Transcriptome Sequencing Analysis (RNA-Seq) of Bone Marrow Hematopoietic Stem Cells from Per2-mutant Mice

Circadian rhythm (CR) and environmental low-dose radiation (LDR) evident on Earth's surface may have coordinated in the evolution of early life; disturbed CR and/or overexposure to radiation are linked with aging and many human diseases including cancer. Although CR affects tumor response and normal tissue radiosensitivity in cancer radiotherapy, it is unclear how CR proteins function in LDR induced radioprotection. Herein, we demonstrated that mice carrying a deficient Period2 gene (C57BL-Per2 def ), a core CR regulator, were highly sensitive to radiation. Compared to Per2 wt mice, the population of bone marrow hemopoietic stem cells (BMHSCs) was reduced and a cluster of genes responsible for DNA damage repair and mitochondrial metabolism was silenced in the Per2 def BMHSCs . Consistently, unlike Per2 wt human and mouse cells capable of inducible radioresistance by LDR, Per2 def cells failed to induce such adaptive protection. Furthermore, LDR enhanced PER2 protein level together with phosphorylated GSK3ß (pGSK3ß) in the Wnt/ß-catenin signaling pathway. Interaction of PER2 with pGSK3ß activated ß -catenin that in turn transactivated Per2 and other prosurvival genes. These results provide new insights into how CR and LDR communicate in genotoxic stress response. The PER2/pGSK3ß/ß-catenin/Per2 pathway may serve as a therapeutic approach to reduce normal cell injury in cancer radiotherapy. Overall design: A total of 2 samples were analyzed in this study. The study included 2 samples of mouse bone marrow hematopoietic stem cells (HMCs) obtained from wild-type (Per2wt) and Per2-deficient (Per2def). The bone marrow HMCs were enriched by cell sorting into culture medium, pelleted by centrifugation, and harvested,. Total RNA was isolated and then submitted for RNA-sequencing analysis.