Effects and mechanism of negative pressure microenvironment on the neogenesis of human umbilical vein endothelial cells / 中华烧伤杂志

Objective: To investigate the effects and mechanism of negative pressure microenvironment on the neogenesis of human umbilical vein endothelial cells (HUVECs). Methods: The experimental research methods were adopted. The third to the fifth passage of HUVECs in the logarithmic growth stage were used for the subsequent experiments. Three batches of cells were taken, with each batch of cells being divided into normal control group and negative pressure treatment alone group (both routinely cultured for 24 h), and 17-allylamino-17-demethoxy-geldanamycin (17-AAG) alone group and 17-AAG+negative pressure treatment group (both cultured with 17-AAG for 24 h). In addition, the intermittent negative pressure suction, with the negative pressure value of -5.33 kPa (suction for 30 s, pause for 10 s) was continuously applied for 8 h on cells in the two negative pressure treatment groups using an automatic three-dimensional cell gradient negative pressure loading device designed and developed by ourselves. After the treatment of the first batch of cells, the cell proliferation level was detected by cell counting kit 8 method at 0 (immediately), 24, 48, and 72 h of culture, with the number of samples being 6. After the treatment of the second batch of cells, the scratch experiment was performed. At 12 h after scratching, the cell migration was observed under an inverted phase contrast microscope and the cell migration rate was calculated, with the number of samples being 3. After the treatment of the third batch of cells, the tubule formation experiment was conducted. After 6 h of culture, the tubulogenesis was observed under an inverted phase contrast microscope and the total tubule length and the number of branch nodes of cells were calculated, with the number of samples being 3. The cells were taken and divided into normal control group, negative pressure treatment alone group, and 17-AAG+negative pressure treatment group. The cells were treated the same as in the previous corresponding group. After the treatment, Western blotting was used to detect the protein expressions of heat shock protein 90 (HSP90), caveolin 1, endothelial nitric oxide synthase (eNOS), and eNOS phosphorylation site 1177 in the cells, and the eNOS phosphorylation site 1177/eNOS ratio was calculated, with the number of samples being 3; co-immunoprecipitation (co-precipitating HSP90 and caveolin 1, caveolin 1 and eNOS) and Western blotting were used to detect the protein expressions of caveolin 1 and eNOS in the cells, with the number of samples being 3; the protein co-localization of HSP90 and caveolin 1 and that of caveolin 1 and eNOS in the cells was assessed by immunofluorescence double staining. The molecular docking prediction of caveolin 1 and eNOS was processed by HADDOCK 2.4 protein-protein docking program. Data were statistically analyzed with analysis of variance for factorial design, one-way analysis of variance, and least significant difference method. Results: Compared with that in normal control group, the cell proliferation level in 17-AAG alone group was significantly decreased at culture hour of 24, 48, and 72 after the treatment (P<0.01), while the cell proliferation level in negative pressure treatment alone group was significantly increased at culture hour of 24, 48, and 72 after the treatment (P<0.01). Compared with that in 17-AAG alone group, the cell proliferation level in 17-AAG+negative pressure treatment group was significantly increased at culture hour of 48 and 72 after the treatment (P<0.05 or P<0.01). Compared with that in negative pressure treatment alone group, the cell proliferation level in 17-AAG+negative pressure treatment group was significantly decreased at culture hour of 24, 48, and 72 after the treatment (P<0.01). At 12 h after scratching, compared with (39.9±2.7)% in normal control group, the cell migration rate in 17-AAG alone group was significantly decreased ((10.7±2.7)%, P<0.01), while the cell migration rate in negative pressure treatment alone group was significantly increased ((61.9±2.4)%, P<0.01). Compared with those in 17-AAG alone group, the cell migration rate in 17-AAG+negative pressure treatment group was significantly increased ((37.7±3.7)%, P<0.01). Compared with that in negative pressure treatment alone group, the cell migration rate in 17-AAG+negative pressure treatment group was significantly decreased (P<0.01). At culture hour of 6 after the treatment, compared with those in normal control group, the total length of the tube formed by the cells in 17-AAG alone group was significantly shortened (P<0.05) and the number of branch nodes was significantly reduced (P<0.05), while the total length of the tube formed by the cells in negative pressure treatment alone group was significantly prolonged (P<0.01) and the number of branch nodes was dramatically increased (P<0.01). Compared with that in 17-AAG alone group, the number of branch nodes of the tube formed by the cells was significantly increased in 17-AAG+negative pressure treatment group (P<0.05). Compared with those in negative pressure treatment alone group, the total length of the tube formed by the cells in 17-AAG+negative pressure treatment group was significantly shortened (P<0.01) and the number of branch nodes was significantly reduced (P<0.01). Western blotting detection showed that after treatment, the overall comparison of eNOS and caveolin 1 protein expressions among the three groups of cells showed no statistically significant differences (P>0.05). The expression of HSP90 protein and the eNOS phosphorylation site 1177/eNOS ratio in the cells of negative pressure treatment alone group were significantly increased (P<0.01) compared with those in normal control group. Compared with those in negative pressure treatment alone group, the HSP90 protein expression and the eNOS phosphorylation site 1177/eNOS ratio in the cells of 17-AAG+negative pressure treatment group were significantly decreased (P<0.01). Co-immunoprecipitation and Western blotting detection after the treatment showed that compared with those in normal control group, the expression of caveolin 1 protein in the cells of negative pressure treatment alone group was significantly increased (P<0.01), while the protein expression of eNOS was significantly decreased (P<0.05). Compared with those in negative pressure treatment alone group, the expression of caveolin 1 protein in the cells of 17-AAG+negative pressure treatment group was significantly decreased (P<0.01), while the protein expression of eNOS was significantly increased (P<0.01). After the treatment, compared with those in normal control group, the co-localization of HSP90 and caveolin 1 protein in the cells of negative pressure treatment alone group was significantly increased, while the co-localization of caveolin 1 and eNOS protein was significantly decreased. Compared with those in negative pressure treatment alone group, the co-localization of HSP90 and caveolin 1 protein in the cells of 17-AAG+negative pressure treatment group was significantly decreased, while the co-localization of caveolin 1 and eNOS protein was significantly increased. Molecular docking prediction suggested that caveolin 1 interacted strongly with eNOS and inhibited the 1177 site phosphorylation of eNOS. Conclusions: The negative pressure microenvironment may inhibit the binding of caveolin 1 to eNOS by promoting the binding of HSP90 to caveolin 1 in HUVECs, so as to relieve the inhibition of 1177 site phosphorylation of eNOS by caveolin 1, thereby promoting the proliferation, migration, and tubulogenesis of HUVECs, and ultimately promoting the neogenesis of HUVECs.

