c-Abl Phosphorylates MFN2 to Regulate Mitochondrial Morphology in Cells under Endoplasmic Reticulum and Oxidative Stress, Impacting Cell Survival and Neurodegeneration.

The endoplasmic reticulum is a subcellular organelle key in the control of synthesis, folding, and sorting of proteins. Under endoplasmic reticulum stress, an adaptative unfolded protein response is activated; however, if this activation is prolonged, cells can undergo cell death, in part due to oxidative stress and mitochondrial fragmentation. Here, we report that endoplasmic reticulum stress activates c-Abl tyrosine kinase, inducing its translocation to mitochondria. We found that endoplasmic reticulum stress-activated c-Abl interacts with and phosphorylates the mitochondrial fusion protein MFN2, resulting in mitochondrial fragmentation and apoptosis. Moreover, the pharmacological or genetic inhibition of c-Abl prevents MFN2 phosphorylation, mitochondrial fragmentation, and apoptosis in cells under endoplasmic reticulum stress. Finally, in the amyotrophic lateral sclerosis mouse model, where endoplasmic reticulum and oxidative stress has been linked to neuronal cell death, we demonstrated that the administration of c-Abl inhibitor neurotinib delays the onset of symptoms. Our results uncovered a function of c-Abl in the crosstalk between endoplasmic reticulum stress and mitochondrial dynamics via MFN2 phosphorylation.

The c-Abl/p73 pathway induces neurodegeneration in a Parkinson's disease model.

Parkinson's disease is the second most common neurodegenerative disorder. Although it is clear that dopaminergic neurons degenerate, the underlying molecular mechanisms are still unknown, and thus, successful treatment is still elusive. One pro-apoptotic pathway associated with several neurodegenerative diseases is the tyrosine kinase c-Abl and its target p73. Here, we evaluated the contribution of c-Abl and p73 in the degeneration of dopaminergic neurons induced by the neurotoxin 6-hydroxydopamine as a model for Parkinson's disease. First, we found that in SH-SY5Y cells treated with 6-hydroxydopamine, c-Abl and p73 phosphorylation levels were up-regulated. Also, we found that the pro-apoptotic p73 isoform TAp73 was up-regulated. Then, to evaluate whether c-Abl tyrosine kinase activity is necessary for 6-hydroxydopamine-induced apoptosis, we co-treated SH-SY5Y cells with 6-hydroxydopamine and Imatinib, a c-Abl specific inhibitor, observing that Imatinib prevented p73 phosphorylation, TAp73 up-regulation, and protected SH-SY5Y cells treated with 6-hydroxydopamine from apoptosis. Interestingly, this observation was confirmed in the c-Abl conditional null mice, where 6-hydroxydopamine stereotaxic injections induced a lesser reduction of dopaminergic neurons than in the wild-type mice significantly. Finally, we found that the intraperitoneal administration of Imatinib prevented the death of dopaminergic neurons induced by injecting 6-hydroxydopamine stereotaxically in the mice striatum. Thus, our findings support the idea that the c-Abl/p73 pathway is involved in 6-hydroxydopamine degeneration and suggest that inhibition of its kinase activity might be used as a therapeutical drug in Parkinson's disease.

Systematic Review: microRNAs as Potential Biomarkers in Mild Cognitive Impairment Diagnosis.

The rate of progression from Mild Cognitive Impairment (MCI) to Alzheimer's disease (AD) is estimated at >10% per year, reaching up to 80-90% after 6 years. MCI is considered an indicator of early-stage AD. In this context, the diagnostic screening of MCI is crucial for detecting individuals at high risk of AD before they progress and manifest further severe symptoms. Typically, MCI has been determined using neuropsychological assessment tools such as the Montreal Cognitive Assessment (MoCA) or Mini-Mental Status Examination (MMSE). Unfortunately, other diagnostic methods are not available or are unable to identify MCI in its early stages. Therefore, identifying new biomarkers for MCI diagnosis and prognosis is a significant challenge. In this framework, miRNAs in serum, plasma, and other body fluids have emerged as a promising source of biomarkers for MCI and AD-related cognitive impairments. Interestingly, miRNAs can regulate several signaling pathways via multiple and diverse targets in response to pathophysiological stimuli. This systematic review aims to describe the current state of the art regarding AD-related target genes modulated by differentially expressed miRNAs in peripheral fluids samples in MCI subjects to identify potential miRNA biomarkers in the early stages of AD. We found 30 articles that described five miRNA expression profiles from peripheral fluid in MCI subjects, showing possible candidates for miRNA biomarkers that may be followed up as fluid biomarkers or therapeutic targets of early-stage AD. However, additional research is needed to validate these miRNAs and characterize the precise neuropathological mechanisms.

c-Abl Inhibition Activates TFEB and Promotes Cellular Clearance in a Lysosomal Disorder.

