High-glucose Induced Mitochondrial Dynamics Disorder of Spinal Cord Neurons in Diabetic Rats and its Effect on Mitochondrial Spatial Distribution

Mitochondrial dynamics-related genes DRP1 and OPA1 contributes to early diagnosis of cognitive impairment in diabetes

BACKGROUND AND AIM

DRP1 and OPA1 play important roles in mitochondrial fusion and fission. However, the role of DRP1 and OPA1 amplification in mitochondrial cognitive impairment has not been reported. This study aimed to investigate the relationship between DRP1 and OPA1 and the risk of cognitive impairment.

METHODS

In this study, 45 elderly patients with diabetes admitted to the Lianyungang Second People's Hospital from September 2020 to January 2021 were included. The patients were divided into normal group, mild cognitive impairment group and dementia group by using MMSE score, and the clinical characteristics of the three groups were compared. The amplification multiples of the two genes' DNA were calculated by ΔΔCT and defined as 2- K. Spearman rank correlation was used to analyze the correlation between the DNA amplification multiples of patients' DRP1 and OPA1 and AD8 and MoCA scores. The sensitivity and specificity of DNA amplification multiples of DRP1 and OPA1 to predict clinical outcomes of diabetic cognitive impairment were evaluated using Receiver operator characteristic (ROC) curves. Multiple logistic regression was used to evaluate the relationship between DNA amplification factor of DRP1 and OPA1 and cognitive function.

RESULTS

DRP1(2- K) and OPA1(2- K) significantly increased and decreased in dementia and MCI groups compared with the normal group (P ≤ 0.001). The DNA amplification factor of DRP1 was positively correlated with AD8 score and negatively correlated with MoCA score (P < 0.001). The DNA amplification factor of OPA1 was positively correlated with the MoCA score (P = 0.0002). Analysis of ROCs showed that the DNA amplification factor of OPA1 had a higher predictive value for dementia (P < 0.0001), and that it had a higher predictive value when used in combination with DRP1. Multiple logistic regression results showed that increased DNA amplification in DRP1 was associated with increased risk of dementia (OR 1.149;95%CI,1.035-1.275), and increased DNA amplification in OPA1 was associated with decreased risk of MCI (OR 0.004;95%CI,0.000-0.251) and dementia (OR 0.000;95%CI,0.000-0.134).

CONCLUSION

DNA amplification multiples of DRP1 and OPA1 are associated with the risk of dementia in elderly patients and may serve as potential biomarkers.

Neuroprotective Effects of Curcumin against Oxygen-Glucose Deprivation/Reoxygenation-Induced Injury in Cultured Primary Rat Astrocyte by Improving Mitochondrial Function and Regulating the ERK Signaling Pathway

Objectives

Curcumin (Cur) is a natural polyphenol isolated from turmeric and has potent anti-inflammatory and antioxidant activities. This study aimed to explore the effects and possible mechanisms of curcumin on oxygen-glucose deprivation/reoxygenation (OGD/R)-induced injury in cultured rat astrocyte primary cells.

Methods

After screening for effective doses, the cultured rat astrocyte primary cells were divided into three groups: control, OGD/R, and OGD/R + curcumin (10 μM, 20 μM, and 40 μM). Cell viability was detected using CCK8 assays. The level of malondialdehyde and superoxide dismutase activity was determined using commercial kits. The endothelial nitric oxide synthase and adenosine triphosphate concentrations were determined by enzyme-linked immunosorbent assay. The mRNA levels of the inflammatory indexes interleukin (IL)-6, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-1β were evaluated by quantitative reverse-transcription polymerase chain reaction. Annexin V-fluorescein isothiocyanate/propidium iodide was used to detect apoptosis. JC-1 was used to assess the mitochondrial membrane potential. The protein expression of apoptosis-related proteins (B-cell lymphoma-2 (Bcl-2), BCL-2-associated X (Bax), and cleaved caspase 3), mitochondria-related proteins (dynamin-related protein 1 (DRP1), phosphorylated DRP1 (p-DRP1), and mitofusin 2), and essential proteins of the extracellular signal-regulated kinase (ERK) signaling pathway (ERK1/2, p-ERK1/2) were analyzed by western blot.

Results

Our data indicated that curcumin reversed OGD/R-induced cell viability loss, oxidative stress, inflammatory cytokine production, and cell apoptosis in a dose-dependent manner. Furthermore, curcumin attenuated OGD/R-induced mitochondrial dysfunction and ERK1/2 phosphorylation in a dose-dependent manner.

Conclusions

Curcumin protected against OGD/R-induced injury in rat astrocyte primary cells through improving mitochondrial function and regulating the ERK signaling pathway.

