DNA double-strand breaks (DSBs) are generated both extrinsically, for example, by chemotherapeutic agents, and physiologically, for example, during V(D)J recombination in developing B and T lymphocytes, and class switch recombination (CSR) in activated mature B cells. 1,2 The DNA damage response (DDR) pathway is initiated upon the induction of DSBs. Ataxia telangiectasia mutated (ATM) is a DDR regulator protein kinase that phosphorylates

Cancer-associated fibroblasts (CAF) form the basis of tumor microenvironment and possess immunomodulatory functions by interacting with other cells surrounding tumor, including T lymphocytes, macrophages, dendritic cells and natural killer cells. Ionizing radiation is a broadly-used method in radiotherapy to target tumors. In mammalian cells, ionizing radiation induces various types of DNA damages and DNA damage response. Being unspecific, radiotherapy affects all the cells in tumor microenvironment, including the tumor itself, CAFs and immune cells. CAFs are extremely radio-resistant and do not initiate apoptosis even at high doses of radiation. However, following radiation, CAFs become senescent and produce a distinct combination of immunoregulatory molecules. Radiosensitivity of immune cells varies depending on the cell type due to inefficient DNA repair in, for example, monocytes and granulocytes. In this minireview, we are summarizing recent findings on the interaction between CAF, ionizing radiation and immune cells in the tumor microenvironment.

Cancer-associated fibroblasts (CAF) form the basis of tumor microenvironment and possess immunomodulatory functions by interacting with other cells surrounding tumor, including T lymphocytes, macrophages, dendritic cells and natural killer cells. Ionizing radiation is a broadly-used method in radiotherapy to target tumors. In mammalian cells, ionizing radiation induces various types of DNA damages and DNA damage response. Being unspecific, radiotherapy affects all the cells in tumor microenvironment, including the tumor itself, CAFs and immune cells. CAFs are extremely radio-resistant and do not initiate apoptosis even at high doses of radiation. However, following radiation, CAFs become senescent and produce a distinct combination of immunoregulatory molecules. Radiosensitivity of immune cells varies depending on the cell type due to inefficient DNA repair in, for example, monocytes and granulocytes. In this minireview, we are summarizing recent findings on the interaction between CAF, ionizing radiation and immune cells in the tumor microenvironment.

The non-homologous end joining (NHEJ) DNA repair pathway is the main mechanism to repair DNA double strand breaks (DSBs) throughout the whole cell cycle. During NHEJ, core Ku70 and Ku80 subunits form the Ku heterodimer; Ku binds DSBs and promotes the recruitment of accessory factors (e.g., DNA-PKcs, PAXX, Mri) and downstream core factors (XLF, Lig4 and XRCC4). DSBs are induced during the V(D)J recombination in developing B and T lymphocytes to increase the repertoire of B and T cell receptors. Furthermore, DSBs are generated during the class switch recombination (CSR) in mature B lymphocytes, providing distinct effector functions of antibody heavy chain constant regions. The NHEJ is required for both V(D)J recombination and CSR. During the last decades, new NHEJ proteins have been reported, increasing the complexity of the molecular pathway. Multiple in vivo mouse models were generated and characterized to identify specific functions of NHEJ factors in the adaptive immune system. Here, we are summarizing available mouse models lacking one or several NHEJ factors, with a particular focus on early B cell development.