Cardiac fibroblasts display endurance to ischemia, high ROS control and elevated respiration regulated by the JAK2/STAT pathway

Cardiac fibroblast; Cellular respiration; SurvivalFibroblast cardíac; Respiració cel·lular; SupervivènciaFibroblasto cardiaco; Respiración celular; SupervivenciaCardiovascular diseases are the leading cause of death globally and more than four out of five cases are due to ischemic events. Cardiac fibroblasts (CF) contribute to normal heart development and function, and produce the post-ischemic scar. Here, we characterize the biochemical and functional aspects related to CF endurance to ischemia-like conditions. Expression data mining showed that cultured human CF (HCF) express more BCL2 than pulmonary and dermal fibroblasts. In addition, gene set enrichment analysis showed overrepresentation of genes involved in the response to hypoxia and oxidative stress, respiration and Janus kinase (JAK)/Signal transducer and Activator of Transcription (STAT) signaling pathways in HCF. BCL2 sustained survival and proliferation of cultured rat CF, which also had higher respiration capacity and reactive oxygen species (ROS) production than pulmonary and dermal fibroblasts. This was associated with higher expression of the electron transport chain (ETC) and antioxidant enzymes. CF had high phosphorylation of JAK2 and its effectors STAT3 and STAT5, and their inhibition reduced viability and respiration, impaired ROS control and reduced the expression of BCL2, ETC complexes and antioxidant enzymes. Together, our results identify molecular and biochemical mechanisms conferring survival advantage to experimental ischemia in CF and show their control by the JAK2/STAT signaling pathway. The presented data point to potential targets for the regulation of cardiac fibrosis and also open the possibility of a general mechanism by which somatic cells required to acutely respond to ischemia are constitutively adapted to survive it.This research was funded by Ministerio de Ciencia e Innovación (MICINN), Gobierno de España, grant numbers SAF2013-44942-R and PID2019-104509RB-I00 to DS; Fundació La Marató TV3, grant number 20153810 to D.S; A.B. holds a contract from Fundació La Marató TV3 and IRBLleida/Diputació de Lleida; Generalitat de Catalunya, (AGAUR) grant number 2017SGR996 to DS; PP-G Laboratory support was obtained through research grants from MICINN (SAF2017/88275R) and CIBERONC (CB16/12/00334); JI and MR-M Laboratory support was obtained from Instituto de Salud Carlos III (ISCIII-FIS) grant PI19-01196; AZ Laboratory support was obtained through research grants from MICINN (PID2019-106209RB-I00), and the Generalitat de Catalunya, (AGAUR) grant number 2017SGR1015. AZ is a recipient of an ICREA ‘Academia’ Award (Generalitat de Catalunya). We gratefully acknowledge institutional funding from the MINECO through the Centres of Excellence Severo Ochoa Award, and from the CERCA Programme of the Generalitat de Catalunya

Context-dependent roles of cellular senescence in normal, aged, and disease states.

Cellular senescence is a state of irreversible cell cycle arrest that often emerges after tissue damage and in age-related diseases. Through the production of a multicomponent secretory phenotype (SASP), senescent cells can impact the regeneration and function of tissues. However, the effects of senescent cells and their SASP are very heterogeneous and depend on the tissue environment and type as well as the duration of injury, the degree of persistence of senescent cells and the organism's age. While the transient presence of senescent cells is widely believed to be beneficial, recent data suggest that it is detrimental for tissue regeneration after acute damage. Furthermore, although senescent cell persistence is typically associated with the progression of age-related chronic degenerative diseases, it now appears to be also necessary for correct tissue function in the elderly. Here, we discuss what is currently known about the roles of senescent cells and their SASP in tissue regeneration in ageing and age-related diseases, highlighting their (negative and/or positive) contributions. We provide insight for future research, including the possibility of senolytic-based therapies and cellular reprogramming, with aims ranging from enhancing tissue repair to extending a healthy lifespan.Work in the authors’ laboratory is supported by MINECO-Spain (RTI2018-096068), H2020 European Research Council-2016-AdG-741966, LaCaixaHEALTH-HR17-00040, MWRF, French Muscular Dystrophy Association, Muscular Dystrophy Association, Fundacio LaMarató TV3 (80/19-202021 and 137/ 38-202033) and UPGRADE-H2020-825825; and María-de-Maeztu-Program for Units of Excellence to UPF (MDM-2014-0370), Severo Ochoa-Program for Centers of Excellence to CNIC (SEV-2015-0505).S

Genome Wide Meta-Analysis identifies common genetic signatures shared by heart function and Alzheimer's disease

