Two-ended recombination at a Flp-nickase-broken replication fork.

Replication fork collision with a DNA nick can generate a one-ended break, fostering genomic instability. The opposing fork's collision with the nick could form a second DNA end, enabling conservative repair by homologous recombination (HR). To study mechanisms of nickase-induced HR, we developed the Flp recombinase "step arrest" nickase in mammalian cells.

Two-ended recombination at a Flp-nickase-broken replication fork.

Collision of a replication fork with a DNA nick is thought to generate a one-ended break, fostering genomic instability. Collision of the opposing converging fork with the nick could, in principle, form a second DNA end, enabling conservative repair by homologous recombination (HR). To study mechanisms of nickase-induced HR, we developed the Flp recombinase "step arrest" nickase in mammalian cells.

MicroRNA, miR-501 regulate the V(D)J recombination in B cells.

The stringent regulation of RAGs (Recombination activating genes), the site-specific endonuclease responsible for V(D)J recombination, is important to prevent genomic rearrangements and chromosomal translocations in lymphoid cells. In the present study, we identify a microRNA, miR-501, which can regulate the expression of RAG1 in lymphoid cells. Overexpression of the pre-miRNA construct led to the generation of mature miRNAs and a concomitant reduction in RAG1 expression, whereas inhibition using anti-miRs resulted in its enhanced expression.

Nonamer dependent RAG cleavage at CpGs can explain mechanism of chromosomal translocations associated to lymphoid cancers.

Chromosomal translocations are considered as one of the major causes of lymphoid cancers. RAG complex, which is responsible for V(D)J recombination, can also cleave non-B DNA structures and cryptic RSSs in the genome leading to chromosomal translocations. The mechanism and factors regulating the illegitimate function of RAGs resulting in oncogenesis are largely unknown.

A novel KU70-mutant human leukemic cell line generated using CRISPR-Cas9 shows increased sensitivity to DSB inducing agents and reduced NHEJ activity.

KU70 (XRCC6 gene in humans) is one of the proteins in the KU70-KU80 heterodimer which is the first component recruited to broken DNA ends during DNA double-strand break repair through nonhomologous end joining (NHEJ). Previous studies have shown that Ku70 deficient mouse cells are defective in NHEJ and V(D)J recombination. In contrast, heterozygous KU70 mutant human cell lines did not show any significant change in cell viability and sensitivity towards ionizing radiation.

MicroRNA miR-29c regulates RAG1 expression and modulates V(D)J recombination during B cell development.

Recombination activating genes (RAGs), consisting of RAG1 and RAG2, are stringently regulated lymphoid-specific genes, which initiate V(D)J recombination in developing lymphocytes. We report the regulation of RAG1 through a microRNA (miRNA), miR-29c, in a B cell stage-specific manner in mice and humans. Various lines of experimentation, including CRISPR-Cas9 genome editing, demonstrate the target specificity and direct interaction of miR-29c to RAG1.

HIV integrase inhibitors that inhibit strand transfer interact with RAG1 and hamper its activities.

Multiple steps of the retroviral infection process have been targeted over the years to develop therapeutic approaches, starting from the entry of the virus into the cell till the viral DNA integration to host genome. Inhibitors against the Human Immunodeficiency Virus (HIV) integrase is the newest among the therapies employed against HIV. Recombination activating gene 1 (RAG1) is an integral protein involved in the generation of diversity of antibodies and T-cell receptors and is one of the partners of the RAG complex.

Characterization of G-quadruplex antibody reveals differential specificity for G4 DNA forms.

Accumulating evidence suggests that human genome can fold into non-B DNA structures, when appropriate sequence and favourable conditions are present. Among these, G-quadruplexes (G4-DNA) are associated with gene regulation, chromosome fragility and telomere maintenance. Although several techniques are used in detecting such structures in vitro, understanding their intracellular existence has been challenging.

Znc2 module of RAG1 contributes towards structure-specific nuclease activity of RAGs.

Recombination activating genes (RAGs), consisting of RAG1 and RAG2 have ability to perform spatially and temporally regulated DNA recombination in a sequence specific manner. Besides, RAGs also cleave at non-B DNA structures and are thought to contribute towards genomic rearrangements and cancer. The nonamer binding domain of RAG1 binds to the nonamer sequence of the signal sequence during V(D)J recombination.

Biochemical activity of RAGs is impeded by Dolutegravir, an HIV integrase inhibitor.

HIV is a retrovirus that infects CD4 T lymphocytes in human beings and causes immunodeficiency. In the recent years, various therapies have been developed against HIV, including targeting the HIV specific protein, integrase, responsible for integration of HIV cDNA into host DNA. Although, integrase is specific to HIV, it has functional and structural similarity with RAG1, one of the partner proteins associated with V(D)J recombination, a process by which immune diversity is generated in humans.

Dietary CCPS from bitter gourd attenuates sodium arsenite induced female reproductive ailments cum infertility in wistar rats: anti-inflammatory and anti-apoptotic role.

This investigation explored a dietary therapy of pectic polysaccharide (CCPS) (2 mg/ Kg BW) against female repro-toxicity and infertility triggered by sodium arsenite (As) (10 mg/ Kg BW) in Wistar rats. The isolated CCPS consists of D-galactose and D-methyl galacturonate with a molar ratio of 1: 4. FTIR spectral analysis of CCPS and CCPS- sodium arsenite (As) complex indicated a possible chelating property of CCPS in presence of binding sites (OH/COOH) for As.

HIV integrase inhibitor, Elvitegravir, impairs RAG functions and inhibits V(D)J recombination.

Integrase inhibitors are a class of antiretroviral drugs used for the treatment of AIDS that target HIV integrase, an enzyme responsible for integration of viral cDNA into host genome. RAG1, a critical enzyme involved in V(D)J recombination exhibits structural similarity to HIV integrase. We find that two integrase inhibitors, Raltegravir and Elvitegravir, interfered with the physiological functions of RAGs such as binding, cleavage and hairpin formation at the recombination signal sequence (RSS), though the effect of Raltegravir was limited.