Targeting mitochondria with folic acid and vitamin B12 ameliorates nicotine mediated islet cell dysfunction

Centella asiatica mitigates the detrimental effects of Bisphenol-A (BPA) on pancreatic islets

Bisphenol-A (BPA) is widely used in food packaging and household products, leading to daily human exposure and potential health risks including metabolic diseases like type 2 diabetes mellitus (T2DM). Understanding BPA's mechanisms and developing intervention strategies is urgent. Centella asiatica, a traditional herbal medicine containing pentacyclic triterpenoids, shows promise due to its antioxidant and anti-inflammatory properties, utilized for centuries in Ayurvedic therapy. We investigated the effect of Centella asiatica (CA) ethanol extract on BPA-induced pancreatic islet toxicity in male Swiss albino mice. BPA administration (10 and 100 μg/kg body weight, twice daily) for 21 days caused glucose homeostasis disturbances, insulin resistance, and islet dysfunction, which were partially mitigated by CA supplementation (200 and 400 mg/kg body weight). Additionally, heightened oxidative stress, elevated levels of proinflammatory cytokines, loss of mitochondrial membrane potential (MMP), abnormal cell cycle, and increased apoptosis were implicated in the detrimental impact of BPA on the endocrine pancreas which were effectively counteracted by CA supplementation. In summary, CA demonstrated a significant ability to mitigate BPA-induced apoptosis, modulate redox homeostasis, alleviate inflammation, preserve MMP, and regulate the cell cycle. As a result, CA emerged as a potent agent in neutralizing the diabetogenic effects of BPA to a considerable extent.

Mitochondria-mediated Ferroptosis in Diseases Therapy: From Molecular Mechanisms to Implications

Ferroptosis, a type of cell death involving iron and lipid peroxidation, has been found to be closely associated with the development of many diseases. Mitochondria are vital components of eukaryotic cells, serving important functions in energy production, cellular metabolism, and apoptosis regulation. Presently, the precise relationship between mitochondria and ferroptosis remains unclear. In this study, we aim to systematically elucidate the mechanisms via which mitochondria regulate ferroptosis from multiple perspectives to provide novel insights into mitochondrial functions in ferroptosis. Additionally, we present a comprehensive overview of how mitochondria contribute to ferroptosis in different conditions, including cancer, cardiovascular disease, inflammatory disease, mitochondrial DNA depletion syndrome, and novel coronavirus pneumonia. Gaining a comprehensive understanding of the involvement of mitochondria in ferroptosis could lead to more effective approaches for both basic cell biology studies and medical treatments.

Vitamin B12-folic acid supplementation improves memory by altering mitochondrial dynamics, dendritic arborization, and neurodegeneration in old and amnesic male mice

Memory impairment during aging and amnesia is attributed to compromised mitochondrial dynamics and mitophagy and other mitochondrial quality control mechanisms. Mitochondrial dynamics involves the continuous process of fission and fusion of mitochondria within a cell and is a fundamental mechanism for regulating mitochondrial quality and function. An extensive range of potential nutritional supplements has been shown to improve mitochondrial health, synaptic plasticity, and cognitive functions. Previous findings revealed that supplementation of vitamin B12-folic acid reduces locomotor deficits and mitochondrial abnormalities but enhances mitochondrial and neuronal health. The present study aims to explore the impact of combined vitamin B12-folic acid supplementation on mitochondrial dynamics, neuronal health, and memory decline in old age and scopolamine-induced amnesia, which remains elusive. The results demonstrated that supplementation led to a noteworthy increase in recognition and spatial memory and expression of memory-related protein BDNF in old and amnesic mice. Moreover, the decrease in the fragmented mitochondrial number was validated by the downregulation of mitochondrial fission p-Drp1 (S616) protein and the increase in elongated mitochondria by the upregulation of mitochondrial fusion Mfn2 protein. The increased spine density and dendritic arborization in old and amnesic mice upon supplementation were confirmed by the enhanced expression level of PSD95 and synaptophysin. Furthermore, supplementation reduced ROS production, inhibited Caspase-3 activation, mitigated neurodegeneration, and enhanced mitochondrial membrane potential, ATP production, Vdac1 expression, myelination, in old and amnesic mice. Collectively, our findings imply that combined supplementation of vitamin B12-folic acid improves mitochondrial dynamics and neuronal health, and leads to recovery of memory during old age and amnesia.