Echocardiography has become an indispensable tool for the study of heart performance, improving the monitoring of individuals with cardiac diseases. Diverse genetic factors associated with echocardiographic measures have been previously reported. The impact of several apoptotic genes in heart development identified in experimental models prompted us to assess their potential association with human cardiac function. This study aimed at investigating the possible association of variants of apoptotic genes with echocardiographic traits and to identify new genetic markers associated with cardiac function. Genome wide data from different studies were obtained from public repositories. After quality control and imputation, a meta-analysis of individual association study results was performed. Our results confirmed the role of caspases and other apoptosis related genes with cardiac phenotypes. Moreover, enrichment analysis showed an over-representation of genes, including some apoptotic regulators, associated with Alzheimer's disease. We further explored this unexpected observation which was confirmed by genetic correlation analyses. Our findings show the association of apoptotic gene variants with echocardiographic indicators of heart function and reveal a novel potential genetic link between echocardiographic measures in healthy populations and cognitive decline later on in life. These findings may have important implications for preventative strategies combating Alzheimer's disease

Caracterització de la biologia dels fibroblasts cardíacs i la seva resposta a estrès cel·lular

Els fibroblasts cardíacs són els principals productors de la matriu extracel·lular que cohesiona la musculatura del cor, conferint-li les propietats ideals per transformar la contracció dels cardiomiòcits en el moviment de la paret cardíaca que permet el bombeig de la sang. A més, aquestes cèl·lules intervenen en el procés de sincronització del batec i la secreció de factors tròfics potenciant el creixement del cor durant el desenvolupament. En condicions patològiques, com ara el tall del flux sanguini al miocardi (isquèmia), els fibroblasts cardíacs secreten la matriu que generarà la cicatriu durant la mort del miocardi. No obstant, tot i que aquest esdeveniment és essencial per sobreviure a l’infart, la deposició de matriu extracel·lular pot representar una complicació si s’allarga en el temps o s’activa excessivament. Per això, s’està destinant molt esforç a la identificació de l’origen embrional i els tipus cel·lulars precisos que constitueixen la població de fibroblasts cardíacs, a re-avaluar la seva abundància al cor, així com a comprendre la regulació de la síntesi i secreció de matriu extracel·lular. El nostre grup havia demostrat que els fibroblasts cardíacs expressen elevats nivells de Bcl-2, una proteïna anti-apoptòtica que els protegeix la integritat mitocondrial durant la isquèmia, reduint l’activació de les caspases. Tot i que estan ben caracteritzats pel que fa a la quantitat, l’origen genètic i l’activitat dels fibroblasts cardíacs, hi ha poca informació sobre els mecanismes implicats en la resistència d’aquestes cèl·lules a la isquèmia i per això, vam decidir seguir investigant aquest aspecte. La hipòtesi inicial era que l’autofàgia, un procés implicat en el reciclatge de components cel·lulars regulat per Bcl-2 i que pot ser utilitzat per obtenir energia, podia estar implicada en la major supervivència dels fibroblasts cardíacs a la isquèmia. L’anàlisi de l’autofàgia a fibroblasts primaris neonatals de rata, utilitzant tant inhibidors químics com el silenciament de gens clau, va mostrar que és un procés important en condicions normals però no durant la isquèmia en aquestes cèl·lules. Malgrat això, vam trobar que l’elevada expressió de Bcl-2 és necessària per la supervivència dels fibroblasts cardíacs en condicions normals, a més de durant la isquèmia i l’estrès de reticle. També vam trobar que aquestes cèl·lules presenten diverses característiques associades a la major capacitat de supervivència en relació a d’altres fibroblasts, incloent major respiració basal i de reserva, nivells de radicals lliures d’oxigen elevats però millor controlats durant la isquèmia, nivells elevats d’expressió d’enzims antioxidants i de complexos de la cadena respiratòria, però menys expressió de Pgc-1α i Mitofusina-2, associat a una xarxa mitocondrial amb més mitocondris aïllats. Aquestes característiques es troben relacionades amb la major activació de senyalització inflamatòria i vam mostrar que moltes depenen d’una activació basal elevada de la via de transducció de senyal Jak/Stat. En conjunt, els nostres resultats ajuden a la millor comprensió de les característiques biològiques subjacents a la major capacitat de supervivència dels fibroblasts cardíacs.Los fibroblastos cardíacos son los principales productores de la matriz extracelular que cohesiona la musculatura del corazón, confiriéndole las propiedades ideales para transformar la contracción de los cardiomiocitos en el movimiento de la pared cardíaca que permite el bombeo de la sangre. Además, estas células intervienen en el proceso de sincronización del latido y la secreción de factores tróficos potenciando el crecimiento del corazón durante el desarrollo. En condiciones patológicas, tales como el corte del flujo sanguíneo al miocardio (isquemia), los fibroblastos cardíacos secretan la matriz que generará la cicatriz durante la muerte del miocardio. Sin embargo, aunque este evento es esencial para sobrevivir al infarto, la