Transcriptome analyses reveal transcriptional profiles of horse oocytes before and after in vitro maturation

Oocyte in vitro maturation is necessary for the study and application of animal-assisted reproduction technology in animal reproduction and breeding. The comprehensive transcriptional profile of equine oocyte maturated in vitro has not been fully mined yet, which makes many key transcriptional events still unidentified. Here, Smart-seq2 was performed to analyse the gene expression pattern and the underlying regulatory mechanism of horse germinal vesicle (GV) and in vitro metaphase II (MII) oocytes. The results showed that 6402 genes (2640 up-regulated and 3762 down-regulated in MII samples compared to GV) and 4021 lncRNA transcripts (1210 up-regulated and 2811 down-regulated in MII samples compared to GV) were differentially expressed in GV and MII oocytes. Further, GO and KEGG analysis found that differentially expressed mRNAs and lncRNAs were mainly enriched in the pathways related to energy and lipid metabolism. In addition, LGALS3 was found a key gene in mediating the regulation of oocyte meiosis recovery and fertilization ability. This study provides novel knowledge about gene expression and energy metabolism during equine oocyte maturation and a reference for the further study and application of assisted reproductive technology in horse reproduction and breeding.

Transcriptional regulatory network during axonal regeneration of dorsal root ganglion neurons: laser-capture microdissection and deep sequencing

The key regulators and regeneration-associated genes involved in axonal regeneration of neurons after injury have not been clarified. In high-throughput sequencing, various factors influence the final sequencing results, including the number and size of cells, the depth of sequencing, and the method of cell separation. There is still a lack of research on the detailed molecular expression profile during the regeneration of dorsal root ganglion neuron axon. In this study, we performed laser-capture microdissection coupled with RNA sequencing on dorsal root ganglion neurons at 0, 3, 6, and 12 hours and 1, 3, and 7 days after sciatic nerve crush in rats. We identified three stages after dorsal root ganglion injury: early (3-12 hours), pre-regeneration (1 day), and regeneration (3-7 days). Gene expression patterns and related function enrichment results showed that one module of genes was highly related to axonal regeneration. We verified the up-regulation of activating transcription factor 3 (Atf3), Kruppel like factor 6 (Klf6), AT-rich interaction domain 5A (Arid5a), CAMP responsive element modulator (Crem), and FOS like 1, AP-1 transcription factor Subunit (Fosl1) in dorsal root ganglion neurons after injury. Suppressing these transcription factors (Crem, Arid5a, Fosl1 and Klf6) reduced axonal regrowth in vitro. As the hub transcription factor, Atf3 showed higher expression and activity at the pre-regeneration and regeneration stages. G protein-coupled estrogen receptor 1 (Gper1), interleukin 12a (Il12a), estrogen receptor 1 (ESR1), and interleukin 6 (IL6) may be upstream factors that trigger the activation of Atf3 during the repair of axon injury in the early stage. Our study presents the detailed molecular expression profile during axonal regeneration of dorsal root ganglion neurons after peripheral nerve injury. These findings may provide reference for the clinical screening of molecular targets for the treatment of peripheral nerve injury.