StarD7 deficiency switches on glycolysis and promotes mitophagy flux in C2C12 myoblasts.

StarD7 is a member of the START protein family required for phosphatidylcholine delivery to the mitochondria, thus key to maintain mitochondrial structure. Its deficiency has been associated with an impairment of cellular processes, such as proliferation and migration, and it has also been reported that it is needed in myogenic differentiation. Here, we show that StarD7 deficiency in C2C12 muscle cells results in the accumulation of abnormal mitochondria, a reduced number of mitochondria per cell area and increased glycolysis. In addition, StarD7-deficient cells undergo an increase in mitochondria-ER contact sites, reduced connexin 43 expression, and disturbances in lipid handling, evidenced by lipid droplet accumulation and decreased levels in phosphatidylserine synthase 1 and 2 expression. Interestingly, StarD7-deficient cells showed alterations in mitophagy markers. We observed accumulation of LC3B-II and BNIP3 proteins in mitochondria-enriched fractions and accumulation of autophagolysosomal and lysosomal vesicles in StarD7-deficient cells. Furthermore, live-cell imaging experiments of StarD7 knockdown cells expressing mitochondria-targeted mKeima indicated an enhanced mitochondria delivery into lysosomes. Importantly, StarD7 reconstitution in StarD7-deficient cells restores LC3B-II expression in mitochondria-enriched fractions at similar levels to those observed in control cells. Collectively, these findings suggest that StarD7-deficient C2C12 myoblasts are associated with altered cristae structure, disturbances in neutral lipid accumulation, glucose metabolism, and increased mitophagy flux. The alterations mentioned above allow for the maintenance of mitochondrial function.

Downregulation of krüppel-like factor 6 expression modulates extravillous trophoblast cell behavior by increasing reactive oxygen species.

INTRODUCTION: Placental extravillous trophoblasts play a crucial role in the establishment of a healthy pregnancy. Reactive oxygen species (ROS) may contribute to their differentiation and function as mediators in signaling processes or might cause oxidative stress resulting in trophoblast dysfunction. The krüppel-like transcription factor 6 (KLF6) regulates many genes involved in essential cell processes where ROS are also involved. However, whether KLF6 regulates ROS levels has not been previously investigated. MATERIALS AND METHODS: KLF6 was silenced by siRNAs in HTR8-SV/neo cells, an extravillous trophoblast model. Total and mitochondrial ROS levels, as well as mitochondrial membrane potential and apoptosis were analyzed by flow cytometry. The expression of genes and proteins of interest were analyzed by qRT-PCR and Western blot, respectively. Cell response to oxidative stress, proliferation, viability, morphology, and migration were evaluated. RESULTS: KLF6 downregulation led to an increase in ROS and NOX4 mRNA levels, accompanied by reduced cell proliferation and increased p21 protein expression. Catalase activity, 2-Cys peroxiredoxin protein levels, Nrf2 cytoplasmic localization and hemoxygenase 1 expression, as well as mitochondrial membrane potential and cell apoptosis were not altered suggesting that ROS increase is not associated with cellular damage. Instead, KLF6 silencing induced cytoskeleton modifications and increased cell migration in a ROS-dependent manner. DISCUSSION: Present data reveal a novel role of KLF6 on ROS balance and signaling demonstrating that KLF6 downregulation induces an increase in ROS levels that contribute to extravillous trophoblast cell migration.

Krüppel-like factor 6 participates in extravillous trophoblast cell differentiation and its expression is reduced in abnormally invasive placenta.

Trophoblast cell differentiation is of paramount importance for successful pregnancy. Krüppel-like factor 6 (KLF6), a transcription factor with diverse roles in cell physiology and tumor biology, is required for trophoblast differentiation through the syncytial pathway. Herein, we demonstrate that extravillous trophoblast (EVT) cell migration and mesenchymal phenotype are increased upon KLF6 downregulation or the expression of a deletion mutant lacking its transcriptional regulatory domain (KΔac). Raman spectroscopy revealed molecular modifications compatible with increased differentiation in cells stably expressing the KΔac mutant. Moreover, abnormally invasive placenta showed lower KLF6 immunostaining compared with the normal placenta. Thus, impaired KLF6 expression or function stimulates EVT migration and differentiation in vitro and may contribute to the physiopathology of the abnormally invasive placenta.

