Molecular cloning of pig Rad51, Rad52, and Rad54 genes, which are involved in homologous recombination machinery

Molecular cloning and expression analysis of rad51 gene associated with gametogenesis in Chinese soft-shell turtle (Pelodiscus sinensis)

Rad51 is a recA-like recombinase that plays a crucial role in repairing DNA double-strand breaks through homologous recombination during mitosis and meiosis in mammals and other organisms. However, its role in reptiles remains largely unclear. In this study, we aimed to investigate the physiological role of the rad51 gene in reptiles, particularly in Pelodiscus sinensis. Firstly, the cDNA of rad51 gene was cloned and analyzed in P. sinensis. The cloned cDNA contained an open reading frame (ORF) of 1020 bp and encodeed a peptide of 339 amino acids. The multiple alignments and phylogenetic tree analysis of Rad51 showed that P. sinensis shares the high identity with Chelonia mydas (97.95%) and Mus musculus (95.89%). Secondly, reverse transcription-polymerase chain reaction (RT-PCR) and real-time quantitative polymerase chain reaction (RT-qPCR) analysis showed that rad51 mRNA was highly expressed in both ovary and testis, while being weak in the somatic tissues examined in this study. Furthermore, chemical in situ hybridization (CISH) was performed to examine the expression profile of rad51 mRNA in germ cells at different stages. In the testis, rad51 mRNA expression was found to be stronger in the germ cells at early stages, specifically in spermatogonia and spermatocytes, but it was undetectable in spermatids. In the ovary, rad51 mRNA exhibited a uniform distribution in the cytoplasm of oocytes at early stages. The signal intensity of rad51 mRNA was highest in primary oocytes and gradually declined during oogenesis as the oocytes developed. These results suggest that rad51 plays a vital role in the development of germ cells, particularly during the early stages of gametogenesis in P. sinensis. The dynamic expression pattern of rad51 mRNA provides insights into the mechanisms underlying germ cell development and differentiation into gametes in turtles, even in reptiles.

Dp71 depleted HBE cells displayed increased DNA damage and apoptosis induced by H2O2

Human bronchial epithelium (HBE)-Dp71 anti-sense(AS)cells with stably transfected Dp71 siRNA plasmids were prepared for further exploration of Dp71 biological traits in cells other than PC12. HBE-Dp71AS cells displayed increased DNA damage induced by H2O2. Apoptosis of HBE-Dp71AS cells induced by H2O2 was increased via enhancing caspase 3, caspase 8 and caspase 9. HBE-Dp71AS cells also displayed decreased proliferation and clonogenic formation. RAD51 was proved to be a new binding partner of Dp71 by co-immunoprecipitation (Ip) and immunofluorescence. Reduced RAD51 mRNA and protein levels were observed in HBE-Dp71AS cells. Decreased lamin B1, focal adhesion kinase (FAK), phosphorylated focal adhesion kinase (p-FAK) and phosphorylated protein kinase B (p-AKT) were detected in the HBE-Dp71AS cells, which functioned together with RAD51 as the molecular explanations for the character alterations of HBE-Dp71AS cells.

Using the CRISPR/Cas9 system to understand neuropeptide biology and regulation

Neuropeptides and their receptors play a role in physiological responses such as appetite, stress and inflammatory pain. With neuropeptides having such diverse and important physiological roles, knocking-out the genes encoding them, their receptors, parts of their regulatory sequences, or reproducing disease associated polymorphic variants are important steps in studying neuropeptides and how they may contribute to disease. Previously, knock-outs were generated using methods such as targeted homologous recombination in embryonic stem cells but this method is costly and time-consuming. The CRISPR/Cas9 system has rapidly taken over the genome editing field and will advance our understanding of neuropeptide genes and their regulation. With CRISPR/Cas9 technology, the time and costs involved in producing transgenic animal models, is greatly reduced. In this review, we describe how the system can be used to manipulate genomic sequences by "knock-out" or "knock-in" mutations in cell lines or in animal models. We also discuss the specificity of the system and methods to limit off-target effects. When combined with the availability of genome sequences, CRISPR/Cas9 directed genome editing in vitro and in vivo, promises to provide a deeper understanding of the biology of the neuropeptides in health and disease than has ever been available before.

Optimization of a CRISPR/Cas9-mediated Knock-in Strategy at the Porcine Rosa26 Locus in Porcine Foetal Fibroblasts

Genetically modified pigs have important roles in agriculture and biomedicine. However, genome-specific knock-in techniques in pigs are still in their infancy and optimal strategies have not been extensively investigated. In this study, we performed electroporation to introduce a targeting donor vector (a non-linearized vector that did not contain a promoter or selectable marker) into Porcine Foetal Fibroblasts (PFFs) along with a CRISPR/Cas9 vector. After optimization, the efficiency of the EGFP site-specific knock-in could reach up to 29.6% at the pRosa26 locus in PFFs. Next, we used the EGFP reporter PFFs to address two key conditions in the process of achieving transgenic pigs, the limiting dilution method and the strategy to evaluate the safety and feasibility of the knock-in locus. This study demonstrates that we establish an efficient procedures for the exogenous gene knock-in technique and creates a platform to efficiently generate promoter-less and selectable marker-free transgenic PFFs through the CRISPR/Cas9 system. This study should contribute to the generation of promoter-less and selectable marker-free transgenic pigs and it may provide insights into sophisticated site-specific genome engineering techniques for additional species.