deposición de matriz extracelular puede representar una complicación si se alarga en el tiempo o se activa excesivamente. Debido a eso, se está destinando mucho esfuerzo a la identificación del origen embrionario y los tipos celulares precisos que constituyen la población de fibroblastos cardíacos, a re-evaluar su abundancia en el corazón, así como a comprender la regulación de la síntesis y secreción de matriz extracelular. Nuestro grupo había demostrado que los fibroblastos cardíacos expresan niveles elevados de Bcl-2, una proteína anti-apoptótica que protege la integridad mitocondrial durante la isquemia, reduciendo la activación de las caspasas. Aunque se han caracterizado bien la cantidad, el origen genético y la actividad de los fibroblastos cardíacos, hay poca información sobre los mecanismos implicados en la resistencia a la isquemia de estas células y por eso decidimos seguir investigando este aspecto. La hipótesis inicial era que la autofagia, un proceso implicado en el reciclaje de componentes celulares regulado por Bcl-2 y que puede ser utilizado para obtener energía, podía estar implicada en la mayor supervivencia de los fibroblastos cardíacos a la isquemia. El análisis de la autofagia en fibroblastos primarios neonatales de rata, utilizando tanto inhibidores químicos como el silenciamiento de genes clave, mostró que es un proceso importante en condiciones normales, pero no durante la isquemia en estas células. Sin embargo, encontramos que la elevada expresión de Bcl-2 es necesaria para la supervivencia de los fibroblastos cardíacos en condiciones normales, además de durante la isquemia y el estrés de retículo. Encontramos también que estas células presentan varias características asociadas a la mayor capacidad de supervivencia en relación a otros fibroblastos, incluyendo mayor respiración basal y de reserva, niveles de radicales libres de oxígeno elevados pero mejor controlados durante la isquemia, niveles elevados de expresión de enzimas antioxidantes y de complejos de la cadena respiratoria, pero menos expresión de Pgc-1α y Mitofusina-2, asociado a una red mitocondrial con más mitocondrias aisladas. Estas características están relacionadas con la mayor activación de señalización inflamatoria y mostramos que muchas dependen de una activación basal elevada de la vía de transducción de señal Jak/Stat. En conjunto, nuestros resultados ayudan a una mejor comprensión de las características biológicas subyacentes a la mayor capacidad de supervivencia de los fibroblastos cardíacos.Cardiac fibroblasts are the main producers of the extracellular matrix that binds together the cardiac muscle, giving it the ideal properties to transform the contraction of cardiomyocytes into the movement of the heart wall that allows blood pumping. In addition, these cells intervene in the process of beat synchronization and the secretion of trophic factors, enhancing the growth of the heart during development. In pathological conditions such as cut off of blood flow to the myocardium (ischemia), cardiac fibroblasts secrete the matrix that will generate the scar during myocardial death. Although this event is essential to survive the infarction, the deposition of extracellular matrix can represent a complication if it is prolonged in time or is excessively activated. That is why a lot of effort is being devoted to identifying the embryonic origin and the precise cell types that make up the population of cardiac fibroblasts, to re-evaluating their abundance in the heart, as well as to understanding the regulation of extracellular matrix synthesis and secretion. Our group had shown that cardiac fibroblasts express a high level of Bcl-2, an anti-apoptotic protein that protects mitochondrial integrity during ischemia, reducing the activation of caspases. Although the number, genetic origin, and activity of cardiac fibroblasts have been well characterized, there is little information on the mechanisms involved in the resistance of these cells to ischemia and that is why we decided to continue investigating this aspect. The initial hypothesis was that autophagy, a process involved in the recycling of cellular components regulated by Bcl-2 and that can be used to obtain energy, could be involved in the greater survival of cardiac fibroblasts to ischemia. Analysis of autophagy in neonatal rat primary fibroblasts, using both chemical inhibitors and key gene silencing, showed that it is an important process under normal conditions, but not during ischemia in these cells. However, we found that the high expression of Bcl-2 is necessary for the survival of cardiac fibroblasts under normal conditions, as well as during ischemia and reticulum stress. We also found that these cells present several characteristics associated with a higher survival capacity in relation to other fibroblasts, including greater basal and reserve respiration, elevated levels of reactive oxygen species, which are better controlled during ischemia, high levels of expression of antioxidant enzymes and of complexes of the respiratory chain, but less expression of Pgc-1α and Mitofusin-2, associated with a mitochondrial network with more isolated mitochondria. These characteristics are related to the greater activation of inflammatory signaling and we show that many of them depend on a high basal activation of the Jak/Stat signal transduction pathway. Taken together, our results help to better understand the biological characteristics underlying the greater survival capacity of cardiac fibroblasts

