Genetics and Diagnostic Approach to Lymphoblastic Leukemia/Lymphoma

Afkhami, Michelle; Ally, Feras; Pullarkat, Vinod; Pillai, Raju

doi:10.1007/978-3-030-78311-2_2

Cited by 1 publication

(1 citation statement)

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“…Even translocations which involve the antigen receptor loci, such as Bcl2-IgH or BCR-ABL1, lack substantial evidence of initial RAG-mediated DSBs (Mossadegh-Keller et al, 2021;Yuan et al, 2021). This may be due to a lack of ability to screen for these type of lesions as the limitations of some sequencing methods may overlook certain breakpoint features, however, recent improvements to next generation sequencing and whole genome sequencing will allow for higher discovery rate of these off-target RAG induced breaks (Nordlund et al, 2020;Afkhami et al, 2021;Xiao et al, 2021). The excised signal circle (ESC) complex consisting of the SEs, RAG proteins, and other factors is another source of potential reintegration into the genome (Kirkham et al, 2019).…”

Section: Tumorigenesismentioning

confidence: 99%

V(D)J Recombination: Recent Insights in Formation of the Recombinase Complex and Recruitment of DNA Repair Machinery

Christie

Fijen

Rothenberg

2022

Front. Cell Dev. Biol.

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V(D)J recombination is an essential mechanism of the adaptive immune system, producing a diverse set of antigen receptors in developing lymphocytes via regulated double strand DNA break and subsequent repair. DNA cleavage is initiated by the recombinase complex, consisting of lymphocyte specific proteins RAG1 and RAG2, while the repair phase is completed by classical non-homologous end joining (NHEJ). Many of the individual steps of this process have been well described and new research has increased the scale to understand the mechanisms of initiation and intermediate stages of the pathway. In this review we discuss 1) the regulatory functions of RAGs, 2) recruitment of RAGs to the site of recombination and formation of a paired complex, 3) the transition from a post-cleavage complex containing RAGs and cleaved DNA ends to the NHEJ repair phase, and 4) the potential redundant roles of certain factors in repairing the break. Regulatory (non-core) domains of RAGs are not necessary for catalytic activity, but likely influence recruitment and stabilization through interaction with modified histones and conformational changes. To form long range paired complexes, recent studies have found evidence in support of large scale chromosomal contraction through various factors to utilize diverse gene segments. Following the paired cleavage event, four broken DNA ends must now make a regulated transition to the repair phase, which can be controlled by dynamic conformational changes and post-translational modification of the factors involved. Additionally, we examine the overlapping roles of certain NHEJ factors which allows for prevention of genomic instability due to incomplete repair in the absence of one, but are lethal in combined knockouts. To conclude, we focus on the importance of understanding the detail of these processes in regards to off-target recombination or deficiency-mediated clinical manifestations.

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