Relationship between PPARα mRNA expression and mitochondrial respiratory function and ultrastructure of the skeletal muscle of patients with COPD

Genome-Wide Gene-Set Analysis Identifies Molecular Mechanisms Associated with ALS

Amyotrophic lateral sclerosis (ALS) is a fatal late-onset motor neuron disease characterized by the loss of the upper and lower motor neurons. Our understanding of the molecular basis of ALS pathology remains elusive, complicating the development of efficient treatment. Gene-set analyses of genome-wide data have offered insight into the biological processes and pathways of complex diseases and can suggest new hypotheses regarding causal mechanisms. Our aim in this study was to identify and explore biological pathways and other gene sets having genomic association to ALS. Two cohorts of genomic data from the dbGaP repository were combined: (a) the largest available ALS individual-level genotype dataset (N = 12,319), and (b) a similarly sized control cohort (N = 13,210). Following comprehensive quality control pipelines, imputation and meta-analysis, we assembled a large European descent ALS-control cohort of 9244 ALS cases and 12,795 healthy controls represented by genetic variants of 19,242 genes. Multi-marker analysis of genomic annotation (MAGMA) gene-set analysis was applied to an extensive collection of 31,454 gene sets from the molecular signatures database (MSigDB). Statistically significant associations were observed for gene sets related to immune response, apoptosis, lipid metabolism, neuron differentiation, muscle cell function, synaptic plasticity and development. We also report novel interactions between gene sets, suggestive of mechanistic overlaps. A manual meta-categorization and enrichment mapping approach is used to explore the overlap of gene membership between significant gene sets, revealing a number of shared mechanisms.

Skeletal Muscle Mitochondrial Dysfunction in Chronic Obstructive Pulmonary Disease: Underlying Mechanisms and Physical Therapy Perspectives

Skeletal muscle dysfunction (SMD) is a prevalent extrapulmonary complication and a significant independent prognostic factor in patients with chronic obstructive pulmonary disease (COPD). Mitochondrial dysfunction is one of the core factors that damage structure and function in COPD skeletal muscle and is closely related to smoke exposure, hypoxia, and insufficient physical activity. The currently known phenotypes of mitochondrial dysfunction are reduced mitochondrial content and biogenesis, impaired activity of mitochondrial respiratory chain complexes, and increased mitochondrial reactive oxygen species production. Significant progress has been made in research on physical therapy (PT), which has broad prospects for treating the abovementioned potential mitochondrial-function changes in COPD skeletal muscle. In terms of specific types of PT, exercise therapy can directly act on mitochondria and improve COPD SMD by increasing mitochondrial density, regulating mitochondrial biogenesis, upregulating mitochondrial respiratory function, and reducing oxidative stress. However, improvements in mitochondrial-dysfunction phenotype in COPD skeletal muscle due to different exercise strategies are not entirely consistent. Therefore, based on the elucidation of this phenotype, in this study, we analyzed the effect of exercise on mitochondrial dysfunction in COPD skeletal muscle and the regulatory mechanism thereof. We also provided a theoretical basis for exercise programs to rehabilitate this condition.

NMR Spectroscopy Identifies Chemicals in Cigarette Smoke Condensate That Impair Skeletal Muscle Mitochondrial Function

Tobacco smoke-related diseases such as chronic obstructive pulmonary disease (COPD) are associated with high healthcare burden and mortality rates. Many COPD patients were reported to have muscle atrophy and weakness, with several studies suggesting intrinsic muscle mitochondrial impairment as a possible driver of this phenotype. Whereas much information has been learned about muscle pathology once a patient has COPD, little is known about how active tobacco smoking might impact skeletal muscle physiology or mitochondrial health. In this study, we examined the acute effects of cigarette smoke condensate (CSC) on muscle mitochondrial function and hypothesized that toxic chemicals present in CSC would impair mitochondrial respiratory function. Consistent with this hypothesis, we found that acute exposure of muscle mitochondria to CSC caused a dose-dependent decrease in skeletal muscle mitochondrial respiratory capacity. Next, we applied an analytical nuclear magnetic resonance (NMR)-based approach to identify 49 water-soluble and 12 lipid-soluble chemicals with high abundance in CSC. By using a chemical screening approach in the Seahorse XF96 analyzer, several CSC-chemicals, including nicotine, o-Cresol, phenylacetate, and decanoic acid, were found to impair ADP-stimulated respiration in murine muscle mitochondrial isolates significantly. Further to this, several chemicals, including nicotine, o-Cresol, quinoline, propylene glycol, myo-inositol, nitrosodimethylamine, niacinamide, decanoic acid, acrylonitrile, 2-naphthylamine, and arsenic acid, were found to significantly decrease the acceptor control ratio, an index of mitochondrial coupling efficiency.

