Regulation of 3-O-Sulfation of Heparan Sulfate During Transition from the Naïve to the Primed State in Mouse Embryonic Stem Cells

Chronic Low-Dose-Rate Radiation-Induced Persistent DNA Damage and miRNA/mRNA Expression Changes in Mouse Hippocampus and Blood

Our previous study demonstrated that the acute high-dose-rate (3.3 Gy/min) γ-ray irradiation (γ-irradiation) of postnatal day-3 (P3) mice with 5 Gy induced depression and drastic neuropathological changes in the dentate gyrus of the hippocampus of adult mice. The present study investigated the effects of chronic low-dose-rate (1.2 mGy/h) γ-irradiation from P3 to P180 with a cumulative dose of 5 Gy on animal behaviour, hippocampal cellular change, and miRNA and mRNA expression in the hippocampus and blood in female mice. The radiation exposure did not significantly affect the animal's body weight, and neuropsychiatric changes such as anxiety and depression were examined by neurobehavioural tests, including open field, light-dark box, elevated plus maze, tail suspension, and forced swim tests. Immunohistochemical staining did not detect any obvious loss of mature and immature neurons (NeuN and DCX) or any inflammatory glial response (IBA1, GFAP, and PDGFRα). Nevertheless, γH2AX foci in the stratum granulosum of the dentate gyrus were significantly increased, suggesting the chronic low-dose-rate irradiation induced persistent DNA damage foci in mice. miRNA sequencing and qRT-PCR indicated an increased expression of miR-448-3p and miR-361-5p but decreased expression of miR-193a-3p in the mouse hippocampus. Meanwhile, mRNA sequencing and qRT-PCR showed the changed expression of some genes, including Fli1, Hs3st5, and Eif4ebp2. Database searching by miRDB and TargetScan predicted that Fli1 and Hs3st5 are the targets of miR-448-3p, and Eif4ebp2 is the target of miR-361-5p. miRNA/mRNA sequencing and qRT-PCR results in blood showed the increased expression of miR-6967-3p and the decreased expression of its target S1pr5. The interactions of these miRNAs and mRNAs may be related to the chronic low-dose-rate radiation-induced persistent DNA damage.

RREB1 regulates neuronal proteostasis and the microtubule network

Transcription factors play vital roles in neuron development; however, little is known about the role of these proteins in maintaining neuronal homeostasis. Here, we show that the transcription factor RREB1 (Ras-responsive element-binding protein 1) is essential for neuron survival in the mammalian brain. A spontaneous mouse mutation causing loss of a nervous system-enriched Rreb1 transcript is associated with progressive loss of cerebellar Purkinje cells and ataxia. Analysis of chromatin immunoprecipitation and sequencing, along with RNA sequencing data revealed dysregulation of RREB1 targets associated with the microtubule cytoskeleton. In agreement with the known role of microtubules in dendritic development, dendritic complexity was disrupted in Rreb1-deficient neurons. Analysis of sequencing data also suggested that RREB1 plays a role in the endomembrane system. Mutant Purkinje cells had fewer numbers of autophagosomes and lysosomes and contained P62- and ubiquitin-positive inclusions. Together, these studies demonstrate that RREB1 functions to maintain the microtubule network and proteostasis in mammalian neurons.