No abstract

In the pituitary, activin stimulates the synthesis and release of FSH. However, the activin receptor signaling pathways that mediate these effects are poorly known. We investigated these mechanisms in primary ovine pituitary cells (POP) and in the murine LbetaT2 gonadotrope cell line. POP cells and LbetaT2 cells express the different activin receptors (types IA, IB, IIA, and IIB) and the Smad proteins (Smad-2, -3, -4, and -7). In both POP and LbetaT2 cells, activin activated several signaling pathways: Smad-2, extracellular regulated kinase-1/2 (ERK1/2), p38, and phosphatidylinositol 3'-kinase (PI3K)/Akt. Phosphorylation of ERK1/2 and p38 were stimulated (3- to 6-fold) rapidly in 5 min, whereas activation of both Smad-2 and Akt (3- to 5-fold) occurred later, in 60 min. Activin also increased the association of activin receptor IIB with PI3K. Using specific inhibitors, we demonstrated that the activation of Smad-2 was partially blocked by the inhibition of PI3K but not by the inhibition of ERK1/2 or p38, suggesting a cross-talk between the Smad and PI3K/Akt pathways. In both POP and LbetaT2 cells, FSH expression and secretion in response to activin were not altered by the inhibition of PI3K/Akt, ERK1/2, or p38 pathways, whereas they were reduced by about 2-fold by expression of a dominant negative of Smad-2 or the natural inhibitory Smad-7 in LbetaT2 cells. These results indicate that activin activates several signaling pathways with different time courses in both POP and LbetaT2 cells, but only the Smad-2 pathway appears to be directly implicated in FSH expression and release in LbetaT2 cells.

The adaptive response to extreme endurance exercise might involve transcriptional and translational regulation by microRNAs (miRNAs). Therefore, the objective of the present study was to perform an integrated analysis of the blood transcriptome and miRNome (using microarrays) in the horse before and after a 160 km endurance competition. A total of 2,453 differentially expressed genes and 167 differentially expressed microRNAs were identified when comparing pre-and post-ride samples. We used a hypergeometric test and its generalization to gain a better understanding of the biological functions regulated by the differentially expressed microRNA. In particular, 44 differentially expressed microRNAs putatively regulated a total of 351 depleted differentially expressed genes involved variously in glucose metabolism, fatty acid oxidation, mitochondrion biogenesis, and immune response pathways. In an independent validation set of animals, graphical Gaussian models confirmed that miR-21-5p, miR-181b-5p and miR-505-5p are candidate regulatory molecules for the adaptation to endurance exercise in the horse. To the best of our knowledge, the present study is the first to provide a comprehensive, integrated overview of the microRNA-mRNA co-regulation networks that may have a key role in controlling post-transcriptomic regulation during endurance exercise.The physiological and biochemical demands of endurance exercise elicit both muscle-based and systemic responses. The main adaptations to endurance exercise include improvement of mechanical, metabolic, neuromuscular and contractile functions in muscle 1 , correction of electrolyte imbalance 2 , a decrease in glycogen storage 3 and an increase in mitochondrial biogenesis in muscle tissue 4 , and the modulation of oxidative stress 5 , intestinal permeability, muscle damage, systemic inflammation and immune responses 5 . Consequently, adaptations to endurance exercise are influenced by the transcriptional and translational regulation of genes that encode the proteins controlling these processes 5 . Over the past decade, microRNAs (miRNAs) have emerged as novel elements in the rapid, reversible regulation of transcription and translation 6 . MiRNAs are small non-coding RNAs molecules (~19-24 bp in length) that are synthesized from short hairpin precursors and that reportedly degrade or inhibit the translation of their target genes by binding to the 3′ untranslated region (UTR) of coding mRNAs 7 . In fact, miRNAs molecules may regulate up to one-third of the mammalian transcriptome 8 and appear to be stable outside the cell (e.g. when incorporated into exosomes 9 , microvesicles 10 , lipoproteins 11 or Argonaute2 protein complexes 12 ).

