scholarly journals The genetic basis of evolutionary change in gene expression levels

2010 ◽  
Vol 365 (1552) ◽  
pp. 2581-2590 ◽  
Author(s):  
J. J. Emerson ◽  
Wen-Hsiung Li

The regulation of gene expression is an important determinant of organismal phenotype and evolution. However, the widespread recognition of this fact occurred long after the synthesis of evolution and genetics. Here, we give a brief sketch of thoughts regarding gene regulation in the history of evolution and genetics. We then review the development of genome-wide studies of gene regulatory variation in the context of the location and mode of action of the causative genetic changes. In particular, we review mapping of the genetic basis of expression variation through expression quantitative trait locus studies and measuring the cis / trans component of expression variation in allele-specific expression studies. We conclude by proposing a systematic integration of ideas that combines global mapping studies, cis / trans tests and modern population genetics methodologies, in order to directly estimate the forces acting on regulatory variation within and between species.

2016 ◽  
Author(s):  
François Aguet ◽  
Andrew A. Brown ◽  
Stephane E. Castel ◽  
Joe R. Davis ◽  
Pejman Mohammadi ◽  
...  

AbstractExpression quantitative trait locus (eQTL) mapping provides a powerful means to identify functional variants influencing gene expression and disease pathogenesis. We report the identification of cis-eQTLs from 7,051 post-mortem samples representing 44 tissues and 449 individuals as part of the Genotype-Tissue Expression (GTEx) project. We find a cis-eQTL for 88% of all annotated protein-coding genes, with one-third having multiple independent effects. We identify numerous tissue-specific cis-eQTLs, highlighting the unique functional impact of regulatory variation in diverse tissues. By integrating large-scale functional genomics data and state-of-the-art fine-mapping algorithms, we identify multiple features predictive of tissue-specific and shared regulatory effects. We improve estimates of cis-eQTL sharing and effect sizes using allele specific expression across tissues. Finally, we demonstrate the utility of this large compendium of cis-eQTLs for understanding the tissue-specific etiology of complex traits, including coronary artery disease. The GTEx project provides an exceptional resource that has improved our understanding of gene regulation across tissues and the role of regulatory variation in human genetic diseases.


2018 ◽  
Vol 115 (47) ◽  
pp. E11081-E11090 ◽  
Author(s):  
Ryan A. York ◽  
Chinar Patil ◽  
Kawther Abdilleh ◽  
Zachary V. Johnson ◽  
Matthew A. Conte ◽  
...  

Many behaviors are associated with heritable genetic variation [Kendler and Greenspan (2006) Am J Psychiatry 163:1683–1694]. Genetic mapping has revealed genomic regions or, in a few cases, specific genes explaining part of this variation [Bendesky and Bargmann (2011) Nat Rev Gen 12:809–820]. However, the genetic basis of behavioral evolution remains unclear. Here we investigate the evolution of an innate extended phenotype, bower building, among cichlid fishes of Lake Malawi. Males build bowers of two types, pits or castles, to attract females for mating. We performed comparative genome-wide analyses of 20 bower-building species and found that these phenotypes have evolved multiple times with thousands of genetic variants strongly associated with this behavior, suggesting a polygenic architecture. Remarkably, F1 hybrids of a pit-digging and a castle-building species perform sequential construction of first a pit and then a castle bower. Analysis of brain gene expression in these hybrids showed that genes near behavior-associated variants display behavior-dependent allele-specific expression with preferential expression of the pit-digging species allele during pit digging and of the castle-building species allele during castle building. These genes are highly enriched for functions related to neurodevelopment and neural plasticity. Our results suggest that natural behaviors are associated with complex genetic architectures that alter behavior via cis-regulatory differences whose effects on gene expression are specific to the behavior itself.


2020 ◽  
Author(s):  
Devanshi Patel ◽  
Xiaoling Zhang ◽  
John J. Farrell ◽  
Jaeyoon Chung ◽  
Thor D. Stein ◽  
...  

ABSTRACTBecause regulation of gene expression is heritable and context-dependent, we investigated AD-related gene expression patterns in cell-types in blood and brain. Cis-expression quantitative trait locus (eQTL) mapping was performed genome-wide in blood from 5,257 Framingham Heart Study (FHS) participants and in brain donated by 475 Religious Orders Study/Memory & Aging Project (ROSMAP) participants. The association of gene expression with genotypes for all cis SNPs within 1Mb of genes was evaluated using linear regression models for unrelated subjects and linear mixed models for related subjects. Cell type-specific eQTL (ct-eQTL) models included an interaction term for expression of “proxy” genes that discriminate particular cell type. Ct-eQTL analysis identified 11,649 and 2,533 additional significant gene-SNP eQTL pairs in brain and blood, respectively, that were not detected in generic eQTL analysis. Of note, 386 unique target eGenes of significant eQTLs shared between blood and brain were enriched in apoptosis and Wnt signaling pathways. Five of these shared genes are established AD loci. The potential importance and relevance to AD of significant results in myeloid cell-types is supported by the observation that a large portion of GWS ct-eQTLs map within 1Mb of established AD loci and 58% (23/40) of the most significant eGenes in these eQTLs have previously been implicated in AD. This study identified cell-type specific expression patterns for established and potentially novel AD genes, found additional evidence for the role of myeloid cells in AD risk, and discovered potential novel blood and brain AD biomarkers that highlight the importance of cell-type specific analysis.


