Development of a tau-V337M mouse model using CRISPR/Cas9 system and enhanced ssODN-mediated recombination / 生物工程学报

The generation of a tau-V337M point mutation mouse model using gene editing technology can provide an animal model with fast disease progression and more severe symptoms, which facilitate the study of pathogenesis and treatment of Alzheimer's disease (AD). In this study, single guide RNAs (sgRNA) and single-stranded oligonucleotides (ssODN) were designed and synthesized in vitro. The mixture of sgRNA, Cas9 protein and ssODN was microinjected into the zygotes of C57BL/6J mice. After DNA cutting and recombination, the site homologous to human 337 valine (GTG) in exon 11 was mutated into methionine (ATG). In order to improve the efficiency of recombination, a Rad51 protein was added. The female mice mated with the nonvasectomy male mice were used as the surrogates. Subsequently, the 2-cell stage gene edited embryos were transferred into the unilateral oviduct, and the F0 tau-V337M mutation mice were obtained. Higher mutation efficiency could be obtained by adding Rad51 protein. The F0 tau-V337M point mutation mice can pass the mutation on to the F1 generation mice. In conclusion, this study successfully established the first tau-V337M mutation mouse by using Cas9, ssODN and Rad51. These results provide a new method for developing AD mice model which can be used in further research on the pathogenesis and treatment of AD.

The role of tyrosine phosphatase Shp2 in spermatogonial differentiation and spermatocyte meiosis / 亚洲男科学杂志(英文版)

The transition from spermatogonia to spermatocytes and the initiation of meiosis are key steps in spermatogenesis and are precisely regulated by a plethora of proteins. However, the underlying molecular mechanism remains largely unknown. Here, we report that Src homology domain tyrosine phosphatase 2 (Shp2; encoded by the protein tyrosine phosphatase, nonreceptor type 11 [Ptpn11] gene) is abundant in spermatogonia but markedly decreases in meiotic spermatocytes. Conditional knockout of Shp2 in spermatogonia in mice using stimulated by retinoic acid gene 8 (Stra8)-cre enhanced spermatogonial differentiation and disturbed the meiotic process. Depletion of Shp2 in spermatogonia caused many meiotic spermatocytes to die; moreover, the surviving spermatocytes reached the leptotene stage early at postnatal day 9 (PN9) and the pachytene stage at PN11-13. In preleptotene spermatocytes, Shp2 deletion disrupted the expression of meiotic genes, such as disrupted meiotic cDNA 1 (Dmc1), DNA repair recombinase rad51 (Rad51), and structural maintenance of chromosome 3 (Smc3), and these deficiencies interrupted spermatocyte meiosis. In GC-1 cells cultured in vitro, Shp2 knockdown suppressed the retinoic acid (RA)-induced phosphorylation of extracellular-regulated protein kinase (Erk) and protein kinase B (Akt/PKB) and the expression of target genes such as synaptonemal complex protein 3 (Sycp3) and Dmc1. Together, these data suggest that Shp2 plays a crucial role in spermatogenesis by governing the transition from spermatogonia to spermatocytes and by mediating meiotic progression through regulating gene transcription, thus providing a potential treatment target for male infertility.

Mutaciones del gen RAD51 en el cáncer familiar de ovario: revisión de la literatura / RAD51 gene mutations in familial ovarian cancer: literature review

ANTECEDENTES: En los últimos 15 años, el carcinoma familiar de ovario, ha sido atribuido en su mayoría a mutaciones en BRCA 1 y 2. Sin embargo, aproximadamente el 25% de los nuevos casos se asocian a mutaciones aisladas de genes implicados en el mecanismo de reparación del ADN por recombinación homóloga. Mutaciones monoalélicas de RAD51 han sido identificadas en pacientes con historia de carcinoma mama y ovario, tamizaje negativo para BRCA 1 y 2, y por lo menos con un caso de carcinoma de ovario en el linaje. OBJETIVO: Describir las mutaciones en el complejo RAD51 con el fin de identificar su papel en el cáncer de ovario familiar. MÉTODO: Se realizó una búsqueda de la literatura en bases de datos de los últimos 10 años con los siguientes términos MeSH: "RAD51", "ovarian cancer" "ovarian neoplasm", "family ovarian cancer". RESULTADOS: Se encontró una prevalencia de la mutación en genes del complejo RAD51 que varía entre 0,2% y 2,5%, según la etnia estudiada, siendo una de las causas de tumores serosos de ovario de alto grado en mujeres entre los 57 y 60 años. CONCLUSIÓN: Mutaciones de RAD51 en pacientes negativas para mutaciones de BRCA 1 y 2, se asocian al síndrome familiar mama-ovario, con un aumento del riesgo para carcinoma de ovario, pero sin modificaciones para el carcinoma de mama.

BACKGROUND: In the last fifteen years, familiar ovarian carcinoma has been related to BRCA 1 and 2 mutations. However, 25% of new cases of ovarian neoplasm are explained by isolated genes involved in the mechanism of homologous recombination. Patients with family history of ovarian and breast carcinoma, negative for BRCA mutations and at least with one case of invasive ovarian carcinoma have been identify with monoallelic mutations in RAD51. OBJECTIVE: To describe mutations on RAD51 complex, in order to identify its role in familiar ovarian cancer. METHODOLOGY: A systematic review of the literature of the last ten years involving the main data bases and using the following MeSH terms: "RAD51", "ovarian cancer", "ovarian neoplasm", "family ovarian cancer". RESULTS: Prevalence reported for RAD51 mutation is between 0.2 and 2.5%, associated with the ethnicity of the population involved. Also is considered a cause for high grade serous ovarian carcinoma in women between 57 and 60 years old. RAD51C and RAD51D germ line mutations are related to ovarian-breast hereditary syndrome, in negative population for BRCA 1 and 2 mutations. CONCLUSION: Patients with RAD51 mutations, negative for BRCA mutation are associated with ovarian-breast cancer syndrome increasing the risk just for ovarian cancer.