Histological investigation of experimentally induced diabetes effects on the distribution of transforming growth factor (TGF beta), nuclear factor kappa b (Nf-KB), heat schock 90 beta (Hsp beta) and E-cadherin proteins in testicular tissue / Investigación histológica de los efectos de la diabetes inducida experimentalmente en la distribución del factor de crecimiento transformante (TGFß), nuclear factor kappa b (Nf-KB), y proteinas heat schock 90ß (Hsp90ß) y E-cadherina en tejido testicular

SUMMARY: Diabetes is a metabolic disorder characterized by high blood sugar levels and it causes complications in many systems, including the reproductive system. As a result of diabetic conditions, one of the mechanisms that can cause repression of reproductive activity is testicular oxidant stress. The identification of diabetes on the cell signaling molecules axis is still under discussion. The aim of this study was to determine the effect of Transforming Growth Factor (TGFβ), Nuclear Factor kappa B (NF-kB), Heat-schock 90β (HSP90β) signal pathways and E-cadherin cell adhesion molecule on infertility in diabetic rat testicular tissue. In our study, includes histological, molecular and biochemical analysis of testicular tissue removed at the end of the 2 weeks experiment period. A total of 14 adult male rats were divided as control and diabetes. No intervention was given to 7 male rats in the control group. For the diabetic group, 7 male rats were injected by intraperitoneal with a single dose of 55 mg/kg streptozotocin (STZ). TGFβ, NF-kB, HSP90β and E-cadherin proteins were immunohistochemically studied to investigate possible tissue damage, inflammatory process, cell stabilization and integrity due to diabetes. In order to determine oxidant stress, lipid peroxidation product malondialdehyde (MDA), glutathione (GSH) and glutathione peroxidase (GPx) analyzes were performed. Fibrosis, inflammatory changes and loss of spermatogenetic series are prominent findings in the diabetic group. On analysis of all the samples with immunostaining, in the diabetic group, TGFβ and NF-kB immunoexpression significantly increased, while Hsp90β and E-cadherin immunoexpression significantly decreased compared with control groups. Experimental diabetes was found to cause fibrosis, inflammation, disrupting cell adhesion and stabilization in testicular tissue. These results suggest that cellular therapy studies are needed for possible damage.

RESUMEN: La diabetes es una enfermedad metabólica caracterizada por niveles altos de azúcar en sangre y causa complicaciones en muchos sistemas, incluido el sistema reproductivo. Como resultado de las condiciones diabéticas, uno de los mecanismos que puede causar alteraciones en la actividad reproductiva es el estrés oxidativo testicular. La identificación de la diabetes en el eje de las moléculas de señalización celular aún está en discusión. El objetivo de este estudio fue determinar el efecto del factor de crecimiento transformante (TGFβ), el factor nuclear kappa B (NF-kB), las vías de señalización de Heat-Schock 90b (HSP90β) y la molécula de adhesión celular de E-cadherina sobre la infertilidad en testículo de rata diabética. Al término de dos semanas se realizaron análisis histológico, molecular y bioquímico del tejido testicular extraído. Las 7 ratas macho del grupo control no fueron intervenidas. Para el grupo de diabéticos, 7 ratas macho fueron inyectadas por vía intraperitoneal con una dosis única de 55 mg / kg de estreptozotocina (STZ). Se estudiaron inmunohistoquímicamente las proteínas TGFβ, NF-kB, HSP90β y E-cadherina para investigar el posible daño tisular, el proceso inflamatorio, la estabilización celular y la integridad debido a la diabetes. Para determinar el estrés oxidativo, se realizaron análisis del producto de peroxidación lipídica malondialdehído (MDA), glutatión (GSH) y glutatión peroxidasa (GPx). La fibrosis, los cambios inflamatorios y la pérdida de series espermatogenéticas son hallazgos destacados en el grupo de ratas diabéticas. En el análisis de todas las muestras con inmunotinción, en el grupo diabético, la inmunoexpresión de TGFβ y NF-kB aumentó significativamente, mientras que la inmunoexpresión de Hsp90β y e-cadherina disminuyó significativamente en comparación con los grupos control. Se encontró que la diabetes experimental causa fibrosis, inflamación, alteración de la adhesión celular y estabilización en el tejido testicular. Estos resultados sugieren que son necesarios estudios de terapia celular para verificar posibles daños.

