BackgroundPre-implantation embryos exhibit sexual dimorphisms in both primates and rodents. To determine whether these differences reflected sex-biased expression patterns, we generated transcriptome profiles for six 40,XX, six 40,XY, and two 39,X mouse embryonic stem (ES) cells by RNA sequencing.ResultsWe found hundreds of coding and non-coding RNAs that were differentially expressed between male and female cells. Surprisingly, the majority of these were autosomal and included RNA encoding transcription and epigenetic and chromatin remodeling factors. We showed differential Prdm14-responsive enhancer activity in male and female cells, correlating with the sex-specific levels of Prdm14 expression. This is the first time sex-specific enhancer activity in ES cells has been reported. Evaluation of X-linked gene expression patterns between our XX and XY lines revealed four distinct categories: (1) genes showing 2-fold greater expression in the female cells; (2) a set of genes with expression levels well above 2-fold in female cells; (3) genes with equivalent RNA levels in male and female cells; and strikingly, (4) a small number of genes with higher expression in the XY lines. Further evaluation of autosomal gene expression revealed differential expression of imprinted loci, despite appropriate parent-of-origin patterns. The 39,X lines aligned closely with the XY cells and provided insights into potential regulation of genes associated with Turner syndrome in humans. Moreover, inclusion of the 39,X lines permitted three-way comparisons, delineating X and Y chromosome-dependent patterns.ConclusionsOverall, our results support the role of the sex chromosomes in establishing sex-specific networks early in embryonic development and provide insights into effects of sex chromosome aneuploidies originating at those stages.Electronic supplementary materialThe online version of this article (doi:10.1186/s13293-017-0150-x) contains supplementary material, which is available to authorized users.

The endangered Przewalski's horse is the closest relative of the domestic horse and is the only true wild horse species surviving today. The question of whether Przewalski's horse is the direct progenitor of domestic horse has been hotly debated. Studies of DNA diversity within Przewalski's horses have been sparse but are urgently needed to ensure their successful reintroduction to the wild. In an attempt to resolve the controversy surrounding the phylogenetic position and genetic diversity of Przewalski's horses, we used massively parallel sequencing technology to decipher the complete mitochondrial and partial nuclear genomes for all four surviving maternal lineages of Przewalski's horses. Unlike single-nucleotide polymorphism (SNP) typing usually affected by ascertainment bias, the present method is expected to be largely unbiased. Three mitochondrial haplotypes were discovered—two similar ones, haplotypes I/II, and one substantially divergent from the other two, haplotype III. Haplotypes I/II versus III did not cluster together on a phylogenetic tree, rejecting the monophyly of Przewalski's horse maternal lineages, and were estimated to split 0.117–0.186 Ma, significantly preceding horse domestication. In the phylogeny based on autosomal sequences, Przewalski's horses formed a monophyletic clade, separate from the Thoroughbred domestic horse lineage. Our results suggest that Przewalski's horses have ancient origins and are not the direct progenitors of domestic horses. The analysis of the vast amount of sequence data presented here suggests that Przewalski's and domestic horse lineages diverged at least 0.117 Ma but since then have retained ancestral genetic polymorphism and/or experienced gene flow.

The imprinted Kcnq1 domain contains a differentially methylated region (KvDMR) in intron 11 of Kcnq1. The Kcnq1ot1 non-coding RNA emerges from the unmethylated paternal KvDMR in antisense direction, resulting in cis-repression of neighboring genes. The KvDMR encompasses the Kcnq1ot1 promoter, CTCF sites and other DNA elements, whose individual contribution to regulation of the endogenous domain is unknown. We find that paternal inheritance of a deletion of the minimal Kcnq1ot1 promoter derepresses the upstream Cdkn1c gene. Surprisingly, Kcnq1ot1 transcripts continue to emerge from alternative sites, evidence that silencing depends, not on the ncRNA, but on the promoter sequence. Detailed analyses of Kcnq1ot during cardiogenesis show substantial chromatin reorganization coinciding with discontinuous RNA production in both wild-type and mutant mice, with loss of imprinting. We show that CTCF binds to both methylated and unmethylated alleles of the KvDMR. Furthermore, we report a multitude of enhancers within the Kcnq1ot1 region, and present conformational dynamics of a novel heart enhancer engaged in Kcnq1 expression. Our results have important implications on tissue-specific imprinting patterns and how transcriptional mechanisms compete to maximize the expression of vital genes, in addition to shifting our perception on the role of the long ncRNA in regulating this imprinted domain.

Ca2+ signals, which facilitate pluripotent changes in cell fate, reflect the balance between cation entry and export. We found that overexpression of either isoform of the Ca2+-extruding plasma membrane calcium ATPase 4 (PMCA4) pump in Jurkat T cells unexpectedly increased activation of the Ca2+-dependent transcription factor nuclear factor of activated T cells (NFAT). Coexpression of the endoplasmic reticulum–resident Ca2+ sensor stromal interaction molecule 1 (STIM1) with the PMCA4b splice variant further enhanced NFAT activity; however, coexpression with PMCA4a depressed NFAT. No PMCA4 splice variant dependence in STIM1 association was observed, whereas partner of STIM1 (POST) preferentially associated with PMCA4b over PMCA4a, which enhanced, rather than inhibited, PMCA4 function. A comparison of global and near-membrane cytosolic Ca2+ abundances during store-operated Ca2+ entry revealed that PMCA4 markedly depressed near-membrane Ca2+ concentrations, particularly when PMCA4b was coexpressed with STIM1. PMCA4b closely associated with both POST and the store-operated Ca2+ channel Orai1. Furthermore, POST knockdown increased the near-membrane Ca2+ concentration, inhibiting the global cytosolic Ca2+ increase. These observations reveal an unexpected role for POST in coupling PMCA4 to Orai1 to promote Ca2+ entry during T cell activation through Ca2+ disinhibition.

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