A single mutation in the ACTR8 gene associated with lineage-specific expression in primates

Relevance of the regulation of the brain-placental axis to the nocturnal bottleneck of mammals

INTRODUCTION

Evolutionary theory suggests that the ancestors of all placental animals were nocturnal. Visual perceptive function of mammalian brain has evolved extensively, but nearly 70 % of today's mammals are still nocturnal. While placental influence on brain development is known, if placenta plays a role in the visual perceptive function of mammalian brain remains untested. The present study aims to test this hypothesis.

METHODS

In this study, single-nuclei RNA sequencing was performed to identify genes expressed in the pig placenta and fetal brain, and then compared with the orthologous genes expressed in the placenta and fetal brain cells of mouse. Differential gene expression analysis was performed to identify placental genes regulated differentially between nocturnal and diurnal animals. Phylogenetic modeling was performed to test correlated evolution between placenta type, and the nocturnal or diurnal activity among different mammals.

RESULTS

The results showed that genes differentially regulated in the fetal brain were related to visual perception whereas the placental genes were related to the nocturnal or diurnal activity in placental animals. Phylogenetic modeling of these genes in thirty-four diverse mammalian species showed evidence for evolutionary link between placenta and the nocturnal/diurnal activity in animals.

DISCUSSION

The findings of this study suggest that the placenta plays a role in the evolution of visual perceptive function of brain to shape the nocturnal or diurnal activity of placental animals.

Exploration of the Noncoding Genome for Human-Specific Therapeutic Targets-Recent Insights at Molecular and Cellular Level

While it is well known that 98-99% of the human genome does not encode proteins, but are nevertheless transcriptionally active and give rise to a broad spectrum of noncoding RNAs [ncRNAs] with complex regulatory and structural functions, specific functions have so far been assigned to only a tiny fraction of all known transcripts. On the other hand, the striking observation of an overwhelmingly growing fraction of ncRNAs, in contrast to an only modest increase in the number of protein-coding genes, during evolution from simple organisms to humans, strongly suggests critical but so far essentially unexplored roles of the noncoding genome for human health and disease pathogenesis. Research into the vast realm of the noncoding genome during the past decades thus lead to a profoundly enhanced appreciation of the multi-level complexity of the human genome. Here, we address a few of the many huge remaining knowledge gaps and consider some newly emerging questions and concepts of research. We attempt to provide an up-to-date assessment of recent insights obtained by molecular and cell biological methods, and by the application of systems biology approaches. Specifically, we discuss current data regarding two topics of high current interest: (1) By which mechanisms could evolutionary recent ncRNAs with critical regulatory functions in a broad spectrum of cell types (neural, immune, cardiovascular) constitute novel therapeutic targets in human diseases? (2) Since noncoding genome evolution is causally linked to brain evolution, and given the profound interactions between brain and immune system, could human-specific brain-expressed ncRNAs play a direct or indirect (immune-mediated) role in human diseases? Synergistic with remarkable recent progress regarding delivery, efficacy, and safety of nucleic acid-based therapies, the ongoing large-scale exploration of the noncoding genome for human-specific therapeutic targets is encouraging to proceed with the development and clinical evaluation of novel therapeutic pathways suggested by these research fields.

Identification and functional analysis of miRNAs in skeletal muscle of juvenile and adult largemouth bass, Micropterus salmoides

MicroRNAs (miRNAs) are considered key regulators to post-transcriptionally regulate gene expression affecting multiple biological activities. However, the developmental process of fish skeletal muscles is regulated by complicated molecular mechanism that has not been completely well-described. In this study, two small RNAs libraries from skeletal muscle of juvenile as well as adult largemouth bass (LMB) were obtained and sequenced using deep sequencing to investigate the development-related miRNAs. We identified an overall number of 486 already recognized miRNAs in addition to 43 novel miRNAs. Comparison of two different skeletal muscle development stages led to the identification of 220 differently expressed miRNAs between juvenile and adult LMB containing 116 up-regulated as well as 104 down-regulated miRNAs. Of them, confirmation of some differently expressed miRNAs was performed via a stem-loop qRT-PCR, which exhibited differently expressed level in juvenile and adult LMB. Furthermore, GO and KEGG enrichment analyses of targets of differently-expressed miRNAs were carried out. Additionally, the analysis of miRNAs-targets interaction network showed that miR-181b-5p_R-1, miR-725 and miR-103 as the nodal miRNAs has over 20 target genes. Moreover, miR-103 could bind the 3'-UTR of actr8, which was validated via dual-luciferase reporter assay. It has been reasonably hypothesized that miR-103 may play a crucial role, which regulate skeletal muscle development of LMB. The present study provides the first identification of miRNA expression profiles at two different skeletal muscle development stages in LMB. Results may be valuable in interpreting the regulatory role miRNAs plays in the growth and developmental process of skeletal muscle and its possible use in LMB breeding.