Carnitine palmitoyltransferase 1 (CPT1) alleviates oxidative stress and apoptosis of hippocampal neuron in response to beta-Amyloid peptide fragment Aβ25-35

CPT1C, which is expressed in hippocampus, influences ceramide level, endogenous cannabinoid and oxidation process, as well as plays an important role in various brain functions such as learning. This study aimed to investigate the role of CPT1C in Alzheimer's disease (AD) and its underlying mechanism. We established a model of Alzheimer's disease in vitro by exposing primary hippocampal neurons to beta-Amyloid peptide fragment 25-35 (Aβ25-35). The cell viability, lactate dehydrogenase (LDH) level, expressions of reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) were detected using Cell Counting Kit-8 (CCK-8), LDH assay, ROS kits, malondialdehyde (MDA) kits and SOD kits, respectively. Moreover, the expression of oxidative stress-related proteins as well as the expressions of amyloid precursor protein (App), p-Tau andβ-site APP-cleaving enzyme1 (Bace-1) were measured using quantitative reverse transcription PCR (RT-qPCR) and western blot. Tunel and western blot were adopted to detect apoptosis as well as its related proteins. After the treatment of peroxisome proliferators-activated receptor alpha (PPARα), CPT1C expression was detected with the application of RT-qPCR and western blot. CPT1C expression was reduced in Aβ25-35-induced HT22 cells. Overexpression of CPT1C relieved cell viability and toxic injury as well as attenuated oxidative stress, apoptosis and expression levels of AD marker proteins. Moreover, higher doses of PPARα agonist activate the expression of CPT1C in Aβ25-35-induced HT22 cells. In conclusion, CPT1C alleviates Aβ25-35-induced oxidative stress, apoptosis and deposition of AD marker proteins in hippocampal neurons, suggesting that CPT1C has favorable effects on alleviating AD and participates in PPARα activation.

Growth retardation-responsive analysis of mRNAs and long noncoding RNAs in the liver tissue of Leiqiong cattle

As an important type of non-coding RNA molecule, long non-coding RNAs (lncRNAs) have varied roles in many biological processes, and have been studied extensively over the past few years. However, little is known about lncRNA-mediated regulation during cattle growth and development. Therefore, in the present study, RNA sequencing was used to determine the expression level of mRNAs and lncRNAs in the liver of adult Leiqiong cattle under the condition of growth retardation and normal growth. We totally detected 1,124 and 24 differentially expressed mRNAs and lncRNAs, respectively. The differentially expressed mRNAs were mainly associated with growth factor binding, protein K63-linked ubiquitination and cellular protein metabolic process; additionally, they were significantly enriched in the growth and development related pathways, including PPAR signaling pathway, vitamin B6 metabolism, glyoxylate and dicarboxylate metabolism. Combined analysis showed that the co-located differentially expressed lncRNA Lnc_002583 might positively influence the expression of the corresponding genes IFI44 and IFI44L, exerting co-regulative effects on Leiqiong cattle growth and development. Thus, we made the hypothesis that Lnc_002583, IFI44 and IFI44L might function synergistically to regulate the growth of Leiqiong cattle. This study provides a catalog of Leiqiong cattle liver mRNAs and lncRNAs, and will contribute to a better understanding of the molecular mechanism underlying growth regulataion.