Involvement of the mitochondrial nuclease EndoG in the regulation of cell proliferation through the control of reactive oxygen species

© 2020 The Author(s).The apoptotic nuclease EndoG is involved in mitochondrial DNA replication. Previous results suggested that, in addition to regulate cardiomyocyte hypertrophy, EndoG could be involved in cell proliferation. Here, by using in vivo and cell culture models, we investigated the role of EndoG in cell proliferation. Genetic deletion of Endog both in vivo and in cultured cells or Endog silencing in vitro induced a defect in rodent and human cell proliferation with a tendency of cells to accumulate in the G1 phase of cell cycle and increased reactive oxygen species (ROS) production. The defect in cell proliferation occurred with a decrease in the activity of the AKT/PKB-GSK-3β-Cyclin D axis and was reversed by addition of ROS scavengers. EndoG deficiency did not affect the expression of ROS detoxifying enzymes, nor the expression of the electron transport chain complexes and oxygen consumption rate. Addition of the micropeptide Humanin to EndoG-deficient cells restored AKT phosphorylation and proliferation without lowering ROS levels. Thus, our results show that EndoG is important for cell proliferation through the control of ROS and that Humanin can restore cell division in EndoG-deficient cells and counteracts the effects of ROS on AKT phosphorylation.This research was funded by Ministerio de Ciencia e Innovación, Gobierno de España, grant numbers SAF2013-44942-R and PID2019-104509RB-I00 to D.S. and SAF2016-80157-R to X.D.; Fundació La Marató, Catalunya, grant number 20153810 to D.S.; AGAUR, Generalitat de Catalunya, Catalunya, grant number 2014-SGR-1609 to D.S. G.B. holds a contract from the University of Lleida; A.B. contract has been funded by Fundació La Marató TV3 and Diputació de Lleida/IRBLleida

Cardiac fibroblasts display endurance to ischemia, high ROS control and elevated respiration regulated by the JAK2/STAT pathway

Cardiovascular diseases are the leading cause of death globally and more than four out of five cases are due to ischemic events. Cardiac fibroblasts (CF) contribute to normal heart development and function, and produce the post-ischemic scar. Here, we characterize the biochemical and functional aspects related to CF endurance to ischemia-like conditions. Expression data mining showed that cultured human CF (HCF) express more BCL2 than pulmonary and dermal fibroblasts. In addition, gene set enrichment analysis showed overrepresentation of genes involved in the response to hypoxia and oxidative stress, respiration and Janus kinase (JAK)/Signal transducer and Activator of Transcription (STAT) signaling pathways in HCF. BCL2 sustained survival and proliferation of cultured rat CF, which also had higher respiration capacity and reactive oxygen species (ROS) production than pulmonary and dermal fibroblasts. This was associated with higher expression of the electron transport chain (ETC) and antioxidant enzymes. CF had high phosphorylation of JAK2 and its effectors STAT3 and STAT5, and their inhibition reduced viability and respiration, impaired ROS control and reduced the expression of BCL2, ETC complexes and antioxidant enzymes. Together, our results identify molecular and biochemical mechanisms conferring survival advantage to experimental ischemia in CF and show their control by the JAK2/STAT signaling pathway. The presented data point to potential targets for the regulation of cardiac fibrosis and also open the possibility of a general mechanism by which somatic cells required to acutely respond to ischemia are constitutively adapted to survive it.This research was funded by Ministerio de Ciencia eInnovación (MICINN), Gobierno de España, grant numbers SAF2013-44942-R and PID2019-104509RB-I00 to DS; Fundació La Marató TV3, grant number 20153810 to D.S; A.B. holds a contract from FundacióLa Marató TV3 and IRBLleida/Diputació de Lleida; Generalitat de Catalunya, (AGAUR) grant number 2017SGR996 to DS; PP-G Laboratory support wasobtained through research grants from MICINN(SAF2017/88275R) and CIBERONC (CB16/12/00334);JI and MR-M Laboratory support was obtained from Instituto de Salud Carlos III (ISCIII-FIS) grant PI19-01196; AZ Laboratory support was obtained throughresearch grants from MICINN (PID2019-106209RB-I00), and the Generalitat de Catalunya, (AGAUR) grant number 2017SGR1015. AZ is a recipient of an ICREA ‘Academia’ Award (Generalitat de Catalunya).We gratefully acknowledge institutional funding fromthe MINECO through the Centres of Excellence Severo Ochoa Award, and from the CERCA Programme of the Generalitat de Cataluny