmico Pequenas/metabolismo , Humanos , Chaperonas Moleculares , Proteínas Serina-Treonina Quinases/química , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Cadeia B de alfa-Cristalina/química
14.
FEBS Lett ; 583(17): 2739-42, 2009 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-19647741

RESUMO

Serine residues phosphorylated by protein kinase A (PKA) in the shortest isoform of human tau protein (tau3) were sequentially replaced by alanine and interaction of phosphorylated tau3 and its mutants with 14-3-3 was investigated. Mutation S156A slightly decreased interaction of phosphorylated tau3 with 14-3-3. Double mutations S156A/S267A and especially S156A/S235A, strongly inhibited interaction of phosphorylated tau3 with 14-3-3. Thus, two sites located in the Pro-rich region and in the pseudo repeats of tau3 are involved in phosphorylation-dependent interaction of tau3 with 14-3-3. The state of tau3 phosphorylation affects the mode of 14-3-3 binding and by this means might modify tau filament formation.


Assuntos
Proteínas 14-3-3/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Isoformas de Proteínas/metabolismo , Proteínas tau/metabolismo , Proteínas 14-3-3/genética , Humanos , Fosforilação , Mutação Puntual , Isoformas de Proteínas/genética , Serina/metabolismo , Proteínas tau/genética
15.
Biochem Biophys Res Commun ; 379(4): 990-4, 2009 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-19138662

RESUMO

Interaction of the shortest isoform of tau protein (tau3) with human 14-3-3zeta was analyzed by means of native gel electrophoresis, chemical crosslinking and size-exclusion chromatography. Phosphorylation by cAMP-dependent protein kinase (up to 2 mole of phosphate per mole of tau3) strongly enhanced interaction of tau3 with 14-3-3. Apparent K(D) of the complexes formed by phosphorylated tau3 and 14-3-3 was close to 2 microM, whereas the corresponding constant for unphosphorylated tau3 was at least 10 times higher. The stoichiometry of the complexes formed by phosphorylated tau3 and 14-3-3 was variable and was different from 1:1. 14-3-3 decreased the probability of formation of chemically crosslinked large homooligomers of phosphorylated tau3 and at the same time induced formation of crosslinked heterooligomeric complexes of tau3 and 14-3-3 with an apparent molecular mass of 120-140 kDa.


Assuntos
Proteínas 14-3-3/metabolismo , Proteínas tau/metabolismo , Proteínas 14-3-3/química , Cromatografia em Gel , Reagentes de Ligações Cruzadas/química , Proteínas Quinases Dependentes de AMP Cíclico/química , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Eletroforese , Humanos , Fosforilação , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Proteínas tau/química
16.
Biochim Biophys Acta ; 1794(3): 486-95, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19100870

RESUMO

Formation of heterooligomeric complexes of human small heat shock proteins (sHsp) HspB6 (Hsp20) and HspB1 (Hsp27) was analyzed by means of native gel electrophoresis, analytical ultracentrifugation, chemical cross-linking and size-exclusion chromatography. HspB6 and HspB1 form at least two different complexes with apparent molecular masses 100-150 and 250-300 kDa, and formation of heterooligomeric complexes is temperature dependent. These complexes are highly mobile, easily exchange their subunits and are interconvertible. The stoichiometry of HspB1 and HspB6 in both complexes is close to 1/1 and smaller complexes are predominantly formed at low, whereas larger complexes are predominantly formed at high protein concentration. Formation of heterooligomeric complexes does not affect the chaperone-like activity of HspB1 and HspB6 if insulin or skeletal muscle F-actin was used as model protein substrates. After formation of heterooligomeric complexes the wild type HspB1 inhibits the rate of phosphorylation of HspB6 by cAMP-dependent protein kinase. The 3D mutant mimicking phosphorylation of HspB1 also forms heterooligomeric complexes with HspB6, but is ineffective in inhibition of HspB6 phosphorylation. Inside of heterooligomeric complexes HspB6 inhibits phosphorylation of HspB1 by MAPKAP2 kinase. Thus, in heterooligomeric complexes HspB6 and HspB1 mutually affect the structure of each other and formation of heterooligomeric complexes might influence diverse processes depending on small heat shock proteins.


Assuntos
Proteínas de Choque Térmico HSP20/metabolismo , Proteínas de Choque Térmico HSP27/metabolismo , Animais , Proteínas Quinases Dependentes de AMP Cíclico/efeitos dos fármacos , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Proteínas de Choque Térmico , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Chaperonas Moleculares/fisiologia , Fosforilação/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/metabolismo , Estrutura Quaternária de Proteína , Coelhos , Temperatura
17.
Arch Biochem Biophys ; 477(2): 305-12, 2008 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-18559254

RESUMO

Effect of mutations mimicking phosphorylation on the structure of human 14-3-3zeta protein was analyzed by different methods. Mutation S58E increased intrinsic Trp fluorescence and binding of bis-ANS to 14-3-3. At low protein concentration mutation S58E increased the probability of dissociation of dimeric 14-3-3 and its susceptibility to proteolysis. Mutation S184E slightly increased Stokes radius and thermal stability of 14-3-3. Mutation T232E induced only small increase of Stokes radius and sedimentation coefficient that probably reflect the changes in the size or shape of 14-3-3. At low protein concentration the triple mutant S58E/S184E/T232E tended to dissociate, whereas at high concentration its properties were comparable with those of the wild type protein. The triple mutant was highly susceptible to proteolysis. Thus, mutation mimicking phosphorylation of Ser58 destabilized, whereas mutation of Ser184 induced stabilization of 14-3-3zeta structure.


