RESUMO
Alzheimer's disease and other neurodegenerative disorders of aging are characterized by clinical and pathological features that are relatively specific to humans. To obtain greater insight into how brain aging has evolved, we compared age-related gene expression changes in the cortex of humans, rhesus macaques, and mice on a genome-wide scale. A small subset of gene expression changes are conserved in all three species, including robust age-dependent upregulation of the neuroprotective gene apolipoprotein D (APOD) and downregulation of the synaptic cAMP signaling gene calcium/calmodulin-dependent protein kinase IV (CAMK4). However, analysis of gene ontology and cell type localization shows that humans and rhesus macaques have diverged from mice due to a dramatic increase in age-dependent repression of neuronal genes. Many of these age-regulated neuronal genes are associated with synaptic function. Notably, genes associated with GABA-ergic inhibitory function are robustly age-downregulated in humans but not in mice at the level of both mRNA and protein. Gene downregulation was not associated with overall neuronal or synaptic loss. Thus, repression of neuronal gene expression is a prominent and recently evolved feature of brain aging in humans and rhesus macaques that may alter neural networks and contribute to age-related cognitive changes.
Assuntos
Envelhecimento/genética , Encéfalo/metabolismo , Evolução Molecular , RNA Mensageiro/genética , Sinapses/fisiologia , Adulto , Idoso , Animais , Western Blotting , Humanos , Camundongos , Filogenia , Especificidade da Espécie , Transmissão Sináptica/genéticaRESUMO
Alternative pre-messenger RNA (pre-mRNA) splicing plays important roles in development, physiology, and disease, and more than half of human genes are alternatively spliced. To understand the biological roles and regulation of alternative splicing across different tissues and stages of development, systematic methods are needed. Here, we demonstrate the use of microarrays to monitor splicing at every exon-exon junction in more than 10,000 multi-exon human genes in 52 tissues and cell lines. These genome-wide data provide experimental evidence and tissue distributions for thousands of known and novel alternative splicing events. Adding to previous studies, the results indicate that at least 74% of human multi-exon genes are alternatively spliced.
Assuntos
Processamento Alternativo , Éxons , Genoma Humano , Análise de Sequência com Séries de Oligonucleotídeos , Monoéster Fosfórico Hidrolases , Precursores de RNA/genética , Precursor de Proteína beta-Amiloide/análise , Precursor de Proteína beta-Amiloide/genética , Linhagem Celular , DNA Complementar , Etiquetas de Sequências Expressas , Humanos , Hidroximetilglutaril-CoA Redutases/análise , Hidroximetilglutaril-CoA Redutases/genética , Dados de Sequência Molecular , Isoformas de Proteínas/análise , Proteínas/análise , Proteínas/genética , Curva ROC , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Distribuição TecidualRESUMO
Microarrays offer a high-resolution means for monitoring pre-mRNA splicing on a genomic scale. We have developed a novel, unbiased amplification protocol that permits labeling of entire transcripts. Also, hybridization conditions, probe characteristics, and analysis algorithms were optimized for detection of exons, exon-intron edges, and exon junctions. These optimized protocols can be used to detect small variations and isoform mixtures, map the tissue specificity of known human alternative isoforms, and provide a robust, scalable platform for high-throughput discovery of alternative splicing.
