Testis development is a vital and tightly regulated process in mammals. Understanding the biological mechanisms underlying testis development will benefit the animal reproduction industry. Expression changes in microRNA and messenger RNA in response to dynamic regulation effects have been associated with this process. However, very little is known about the roles of these molecules in yak development. Using whole-genome small RNA and messenger RNA sequencing, we performed a comprehensive analysis of the microRNA–messenger RNA interaction network expression in the testicles of Tianzhu white yaks during three developmental stages. Using Short Time-series Expression Miner analysis we identified 589 differentially expressed microRNAs (DERs) and 3383 differentially expressed messenger RNAs (DEGs) in the three age groups. A total of 93 unique DEGs are primarily involved in reproduction and testis development. Subsequently, four integration networks were constructed according to the DEGs and DERs in three biological processes. Nineteen DEGs were potentially regulated by 60 DERs, of which miR-574 and target gene AURKA played a crucial role in yak testis development and reproduction. The results of this study provide a basis for further exploration of the microRNA–messenger RNA interactions in testis development and reproduction and aid in uncovering the molecular mechanisms of spermatogenesis in male mammals.

Insulin-like growth factor 2 (IGF2) recapitulates many of the activities of insulin and promotes differentiation of myoblasts and osteoblasts, which likely contribute to genetic variations of growth potential. However, little is known about the functions and signaling properties of IGF2 variants in yaks. The over-expression vector and knockdown sequence of yak IGF2 were transfected into yak fibroblasts, and the effects were detected by a series of assays. IGF2 expression in yak muscle tissues was significantly lower than that of other tissues. In yak fibroblasts, the up-regulated expression of IGF2 inhibits expression of IGF1 and insulin-like growth factor 2 receptor (IGF2R) and significantly up-regulates expression of IGF1R. Inhibition of IGF2 expression caused the up-regulates expression of IGF1, IGF1R and IGF2R. Both over-expression and knockdown of IGF2 resulted in up-regulation of threonine protein kinase 1 (Akt1) expression and down-regulation of phosphatidylinositol 3-kinase, catalytic subunit gamma (PIK3CG). Cell cycle and cell proliferation assays revealed that over-expression of IGF2 enhanced the DNA synthesis phase and promoted yak fibroblasts proliferation. Conversely, knockdown of IGF2 decreased DNA synthesis and inhibited proliferation. These results suggested that IGF2 was negatively correlated with IGF1R and PIK3CG and demonstrated an association with the IGFs-PI3K-Akt (IGFs-phosphatidylinositol 3-kinase- threonine protein kinase) pathway in cell proliferation and provided evidence supporting the functional role of IGF2 for use in improving the production performance of yaks.

Background: Camelidae are inducing ovulators, ovulation is tightly regulated by multiple factors, and understanding the biological mechanisms underlying follicular development, hormone secretion and ovulation requires investigation of the potential molecular pathways. However, little is known about the pathways of these factors in the camel. To screening and identification candidate biomarkers after inducing ovulators in ovary.Methods: In this paper, the quantitative proteomics method iTRAQ analysis technology was used to analyze the proteomic differences of ovarian before and after induced ovulation in Bactrian camels. The differentially expressed protein was validated by Western blot, qRT-PCR and Immunofluorescence staining analysis.Results: A total of 5,075 ovarian expressed proteins were detected, and 404 proteins were differentially expressed (264 up-regulated, 140 down-regulated) in samples from treated versus control camels. Gene ontology annotation identified potential functions of the differentially expressed proteins (DEPs). We validated the differential expression for a subset of these proteins using western blotting and immunofluorescence staining. Three DEPs (FST, NR5A1 and PRL) were involved in neurochemical signal transduction, endocrine and reproductive hormones regulatory processes. KEGG analysis indicated the involvement of several pathways, such as calcium, cAMP, gonadotropin-releasing hormone, MAPK, and neuroactive ligand-receptor signaling pathways, further suggesting that the induced ovulation process depends on the hypothalamic-pituitary-ovarian axis. Conclusions: This study is the first to perform quantitative proteomic investigation by iTRAQ labeling and LC-MS/MS to identify differentially expressed proteins induced ovulation in Bactrian camels. Our study has revealed distinct molecular functions and metabolic pathways that are active during reproduction in Bactrian camels. These results have demonstrated the pivotal role played by 3 DEPs in the modulation and activation of the reproductive axis during induced ovulation in the Bactrian camel, followed by the measurement of selected proteins using more targeted methods, offers a promising approach for studying potential mechanism of ovary development and ovulation.