Role of the lipid transport protein StarD7 in mitochondrial dynamics.

Mitochondria are dynamic organelles crucial for cell function and survival implicated in oxidative energy production whose central functions are tightly controlled by lipids. StarD7 is a lipid transport protein involved in the phosphatidylcholine (PC) delivery to mitochondria. Previous studies have shown that StarD7 knockdown induces alterations in mitochondria and endoplasmic reticulum (ER) with a reduction in PC content, however whether StarD7 modulates mitochondrial dynamics remains unexplored. Here, we generated HTR-8/SVneo stable cells expressing the precursor StarD7.I and the mature processed StarD7.II isoforms. We demonstrated that StarD7.I overexpression altered mitochondrial morphology increasing its fragmentation, whereas no changes were observed in StarD7.II-overexpressing cells compared to the control (Ct) stable cells. StarD7.I (D7.I) stable cells were able to transport higher fluorescent PC analog to mitochondria than Ct cells, yield mitochondrial fusions, maintained the membrane potential, and produced lower levels of reactive oxygen species (ROS). Additionally, the expression of Dynamin Related Protein 1 (Drp1) and Mitofusin (Mfn2) proteins were increased, whereas the amount of Mitofusin 1 (Mfn1) decreased. Moreover, transfections with plasmids encoding Drp1-K38A, Drp1-S637D or Drp1-S637A mutants indicated that mitochondrial fragmentation in D7.I cells occurs in a fission-dependent manner via Drp1. In contrast, StarD7 silencing decreased Mfn1 and Mfn2 fusion proteins without modification of Drp1 protein level. These cells increased ROS levels and presented donut-shape mitochondria, indicative of metabolic stress. Altogether our findings provide novel evidence indicating that alterations in StarD7.I expression produce significant changes in mitochondrial morphology and dynamics.

Diez años de experiencia con el estimulador del nervio vago en una población pediátrica / Ten years' experience with vagus nerve stimulation in a paediatric population

Introducción. La epilepsia afecta a 50 millones de personas. Hasta un 30% no se controla con fármacos antiepilépticos. El estimulador del nervio vago (ENV) constituye una alternativa terapéutica que hay que valorar. Objetivo. Determinar el efecto del ENV en una cohorte pediátrica con epilepsia refractaria. Pacientes y métodos. Estudio retrospectivo de niños con ENV implantado entre 2008 y 2017 en un hospital terciario. Se han analizado datos epidemiológicos, etiológicos, clínicos, electrofisiológicos y parámetros del ENV. Resultados. Se incluyó a 35 pacientes, con una mediana de edad de implantación de 12,84 años (rango: 3,1-18,7 años) y una mediana de evolución entre el inicio de la epilepsia y la implantación de 7,2 años (rango: 1,3-17,7 años). La etiología fue estructural en el 62,9% de los casos. Cuadros epilépticos más frecuentes: síndrome de Lennox-Gastaut y epilepsia focal, con predominio de las crisis tónicas (57,1%). El videoelectroencefalograma mostró anomalías multifocales (54%) y un patrón de encefalopatía epiléptica (34,3%). El 94% asociaba discapacidad intelectual. La media de fármacos antiepilépticos previos fue de 9,6 ± 3 (rango: 4-16). El 43% fueron respondedores (>= 50% reducción de crisis), con una media de reducción del 67,3%, mejor cuanto mayor era la edad de inicio de la epilepsia. Tres pacientes quedaron libres de crisis (8,5%). La reducción de crisis fue del 33% a los 6 meses y del 47,4% a los 24 meses. Mejoría cognitiva (57%) y conductual (53%). El 28% tuvo efectos secundarios, generalmente leves. Conclusiones. El ENV es una opción válida en la epilepsia refractaria con mejoría no sólo de las crisis, sino también cognitiva y conductual, con la importancia que ello tiene para la población pediátrica

