Role and mechanism of histone deacetylases in mouse neuronal development

OBJECTIVE To study the role and mechanism of histone deacetylase 1 (HDAC1) and histone deacetylase 2 (HDAC2) in mouse neuronal development. METHODS The mice with Synapsin1-Cre recombinase were bred with HDAC1&2flox/flox mice to obtain the mice with neuron-specific HDAC1&2 conditional knockout (knockout group), and their littermates without HDAC1&2 knockout were used as the control group. The general status of the mice was observed and survival curves were plotted. Brain tissue samples were collected from the knockout group and the control group. Western blot and immunohistochemistry were used to measure the protein expression of related neuronal and axonal markers, neuronal nuclear antigen (NeuN), non-phosphorylated neurofilament heavy chain (np-NF200), and phosphorylated neurofilament heavy chain (p-NF200), as well as the downstream effector of the mTOR signaling pathway, phosphorylated S6 ribosomal protein (p-S6). RESULTS The mice with HDAC1&2 conditional knockout usually died within one month after birth and were significantly smaller than those in the control group, with motor function abnormalities such as tremor and clasping of hindlimbs. Compared with the control group, the knockout group had significant reductions in the protein expression levels of NeuN, np-NF200, p-NF200, and p-S6 (P < 0.05; n=3). CONCLUSIONS Deletion of HDAC1 and HDAC2 in mouse neurons results in reduced neuronal maturation and axonal dysplasia, which may be associated with the mTOR signaling pathway.