Genome-wide DNA methylation and gene expression patterns of androgenetic haploid tiger pufferfish (Takifugu rubripes) provide insights into haploid syndrome

Androgenesis is an important chromosome set manipulation technique used in sex control in aquaculture. Haploid embryos exhibit haploid syndrome with body abnormalities and even die during early embryonic development. In this study, we used whole genome bisulfite sequencing (WGBS) to investigate the genome-wide DNA methylation profiles in haploid females (1n-X) and males (1n-Y), and diploid females (2n-XX) and males (2n-XY) of tiger pufferfish (Takifugu rubripes), an economically important fish in China. A total of 96.32 Gb clean data was produced. Differentially methylated regions (DMRs) were found between haploids and diploids, which may be related to abnormal development and early embryonic death in haploids. There were 3,641 hyper-methylated differentially methylated genes (DMGs) and 2,179 hypo-methylated DMGs in haploid vs. diploid comparisons in both females and males. These DMGs were mainly related to genomic stability maintenance and cell cycle regulation. slf1, actr8, gas2, and pbrm1 genes were selected to validate the methylation sequencing. After combining the methylation data with the corresponding transcriptome data, we identified several genes, including guca2a, myoc, fezf2, rprml, telo2, s100a1, and marveld1, which exhibited differential expression levels modulated by DNA methylation. In conclusion, our study revealed different methylation and expression profiles between haploid and diploid T. rubripes for the first time. Several DMGs were identified between different ploidy levels, which may be related to haploid syndrome formation. The results expand the understanding of the effects of ploidy on the early development of teleosts and provide knowledge about target genes and networks to improve the survival rate of haploids.

The identification of novel gene mutations for degenerative lumbar spinal stenosis using whole-exome sequencing in a Chinese cohort

BACKGROUND

Degenerative lumbar spinal stenosis (DLSS) is a common lumbar disease that requires surgery. Previous studies have indicated that genetic mutations are implicated in DLSS. However, studies on specific gene mutations are scarce. Whole-exome sequencing (WES) is a valuable research tool that identifies disease-causing genes and could become an effective strategy to investigate DLSS pathogenesis.

METHODS

From January 2016 to December 2017, we recruited 50 unrelated patients with symptoms consistent with DLSS and 25 unrelated healthy controls. We conducted WES and exome data analysis to identify susceptible genes. Allele mutations firstly identified potential DLSS variants in controls to the patients' group. We conducted a site-based association analysis to identify pathogenic variants using PolyPhen2, SIFT, Mutation Taster, Combined Annotation Dependent Depletion, and Phenolyzer algorithms. Potential variants were further confirmed using manual curation and validated using Sanger sequencing.

RESULTS

In this cohort, the major classification variant was missense_mutation, the major variant type was single nucleotide polymorphism (SNP), and the major single nucleotide variation was C > T. Multiple SNPs in 34 genes were identified when filtered allele mutations in controls to retain only patient mutations. Pathway enrichment analyses revealed that mutated genes were mainly enriched for immune response-related signaling pathways. Using the Novegene database, site-based associations revealed several novel variants, including HLA-DRB1, PARK2, ACTR8, AOAH, BCORL1, MKRN2, NRG4, NUP205 genes, etc., were DLSS related.

CONCLUSIONS

Our study revealed that deleterious mutations in several genes might contribute to DLSS etiology. By screening and confirming susceptibility genes using WES, we provided more information on disease pathogenesis. Further WES studies incorporating larger DLSS patient cohorts are required to comprehend the genetic landscape of DLSS pathophysiology fully.