Induced Effect of Zinc oxide nanoparticles on human acute myeloid leukemia cell apoptosis by regulating mitochondrial division

Zinc oxide nanoparticles (ZnO NPs) have exhibited excellent anti-tumor, the present study aimed to elucidate the underlying mechanism of ZnO NPs induced apoptosis in acute myeloid leukemia (AML) cells by regulating mitochondrial division. THP-1 cells, an AML cell line, were first incubated with different concentrations ZnO NPs for 24 h. Next, the expression of Drp-1, Bcl-2, Bax mRNA and protein was detected, and the effects of ZnO NPs on the levels of reactive oxygen species (ROS), mitochondrial membrane potential (Δψm), apoptosis and ATP generation in THP-1 cells were measured. Moreover, the effect of Drp-1 inhibitor Mdivi-1 and ZnO NPs on THP-1 cells was also detected. The results showed that the THP-1 cells survival rate decreased with the increment of ZnO NPs concentration and incubation time in a dose- and time-dependent manner. ZnO NPs can reduce the cell Δψm and ATP levels, induce the ROS production, and increase the levels of mitochondrial division and apoptosis. In contrast, the apoptotic level was significantly reduced after intervention of Drp-1 inhibitor, suggesting that ZnO NPs can induce the apoptosis of THP-1 cells by regulating mitochondrial division. Overall, ZnO NPs may provide a new basis and idea in treating human acute myeloid leukemia in clinical practice. This article is protected by copyright. All rights reserved.

Opa1 Deficiency Promotes Development of Retinal Vascular Lesions in Diabetic Retinopathy

This study investigates whether reduced optic atrophy 1 (Opa1) level promotes apoptosis and retinal vascular lesions associated with diabetic retinopathy (DR). Four groups of mice: wild type (WT) control mice, streptozotocin (STZ)-induced diabetic mice, Opa1^+/- mice, and diabetic Opa1^+/- mice were used in this study. 16 weeks after diabetes onset, retinas were assessed for Opa1 and Bax levels by Western blot analysis, and retinal networks were examined for acellular capillaries (AC) and pericyte loss (PL). Apoptotic cells were detected in retinal capillaries using TUNEL assay, and caspase-3 activity was assessed using fluorometric analysis. Opa1 expression was significantly downregulated in retinas of diabetic and Opa1^+/- mice compared with those of WT mice. Inducing diabetes further decreased Opa1 expression in retinas of Opa1^+/- mice. Increased cytochrome c release concomitant with increased level of pro-apoptotic Bax and elevated caspase-3 activity were observed in retinas of diabetic and Opa1^+/- mice; the number of TUNEL-positive cells and AC/PL was also significantly increased. An additional decrease in the Opa1 level in retinas of diabetic Opa1^+/- mice exacerbated the development of apoptotic cells and AC/PL compared with those of diabetic mice. Diabetes-induced Opa1 downregulation contributes, at least in part, to the development of retinal vascular lesions characteristic of DR.

Interactions between dietary carbohydrate and thiamine: implications on the growth performance and intestinal mitochondrial biogenesis and function of Megalobrama amblycephala

A12-week experiment was conducted to evaluate the influences of thiamine ongrowth performance, and intestinal mitochondrial biogenesis and function of Megalobramaamblycephala fed a high-carbohydrate (HC) diet. Fish (24·73 (sem 0·45) g) were randomly assigned to one of four diets: two carbohydrate (CHO) levels (30 and 45 %) and two thiamine levels (0 and 1·5 mg/kg). HC diets significantly decreased DGC, GRMBW, FIMBW, intestinal activities of amylase, lipase, Na+, K+-ATPase, CK, complexes I, III and IV, intestinal ML, number of mitochondrial per field, ΔΨm, the P-AMPK: T-AMPK ratio, PGC-1β protein expression as well as the transcriptions of AMPKα1, AMPKα2, PGC-1β, mitochondrial transcription factor A, Opa-1, ND-1 and COX-1 and 2, while the opposite was true for ATP, AMP and reactive oxygen species, and the transcriptions of dynamin-related protein-1, fission-1 and mitochondrial fission factor. Dietarythiamine concentrations significantly increased DGC, GRMBW, intestinal activities of amylase, Na+, K+-ATPase, CK, complexes I and IV, intestinal ML, number of mitochondrial per field, ΔΨm, the P-AMPK:T-AMPK ratio, PGC-1β protein expression as well as the transcriptions of AMPKα1, AMPKα2, PGC-1β, Opa-1, ND-1, COX-1 and 2, SGLT-1 and GLUT-2. Furthermore, a significant interaction between dietary CHO and thiamine was observed in DGC, GRMBW, intestinal activities of amylase, CK, complexes I and IV, ΔΨm, the AMP:ATP ratio, the P-AMPK:T-AMPK ratio, PGC-1β protein expression as well as the transcriptions of AMPKα1, AMPKα2, PGC-1β, Opa-1, COX-1 and 2, SGLT-1 and GLUT-2. Overall, thiamine supplementation improved growth performance, and intestinal mitochondrial biogenesis and function of M. amblycephala fed HC diets.

Diabetes Mellitus, Mitochondrial Dysfunction and Ca2+-Dependent Permeability Transition Pore

Diabetes mellitus is one of the most common metabolic diseases in the developed world, and is associated either with the impaired secretion of insulin or with the resistance of cells to the actions of this hormone (type I and type II diabetes, respectively). In both cases, a common pathological change is an increase in blood glucose—hyperglycemia, which eventually can lead to serious damage to the organs and tissues of the organism. Mitochondria are one of the main targets of diabetes at the intracellular level. This review is dedicated to the analysis of recent data regarding the role of mitochondrial dysfunction in the development of diabetes mellitus. Specific areas of focus include the involvement of mitochondrial calcium transport systems and a pathophysiological phenomenon called the permeability transition pore in the pathogenesis of diabetes mellitus. The important contribution of these systems and their potential relevance as therapeutic targets in the pathology are discussed.