The transcription factor EB (TFEB) has emerged as a master regulator of lysosomal biogenesis, exocytosis, and autophagy, promoting the clearance of substrates stored in cells. c-Abl is a tyrosine kinase that participates in cellular signaling in physiological and pathophysiological conditions. In this study, we explored the connection between c-Abl and TFEB. Here, we show that under pharmacological and genetic c-Abl inhibition, TFEB translocates into the nucleus promoting the expression of its target genes independently of its well-known regulator, mammalian target of rapamycin complex 1. Active c-Abl induces TFEB phosphorylation on tyrosine and the inhibition of this kinase promotes lysosomal biogenesis, autophagy, and exocytosis. c-Abl inhibition in Niemann-Pick type C (NPC) models, a neurodegenerative disease characterized by cholesterol accumulation in lysosomes, promotes a cholesterol-lowering effect in a TFEB-dependent manner. Thus, c-Abl is a TFEB regulator that mediates its tyrosine phosphorylation, and the inhibition of c-Abl activates TFEB promoting cholesterol clearance in NPC models.

Genotoxic stress triggers the activation of IRE1α-dependent RNA decay to modulate the DNA damage response.

The molecular connections between homeostatic systems that maintain both genome integrity and proteostasis are poorly understood. Here we identify the selective activation of the unfolded protein response transducer IRE1α under genotoxic stress to modulate repair programs and sustain cell survival. DNA damage engages IRE1α signaling in the absence of an endoplasmic reticulum (ER) stress signature, leading to the exclusive activation of regulated IRE1α-dependent decay (RIDD) without activating its canonical output mediated by the transcription factor XBP1. IRE1α endoribonuclease activity controls the stability of mRNAs involved in the DNA damage response, impacting DNA repair, cell cycle arrest and apoptosis. The activation of the c-Abl kinase by DNA damage triggers the oligomerization of IRE1α to catalyze RIDD. The protective role of IRE1α under genotoxic stress is conserved in fly and mouse. Altogether, our results uncover an important intersection between the molecular pathways that sustain genome stability and proteostasis.

Lysosome motility and distribution: Relevance in health and disease.

Lysosomes are dynamic organelles, which can fuse with a variety of targets and undergo constant regeneration. They can move along microtubules in a retrograde and anterograde fashion by using motor proteins, kinesin and dynein, being main players in extracellular secretion, intracellular components degradation and recycling. Moreover, lysosomes interact with other intracellular organelles to regulate their turnover, such as ER, mitochondria and peroxisomes. The correct localization of lysosomes is relevant in several physiological processes, including appropriate antigen presentation, neurotransmission and receptors modulation in neuronal synapsis, whereas hepatic lysosomes and autophagy are master regulators of nutrient homeostasis. Alterations in lysosome function due to mutation of genes encoding lysosomal proteins, soluble hydrolases as well as membrane proteins, lead to lysosomal storage diseases (LSDs). Lysosomes containing undegraded substrates are finally stacked and therefore miss positioned inside the cell, leading to lysosomal dysfunction, which impacts a wide range of cellular functions.

Evaluación del consumo de antimicrobianos en una Unidad de Neonatologia: un trabajo en equipo para promover el uso racional de antimicrobianos / Evaluation of antimicrobial consumption in a Neonatology Unit: a team work to promote the rational use of antibiotics

