ABSTRACT
Leigh syndrome (LS) associated with cytochrome c oxidase (COX) deficiency is an early onset, fatal mitochondrial encephalopathy, leading to multiple neurological failure and eventually death, usually in the first decade of life. Mutations in SURF1, a nuclear gene encoding a mitochondrial protein involved in COX assembly, are among the most common causes of LS. LSSURF1 patients display severe, isolated COX deficiency in all tissues, including cultured fibroblasts and skeletal muscle. Recombinant, constitutive SURF1-/- mice show diffuse COX deficiency, but fail to recapitulate the severity of the human clinical phenotype. Pigs are an attractive alternative model for human diseases, because of their size, as well as metabolic, physiological and genetic similarity to humans. Here, we determined the complete sequence of the swine SURF1 gene, disrupted it in pig primary fibroblast cell lines using both TALENs and CRISPR/Cas9 genome editing systems, before finally generating SURF1-/- and SURF1-/+ pigs by Somatic Cell Nuclear Transfer (SCNT). SURF1-/- pigs were characterized by failure to thrive, muscle weakness and highly reduced life span with elevated perinatal mortality, compared to heterozygous SURF1-/+ and wild type littermates. Surprisingly, no obvious COX deficiency was detected in SURF1-/- tissues, although histochemical analysis revealed the presence of COX deficiency in jejunum villi and total mRNA sequencing (RNAseq) showed that several COX subunit-encoding genes were significantly down-regulated in SURF1-/- skeletal muscles. In addition, neuropathological findings, indicated a delay in central nervous system development of newborn SURF1-/- piglets. Our results suggest a broader role of sSURF1 in mitochondrial bioenergetics.
Subject(s)
Central Nervous System/growth & development , Disease Models, Animal , Leigh Disease/genetics , Membrane Proteins/genetics , Mitochondrial Proteins/genetics , Sus scrofa/genetics , Animals , Animals, Genetically Modified , Animals, Newborn , Behavior, Animal , CRISPR-Cas Systems , Cells, Cultured , Down-Regulation , Electron Transport Complex IV/metabolism , Female , Fibroblasts , Gene Editing , Gene Knockout Techniques , Humans , Jejunum/pathology , Leigh Disease/pathology , Male , Mitochondria/pathology , Muscle, Skeletal/cytology , Muscle, Skeletal/pathology , Nuclear Transfer Techniques , Primary Cell CultureABSTRACT
Unlike non mammalian vertebrates, adult neurogenesis in mammals is detectable in highly restricted brain sites. Persistent neurogenesis is thought to depend on stem cells residing in neural stem cell niches which are remnants of the embryonic germinal layers. Local progenitors which retain some proliferative capacity have been identified in the mature brain parenchyma, yet they do not support a constitutive, 'actual' neurogenesis, but rather a 'potential' neurogenesis which does not extrinsecate fully and spontaneously in vivo. In contrast with such a view, genesis of neuronal and glial cells from local progenitors does occur in the peripuberal and adult rabbit cerebellum. This process is independent from persisting germinal layers and involves different cell populations.