Assuntos
Proteínas 14-3-3/química , Proteínas 14-3-3/ultraestrutura , Modelos Químicos , Modelos Moleculares , Simulação por Computador , Humanos , Mutagênese Sítio-Dirigida , Mutação , Fosforilação , Conformação Proteica , Relação Estrutura-Atividade
18.
J Neurosci Res ; 86(2): 264-9, 2008 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-17722063

RESUMO

The recently described human HSP22 belongs to the superfamily of small heat-shock proteins containing a conservative alpha-crystallin domain. HSP22 seems to be involved in regulation of cell proliferation, cardiac hypertrophy, apoptosis, and carcinogenesis, and expression of point mutants of HSP22 correlates with development of different neuromuscular diseases. Therefore, an investigation of the structure and properties of HSP22 is desirable for understanding its multiple functions. HSP22 seems to belong to the group of so-called intrinsically disordered proteins and possesses a highly flexible structure. HSP22 tends to form small-molecular-mass oligomers and interacts with biological membranes and many different proteins, among them glycolytic enzymes and different protein kinases. HSP22 possesses chaperonelike activity and prevents aggregation of denatured proteins both in vitro and in vivo. Depending on the cell type and its expression, HSP22 might have either pro- or anti-apoptotic effects. Chaperonelike activity seems to be important for antiapoptotic effects, whereas interaction with and regulation of certain protein kinases might be important for the proapoptotic effects of HSP22. Expression of K141N or K141E mutants of HSP22 correlates with development of distal hereditary motor neuropathy and/or Charcot-Marie-Tooth disease. These mutations destabilize the structure of HSP22, affect its interaction with other small heat-shock proteins, and decrease its chaperonelike activity. HSP22 decreases or prevents aggregation of Huntingtin fragments and amyloid-beta peptide 1-40 of the Dutch type. Thus, HSP22 seems to play an important role in the nervous system, and further investigations are needed to understand the molecular mechanisms of its functioning.


Assuntos
Proteínas de Choque Térmico/química , Proteínas de Choque Térmico/fisiologia , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/fisiologia , Humanos , Chaperonas Moleculares , Relação Estrutura-Atividade
19.
FEBS J ; 274(21): 5628-42, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17922839

RESUMO

The human genome encodes ten different small heat shock proteins, each of which contains the so-called alpha-crystallin domain consisting of 80-100 residues and located in the C-terminal part of the molecule. The alpha-crystallin domain consists of six or seven beta-strands connected by different size loops and combined in two beta-sheets. Mutations in the loop connecting the beta5 and beta7 strands and conservative residues of beta7 in alphaA-, alphaB-crystallin and HSP27 correlate with the development of different congenital diseases. To understand the role of this part of molecule in the structure and function of small heat shock proteins, we mutated two highly conservative residues (K137 and K141) of human HSP22 and investigated the properties of the K137E and K137,141E mutants. These mutations lead to a decrease in intrinsic Trp fluorescence and the double mutation decreased fluorescence resonance energy transfer from Trp to bis-ANS bound to HSP22. Mutations K137E and especially K137,141E lead to an increase in unordered structure in HSP22 and increased susceptibility to trypsinolysis. Both mutations decreased the probability of dissociation of small oligomers of HSP22, and mutation K137E increased the probability of HSP22 crosslinking. The wild-type HSP22 possessed higher chaperone-like activity than their mutants when insulin or rhodanase were used as the model substrates. Because conservative Lys residues located in the beta5-beta7 loop and in the beta7 strand appear to play an important role in the structure and properties of HSP22, mutations in this part of the small heat shock protein molecule might have a deleterious effect and often correlate with the development of different congenital diseases.


Assuntos
Proteínas de Choque Térmico/química , Proteínas de Choque Térmico/genética , Mutação , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Sequência de Aminoácidos , Dicroísmo Circular , Proteínas de Choque Térmico/metabolismo , Humanos , Modelos Moleculares , Chaperonas Moleculares , Dados de Sequência Molecular , Proteínas Serina-Treonina Quinases/metabolismo , Estrutura Secundária de Proteína , Tripsina/metabolismo
20.
Mol Cell Biochem ; 295(1-2): 9-17, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17109079

RESUMO

Interaction of human 14-3-3gamma with the small heat shock protein Hsp20 was analyzed by means of size-exclusion chromatography and chemical crosslinking. Unphosphorylated Hsp20 and its mutant S16D mimicking phosphorylation by cAMP-dependent protein kinase did not interact with 14-3-3. Phosphorylated Hsp20 formed a tight complex with 14-3-3 in which dimer of 14-3-3 was bound to dimer of Hsp20. 14-3-3 did not affect the chaperone activity of unphosphorylated Hsp20 but increased the chaperone activity of phosphorylated Hsp20 if insulin was used as a model substrate. Estimation of the effect of 14-3-3 on the chaperone activity of Hsp20 with other model substrates was complicated by the fact that under in vitro conditions isolated 14-3-3 possessed its own high chaperone activity. Taken into account high content of Hsp20 in different muscles it is supposed that upon phosphorylation Hsp20 might effectively compete with multiple protein targets of 14-3-3 and by this means indirectly affect many intracellular processes.


Assuntos
Proteínas 14-3-3/metabolismo , Proteínas de Choque Térmico HSP20/metabolismo , Domínio Catalítico/efeitos dos fármacos , Cromatografia em Gel , Reagentes de Ligações Cruzadas/farmacologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Humanos , Insulina/metabolismo , Peso Molecular , Fosforilação/efeitos dos fármacos , Ligação Proteica/efeitos dos fármacos , Estrutura Quaternária de Proteína/efeitos dos fármacos
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