Natural killer (NK) cells are innate lymphoid cells with antitumor functions

Natural killer (NK) cells are innate lymphoid cells with antitumor functions. cells (ILCs) with cytotoxic and regulatory capacities. They develop Praziquantel (Biltricide) in the BM and become dependent on the pleiotropic cytokine IL-15 shortly after committing to the NK cell lineage (Huntington et al., 2007b,c; Huntington, 2014). Mature NK cells can be identified in peripheral tissues by the coexpression of NKp46 (encoded by mice. This indicates that IL-15 is essential for NK cell survival in vivo (Cooper et al., 2002; Dubois et al., 2002; Koka et al., 2003; Burkett et al., 2004; Sandau et al., 2004; Huntington et al., 2007a). IL-15 has long been known to promote NK cell survival, and several apoptosis inhibitory mechanisms have been uncovered. For example, IL-15 was shown to increase the expression of antiapoptotic proteins belonging to the BCL2 (B cell lymphoma 2) family, including BCL2, BCL-XL (encoded by expression by binding its 3 UTR Rabbit Polyclonal to ATG4D (Sathe et al., 2014). We exhibited that when was deleted specifically in NK cells using knock-in mice, NKp46+ NK cells and ILC1 were missing from all primary and secondary lymphoid organs. This demonstrates the essential role for MCL1 in regulating NK cell survival (Huntington et al., 2007a; Sathe et al., 2014). In the same study, we found that (BCLXL-deficient) mice had normal NK cell development, indicating the redundant role for this protein in the IL-15Cdependent antiapoptotic pathway in NK cells. Although BCL2 had originally been shown to increase in NK cells in response to IL-15, we failed to detect any alteration in BCL2 levels after IL-15 withdrawal from NK cells, whereas MCL1 levels decreased dramatically corresponding with impaired NK cell survival (Huntington et al., 2007a). These data demonstrate an essential role for MCL1 in NK cell survival and questioned the role of BCL2. Results Characterization of (mouse was subjected to whole-exome sequencing. DNA from six unrelated mice originating from other pedigrees generated in our ENU mutagenesis program was also sequenced. Only seven nonsense or missense homozygous mutations were Praziquantel (Biltricide) selectively present in the mutant mouse. To identify the mutation responsible for the phenotype, we sequenced these seven genes in six other animals from the ENU-148 colony that did or did not exhibit the phenotype. Among these seven mutations, a homozygous mutation in (A1463G) was found to be the only one associated with the phenotype (Table 1 and Fig. 1 D). In accordance with the fact that a mutation in is responsible for the phenotype, the NK cell deficiency observed in mice was associated with a pan-lymphocytopenia also affecting CD4, CD8 T cells and B cells (Fig. 1 E) and abnormally small spleens (Fig. 1 F), as described earlier in mice, we observed that this T and B cells were unaffected compared with control mice whereas NK cells were significantly reduced (Fig. 1 H and not depicted), and we thus focused on dissecting the mechanisms by which mutation in was impacting NK cell homeostasis. Open in a separate window Physique 1. Analysis of the mutant mouse phenotype and identification of the causative mutation. (A) Selection of the ENU-148 pedigree using a functional screen based on an in vivo NK cellCkilling assay. Splenocytes from WT and cell killing were calculated. Three G3 mice with a defect in NK cellCmediated target cell killing were Praziquantel (Biltricide) selected (red circle) and crossed to WT animals to generate a colony of mutant mice. An autosomal-recessive transmission of the mutation was observed, and the phenotype of affected animals was called (B) In the ENU-148 colony, some mice showed progressive hair hypopigmentation. The pictures show a typical example of this phenotype for mice aged between 6 wk and 10 mo, as indicated. (C) NK cell counts in the blood of control (C57BL/6J) mice and mice from the pedigree ENU-148 presenting or not with Praziquantel (Biltricide) hair hypopigmentation (gray and black, respectively). Each dot represents the results obtained for one mouse (= 31C82, KruskalCWallis statistical test). (D) ENU-148 mice were segregated depending on their genotype, and the NK cell counts in peripheral blood were measured. Praziquantel (Biltricide) Each dot represents the results obtained from an individual mouse (= 18C79, KruskalCWallis statistical test). (E) Enumeration of CD4+, CD8+ T cells and B cells in the blood of and mice (=.