Biology subjects

Petrini, J.

Publications and source records attributed to Petrini, J..

5 recordsLinked to original sources

bioRxiv2022

The Structure-Selective Endonucleases GEN1 and MUS81 are Functionally Complementary in Safeguarding the Genome of Proliferating B Lymphocytes

During the development of humoral immunity, activated B lymphocytes undergo vigorous proliferative, transcriptional, metabolic, and DNA remodeling activities; hence, their genomes are constantly exposed to an onslaught of genotoxic agents and processes. Recombination-dependent DNA transactions that preserve the integrity of the genome and of the DNA replication process generates Holliday junctions that must be eliminated for the accurate segregation of sister chromatids and faithful propagation of genomic material. To investigate the role of two Holliday junction resolvases, GEN1 and MUS81, in B cell biology, we established B-cell conditional knockout mouse models and found that targeted deletion of GEN1 and MUS81 in early B cell precursors halts their development and maturation while selective loss of the resolvases in mature B cells inhibits the generation of robust germinal centers. Upon activation, these double-null mature B lymphocytes fail to proliferate and survive while exhibiting transcriptional signatures of p53 signaling, apoptosis, and type I interferon response. Metaphase spreads of these resolvase-deficient cells showed severe and diverse chromosomal abnormalities, including a preponderance of chromosome breaks, consistent with a defect in resolving DNA recombination intermediates. These observations underscore the essential roles of GEN1 and MUS81 in safeguarding the genome to ensure the proper development and maintenance of B lymphocytes.

immunology↗

bioRxiv2019

Genetic regulators of mineral amount in Nelore cattle muscle predicted by a new co-expression and regulatory impact factor approach

Mineral amount in bovine muscle affect meat quality, growth, health and reproductive traits in beef cattle. To better understand the genetic basis of this phenotype, we implemented new applications of use for two complementary algorithms: the partial correlation and information theory (PCIT) and the regulatory impact factor (RIF), by including GEBVs as part of the input. We used PCIT to determine putative regulatory relationships based on significant associations between gene expression and mineral amount. Then, RIF was used to determine the regulatory impact of genes and miRNA expression over mineral amount. We also investigated over-represented pathways, as well as evidences from previous studies carried in the same population, to determine regulatory genes for mineral amount e.g. NOX1, whose expression was positively correlated to Zn and was described as regulated by this mineral in humans. With this methodology, we were able to identify genes, miRNAs and pathways not yet described as important for mineral amount. The results support the hypothesis that extracellular matrix interactions are the core regulator of mineral amount in muscle cells. Putative regulators described here add information to this hypothesis, expanding the molecular relationships between gene expression and minerals.

genomics↗

bioRxiv2019

Nbs1 Mediates Assembly and Activity of the Mre11 complex

We derived a mouse model in which a mutant form of Nbs1 (Nbs1mid8) exhibits severely impaired binding to the Mre11-Rad50 core of the Mre11 complex. The Nbs1mid8 allele was expressed exclusively in hematopoietic lineages (in Nbs1-/mid8vav mice). Unlike Nbs1flox/floxvav mice, which are Nbs1 deficient in the bone marrow, Nbs1-/mid8vav mice were viable. Nbs1-/mid8vav hematopoiesis was profoundly defective, exhibiting reduced cellularity of thymus and bone marrow, and stage specific blockage of B cell development. Within six months, Nbs1-/mid8 mice developed highly penetrant T cell leukemias. Nbs1-/mid8vav leukemias recapitulated mutational features of human T-ALL, containing mutations in Notch1, Trp53, Bcl6, Bcor, and Ikzf1, suggesting that Nbs1mid8 mice may provide a venue to examine the relationship between the Mre11 complex and oncogene activation in the hematopoietic compartment. Genomic analysis of Nbs1-/mid8vav malignancies showed focal amplification of 9qA2, causing overexpression of MRE11 and CHK1. We propose that overexpression compensates for the meta-stable Mre11-Nbs1mid8 interaction, and that selection pressure for overexpression reflects the essential role of Nbs1 in promoting assembly and activity of the Mre11 complex.

cancer biology↗

bioRxiv2018

Association of predicted deleterious single nucleotide polymorphisms with carcass traits in meat-type chickens

In previous studies, we used genome wide association (GWAS) to identify quantitative trait loci (QTL) associated with weight and yield of abdominal fat, drumstick, thigh and breast traits in chickens. However, this methodology assumes that the studied variants are in linkage disequilibrium with the causal mutation and consequently do not identify it. In an attempt to identify causal mutations in candidate genes for carcass traits in broilers, we selected 20 predicted deleterious SNPs within QTLs for association analysis. Additive, dominance and allele substitution effects were tested. From the 20 SNPs analyzed, we identified six SNPs with significant association (p-value <0.05) with carcass traits, and three are highlighted here. The SNP rs736010549 was associated with drumstick weight and yield with significant additive and dominance effects. The SNP rs739508259 was associated with thigh weight and yield, and with significant additive and allele substitution effects. The SNP rs313532967 was associated with breast weight and yield. The three SNPs that were associated with carcass traits (rs736010549, rs739508259 and rs313532967) are respectively located in the coding regions of the WDR77, VWA8 and BARL genes. These genes are involved in biological processes such as steroid hormone signaling pathway, estrogen binding, and regulation of cell proliferation. Our strategy allowed the identification of putative casual mutations associated with muscle growth.

genetics↗

bioRxiv2017

Therapeutic targeting of PGBD5-induced DNA repair dependency in pediatric solid tumors

Despite intense efforts, the cure rates of childhood and adult solid tumors are not satisfactory. Resistance to intensive chemotherapy is common, and targets for molecular therapies are largely undefined. We have now found that the majority of childhood solid tumors, including rhabdoid tumors, neuroblastoma, medulloblastoma and Ewing sarcoma, express an active DNA transposase PGBD5 that can promote site-specific genomic rearrangements in human cells. Using functional genetic approaches, we found that mouse and human cells deficient in non-homologous end joining (NHEJ) DNA repair cannot tolerate the expression of PGBD5. In a chemical screen of DNA damage signaling inhibitors, we identified AZD6738 as a specific sensitizer of PGBD5-dependent DNA damage and apoptosis. We found that expression of PGBD5, but not its nuclease activity-deficient mutant, was sufficient to induce hypersensitivity to AZD6738. Depletion of endogenous PGBD5 conferred resistance to AZD6738 in human tumor cells. PGBD5-expressing tumor cells accumulated unrepaired DNA damage in response to AZD6738 treatment, and underwent apoptosis in both dividing and G1 phase cells in the absence of immediate DNA replication stress. Accordingly, AZD6738 exhibited nanomolar potency against the majority of neuroblastoma, medulloblastoma, Ewing sarcoma and rhabdoid tumor cells tested, while sparing non-transformed human and mouse embryonic fibroblasts in vitro. Finally, treatment with AZD6738 induced apoptosis and regression of human neuroblastoma and medulloblastoma tumors engrafted in immunodeficient mice in vivo. This effect was potentiated by combined treatment with cisplatin, including significant anti-tumor activity against patient-derived primary neuroblastoma xenografts. These findings delineate a therapeutically actionable synthetic dependency induced in PGBD5-expressing solid tumors.

cancer biology↗