2004 ◽  
Vol 383 (1) ◽  
Author(s):  
Chris P. F. REDFERN

Retinoic acid is a signalling molecule central to morphogenesis and musculoskeletal development. It can exist in several isomeric forms, of which all-trans- and 9-cis-retinoic acid are thought to be the most relevant as signalling molecules. Retinoic acid regulates gene expression via RARs (retinoic acid receptors) working as heterodimers with RXRs (retinoid X receptors). RXRs also heterodimerize with other nuclear receptors. In this issue of the Biochemical Journal, Harris et al. have shown that an enhancer responsible for chondrocyte-specific expression of the col11a2 gene is itself regulated by a retinoic-acid-dependent interaction with RXRβ bound to a downstream response element. Thus, RXRs bound to hormone-response elements can regulate gene expression indirectly via interactions with tissue-specific enhancers. This study raises interesting questions about the nature of the response element, the RXRβ partner and the ligands able to influence col11a2 expression, and will provide a model system with which to understand tissue and ligand specificity of retinoid responses.


Endocrinology ◽  
2008 ◽  
Vol 149 (9) ◽  
pp. 4346-4356 ◽  
Author(s):  
Masato Aoyama ◽  
Tsuyoshi Kawada ◽  
Manabu Fujie ◽  
Kohji Hotta ◽  
Tsubasa Sakai ◽  
...  

Tachykinins (TKs) and their receptors have been shown to be expressed in the mammalian ovary. However, the biological roles of ovarian TKs have yet to be verified. Ci-TK-I and Ci-TK-R, characterized from the protochordate (ascidian), Ciona intestinalis, are prototypes of vertebrate TKs and their receptors. In the present study, we show a novel biological function of TKs as an inducible factor for oocyte growth using C. intestinalis as a model organism. Immunostaining demonstrated the specific expression of Ci-TK-R in test cells residing in oocytes at the vitellogenic stage. DNA microarray and real-time PCR revealed that Ci-TK-I induced gene expression of several proteases, including cathepsin D, chymotrypsin, and carboxy-peptidase B1, in the ovary. The enzymatic activities of these proteases in the ovary were also shown to be enhanced by Ci-TK-I. Of particular significance is that the treatment of Ciona oocytes with Ci-TK-I resulted in progression of growth from the vitellogenic stage to the post-vitellogenic stage. The Ci-TK-I-induced oocyte growth was blocked by a TK antagonist or by protease inhibitors. These results led to the conclusion that Ci-TK-I enhances growth of the vitellogenic oocytes via up-regulation of gene expression and enzymatic activities of the proteases. This is the first clarification of the biological roles of TKs in the ovary and the underlying essential molecular mechanism. Furthermore, considering the phylogenetic position of ascidians as basal chordates, we suggest that the novel TK-regulated oocyte growth is an “evolutionary origin” of the tachykininergic functions in the ovary.


Cells ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2395
Author(s):  
Tobias Strunz ◽  
Martin Kellner ◽  
Christina Kiel ◽  
Bernhard H. F. Weber

Elucidating the role of genetic variation in the regulation of gene expression is key to understanding the pathobiology of complex diseases which, in consequence, is crucial in devising targeted treatment options. Expression quantitative trait locus (eQTL) analysis correlates a genetic variant with the strength of gene expression, thus defining thousands of regulated genes in a multitude of human cell types and tissues. Some eQTL may not act independently of each other but instead may be regulated in a coordinated fashion by seemingly independent genetic variants. To address this issue, we combined the approaches of eQTL analysis and colocalization studies. Gene expression was determined in datasets comprising 49 tissues from the Genotype-Tissue Expression (GTEx) project. From about 33,000 regulated genes, over 14,000 were found to be co-regulated in pairs and were assembled across all tissues to almost 15,000 unique clusters containing up to nine regulated genes affected by the same eQTL signal. The distance of co-regulated eGenes was, on average, 112 kilobase pairs. Of 713 genes known to express clinical symptoms upon haploinsufficiency, 231 (32.4%) are part of at least one of the identified clusters. This calls for caution should treatment approaches aim at an upregulation of a haploinsufficient gene. In conclusion, we present an unbiased approach to identifying co-regulated genes in and across multiple tissues. Knowledge of such common effects is crucial to appreciate implications on biological pathways involved, specifically when a treatment option targets a co-regulated disease gene.


eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Zoë A Hilbert ◽  
Dennis H Kim

Animal behavior is directed by the integration of sensory information from internal states and the environment. Neuroendocrine regulation of diverse behaviors of Caenorhabditis elegans is under the control of the DAF-7/TGF-β ligand that is secreted from sensory neurons. Here, we show that C. elegans males exhibit an altered, male-specific expression pattern of daf-7 in the ASJ sensory neuron pair with the onset of reproductive maturity, which functions to promote male-specific mate-searching behavior. Molecular genetic analysis of the switch-like regulation of daf-7 expression in the ASJ neuron pair reveals a hierarchy of regulation among multiple inputs—sex, age, nutritional status, and microbial environment—which function in the modulation of behavior. Our results suggest that regulation of gene expression in sensory neurons can function in the integration of a wide array of sensory information and facilitate decision-making behaviors in C. elegans.


2011 ◽  
Vol 278 (1722) ◽  
pp. 3161-3170 ◽  
Author(s):  
Pamela Wiener ◽  
Samantha Wilkinson

Genomic technologies for livestock and companion animal species have revolutionized the study of animal domestication, allowing an increasingly detailed description of the genetic changes accompanying domestication and breed development. This review describes important recent results derived from the application of population and quantitative genetic approaches to the study of genetic changes in the major domesticated species. These include findings of regions of the genome that show between-breed differentiation, evidence of selective sweeps within individual genomes and signatures of demographic events. Particular attention is focused on the study of the genetics of behavioural traits and the implications for domestication. Despite the operation of severe bottlenecks, high levels of inbreeding and intensive selection during the history of domestication, most domestic animal species are genetically diverse. Possible explanations for this phenomenon are discussed. The major insights from the surveyed studies are highlighted and directions for future study are suggested.


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