Introduction. Fifty million people are aff ected by epilepsy. Up to 30% are not controlled with the aid of antiepileptic drugs. The vagus nerve stimulator (VNS) is a therapeutic alternative that must be taken into account. Aim. To determine the eff ect of the VNS in a cohort of paediatric patients with refractory epilepsy. Patients and methods. A retrospective study of children with a VNS implanted between 2008 and 2017 in a tertiary hospital. Epidemiological, aetiological, clinical and electrophysiological data, along with VNS parameters were analysed. Results. The study included 35 patients, with a mean age when the VNS was implanted of 12.84 years (range: 3.1-18.7 years) and a mean time between onset of epilepsy and implantation of 7.2 years (range: 1.3-17.7 years). The causation was structural in 62.9% of cases. The most frequent epileptic conditions were: Lennox-Gastaut syndrome and focal epilepsy, with a redominance of tonic seizures (57.1%). The video electroencephalogram showed multifocal anomalies (54%) and a pattern of epileptic encephalopathies (34.3%). Intellectual disability was associated in 94% of the cases. The mean of previous antiepileptic drugs was 9.6 ± 3 (range: 4-16). 43% responded to treatment (≥ 50% reduction in number of seizures), with a mean reduction of 67.3%, which improved with higher ages of onset of epilepsy. Three patients were seizure-free (8.5%). The number of seizures decreased by 33% at six months and by 47.4% at 24 months. There was also a notable degree of cognitive (57%) and behavioural improvement (53%). In 28% of cases there were some side eff ects, but in general they were mild. Conclusions. The VNS is a valid option in refractory epilepsy, with improvements not only in terms of seizures but also regarding cognitive-behavioural aspects, this being very important for the paediatric population

Hexosamine pathway regulates StarD7 expression in JEG-3 cells.

StarD7 is a lipid binding protein involved in the delivery of phosphatidylcholine to the mitochondria whose promoter is activated by Wnt/ß-catenin signaling. Although the majority of glucose enters glycolysis, ~ 2-5% of it can be metabolized via the hexosamine biosynthetic pathway (HBP). Considering that HBP has been implicated in the regulation of ß-catenin we explored if changes in glucose levels modulate StarD7 expression by the HBP in trophoblast cells. We found an increase in StarD7 as well as in ß-catenin expression following high-glucose (25 mM) treatment in JEG-3 cells; these effects were abolished in the presence of HBP inhibitors. Moreover, since HBP is able to promote unfolded protein response (UPR) the protein levels of GRP78, Ire1α, calnexin, p-eIF2α and total eIF2α as well as XBP1 mRNA was measured. Our results indicate that a diminution in glucose concentration leads to a decrease in StarD7 expression and an increase in the UPR markers: GRP78 and Ire1α. Conversely, an increase in glucose is associated to high StarD7 levels and low GRP78 expression, phospho-eIF2α and XBP1 splicing, although Ire1α remains high when cells are restored to high glucose. Taken together these findings indicate that glucose modulates StarD7 and ß-catenin expression through the HBP associated to UPR, suggesting the existence of a link between UPR and HBP in trophoblast cells. This is the first study reporting the effects of glucose on StarD7 in trophoblast cells. These data highlight the importance to explore the role of StarD7 in placenta disorders related to nutrient availability.

Production of bioethanol from carrot discards.

A revalorization of discarded carrots as substrate for the production of second-generation ethanol is proposed. In order to increase the fermentable sugar concentration of the musts two strategies were studied: Strategy 1 consisted in the enzymatic hydrolysis of bagasse must and Strategy 2 by which carrots were milled, dropped into distilled water and hydrolyzed with different enzymes prior to compressing and filtering to obtain carrot must. By applying Strategy 2 using 0.05% (v/v) of the enzyme Optimase CX255 at 70°C and pH 5.5 during 2.5h, the fermentable sugars extracted increased 3.5 times. In this way, the production of 77.5L of ethanol for each ton of discarded carrots was achieved. This process yielded bagasse as byproduct, which could be used for animal feed.