| Objective: With the living standard of Chinese improving gradually,the aging of social population is becoming more and more serious,and many kinds of chronic metabolic diseases are increasingly affecting the health of the elderly.The patients number of type 2 diabetes among all chronic metabolic diseases increased year by year,and the incidence of fracture was higher than that of normal patients,which brought huge economic and social burden.However,compared with other types of osteoporosis,osteoporosis induced by type 2 diabetes has complex pathological mechanism,which has not been explained clearly.The relationship between iron overload caused by high glucose and osteoporosis has been confirmed by several studies,but whether the mitochondrial ferritin(Ft Mt),which stores iron ions in mitochondrion,is related to the occurrence of osteoporosis has not been studied.As a new cell death mode found in research on a cancer drug(erastin)in recent years,ferroptosis is closely related to iron overload,but the relationship between ferroptosis and osteoporosis has not been studied.We believe that the ferroptosis of osteoblasts caused by high glucose induced iron overload is one of the reasons of type 2 diabetic osteoporosis.Ft Mt,which is involved in the regulation of iron homeostasis in cell mitochondrion,may play a role in the pathogenesis of diabetic osteoporosis.Iron overload in mitochondria can produce a large number of ROS via fendon reaction and lead to ferroptosis.Mitophagy,as a way of degrading damaged mitochondria,may regulate the occurrence of ferroptosis,and then affect the function of osteoblasts.Our research can further explain the pathogenesis of type 2 diabetic osteoporosis,and provide a new direction for the treatment and drug target of type 2 diabetic osteoporosis.Methods: We first induced the rat model of type 2 diabetic osteoporosis,and observed whether there was ferroptosis,mitophagy and the change of Ft Mt in the bone tissue of type 2 diabetic osteoporosis rats.Then we treated h FOB 1.19 cells with high concentrations of glucose(35mmol/L)for 72 hours.The expression of Ft Mt,glutathione peroxidase 4(GPX4)and osteogenic function related proteins were detected by western blot and PCR.The production of reactive oxygen species(ROS)was detected by flow cytometer with DCFH-DA probe,and the accumulation of lipid peroxidation in osteoblasts was observed by a microplate reader through the reaction of malondialdehyde(MDA)and thiobarbituric acid(TBA),and the morphology of mitochondria was observed by transmission electron microscope to determine the effect of high glucose on ferroptosis of osteoblasts.Then we used Ft Mt lentiviral to interfere osteoblasts,causing the knockdown and overexpression of Ft Mt.We observed the ferroptosis,the occurrence of mitophagy,the expression of osteogenic function related proteins,the formation of calcium nodules stained with alizarin red S in each group,and studied the effects of Ft Mt silence and overexpression on the ferroptosis,mitophagy and osteogenic function of osteoblasts.Finally,we used the agonists of mitophagy to observe the effect of mitophagy on ferroptosis and osteogenic function of osteoblasts.Results:(1)There was ferroptosis and increased mitophagy level in the bone tissue of type 2 diabetic osteoporosis rats.(2)High glucose promoted the decrease of GPX4 expression,the increase of ROS,the accumulation of lipid peroxidation,ferroptosis and the decrease of osteogenic function in h FOB 1.19 cells.(3)High glucose increased the expression of divalent metal transporter 1(DMT1)and Ft Mt in the mitochondria of osteoblasts,indicating iron overload in the mitochondria of osteoblasts.(4)After over expression of Ft Mt,GPX4 expression increased,ROS and lipid peroxidation decreased,which inhibited the ferroptosis of osteoblasts caused by high glucose and improved the function of osteoblasts.(5)Downexpression of Ft Mt increased mitophagy via ROS/PINK1/Parkin pathway.(6)Mitophagy increased ROS and lipid peroxidation in cells,and then promoted cell ferroptosis.Conclusion:(1)There was ferroptosis in the bone tissue of type 2 diabetic osteoporosis rats.(2)High glucose caused iron overload in mitochondria of osteoblasts and induced ferroptosis.(3)Overexpression of Ft Mt inhibited the ferroptosis of osteoblasts induced by high glucose,thus improving the function of osteoblasts.(4)Ft Mt silencing induced mitophagy via ROS/PINK1/Parkin pathway.Activation of mitophagy increased intracellular ROS and lipid peroxide to promote ferroptosis. |
PDF Full Text Request