Neuropathies are neurodegenerative diseases affecting humans and other mammals. Many genetic causes have been identified so far, including mutations of genes encoding proteins involved in mitochondrial dynamics. Recently, the “Turning calves syndrome”, a novel sensorimotor polyneuropathy was described in the French Rouge-des-Prés cattle breed. In the present study, we determined that this hereditary disease resulted from a single nucleotide substitution in SLC25A46, a gene encoding a protein of the mitochondrial carrier family. This mutation caused an apparent damaging amino-acid substitution. To better understand the function of this protein, we knocked out the Slc25a46 gene in a mouse model. This alteration affected not only the nervous system but also altered general metabolism, resulting in premature mortality. Based on optic microscopy examination, electron microscopy and on biochemical, metabolic and proteomic analyses, we showed that the Slc25a46 disruption caused a fusion/fission imbalance and an abnormal mitochondrial architecture that disturbed mitochondrial metabolism. These data extended the range of phenotypes associated with Slc25a46 dysfunction. Moreover, this Slc25a46 knock-out mouse model should be useful to further elucidate the role of SLC25A46 in mitochondrial dynamics.

BackgroundMicroRNAs (miRNAs) are an abundant class of small single-stranded non-coding RNA molecules ranging from 18 to 24 nucleotides. They negatively regulate gene expression at the post-transcriptional level and play key roles in many biological processes, including skeletal development and cartilage maturation. In addition, miRNAs involvement in osteoarticular diseases has been proved and some of them were identified as suitable biomarkers for pathological conditions. Equine osteochondrosis (OC) is one of the most prevalent juvenile osteoarticular disorders in horses and represents a major concern for animal welfare and economic reasons. Its etiology and pathology remain controversial and biological pathways as well as molecular mechanisms involved in the physiopathology are still unclear. This study aims to investigate the potential role of miRNAs in equine osteochondrosis (OC) physiopathology.Short-read NGS technology (SOLID™, Life Technologies) was used to establish a comprehensive repertoire of miRNA expressed in either equine cartilage or subchondral bone. Undamaged cartilage and subchondral bone samples from healthy (healthy samples) and OC-affected (predisposed samples) 10-month Anglo-Arabian foals were analysed. Samples were also subjected or not to an experimental mechanical loading to evaluate the role of miRNAs in the regulation of mechano-transduction pathways. Predicted targets of annotated miRNAs were identified using miRmap.ResultsEpiphyseal cartilage and subchondral bone miRNome were defined, including about 300 new miRNAs. Differentially expressed miRNAs were identified between bone and cartilage from healthy and OC foals, as well as after an experimental mechanical loading. In cartilage, functional annotation of their predicted targets suggests a role in the maintenance of cartilage integrity through the control of cell cycle and differentiation, energy production and metabolism as well as extracellular matrix structure and dynamics. In bone, miRNA predicited targets were associated with osteoblasts and osteoclasts differentiation, though the regulation of energy production, vesicle transport and some growth factor signaling pathways.ConclusionTaken together, our results suggest a role of miRNAs in equine OC physiopathology and in the cellular response to biomechanical stress in cartilage and bone. In silico target prediction and functional enrichment analysis provides new insight into OC molecular physiopathology.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-798) contains supplementary material, which is available to authorized users.