The Role of Serotonin in Ventricular Repolarization in Pregnant Mice

PURPOSE: The mechanisms underlying repolarization abnormalities during pregnancy are not fully understood. Although maternal serotonin (5-hydroxytryptamine, 5-HT) production is an important determinant for normal fetal development in mice, its role in mothers remains unclear. We evaluated the role of serotonin in ventricular repolarization in mice hearts via 5Htr3 receptor (Htr3a) and investigated the mechanism of QT-prolongation during pregnancy. MATERIALS AND METHODS: We measured current amplitudes and the expression levels of voltage-gated K⁺ (Kv) channels in freshly-isolated left ventricular myocytes from wild-type non-pregnant (WT-NP), late-pregnant (WT-LP), and non-pregnant Htr3a homozygous knockout mice (Htr3a(−/−)-NP). RESULTS: During pregnancy, serotonin and tryptophan hydroxylase 1, a rate-limiting enzyme for the synthesis of serotonin, were markedly increased in hearts and serum. Serotonin increased Kv current densities concomitant with the shortening of the QT interval in WT-NP mice, but not in WT-LP and Htr3a(−/−)-NP mice. Ondansetron, an Htr3 antagonist, decreased Kv currents in WT-LP mice, but not in WT-NP mice. Kv4.3 directly interacted with Htr3a, and this binding was facilitated by serotonin. Serotonin increased the trafficking of Kv4.3 channels to the cellular membrane in WT-NP. CONCLUSION: Serotonin increases repolarizing currents by augmenting Kv currents. Elevated serotonin levels during pregnancy counterbalance pregnancy-related QT prolongation by facilitating Htr3-mediated Kv currents.

Social determinants of health, inequality and social inclusion among people with disabilities / Determinantes sociais da saúde, iniquidades e inclusão social entre pessoas com deficiência / Determinantes sociales de la salud, iniquidades e inclusión social entre personas con deficiencia

OBJECTIVE: to analyze the socio-familial and community inclusion and social participation of people with disabilities, as well as their inclusion in occupations in daily life. METHOD: qualitative study with data collected through open interviews concerning the participants' life histories and systematic observation. The sample was composed of ten individuals with acquired or congenital disabilities living in the region covered by a Family Health Center. The social conception of disability was the theoretical framework used. Data were analyzed according to an interpretative reconstructive approach based on Habermas' Theory of Communicative Action. RESULTS: the results show that the socio-familial and community inclusion of the study participants is conditioned to the social determinants of health and present high levels of social inequality expressed by difficult access to PHC and rehabilitation services, work and income, education, culture, transportation and social participation. CONCLUSION: there is a need to develop community-centered care programs in cooperation with PHC services aiming to cope with poverty and improve social inclusion. .

OBJETIVO: analisar a inclusão sociofamiliar e comunitária e a participação social de pessoas com deficiência, bem como sua inserção em ocupações na vida cotidiana. MÉTODO: estudo qualitativo, com coleta de dados por meio de entrevistas abertas sobre história de vida e observação sistemática. A amostra foi composta por dez pessoas com deficiência, adquirida ou congênita, moradoras de região adstrita a um Núcleo de Saúde da Família. O referencial teórico foi a concepção social da deficiência. Os dados foram analisados segundo abordagem interpretativa reconstrutiva, fundamentada no referencial da Teoria da Ação Comunicativa de Habermas. RESULTADOS: os resultados evidenciaram que a inclusão sociofamiliar e comunitária dos sujeitos do estudo condiciona-se a determinantes sociais da saúde, apresentando índices de iniquidades sociais, expressos pela dificuldade de acesso a serviços de Atenção Primária à Saúde e de reabilitação, trabalho e renda, educação, cultura, transporte e participação social. CONCLUSÃO: conclui-se a necessidade da elaboração de programas de atenção centrados na comunidade, voltados ao enfrentamento da pobreza e à inclusão social, em articulação com serviços de Atenção Primaria à Saúde. .

OBJETIVO: analizar la inclusión social familiar y comunitaria, y la participación social de personas con deficiencia, así como su inserción en ocupaciones en la vida cotidiana. MÉTODO: estudio cualitativo, con recolección de datos por medio de entrevistas abiertas sobre historia de vida y por observación sistemática. La muestra estuvo compuesta por diez personas con deficiencia, adquirida o congénita, habitantes de una región adscrita a un Núcleo de Salud de la Familia. El referencial teórico fue la concepción social de la deficiencia. Los datos fueron analizados según abordaje interpretativo reconstructivo, fundamentado en el referencial de la Teoría de la Acción Comunicativa de Habermas. RESULTADOS: los resultados evidenciaron que la inclusión social familiar y comunitaria de los sujetos del estudio se condiciona a determinantes sociales de la salud, presentando índices de iniquidades sociales, expresados por la dificultad de acceso a servicios de Atención Primaria de la Salud y de rehabilitación, trabajo y renta, educación, cultura, transporte y participación social. CONCLUSIÓN: se concluye que existe la necesidad de elaborar programas de atención centrados en la comunidad, dirigidos al enfrentamiento de la pobreza y a la inclusión social, en articulación con servicios de Atención Primaria a la Salud. .