Resumen Antecedentes: Los antimicrobianos (ATM) son uno de los medicamentos más utilizados en recién nacidos (RN) hospitalizados. El uso indiscriminado de ATM trae consecuencias negativas como son el predominio de bacterias resistentes a los ATM usualmente utilizados y asociaciones individuales a morbilidad relevante como son la displasia broncopulmonar, enterocolitis necrosante, sepsis tardía y/o muerte. Objetivo: Registrar y evaluar las tendencias del uso de ATM a lo largo del tiempo en RN hospitalizados en el Servicio de Neonatología (SRN) del Complejo Asistencial Dr. Sótero del Río, con el fin de objetivar los cambios en la práctica habitual de la indicación de ATM. Un objetivo secundario fue evaluar el impacto de estas conductas sobre la resistencia antimicrobiana. Métodos: Estudio de cohorte, prospectivo, observacional, unicéntrico, en todos los pacientes hospitalizados entre enero de 2011 y diciembre de 2014. Se registró el peso al nacer, días de hospitalización, indicación y días de uso de ATM para cada paciente. El uso de ATM fue cuantificado por medio de distintas tasas: días de indicación de un o más ATM para el consumo global (TUA), sumatoria total de días de uso (STUA) como para los ATM más frecuentemente utilizados. Cada tasa calculada por 100 días hospitalizados. Además, se registró la susceptibilidad antimicrobiana de las bacterias más frecuentemente aisladas en nuestro servicio: Staphylococcus coagulasa negativa (SCN) y bacilos gramnegativos (BGNs). Resultados: El 34,7% de los pacientes hospitalizados recibió algún tipo de antimicrobiano, correspondiendo 32,3% a antibacterianos. El ATM más utilizado fue ampicilina (20,2% del total) y luego cefadroxilo (11,6%). El TUA no cambió entre 2011 y 2014. La STUA disminuyó en 10,7% entre 2011 y 2014 (p < 0,05). En el análisis por rangos de peso, en el grupo < 750 g disminuyó la tendencia de uso de vancomicina (descenso de uso en 9,9%) y un aumento de 18,8% para metronidazol. Por otra parte, hubo un aumento en el uso del régimen de piperacilina/tazobactam en el grupo > 1.500 g. Al evaluar la susceptibilidad antimicrobiana, hubo una disminución de la susceptibilidad a cloxacilina en SCN entre 2011 y 2014 desde 27 a 10,3%, respectivamente. Para BGN hubo una disminución desde 76,9 a 40,5% en la susceptibilidad a cefalosporinas de tercera generación, principalmente debido a Klebsiella pneumoniae que pasó a ser el BGN predominante, con un aumento de 6,7 a 50% en los años 2011 y 2014, respectivamente. Para Klebsiella pneumoniae la susceptibilidad a cefalosporinas de tercera generación descendió desde 77 a 22%. Por último, amikacina mostró una actividad sobre 85% en todos los BGNs entre 2011 y 2014. Conclusiones: Es recomendable planificar y mantener un registro continuo del consumo de ATM tanto como terapia y profilaxis, idealmente llevar el TUA, el STUA y siendo categorizado por tipo de ATM y rango de peso de los RN. En forma concomitante, es de considerable importancia analizar y evaluar la susceptibilidad de microorganismos. Es esencial que un equipo interdisciplinario prepare este registro, y que continuamente proporcione retroalimentación a los profesionales que mantienen el funcionamiento de las unidades de cuidados neonatales.

Background: Antibiotics (ATB) are drugs widely used in hospitalized newborns. The indiscriminate use of ATBs promote the rise of resistant bacteria to the most commonly indicated antimicrobials. In addition, ATB prescription presents associations to morbidity, such as bronchopulmonary dysplasia, necrotizing enterocolitis, late sepsis and even death. All of the above leads to an increase in health care costs. Aim: To record and to evaluate trends of antibiotic use over time in hospitalized NB in the Neonatology Unit at Dr. Sótero del Río Hospital, in order to objectify the changes in the usual practice of the ATM indication. A secondary objective was to assess its impact on antimicrobial resistance. Methods: Cohort, observational, prospective unicenter study which included all hospitalized patients between January 2011 and December 2014. Birth weight, hospitalization days, ATB indication and days of ATB use were recorded for each patient. The use of ATB was quantified by means of different rates; days of indication of one or more ATBs for global consumption (RUA), total sum of days of use (TSUA) and for the most frequently used ATBs. Each calculated rate for 100 days hospitalized. In addition, the antimicrobial susceptibility of the most frequently isolated bacteria in our service: coagulase-negative Staphylococcus (SCN) and Gram-negative bacilli (BGN) were recorded continuously. Results: The 34.7% of the hospitalized patients received some type of antimicrobial agent. ATBs were 32.3% of medicines used. The most widely used was ampicillin (with 20.2% of the total) and cefadroxyl (with 11.6%). The RUA did not change during the study time, but STUA decreased by 10.7% between 2011 and 2014 with p < 0.05. When subgroup analyzes were divided by weight ranges, in the < 750 g group, the use of vancomycin decreased in use by 9.9% and an increase of 18.8% for metronidazole was observed. On the other hand, there was an increase in the use of the piperacillin-tazobactam regimen in the range > 1,500 g. When evaluating antimicrobial susceptibility, there was a decrease in susceptibility for oxacillin in SCN between 2011 and 2014 from 27% to 10.3% respectively. In addition, for Gram negative there was a decrease from 76.9% to 40.5% in susceptibility to third generation cephalosporins, mainly due to Klebsiella pneumoniae, which became the predominantly isolated BGN with an increase of 6.7% to 50% between 2011 and 2014, respectively. For K. pneumoniae the loss of susceptibility to third generation cephalosporins decreased from 77% to 22%. Finally, amikacin showed an activity over 85% in all BGNs between 2011 and 2014. Conclusions: It is advisable to plan and to maintain a continuous record of ATB consumption, as well as therapy and prophylaxis, being categorized by ATB type and range of newborn weight. It is of considerable importance to analyze and to evaluate the susceptibility of microorganisms. It is essential that an interdisciplinary team prepare this recording, and to continuously provide feedback to professionals who maintain the functioning of neonatal care units.

