ABSTRACT
Plant circadian clock coordinates endogenous transcriptional rhythms with diurnal changes of environmental cues. OsPRR37, a negative component in the rice circadian clock, reportedly regulates transcriptome rhythms, and agronomically important traits. However, the underlying regulatory mechanisms of OsPRR37-output genes remain largely unknown. In this study, whole genome bisulfite sequencing and high-throughput RNA sequencing were applied to verify the role of DNA methylation in the transcriptional control of OsPRR37-output genes. We found that the overexpression of OsPRR37 suppressed rice growth and altered cytosine methylations in CG and CHG sequence contexts in but not the CHH context (H represents A, T, or C). In total, 35 overlapping genes were identified, and 25 of them showed negative correlation between the methylation level and gene expression. The promoter of the hexokinase gene OsHXK1 was hypomethylated at both CG and CHG sites, and the expression of OsHXK1 was significantly increased. Meanwhile, the leaf starch content was consistently lower in OsPRR37 overexpression lines than in the recipient parent Guangluai 4. Further analysis with published data of time-course transcriptomes revealed that most overlapping genes showed peak expression phases from dusk to dawn. The genes involved in DNA methylation, methylation maintenance, and DNA demethylation were found to be actively expressed around dusk. A DNA glycosylase, namely ROS1A/DNG702, was probably the upstream candidate that demethylated the promoter of OsHXK1. Taken together, our results revealed that CG and CHG methylation contribute to the transcriptional regulation of OsPRR37-output genes, and hypomethylation of OsHXK1 leads to decreased starch content and reduced plant growth in rice.
ABSTRACT
BACKGROUND: Giant cell tumour (GCT) of the bone is a rare, invasive benign bone tumour, which typically originates in the metaphyseal ends of long bones and rarely in the spine. Here, we report a rare case of recurrent GCT of the thoracic vertebra, which was managed by three-level total en bloc spondylectomy (TES) after denosumab therapy. CASE PRESENTATION: A 50-year-old woman presented with a 2-month history of progressive lower back pain. Magnetic resonance imaging revealed destruction of the T11 vertebra and a soft tissue mass. The patient underwent tumour resection. Computed tomography at the 2-year follow-up revealed relapse of the resected tumour, which had spread to the T12 vertebral body. Subsequently, denosumab therapy was administered to the patient for 1 year. The growth of the tumour was controlled, and its boundary line was clear. Thereafter, TES for the T10-T12 vertebrae was performed, and spinal reconstruction was completed through a one-stage single posterior approach. The patient's condition improved postoperatively, and no evidence of recurrence of GCT of the bone or spinal deformity was observed at the 32-month follow-up. CONCLUSIONS: Denosumab therapy contributed to tumour regression. Three-level TES may be an effective and feasible strategy for managing large recurrent GCTs of the spine after denosumab therapy.
