Gene duplication and alternative splicing play a role in modulating the functions of the ZNF286A transcription factor

Neurogenesis, and the processes through which neural stem cells and progenitor cells differentiate into neurons, occurs most actively during embryonic development, although neural differentiation continues at lower levels in certain brain regions well into adulthood. A vast regulatory network involving many known and conserved transcription factors regulates these functions. We have identified a novel zinc finger transcription factor (TF), ZNF286A, which is conserved in all eutherians and marsupials and provide evidence that this novel TF plays a role in regulation of mammalian neurogenesis. ZNF286 occurs as a unique gene in most species. However, we demonstrate evidence that a gene duplication event in very recent primate history created a human-specific duplicate of ZNF286A, called ZNF286B. ZNF286B arose as part of a larger duplication in human chromosome 17, approximately 600,000 kb in length, that also includes many surrounding genes. Concomitant with (or shortly after) duplication, a processed and incomplete FOXO3B pseudo-gene was inserted into the ZNF286B genomic sequence and a DNA segment, encompassing a coding exon and regulatory sequences present in the ancestral ZNF286A gene, was deleted. As a result, ZNF286B encodes a protein with significant structural and expression differences relative to the ancestral gene. Most strikingly, the exon deleted in ZNF286B codes for the chromatin-interacting KRAB-domains that are present in the ZNF286A gene; in this respect the new human paralog resembles a natural KRAB-less alternative isoform that we demonstrate to be expressed naturally from the parental ZNF286A gene. Using ChIP and siRNA knockdown, we show that ZNF286A protein binds to DNA at or near genes involved in the networks controlling the differentiation of neurons and the formation of axons during neurogenesis, and that both ZNF286A and ZNF286B directly regulate expression of many of those same genes. The pattern of DNA binding closely parallels binding of well-known neuronal differentiation factor, REST, in the same cell lines; siRNA results suggest that ZNF286 proteins act antagonistically to REST during development. We show that the mouse gene, Zfp286, is expressed at high levels in the developing nervous system and that both mouse and human genes and proteins are up-regulated transiently over the course of neurogenic differentiation in vitro, consistent with the predicted biological role. We hypothesize that the duplication event that gave rise to ZNF286B allowed for independent regulation of the KRAB-less isoform of the ZNF286 protein, permitting this ancient mammalian gene to take on novel functions in the adult human brain

Transcriptional regulatory dynamics drive coordinated metabolic and neural response to social challenge in mice

Agonistic encounters are powerful effectors of future behavior, and the ability to learn from this type of social challenge is an essential adaptive trait. We recently identified a conserved transcriptional program defining the response to social challenge across animal species, highly enriched in transcription factor (TF), energy metabolism, and developmental signaling genes. To understand the trajectory of this program and to uncover the most important regulatory influences controlling this response, we integrated gene expression data with the chromatin landscape in the hypothalamus, frontal cortex, and amygdala of socially challenged mice over time. The expression data revealed a complex spatiotemporal patterning of events starting with neural signaling molecules in the frontal cortex and ending in the modulation of developmental factors in the amygdala and hypothalamus, underpinned by a systems-wide shift in expression of energy metabolism-related genes. The transcriptional signals were correlated with significant shifts in chromatin accessibility and a network of challenge-associated TFs. Among these, the conserved metabolic and developmental regulator ESRRA was highlighted for an especially early and important regulatory role. Cell-type deconvolution analysis attributed the differential metabolic and developmental signals in this social context primarily to oligodendrocytes and neurons, respectively, and we show that ESRRA is expressed in both cell types. Localizing ESRRA binding sites in cortical chromatin, we show that this nuclear receptor binds both differentially expressed energy-related and neurodevelopmental TF genes. These data link metabolic and neurodevelopmental signali ng to social challenge, and identify key regulatory drivers of this process with unprecedented tissue and temporal resolution

Gain, Loss and Divergence in Primate Zinc-Finger Genes: A Rich Resource for Evolution of Gene Regulatory Differences between Species

The molecular changes underlying major phenotypic differences between humans and other primates are not well understood, but alterations in gene regulation are likely to play a major role. Here we performed a thorough evolutionary analysis of the largest family of primate transcription factors, the Krüppel-type zinc finger (KZNF) gene family. We identified and curated gene and pseudogene models for KZNFs in three primate species, chimpanzee, orangutan and rhesus macaque, to allow for a comparison with the curated set of human KZNFs. We show that the recent evolutionary history of primate KZNFs has been complex, including many lineage-specific duplications and deletions. We found 213 species-specific KZNFs, among them 7 human-specific and 23 chimpanzee-specific genes. Two human-specific genes were validated experimentally. Ten genes have been lost in humans and 13 in chimpanzees, either through deletion or pseudogenization. We also identified 30 KZNF orthologs with human-specific and 42 with chimpanzee-specific sequence changes that are predicted to affect DNA binding properties of the proteins. Eleven of these genes show signatures of accelerated evolution, suggesting positive selection between humans and chimpanzees. During primate evolution the most extensive re-shaping of the KZNF repertoire, including most gene additions, pseudogenizations, and structural changes occurred within the subfamily homininae. Using zinc finger (ZNF) binding predictions, we suggest potential impact these changes have had on human gene regulatory networks. The large species differences in this family of TFs stands in stark contrast to the overall high conservation of primate genomes and potentially represents a potent driver of primate evolution

Origins and evolution of modern biochemistry: insights from genomes and molecular structure.

The survey of components in living systems at different levels of organization enables an evolutionary exploration of patterns and processes in macromolecules, networks, and genomic repertoires. Here we discuss how phylogenetic strategies that generate intrinsically rooted phylogenies impact the evolutionary study of RNA and protein components of the macromolecular machinery that is responsible for biological function. We used these methods to generate timelines of discovery of components in systems, such as substructures in RNA molecules, architectures in proteomes, domains in multi-domain proteins, enzymes in metabolic networks, and protein architectures in proteomes. These timelines unfolded remarkable patterns of origin and evolution of molecules, repertoires and networks, showing episodes of both functional specialization (e.g., rise of domains with specialized functions) and molecular simplification (e.g., reductive tendencies in molecules and proteomes). These observations have important evolutionary implications for origins of translation, the genetic code, modules in the protein world, and diversification of life, and suggest early evolution of modern biochemistry was driven by recruitment of both RNA and protein catalysts in an ancient community of complex organisms.published or submitted for publicationis peer reviewe