Folate-assisted targeted photocytotoxicity of red-light-activable iron(III) complex co-functionalized gold nanoconjugates (Fe@FA-AuNPs) against HeLa and triple-negative MDA-MB-231 cancer cells

Photo-redox chemistry resulting from ligand to metal charge transfer in red-light-activable iron(III) complexes could be a potent strategic tool for next-generation photochemotherapeutic applications. Herein, we developed an iron(III) complex and folate co-functionalized gold nanoconjugate (Fe@FA-AuNPs) and thoroughly characterized it with NMR, ESI MS, UV-visible, EPR, EDX, XPS, powder X-ray diffraction, TEM and DLS studies. There was a remarkable shift in the SPR band of AuNPs to 680 nm, and singlet oxygen (1O2) and hydroxyl radicals were potently generated upon red-light activation, which were probed by UV-visible and EPR spectroscopic assays. Cellular uptake studies of the nanoconjugate (Fe@FA-AuNPs) revealed significantly higher uptake in folate(+) cancer cells (HeLa and MDA-MB-231) than folate(-) (A549) cancer cells or normal cells (HPL1D), indicating the targeting potential of the nanoconjugate. Confocal imaging indicated primarily mitochondrial localization. The IC50 values of the nanoconjugate determined from a cell viability assay in HeLa, MDA-MB-231, and A549 cells were 27.83, 39.91, and 69.54 μg mL-1, respectively in red light, while in the dark the values were >200 μg mL-1; the photocytotoxicity was correlated with the cellular uptake of the nanoconjugate. The nanocomposite exhibited similar photocytotoxicity (IC50 in red light, 37.35 ± 8.29 μg mL-1 and IC50 in the dark, >200 μg mL-1). Mechanistic studies revealed that intracellular generation of ROS upon red-light activation led to apoptosis in HeLa cells. Scratch-wound-healing assays indicated the inhibition of the migration of MDA-MB-231 cells treated with the nanoconjugate and upon photo-activation. Overall, the nanoconjugate has emerged as a potent tool for next-generation photo-chemotherapeutics in the clinical arena of targeted cancer therapy.

Systematic Review of Nicotine Exposure's Effects on Neural Stem and Progenitor Cells

While various modalities of chronic nicotine use have been associated with numerous negative consequences to human health, one possible benefit of nicotine exposure has been uncovered. The discovery of an inverse correlation between smoking and Parkinson's disease, and later Alzheimer's disease as well, motivated investigation of nicotine as a neuroprotective agent. Some studies have demonstrated that nicotine elicits improvements in cognitive function. The hippocampus, along with the subventricular zone (SVZ), is a distinct brain region that allow for ongoing postnatal neurogenesis throughout adulthood and plays a major role in certain cognitive behaviors like learning and memory. Therefore, one hypothesis underlying nicotine-induced neuroprotection is possible effects on neural stem cells and neural precursor cells. On the other hand, nicotine withdrawal frequently leads to cognitive impairments, particularly in hippocampal-dependent behaviors, possibly suggesting an impairment of hippocampal neurogenesis with nicotine exposure. This review discusses the current body of evidence on nicotine's effects on neural stem cells and neural progenitors. Changes in neural stem cell proliferation, survival, intracellular dynamics, and differentiation following acute and chronic nicotine exposure are examined.

MiR-122 Participates in Oxidative Stress and Apoptosis in STZ-Induced Pancreatic β Cells by Regulating PI3K/AKT Signaling Pathway

At present, there are few reports concerning the relationship between miR-122 and diabetes. In addition, the effect of miR-122 on streptozotocin- (STZ-) induced oxidative damage in INS-1 cells remains unclear. The present study aimed to investigate the role and modulatory mechanisms involving miR-122 in diabetes. STZ was used to induce INS-1 cell damage. Reverse transcription-quantitative PCR was used to investigate the expression of miR-122. A TUNEL cell apoptosis detection kit was used to detect apoptosis. Intracellular ROS levels were determined using dichlorofluorescein-diacetate. The activities of insulin secretion, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-px) were measured using ELISA kits. Western blotting was used to measure the expression levels of Bax, Bcl-2, PI3K, p-PI3K, caspase-3 and caspase-9, cleaved-caspase-3 and cleaved-caspase-9, AKT, and p-AKT. Then, LY294002 (LY, PI3K inhibitor) was used to treat INS-1 cells, and oxidative stress and apoptosis were measured. The results showed that STZ-induced inhibitory effects on insulin secretion were mitigated by miR-122 inhibitor, and the activities of SOD, CAT, and GSH-px were also increased. Furthermore, miR-122 inhibitor inhibited apoptosis and oxidative stress in STZ-induced INS-1 cells. Finally, the addition of LY increased insulin levels; reduced the activities of SOD, CAT, and GSH-px; and promoted apoptosis in STZ-induced INS-1 cells. In conclusion, interference with miR-122 can inhibit oxidative stress and apoptosis in STZ-induced INS-1 cells, involving a mechanism of action related to the PI3K/AKT pathway.