BackgroundMiRNAs regulate multiple genes at the post-transcriptional level and therefore play an important role in many biological processes. It has been suggested that miRNA exported outside the cells contribute to inter-cellular communication. Consequently, circulating miRNAs are of particular interest and are promising biomarkers for many diseases. The number of miRNAs annotated in the horse genome is much lower compared to model organisms like human and mouse. We therefore aimed to identify novel equine miRNAs for tissue types and breed in serum.ResultsWe analysed 71 small RNA-seq libraries derived from nine tissues (gluteus medius, platysma, masseter muscle, heart, liver, cartilage, bone, total blood and serum) using miRDeep2 and miRdentify tools. Known miRNAs represented between 2.3 and 62.9 % of the reads in 71 libraries. A total of 683 novel miRNAs were identified. Breed and tissue type affected the number of miRNAs detected and interestingly, affected its average intensity. A total of 50 miRNAs in serum proved to be potential biomarkers to differentiate specific breed types, of which miR-122, miR-200, miR-483 were over-expressed and miR-328 was under-expressed in ponies compared to Warmbloods. The different miRNAs profiles, as well as the differences in their expression levels provide a foundation for more hypotheses based on the novel miRNAs discovered.ConclusionsWe identified 683 novel equine miRNAs expressed in seven solid tissues, blood and serum. Additionally, our approach evidenced that such data supported identification of specific miRNAs as markers of functions related to breeds or disease tissues.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3168-2) contains supplementary material, which is available to authorized users.

The fur of common rabbits is constituted of 3 types of hair differing in length and diameter while that of rex animals is essentially made up of amazingly soft down-hair. Rex short hair coat phenotypes in rabbits were shown to be controlled by three distinct loci. We focused on the “r1” mutation which segregates at a simple autosomal-recessive locus in our rabbit strains. A positional candidate gene approach was used to identify the rex gene and the corresponding mutation. The gene was primo-localized within a 40 cM region on rabbit chromosome 14 by genome scanning families of 187 rabbits in an experimental mating scheme. Then, fine mapping refined the region to 0.5 cM (Z = 78) by genotyping an additional 359 offspring for 94 microsatellites present or newly generated within the first defined interval. Comparative mapping pointed out a candidate gene in this 700 kb region, namely LIPH (Lipase Member H). In humans, several mutations in this major gene cause alopecia, hair loss phenotypes. The rabbit gene structure was established and a deletion of a single nucleotide was found in LIPH exon 9 of rex rabbits (1362delA). This mutation results in a frameshift and introduces a premature stop codon potentially shortening the protein by 19 amino acids. The association between this deletion and the rex phenotype was complete, as determined by its presence in our rabbit families and among a panel of 60 rex and its absence in all 60 non-rex rabbits. This strongly suggests that this deletion, in a homozygous state, is responsible for the rex phenotype in rabbits.

Recurrent exertional rhabdomyolysis (RER) is frequently observed in race horses like trotters. Some predisposing genetic factors have been described in epidemiological studies. However, the exact aetiology is still unknown. A calcium homeostasis disruption was suspected in previous experimental studies, and we suggested that a transcriptome analysis of RER muscles would be a possible way to investigate the pathway disorder. The purpose of this study was to compare the gene expression profile of RER vs. control muscles in the French Trotter to determine any metabolic or structural disruption. Total RNA was extracted from the gluteal medius and longissimus lumborum muscles after biopsies in 15 French Trotter horses, including 10 controls and 5 RER horses affected by 'tying-up' with high plasmatic muscular enzyme activities. Gene expression analysis was performed on the muscle biopsies using a 25K oligonucleotide microarray, which consisted of 24,009 mouse and 384 horse probes. Transcriptome analysis revealed 191 genes significantly modulated in RER vs. control muscles (P < 0.05). Many genes involved in fatty acid oxidation (CD36/FAT, SLC25A17), the Krebs cycle (SLC25A11, SLC25A12, MDH2) and the mitochondrial respiratory chain were severely down-regulated (tRNA, MT-ND5, MT-ND6, MT-COX1). According to the down-regulation of RYR1, SLC8A1 and UCP2 and up-regulation of APP and HSPA5, the muscle fibre calcium homeostasis seemed to be greatly affected by an increased cytosolic calcium and a depletion of the sarcoplasmic reticulum calcium. Gene expression analysis suggested an alteration of ATP synthesis, with severe mitochondrial dysfunction that could explain the disruption of cytosolic calcium homeostasis and inhibition of muscular relaxation.