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Although stem cells can proliferate and differentiate through the completion of cell cycle progression, little is known about the genes and molecular mechanisms controlling this process. Here, we investigated the effect of the inhibition of cell cycle by cyclin D1 gene knockout on proliferation and differentiation of neural stem cells (NSCs). Knockout of cyclin D1 induced the cultured neural stem cells arrested at the G0/G1 phase as detected by flow cytometry. Cyclin D1 knockout led to the apoptosis of NSCs and inhibited the differentiation into astrocytes without affecting the differentiation into neurons. We further demonstrated that a significant reduction of BrdU+ cells in the subgranular zone of the dentate gyrus and subventricular zone was found in cyclin D1 gene knockout (cyclin D1(-/-)) mice compared with cyclin D1(+/+) and cyclin D1(+/-) mice. These observations demonstrated that cyclin D1 plays essential roles in the proliferation and differentiation of neural stem cells.

Background Schizophrenia is a severe psychiatric disorder with a high heritability. A single nucleotide polymorphism (SNP) rs1625579 (G/T; T is the common and presumed risk allele) within an intron of miR-137 gene has been recently suggested to contribute to the susceptibility to schizophrenia by a large-scale genome-wide association study (GWAS) in a sample of predominantly European ancestry. However, subsequent genetic association studies in Chinese population yielded inconsistent results. Methods A meta-analysis reporting the association between rs1625579 and schizophrenia in Chinese population was carried out, pooling 4 eligible case–control studies involving 2847 patients and 3018 controls. Results This meta-analysis demonstrated a significant association between rs1625579 and schizophrenia under the allele model [T versus G, odds ratio (OR):1.20, 95% confidence interval (CI): 1.06–1.36] and the recessive model (TT versus GT + GG; OR: 1.19; 95% CI: 1.04–1.37). Additionally, a marginal significant association under the additive model (TT versus GG; OR: 1.64; 95% CI: 1.00–2.69) was observed. However, no significant association was observed under the dominant model (TT + GT versus GG; OR: 1.58; 95% CI: 0.97–2.59). Conclusions This meta-analysis suggested that the SNP rs1625579 in miR-137 gene might be involved in schizophrenia susceptibility in Chinese Han population.