The toxic effects of titanium dioxide nanoparticles on plasma glucose metabolism are more severe in developing mice than in adult mice

Titanium dioxide nanoparticles (TiO₂ NPs) are authorized food additives, and children have the highest exposure. Therefore, children are likely more susceptible to the adverse effects of TiO₂ NPs than adults. Previous study showed that oral administration of 50 mg/kg body weight (bw) TiO₂ NPs increase plasma glucose in mice. However, few studies have directly compared the adverse effects of exposure to TiO₂ NPs on plasma glucose metabolism of different age groups. In this study, the developing (age 3 weeks) and adult mice (age 10 weeks) were orally administered with 50 mg/kg bw TiO₂ NPs per day. The TiO₂ NPs induced hyperglycemia earlier in the developing mice than in the adult mice. Then mechanisms were analyzed after mice were oral administration of TiO2 NPs for 8 weeks and 26 weeks, respectively. Results showed that the treatment with TiO₂ NPs activated xenobiotic biodegradation in livers of both developing and adult mice at the early stage. However, only in the developing mice, TiO₂ NPs induced endoplasmic reticulum (ER) stress in livers and increased reactive oxygen species in livers and sera in the early stage. The ER stress and ROS activated an inflammation response and mitogen-activated protein kinase pathways, thereby inducing insulin resistance in the livers of developing mice at the early stage. The response of the adult mice was delayed, and these changes were observed in the late stage of the study. The results of this study all suggest that children are more susceptible than adults to the toxicity of orally administered TiO₂ NPs.

Cigarette smoke exposure impairs β-cell function through activation of oxidative stress and ceramide accumulation

OBJECTIVES

Epidemiological studies indicate that first- and second-hand cigarette smoke (CS) exposure are important risk factors for the development of type 2 diabetes (T2D). Additionally, elevated diabetes risk has been reported to occur within a short period of time after smoking cessation, and health risks associated with smoking are increased when combined with obesity. At present, the mechanisms underlying these associations remain incompletely understood. The objective of this study was to test the impact of CS exposure on pancreatic β-cell function using rodent and in vitro models.

METHODS

Beginning at 8 weeks of age, C57BL/6 J mice were concurrently fed a high-fat diet (HFD) and exposed to CS for 11 weeks, followed by an additional 11 weeks of smoking cessation with continued HFD. Glucose tolerance testing was performed during CS exposure and during the cessation period. Cultured INS-1 β-cells and primary islets were exposed ex vivo to CS extract (CSE), and β-cell function and viability were tested. Since CS increases ceramide accumulation in the lung and these bioactive sphingolipids have been implicated in pancreatic β-cell dysfunction in diabetes, islet and β-cell sphingolipid levels were measured in islets from CS-exposed mice and in CSE-treated islets and INS-1 cells using liquid chromatography-tandem mass spectrometry.

RESULTS

Compared to HFD-fed, ambient air-exposed mice, HFD-fed and CS-exposed mice had reduced weight gain and better glucose tolerance during the active smoking period. Following smoking cessation, CS-mice exhibited rapid weight gain and had accelerated worsening of their glucose tolerance. CS-exposed mice had higher serum proinsulin/insulin ratios, indicative of β-cell dysfunction, significantly lower β-cell mass (p = 0.017), reduced β-cell proliferation (p = 0.006), and increased islet ceramide content compared to non-smoking control mice. Ex vivo exposure of isolated islets to CSE was sufficient to increase islet ceramide levels, which was correlated with reduced insulin gene expression and glucose-stimulated insulin secretion, and increased β-cell oxidative and endoplasmic reticulum (ER) stress. Treatment with the antioxidant N-acetylcysteine markedly attenuated the effects of CSE on ceramide levels, restored β-cell function and survival, and increased cyclin D2 expression, while also reducing activation of β-cell ER and oxidative stress.

CONCLUSIONS

Our results indicate that CS exposure leads to impaired insulin production, processing, secretion and reduced β-cell viability and proliferation. These effects were linked to increased β-cell oxidative and ER stress and ceramide accumulation. Mice fed HFD continued to experience detrimental effects of CS exposure even during smoking cessation. Elucidation of the mechanisms by which CS exposure impairs β-cell function in synergy with obesity will help design therapeutic and preventive interventions for both active and former smokers.