Polycytosine RNA-binding protein 1 regulates osteoblast function via a ferroptosis pathway in type 2 diabetic osteoporosis

BACKGROUND Recently,type 2 diabetic osteoporosis(T2DOP)has become a research hotspot for the complications of diabetes,but the specific mechanism of its occurrence and development remains unknown.Ferroptosis caused by iron overload is con-sidered an important cause of T2DOP.Polycytosine RNA-binding protein 1(PCBP1),an iron ion chaperone,is considered a protector of ferroptosis.AIM To investigate the existence of ferroptosis and specific role of PCBP1 in the development of type 2 diabetes.METHODS A cell counting kit-8 assay was used to detect changes in osteoblast viability under high glucose(HG)and/or ferroptosis inhibitors at different concentrations and times.Transmission electron microscopy was used to examine the morpho-logical changes in the mitochondria of osteoblasts under HG,and western blotting was used to detect the expression levels of PCBP1,ferritin,and the ferroptosis-related protein glutathione peroxidase 4(GPX4).A lentivirus silenced and overex-pressed PCBP1.Western blotting was used to detect the expression levels of the osteoblast functional proteins osteoprotegerin(OPG)and osteocalcin(OCN),whereas flow cytometry was used to detect changes in reactive oxygen species(ROS)levels in each group.RESULTS Under HG,the viability of osteoblasts was considerably decreased,the number of mitochondria undergoing atrophy was considerably increased,PCBP1 and ferritin expression levels were increased,and GPX4 expression was decreased.Western blotting results demonstrated that infection with lentivirus overexpressing PCBP1,increased the expression levels of ferritin,GPX4,OPG,and OCN,compared with the HG group.Flow cytometry results showed a reduction in ROS,and an opposite result was obtained after silencing PCBP1.CONCLUSION PCBP1 may protect osteoblasts and reduce the harm caused by ferroptosis by promoting ferritin expression under a HG environment.Moreover,PCBP1 may be a potential therapeutic target for T2DOP.

Establishment and evaluation of Type 2 Diabetes Mellitus andits complications induced by low dose of multiple streptozotocin

Objective: To explore a simple, economical and feasible method for establishing type 2 diabetes mellitus and its complication model. Method: SD rats were randomly divided into two groups: normal group (15 rats) normal diet, model group (20 rats) with high glucose and high fat diet. After 2 weeks of feeding, model group was injected low dose(30mg/Kg) streptozotocin in the abdominal cavity, once a day for 6 days, normal group was injected with the same dose of citric acid buffer. Observe the changes of rat diet, body, hair, spirit, urine volume, and monitor weight, blood glucose. After 6 weeks, fast insulin, blood lipid, serum calcium, phosphorus and other biochemical indexes of rats, after HE staining observe morphologic variations changes of pancreas and kidney using microscope, and the changes of femoral bone in SD rats. Results: Compared with the normal group, the model group showed obvious symptoms, drink more, eat more, polyuria, emaciation, hyperglycemia, low calcium, low phosphorus, hyperlipidemia and other metabolic abnormalities, pancreatic atrophy, tissue fibrosis, glomerular area increased, basement membrane thickening, osteoporosis. Conclusion:High glucose and high fat diet combined with repeated intraperitoneal injecti on of low dose STZ can be successfully established the model of type 2 diabetes, and its high successful rate, low mortality rate, relatively simple, economical and feasible, has a certain significance of research on diabetes and its complications.

Effect of Chongcao Bushen Capsule on bone turnover markers in patients with diabetic osteoporosis

Objective:To study the effect of Chongcao Bushen Capsules on bone turnover markers in patients with diabetic osteoporosis.Methods:107 patients with diabetic osteoporosis treated in the Hospital from December 2016 to November 2019were enrolled.They were divided into a control group(n=54)and an observation group(n=53)by random number table.The control group was treated with calcium carbonate,and the observation group was treated with Chongcao Bushen Capsules.The treatment effects,TCM syndrome scores,and bone turnover markers[including osteocalcin,type 1 procollagen amino-terminal propeptide(tP1NP),parathyroid hormone(PTH),25-hydroxyvitamin D,andβ-isomerized c-terminal peptide(β-CTx)],and the incidence of adverse reactions in the two groups were observed and compared.Results:After treatment,the total effective rate of treatment in the observation group(94.44%)was higher than that in the control group(73.58%),and the difference was statistically significant(P<0.05).The scores of symptoms including waist and knee weakness,back and waist pain,lower limb weakness,fatigue and tiredness,difficult walking and dizziness in the observation group were shown to be lower than the control group,and the difference was statistically significant(P<0.05).The levels of osteocalcin,PTH,tP1NP,andβ-CTx in the observation group were lower than those in the control group,and the difference was statistically significant(P<0.05).The 25-hydroxyvitamin D in the observation group was higher than the control group,and the difference was statistically significant(P<0.05).Bone density in both male and female in the observation group was higher than that in the control group,and the difference was statistically significant(P<0.05).Conclusion:For patients with diabetic osteoporosis,Chongcao Bushen Capsule can help improve their clinical symptoms,bone density and the level of bone turnover markers.

IGF-1R/β-catenin signaling axis is involved in type 2 diabetic osteoporosis

Insulin-like growth factor-1 receptor(IGF-1 R)is involved in both glucose and bone metabolism.IGF-1 R signaling regulates the canonical Wnt/β-catenin signaling pathway.In this study,we investigated whether the IGF-1 R/β-catenin signaling axis plays a role in the pathogenesis of diabetic osteoporosis(DOP).Serum from patients with or without DOP was collected to measure the IGF-1 R level using enzyme-linked immunosorbent assay(ELISA).Rats were given streptozotocin following a four-week high-fat diet induction(DOP group),or received vehicle after the same period of a normal diet(control group).Dual energy X-ray absorption,a biomechanics test,and hematoxylin-eosin(HE)staining were performed to evaluate bone mass,bone strength,and histomorphology,respectively,in vertebrae.Quantitative real-time polymerase chain reaction(qRT-PCR)and western blotting were performed to measure the total and phosphorylation levels of IGF-1 R,glycogen synthase kinase-3β(GSK-3β),andβ-catenin.The serum IGF-1 R level was much higher in patients with DOP than in controls.DOP rats exhibited strikingly reduced bone mass and attenuated compression strength of the vertebrae compared with the control group.HE staining showed that the histomorphology of DOP vertebrae was seriously impaired,which manifested as decreased and thinned trabeculae and increased lipid droplets within trabeculae.PCR analysis demonstrated that IGF-1 R mRNA expression was significantly up-regulated,and western blotting detection showed that phosphorylation levels of IGF-1 R,GSK-3β,andβ-catenin were enhanced in DOP rat vertebrae.Our results suggest that the IGF-1 R/β-catenin signaling axis plays a role in the pathogenesis of DOP.This may contribute to development of the underlying therapeutic target for DOP.