Browsing by Subject "Homologous recombination"

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    Relationship between B-Cell-specific moloney murine leukemia virus integration site 1 (BMI-1) and homologous recombination regulatory genes in invasive ductal breast carcinomas
    (F. Hernández y Juan F. Madrid. Universidad de Murcia. Departamento de Biología Celular e Histología, 2012) da Silveira, Giórgia Gobbi; Oliveira-Costa, João Paulo; Soave, Danilo Figueiredo; Zanetti, Juliana Silva; Soares, Fernando Augusto; Ribeiro-Silva, Alfredo
    B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi-1) is a Polycomb group protein that is able to induce telomerase activity, enabling the immortalization of epithelial cells. Immortalized cells are more susceptible to double-strand breaks (DSB), which are subsequently repaired by homologous recombination (HR). BRCA1 is among the HR regulatory genes involved in the response to DNA damage associated with the RAD51 protein, which accumulates in DNA damage foci after signaling H2AX, another important marker of DNA damage. Topoisomerase IIIß (topoIIIß) removes HR intermediates before chromosomal segregation, preventing damage to cellular DNA structure. In breast carcinomas positive for BMI-1 the role of proteins involved in HR remains to be investigated. The aim of this study was to evaluate the association between BMI-1 and homologous recombination proteins. Using tissue microarrays containing 239 cases of primary breast tumors, the expression of Bmi-1, BRCA-1, H2AX, Rad51, p53, Ki-67, topoIIIß, estrogen receptors (ER), progesterone receptors (PR), and HER-2 was analyzed by immunohistochemistry. We observed high Bmi-1 expression in 66 cases (27.6%). Immunohistochemical overexpression of BMI-1 was related to ER (p=0.004), PR (p<0.001), Ki-67 (p<0.001), p53 (p=0.003), BRCA-1 (p= 0.003), H2AX (p=0.024) and topoIIIß (p<0,001). Our results show a relationship between the expression of BMI-1 and HR regulatory genes, suggesting that Bmi-1 overexpression might be an important event in HR regulation. However, further studies are necessary to understand the mechanisms in which Bmi-1 could regulate HR pathways in invasive ductal breast carcinomas.
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    Stable and reproducible homologous recombination enables CRISPR-based engineering in the fungus Rhizopus microsporus
    (Cell Press, 2021-12-20) Lax Molina, Carlos; Navarro Mendoza, María Isabel; Pérez Arques, Carlos; Navarro Ros, Eusebio; Nicolás Molina, Francisco Esteban; Garre Mula, Victoriano; Genética y Microbiología; Facultades de la UMU::Facultad de Biología
    Mucormycosis is a lethal and emerging disease that has lacked a genetic model fulfilling both high virulence and the possibility of performing stable and reproducible gene manipulation by homologous recombination (HR). Here, we developed a new methodology to successfully perform HR in Rhizopus microsporus. We isolated an uracil auxotrophic recipient strain and optimized the critical steps in the genetic transformation of this fungus. This was followed by an adaptation of a plasmid-free CRISPR-Cas9 system coupled with microhomology repair templates. We reproducibly generated stable mutants in the genes leuA and crgA, encoding a 3-isopropylmalate dehydratase and an ubiquitin ligase, respectively. Our new genetic model showed that mutations in the gene pyrF, a key virulence gene in several bacterial and fungal pathogens, correlated with an avirulent phenotype in an immunocompetent murine host. This was reverted by gene complementation, showing the broad possibilities of our methodology.