RESUMEN
Differences in DNA repair capacity have been hypothesized to underlie the great range of maximum lifespans among mammals. However, measurements of individual DNA repair activities in cells and animals have not substantiated such a relationship because utilization of repair pathways among animals--depending on habitats, anatomical characteristics, and life styles--varies greatly between mammalian species. Recent advances in high-throughput genomics, in combination with increased knowledge of the genetic pathways involved in genome maintenance, now enable a comprehensive comparison of DNA repair transcriptomes in animal species with extreme lifespan differences. Here we compare transcriptomes of liver, an organ with high oxidative metabolism and abundant spontaneous DNA damage, from humans, naked mole rats, and mice, with maximum lifespans of ~120, 30, and 3 years, respectively, with a focus on genes involved in DNA repair. The results show that the longer-lived species, human and naked mole rat, share higher expression of DNA repair genes, including core genes in several DNA repair pathways. A more systematic approach of signaling pathway analysis indicates statistically significant upregulation of several DNA repair signaling pathways in human and naked mole rat compared with mouse. The results of this present work indicate, for the first time, that DNA repair is upregulated in a major metabolic organ in long-lived humans and naked mole rats compared with short-lived mice. These results strongly suggest that DNA repair can be considered a genuine longevity assurance system.
Asunto(s)
Reparación del ADN/fisiología , Longevidad/genética , Longevidad/fisiología , Animales , Regulación de la Expresión Génica/fisiología , Humanos , Ratones , Ratas , Especificidad de la Especie , TranscriptomaRESUMEN
Affymetrix Human Gene 1.0-ST arrays were used to assess the gene expression profiles of kidney transplant patients who presented with donor-specific antibodies (DSAs) but showed normal biopsy histopathology and did not develop antibody-mediated rejection (AMR). Biopsy and whole-blood profiles for these DSA-positive, AMR-negative (DSA +/AMR-) patients were compared to both DSA-positive, AMR-positive (DSA +/AMR +) patients as well as DSA-negative (DSA -) controls. While individual gene expression changes across sample groups were relatively subtle, gene-set enrichment analysis using previously identified pathogenesis-based transcripts (PBTs) identified a clear molecular signature involving increased rejection-associated transcripts in AMR - patients. Results from this study have been published in Kidney International (Hayde et al., 2014 [1]) and the associated data have been deposited in the GEO archive and are accessible via the following link: http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE50084.
RESUMEN
Pantothenate kinase (PanK) is the key regulatory enzyme in the CoA biosynthetic pathway in bacteria and is thought to play a similar role in mammalian cells. We examined this hypothesis by identifying and characterizing two murine cDNAs that encoded PanK. The two cDNAs were predicted to arise from alternate splicing of the same gene to yield different mRNAs that encode two isoforms (mPanK1alpha and mPanK1beta) with distinct amino termini. The predicted protein sequence of mPanK1 was not related to bacterial PanK but exhibited significant similarity to Aspergillus nidulans PanK. mPanK1alpha was most highly expressed in heart and kidney, whereas mPanK1beta mRNA was detected primarily in liver and kidney. Pantothenate was the most abundant pathway component (42.8%) in normal cells providing clear evidence that pantothenate phosphorylation was a rate-controlling step in CoA biosynthesis. Enhanced mPanK1beta expression eliminated the intracellular pantothenate pool and triggered a 13-fold increase in intracellular CoA content. mPanK1beta activity in vitro was stimulated by CoA and strongly inhibited by acetyl-CoA illustrating that differential modulation of mPanK1beta activity by pathway end products also contributed to the management of CoA levels. These data support the concept that the expression and/or activity of PanK is a determining factor in the physiological regulation of the intracellular CoA concentration.
Asunto(s)
Coenzima A/metabolismo , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Empalme Alternativo , Secuencia de Aminoácidos , Animales , Aspergillus nidulans/enzimología , Aspergillus nidulans/genética , Clonación Molecular , Etiquetas de Secuencia Expresada , Homeostasis , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Cinética , Masculino , Ratones , Modelos Químicos , Datos de Secuencia Molecular , Fosfotransferasas (Aceptor de Grupo Alcohol)/química , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/enzimología , Saccharomyces cerevisiae/genética , Alineación de Secuencia , Homología de Secuencia de AminoácidoRESUMEN
Pantothenate kinase (PanK) is the key regulatory enzyme in the CoA biosynthetic pathway. The PanK gene from Escherichia coli (coaA) has been previously cloned and the enzyme biochemically characterized; highly related genes exist in other prokaryotes. We isolated a PanK cDNA clone from the eukaryotic fungus Aspergillus nidulans by functional complementation of a temperature-sensitive E. coli PanK mutant. The cDNA clone allowed the isolation of the genomic clone and the characterization of the A. nidulans gene designated panK. The panK gene is located on chromosome 3 (linkage group III), is interrupted by three small introns, and is expressed constitutively. The amino acid sequence of A. nidulans PanK (aPanK) predicted a subunit size of 46.9 kDa and bore little resemblance to its bacterial counterpart, whereas a highly related protein was detected in the genome of Saccharomyces cerevisiae. In contrast to E. coli PanK (bPanK), which is regulated by CoA and to a lesser extent by its thioesters, aPanK activity was selectively and potently inhibited by acetyl-CoA. Acetyl-CoA inhibition of aPanK was competitive with respect to ATP. Thus, the eukaryotic PanK has a distinct primary structure and unique regulatory properties that clearly distinguish it from its prokaryotic counterpart.