Circadian modulation of glucose utilization via CRY1-mediated repression of Pdk1 expression.

Life adapts to daily environmental changes through circadian rhythms, exhibiting spontaneous oscillations of biological processes. These daily functional oscillations must match the metabolic requirements responding to the time of the day. We focus on the molecular mechanism of how the circadian clock regulates glucose, the primary resource for energy production and other biosynthetic pathways. The complex regulation of the circadian rhythm includes many proteins that control this process at the transcriptional and translational levels and by protein-protein interactions. We have investigated the action of one of these proteins, cryptochrome (CRY), whose elevated mRNA and protein levels repress the function of an activator in the transcription-translation feedback loop, and this activator causes elevated Cry1 mRNA. We used a genome-edited cell line model to investigate downstream genes affected explicitly by the repressor CRY. We found that CRY can repress glycolytic genes, particularly that of the gatekeeper, pyruvate dehydrogenase kinase 1 (Pdk1), decreasing lactate accumulation and glucose utilization. CRY1-mediated decrease of Pdk1 expression can also be observed in a breast cancer cell line MDA-MB-231, whose glycolysis is associated with Pdk1 expression. We also found that exogenous expression of CRY1 in the MDA-MB-231 decreases glucose usage and growth rate. Furthermore, reduced CRY1 levels and the increased phosphorylation of PDK1 substrate were observed when cells were grown in suspension compared to cells grown in adhesion. Our data supports a model that the transcription-translation feedback loop can regulate the glucose metabolic pathway through Pdk1 gene expression according to the time of the day.

Clinical features of postinfectious bronchiolitis obliterans in children undergoing long-term nebulization treatment.

BACKGROUND: Limited data are available in relation to the clinical features of PIBO undergoing prolonged nebulization treatment with budesonide, terbutaline and ipratropium bromide. This retrospective study aimed to outline the features of clinical, high-resolution computed tomography (HRCT) and pulmonary function test (PFT) of PIBO, undergoing maintenance therapy utilizing a triple nebulization treatment and to determine the factors associated with prognosis. METHODS: Children diagnosed with PIBO were followed up between April 2014 and March 2017. The clinical features after maintenance nebulization treatment for 12 months were thereafter summarized. RESULTS: Thirty patients, 21 boys and 9 girls, were enrolled in the study. The median age of patients was 17.4 months, with a range between 3.0 and 33 months. Persistent coughing and wheezing were detected whilst wheezing and crackles were the common manifestations presented. HRCT scans revealed patchy ground and glass opacity, while PFT showed fixed airway obstruction in all patients. Four patients were lost during follow-up. After treatment, the clinical symptoms were improved greatly in all patients (P < 0.01). The mean increase in the percentage of TPEF%TE and VPEF%VE were improved greatly (P < 0.01). Images of the HRCT scan indicated marked improvements in 18 patients (81.8%) in comparison with scans obtained pre-treatment. CONCLUSIONS: Our data suggest a potential role of long-term nebulization treatment of budesonide, terbutaline, ipratropium bromide on PIBO, due to its efficacy as indicated in the improved clinical symptoms, pulmonary functions and CT manifestations identified in the children. New prospective and controlled studies are required to confirm this proposition.