Fig 1: Mysm1 is expressed in NSCs, and Mysm1-deficient mice reveal overactivation and preferential neuronal differentiation of NSCs.A, B Immunofluorescence for the indicated markers in the SGZ and SVZ of 4-week-old mice. Mysm1 was coexpressed in some Nestin+ NSCs or rGfap+ NSCs (white arrows). The boxed areas are shown in detail as insets. C Nestin-Cre mice were crossed with Mysm1fl/fl mice to generate Mysm1 conditional knockout embryos. D Genotyping was performed with the indicated primers. The upper band indicates floxed, and the lower band indicates wild-type. E The knockout efficiency was verified by qRT-PCR analysis and western blot analysis of NSCs prepared from CTRL and cKO mice (n = 3). F Comparisons of the appearance of the brain parenchyma (left) and the external morphology (right, 9-week-old) of CTRL and Mysm1 cKO mice. G Schematic diagram of NSC development in neurogenesis niches. New neurons in the OB and DG of the adult brain are generated from NSCs in the SVZ and SGZ, respectively. Immunofluorescence (left) for Nestin, Ki67, and DAPI in the SGZ (H) or SVZ (I) of 2-week-old CTRL and Mysm1 cKO mice. Number (right upper) of Nestin+ NSCs and percentage (right lower) of Ki67+ Nestin+ NSCs among total Nestin+ NSCs in the SGZ (H) or SVZ (I) of 2-week-old CTRL and Mysm1 cKO mice (n = 3). Immunofluorescence (left) for Nestin, Ki67, and DAPI in the SGZ of 4-week-old (J) and 6-week-old (K) CTRL and Mysm1 cKO mice. Number (right upper) of Nestin+ NSCs and percentage (right lower) of Ki67+ Nestin+ NSCs among total Nestin+ NSCs in the SGZ of 4-week-old (J) and 6-week-old (K) CTRL and Mysm1 cKO mice (n = 3). L Immunofluorescence (left) for Tbr2 and DAPI in the DG of 6-week-old CTRL and Mysm1 cKO mice. Quantification (right) of Tbr2+ cells per DG section in 6-week-old CTRL and Mysm1 cKO mice (n = 3). M Immunofluorescence (left and middle) for Dcx and DAPI in the DG of CTRL and Mysm1 cKO mice at 6 weeks and 9 weeks. The boxed areas are shown in detail on the right side. Quantification (right) of Dcx+ cells per DG section in CTRL and Mysm1 cKO mice at 6 weeks and 9 weeks (n = 3). SGZ subgranular zone, SVZ subventricular zone, Hi Hilus, LV lateral ventricles, GCL granule cell layer, DG dentate gyrus, cc corpus callosum, St striatum, wk week. Data are presented as the mean value ± SEM. ns not significant; *p < 0.05, **p < 0.01, and ****P < 0.0001. Scale bars represent 20 μm (A, B), 50 μm (H–K), and 100 μm (L, M).