Circadian rhythm is ubiquitous in nature.Circadian clock genes such as Bmal1 and Clock form a multi-level transcription-translation feedback network,and regulate a variety of physiological and pathological processes,i...Circadian rhythm is ubiquitous in nature.Circadian clock genes such as Bmal1 and Clock form a multi-level transcription-translation feedback network,and regulate a variety of physiological and pathological processes,including bone and cartilage metabolism.Deletion of the core clock gene Bmal1 leads to pathological bone alterations,while the phenotypes are not consistent.Studies have shown that multiple signaling pathways are involved in the process of Bmal1 regulating bone and cartilage metabolism,but the exact regulatory mechanisms remain unclear.This paper reviews the signaling pathways by which Bmal1 regulates bone/cartilage metabolism,the upstream regulatory factors that control Bmal1,and the current Bmal1 knockout mouse models for research.We hope to provide new insights for the prevention and treatment of bone/cartilage diseases related to circadian rhythms.展开更多
Objective To investigate the structural changes of rat thoracic aorta and changes in expression levels of Bmal1 and cyclins in thoracic aorta endothelial cells following heat stress.Methods Twenty male SD rats were ra...Objective To investigate the structural changes of rat thoracic aorta and changes in expression levels of Bmal1 and cyclins in thoracic aorta endothelial cells following heat stress.Methods Twenty male SD rats were randomized equally into control group and heat stress group.After exposure to 32℃for 2 weeks in the latter group,the rats were examined for histopathological changes and Bmal1 expression in the thoracic aorta using HE staining and immunohistochemistry.In the cell experiments,cultured rat thoracic aortic endothelial cells(RTAECs)were incubated at 40℃for 12 h with or without prior transfection with a Bmal1-specific small interfering RNA(si-Bmal1)or a negative sequence.In both rat thoracic aorta and RTAECs,the expressions of Bmal1,the cell cycle proteins CDK1,CDK4,CDK6,and cyclin B1,and apoptosis-related proteins Bax and Bcl-2 were detected using Western blotting.TUNEL staining was used to detect cell apoptosis in rat thoracic aorta,and the changes in cell cycle distribution and apoptosis in RTAECs were analyzed with flow cytometry.Results Compared with the control rats,the rats exposed to heat stress showed significantly increased blood pressures and lowered heart rate with elastic fiber disruption and increased expressions of Bmal1,cyclin B1 and CDK1 in the thoracic aorta(P<0.05).In cultured RTAECs,heat stress caused significant increase of Bmal1,cyclin B1 and CDK1 protein expression levels,which were obviously lowered in cells with prior si-Bmal1 transfection.Bmal1 knockdown also inhibited heat stress-induced increase of apoptosis in RTAECs as evidenced by decreased expression of Bax and increased expression of Bcl-2.Conclusion Heat stress upregulates Bmal1 expression and causes alterations in expressions of cyclins to trigger apoptosis of rat thoracic aorta endothelial cells,which can be partly alleviated by suppressing Bmal1 expression.展开更多
基金National Natural Science Foundation of China(82171003 and 82171002)Research and Develop Program of West China Hospital of Stomatology Sichuan University(NO.LCYJ-2022-YY-1)。
文摘Circadian rhythm is ubiquitous in nature.Circadian clock genes such as Bmal1 and Clock form a multi-level transcription-translation feedback network,and regulate a variety of physiological and pathological processes,including bone and cartilage metabolism.Deletion of the core clock gene Bmal1 leads to pathological bone alterations,while the phenotypes are not consistent.Studies have shown that multiple signaling pathways are involved in the process of Bmal1 regulating bone and cartilage metabolism,but the exact regulatory mechanisms remain unclear.This paper reviews the signaling pathways by which Bmal1 regulates bone/cartilage metabolism,the upstream regulatory factors that control Bmal1,and the current Bmal1 knockout mouse models for research.We hope to provide new insights for the prevention and treatment of bone/cartilage diseases related to circadian rhythms.
文摘Objective To investigate the structural changes of rat thoracic aorta and changes in expression levels of Bmal1 and cyclins in thoracic aorta endothelial cells following heat stress.Methods Twenty male SD rats were randomized equally into control group and heat stress group.After exposure to 32℃for 2 weeks in the latter group,the rats were examined for histopathological changes and Bmal1 expression in the thoracic aorta using HE staining and immunohistochemistry.In the cell experiments,cultured rat thoracic aortic endothelial cells(RTAECs)were incubated at 40℃for 12 h with or without prior transfection with a Bmal1-specific small interfering RNA(si-Bmal1)or a negative sequence.In both rat thoracic aorta and RTAECs,the expressions of Bmal1,the cell cycle proteins CDK1,CDK4,CDK6,and cyclin B1,and apoptosis-related proteins Bax and Bcl-2 were detected using Western blotting.TUNEL staining was used to detect cell apoptosis in rat thoracic aorta,and the changes in cell cycle distribution and apoptosis in RTAECs were analyzed with flow cytometry.Results Compared with the control rats,the rats exposed to heat stress showed significantly increased blood pressures and lowered heart rate with elastic fiber disruption and increased expressions of Bmal1,cyclin B1 and CDK1 in the thoracic aorta(P<0.05).In cultured RTAECs,heat stress caused significant increase of Bmal1,cyclin B1 and CDK1 protein expression levels,which were obviously lowered in cells with prior si-Bmal1 transfection.Bmal1 knockdown also inhibited heat stress-induced increase of apoptosis in RTAECs as evidenced by decreased expression of Bax and increased expression of Bcl-2.Conclusion Heat stress upregulates Bmal1 expression and causes alterations in expressions of cyclins to trigger apoptosis of rat thoracic aorta endothelial cells,which can be partly alleviated by suppressing Bmal1 expression.