Pontos de venda de alimentos e associação com sobrepeso/obesidade em escolares de Florianópolis, Santa Catarina, Brasil / Retail food outlets and the association with overweight/obesity in schoolchildren from Florianópolis, Santa Catarina State, Brazil / Puntos de venta de alimentos y asociación con sobrepeso/obesidad en escolares de Florianópolis, Santa Catarina, Brasil

O estudo descreve os pontos de venda de alimentos e sua associação com sobrepeso/obesidade em escolares de Florianópolis, Santa Catarina, Brasil. Desenho transversal com amostra probabilística de 2.506 escolares de escolas públicas (n = 19) e privadas (n = 11). O sobrepeso/obesidade foi classificado pela referência da Organização Mundial da Saúde de 2007. Foram realizadas análises brutas e ajustadas por meio de regressão de Poisson. A prevalência de sobrepeso/obesidade foi de 34,2%. Na rede pública, foram verificados 19,6% de sobrepeso e 13,5% de obesidade. Na rede privada, observaram-se 22,4% de sobrepeso e 11,1% de obesidade. Na rede pública, foi encontrada associação entre sobrepeso/obesidade e utilização da padaria (p = 0,004). Na rede privada, observou-se que os escolares de famílias que utilizaram o supermercado apresentaram 26% menos de sobrepeso/obesidade do que os escolares que não utilizam esses pontos de venda de alimentos (p = 0,003). Os dados encontrados evidenciam a existência de associação entre a utilização de alguns tipos de pontos de venda de alimentos (supermercado e padaria) e a prevalência de sobrepeso/obesidade na população escolar.

The study analyzes retail food outlets and their association with overweight/obesity in schoolchildren from Florianópolis, Santa Catarina State, Brazil. The study used a cross-sectional design with a random sample of 2,506 schoolchildren from public (n = 19) and private schools (n = 11). Overweight and obesity were classified according to World Health Organization guidelines for 2007, and crude and adjusted analyses were performed using Poisson regression. Prevalence of overweight/obesity was 34.2%. In public schools, 19.6% of the children were overweight and 13.5% were obese, as compared to 22.4% and 11.1% in private schools. An association was found in the public school system between overweight/obesity and the use of bakeries for food purchases (p = 0.004). In the private school system, children of families that bought groceries at the supermarket showed 26% less overweight/obesity compared to those who did not (p = 0.003). The data show an association between some types of food outlets (supermarkets and bakeries) and prevalence of overweight/obesity in the school-age population.

El estudio describe los puntos de venta de alimentos y su asociación con el sobrepeso/obesidad en escolares de Florianópolis, Santa Catarina, Brasil. Se trata de un estudio transversal con una muestra aleatoria de 2.506 escolares de las escuelas públicas (n = 19) y privadas (n = 11). El sobrepeso/obesidad se clasifica, en función de la OMS en 2007, con análisis ajustados y crudos que se realizaron mediante la regresión de Poisson. La prevalencia de sobrepeso/obesidad fue de un 34,2%. En el sistema público el resultado fue de un 19,6% sobrepeso y un 13,5% obesidad. En el privado se observó un 22,4% de sobrepeso y 11,1% obesidad. En el primero se encontró una correlación entre el sobrepeso/obesidad y el consumo de bollería (p = 0,004). En las escuelas privadas se observó que los escolares de familias que habían utilizado el supermercado tenían un 26% menos de sobrepeso/ obesidad que los niños en edad escolar que no utilizaron este punto de venta de alimentos (p = 0,003). En el momento del estudio existe una asociación entre el uso de algunos tipos de punto de venta de alimentos (supermercado y panadería) y la prevalencia de sobrepeso/obesidad en escolares.