[Evaluation of antimicrobial consumption in a Neonatology Unit: a team work to promote the rational use of antibiotics]. / Evaluación del consumo de antimicrobianos en una Unidad de Neonatologia: un trabajo en equipo para promover el uso racional de antimicrobianos.

BACKGROUND: Antibiotics (ATB) are drugs widely used in hospitalized newborns. The indiscriminate use of ATBs promote the rise of resistant bacteria to the most commonly indicated antimicrobials. In addition, ATB prescription presents associations to morbidity, such as bronchopulmonary dysplasia, necrotizing enterocolitis, late sepsis and even death. All of the above leads to an increase in health care costs. AIM: To record and to evaluate trends of antibiotic use over time in hospitalized NB in the Neonatology Unit at Dr. Sótero del Río Hospital, in order to objectify the changes in the usual practice of the ATM indication. A secondary objective was to assess its impact on antimicrobial resistance. METHODS: Cohort, observational, prospective unicenter study which included all hospitalized patients between January 2011 and December 2014. Birth weight, hospitalization days, ATB indication and days of ATB use were recorded for each patient. The use of ATB was quantified by means of different rates; days of indication of one or more ATBs for global consumption (RUA), total sum of days of use (TSUA) and for the most frequently used ATBs. Each calculated rate for 100 days hospitalized. In addition, the antimicrobial susceptibility of the most frequently isolated bacteria in our service: coagulase-negative Staphylococcus (SCN) and Gram-negative bacilli (BGN) were recorded continuously. RESULTS: The 34.7% of the hospitalized patients received some type of antimicrobial agent. ATBs were 32.3% of medicines used. The most widely used was ampicillin (with 20.2% of the total) and cefadroxyl (with 11.6%). The RUA did not change during the study time, but STUA decreased by 10.7% between 2011 and 2014 with p < 0.05. When subgroup analyzes were divided by weight ranges, in the < 750 g group, the use of vancomycin decreased in use by 9.9% and an increase of 18.8% for metronidazole was observed. On the other hand, there was an increase in the use of the piperacillin-tazobactam regimen in the range > 1,500 g. When evaluating antimicrobial susceptibility, there was a decrease in susceptibility for oxacillin in SCN between 2011 and 2014 from 27% to 10.3% respectively. In addition, for Gram negative there was a decrease from 76.9% to 40.5% in susceptibility to third generation cephalosporins, mainly due to Klebsiella pneumoniae, which became the predominantly isolated BGN with an increase of 6.7% to 50% between 2011 and 2014, respectively. For K. pneumoniae the loss of susceptibility to third generation cephalosporins decreased from 77% to 22%. Finally, amikacin showed an activity over 85% in all BGNs between 2011 and 2014. CONCLUSIONS: It is advisable to plan and to maintain a continuous record of ATB consumption, as well as therapy and prophylaxis, being categorized by ATB type and range of newborn weight. It is of considerable importance to analyze and to evaluate the susceptibility of microorganisms. It is essential that an interdisciplinary team prepare this recording, and to continuously provide feedback to professionals who maintain the functioning of neonatal care units.