A tissue‐specific screen of ceramide expression in aged mice identifies ceramide synthase‐1 and ceramide synthase‐5 as potential regulators of fiber size and strength in skeletal muscle

Abstract

Loss of skeletal muscle mass is one of the most widespread and deleterious processes in aging humans. However, the mechanistic metabolic principles remain poorly understood. In the framework of a multi‐organ investigation of age‐associated changes of ceramide species, a unique and distinctive change pattern of C16:0 and C18:0 ceramide species was detected in aged skeletal muscle. Consistently, the expression of CerS1 and CerS5 mRNA, encoding the ceramide synthases (CerS) with substrate preference for C16:0 and C18:0 acyl chains, respectively, was down‐regulated in skeletal muscle of aged mice. Similarly, an age‐dependent decline of both CerS1 and CerS5 mRNA expression was observed in skeletal muscle biopsies of humans. Moreover, CerS1 and CerS5 mRNA expression was also reduced in muscle biopsies from patients in advanced stage of chronic heart failure (CHF) suffering from muscle wasting and frailty. The possible impact of CerS1 and CerS5 on muscle function was addressed by reversed genetic analysis using CerS1Δ/Δ and CerS5Δ/Δ knockout mice. Skeletal muscle from mice deficient of either CerS1 or CerS5 showed reduced caliber sizes of both slow (type 1) and fast (type 2) muscle fibers, fiber grouping, and fiber switch to type 1 fibers. Moreover, CerS1‐ and CerS5‐deficient mice exhibited reduced twitch and tetanus forces of musculus extensor digitorum longus. The findings of this study link CerS1 and CerS5 to histopathological changes and functional impairment of skeletal muscle in mice that might also play a functional role for the aging skeletal muscle and for age‐related muscle wasting disorders in humans.

Mitochondrial respiration controls neoangiogenesis during wound healing and tumour growth

“…Samples were measured in technical triplicates in a 96-well plate Multicolour real-time PCR Detection System (IQ TM 5, Bio-Rad) using LightCycler®SYBR-Green I Mix (Roche). Data analysis was done based on linear regression of the logarithmic fluorescence values/cycle with the programme LinRegPCR 55 , 56 and target gene expression was normalised to the reference gene Actin . Primers used:…”

“…linear regression of the logarithmic fluorescence values/cycle with the programme LinRegPCR 55,56 and target gene expression was normalised to the reference gene Actin. Primers used:…”

Ceramide Synthase 5 Deficiency Aggravates Dextran Sodium Sulfate-Induced Colitis and Colon Carcinogenesis and Impairs T-Cell Activation

“…To analyze the role of CerS5 in inflammation and colon cancer development, we used CerS5 knockout (ko) mice and CerS5 fl/fl mice (obtained from Prof. Martin Krönke and Prof. Jens Brüning (Institute for Medical Microbiology, Immunology and Hygiene (IMMIH); University of Cologne, Cologne, Germany)) crossed with B6.Cg-Tg(Vil-cre) mice (The Jackson Laboratory (by Charles River, Sulzfeld, Germany)) in the dextran sodium sulfate (DSS)-induced acute colitis and the azoxymethane (AOM)/DSS colitis-associated colon cancer (CAC) model. The generation of CerS5-ko mice is based on the deletion of exon 4 of the CerS5 gene by the insertion of exon 4 flanking loxP sites and crossing these mice with Cre-deleter mice, as described in [ 35 ]. The deletion of exon 4 results in a frameshift in downstream exons that prevents the translation of the catalytic LAG1 domain [ 35 ].…”

“…The generation of CerS5-ko mice is based on the deletion of exon 4 of the CerS5 gene by the insertion of exon 4 flanking loxP sites and crossing these mice with Cre-deleter mice, as described in [ 35 ]. The deletion of exon 4 results in a frameshift in downstream exons that prevents the translation of the catalytic LAG1 domain [ 35 ]. Mice with a specific deletion of CerS5 in villus and crypt epithelial cells of the small and large intestine were generated by interbreeding CerS5fl/fl mice with mice expressing the Cre-recombinase under the control of the villin 1-promoter (Vil1Cre).…”

Mitochondrial Homeostasis Mediates Lipotoxicity in the Failing Myocardium

“…Despite the origin of proinflammatory ceramides differing, the outcomes are the same. The lipotoxicity-associated damages in mitochondrial structure and function result in apoptosis and autophagy [ 122 , 123 , 124 ].…”