Chikungunya en la República Dominicana: lecciones aprendidas en los primeros seis meses / Chikungunya in the Dominican Republic: lessons learned in the first six months

La epidemia de chikungunya en la República Dominicana se inició en febrero de 2014. En los primeros seis meses se registraron 429 421 casos, que representaron 65% de todos los notificados a la Organización Panamericana de la Salud por 33 países y territorios de la Región de las Américas. Esta epidemia se ha transmitido con rapidez en dicho país y ha demandado una intensa respuesta intersectorial, que ha liderado el Ministerio de Salud Pública y, especialmente, el Sistema Nacional de Vigilancia Epidemiológica y la red de los servicios de salud. Considerando que afectará a miles de personas, el objetivo de este artículo es describir las actuaciones realizadas y compartir los resultados y las lecciones aprendidas durante estos primeros meses con los ministerios de salud y los profesionales de los países de la Región para ayudarles a preparar una respuesta adecuada para afrontarla de forma efectiva y eficiente.

The chikungunya epidemic in the Dominican Republic began in February 2014. During the first six months 429 421 cases were recorded, representing 65% of all those notified to the Pan American Health Organization by 33 countries and territories of the Region of the Americas. This epidemic has spread quickly in the Dominican Republic, requiring a focused intersectoral response, led by the Ministry of Public Health and involving major efforts by the National Epidemiological System and the health services network. Given that the virus will affect thousands of people, this article seeks to describe the actions that have already been carried out, and to share the results and lessons learned during these first months with health ministries and professionals in the countries of the Region, in order to assist them to prepare an appropriate response to confront the epidemic effectively and efficiently.

Comparative proteomic analysis of the nucleus accumbens during extinction and reinstatement of morphine dependence / Análisis proteómico comparativo del núcleo accumbens durante laextinción y recaída de la dependencia a la morfina

BACKGROUND: The aim of this study was to detect differentially expressed proteins in the nucleus accumbens between the states of extinction and reinstatement of morphine addiction. Numerous studies on the neurobiological mechanisms concerning drug craving and relapse have been reported to date, but data on their relationship with the underlying key molecular mechanisms involved remain limited. METHODS: In this study, 40 male SpragueDawley rats were equally randomized into a saline group and a morphine group. Both groups received drug selfadministration training, after which extinction models were established naturally. The groups were further divided into two subgroups for extinction and reinstatement tests. Cerebral nucleus accumbens masses were measured for total protein extraction. Twodimensional electrophoresis was performed to determine differential protein spots. These differential proteins were then enzymolysed and identified using mass spectrography. RESULTS: The proteins were classified as fatty acidbinding protein, serine/threonine protein phosphatase 2A catalytic subunit beta isoform, serine/threonine protein phosphatase 2A catalytic subunit alpha isoform, serine/threonine protein phosphatase 2A regulatory subunit B² subunit gamma or heat shock protein 90 cochaperone CDC37. CONCLUSION: Significant changes in five proteins were detected between extinction and reinstatement. These proteins are correlated with phosphorylation and the tricarboxylic acid cycle.

ANTECEDENTES: El objetivo de este estudio fue detectar las proteínas diferencialmente expresadas en el núcleo accumbens entre los estados de extinción y recaída de la adicción a la morfina. Hasta la fecha se han reportado numerosos estudios en relación con los mecanismos neurobiológicos del deseo incontenible y recaída en el consumo de drogas, pero los datos sobre su relación con los mecanismos moleculares fundamentales subyacentes implicados, siguen siendo limitados. MÉTODO: En este estudio, 40 ratas machos SpragueDawley fueron por igual asignadas de manera aleatoria a un grupo salino y un grupo de morfina. Ambos grupos recibieron entrenamiento de autoadministración de drogas, después de lo cual se establecieron modelos de extinción de manera natural. A su vez, los grupos fueron luego subdivididos en dos subgrupos para realizar pruebas de extinción y recaída. Se procedió a medir las masas cerebrales del núcleo accumbens para la extracción total de proteína. Se realizó una electroforesis bidimensional para determinar manchas proteicas diferenciales. Estas proteínas diferenciales fueron entonces sometidas a enzimólisis e identificadas mediante espectrografía de masa. RESULTADOS: Las proteínas fueron clasificadas como proteína de unión a ácidos grasos, isoforma beta de la subunidad catalítica serinatreonina proteína fosfatasa 2A, isoforma alfa de la subunidad catalítica serinatreonina proteína fosfatasa 2A, subunidad gamma subunidad B" de la serinatreonina proteína fosfatasa 2A, o la proteína CDC37 cochaperona 90 de choque térmico. CONCLUSIÓN: Se detectaron cambios significativos en cinco proteínas entre la extinción y la recaída. Estas proteínas están correlacionadas con la fosforilación y el ciclo del ácido tricarboxílico.

Hsp90 mediates activation of the heme regulated eIF-2 kinase during oxidative stress.

The heme-regulated inhibitor (HRI), a member of the eIF-2 kinase family is crucial for regulating protein synthesis during stress. In addition to heme, stress proteins Hsp90 and Hsp70 are known to regulate HRI. The present study aims to determine the physical association of these Hsps in the regulation of HRI activation during oxidative stress using human K562 cells as a model. Extracts from the stress-induced cells were used for determining HRI kinase activity by measuring eIF-2 phosphorylation, and Hsp-HRI interaction by immunoprecipitation and immunoblot analyses. The results indicate a significant increase in both Hsp70 and Hsp90 expression during AAPH (2, 2’-azobis (2-amidinopropane) dihydrochloride)-induced oxidative stress. Further, their interaction with HRI, which correlates well with its increased HRI kinase activity leads to inhibition of protein synthesis. Thus, we demonstrate that Hsps play an important role in the regulation of initiation of protein synthesis during oxidative stress.

Identification of the divergent calmodulin binding motif in yeast Ssb1/Hsp75 protein and in other HSP70 family members

Yeast soluble proteins were fractionated by calmodulin-agarose affinity chromatography and the Ca2+/calmodulin-binding proteins were analyzed by SDS-PAGE. One prominent protein of 66 kDa was excised from the gel, digested with trypsin and the masses of the resultant fragments were determined by MALDI/MS. Twenty-one of 38 monoisotopic peptide masses obtained after tryptic digestion were matched to the heat shock protein Ssb1/Hsp75, covering 37 percent of its sequence. Computational analysis of the primary structure of Ssb1/Hsp75 identified a unique potential amphipathic alpha-helix in its N-terminal ATPase domain with features of target regions for Ca2+/calmodulin binding. This region, which shares 89 percent similarity to the experimentally determined calmodulin-binding domain from mouse, Hsc70, is conserved in near half of the 113 members of the HSP70 family investigated, from yeast to plant and animals. Based on the sequence of this region, phylogenetic analysis grouped the HSP70s in three distinct branches. Two of them comprise the non-calmodulin binding Hsp70s BIP/GR78, a subfamily of eukaryotic HSP70 localized in the endoplasmic reticulum, and DnaK, a subfamily of prokaryotic HSP70. A third heterogeneous group is formed by eukaryotic cytosolic HSP70s containing the new calmodulin-binding motif and other cytosolic HSP70s whose sequences do not conform to those conserved motif, indicating that not all eukaryotic cytosolic Hsp70s are target for calmodulin regulation. Furthermore, the calmodulin-binding domain found in eukaryotic HSP70s is also the target for binding of Bag-1 - an enhancer of ADP/ATP exchange activity of Hsp70s. A model in which calmodulin displaces Bag-1 and modulates Ssb1/Hsp75 chaperone activity is discussed.