Tat-ATOX1 inhibits streptozotocin-induced cell death in pancreatic RINm5F cells and attenuates diabetes in a mouse model

The Molecular Mechanisms of Cuproptosis and Small-Molecule Drug Design in Diabetes Mellitus

In the field of human health research, the homeostasis of copper (Cu) is receiving increased attention due to its connection to pathological conditions, including diabetes mellitus (DM). Recent studies have demonstrated that proteins associated with Cu homeostasis, such as ATOX1, FDX1, ATP7A, ATPB, SLC31A1, p53, and UPS, also contribute to DM. Cuproptosis, characterized by Cu homeostasis dysregulation and Cu overload, has been found to cause the oligomerization of lipoylated proteins in mitochondria, loss of iron-sulfur protein, depletion of glutathione, production of reactive oxygen species, and cell death. Further research into how cuproptosis affects DM is essential to uncover its mechanism of action and identify effective interventions. In this article, we review the molecular mechanism of Cu homeostasis and the role of cuproptosis in the pathogenesis of DM. The study of small-molecule drugs that affect these proteins offers the possibility of moving from symptomatic treatment to treating the underlying causes of DM.

Atox1 regulates macrophage polarization in intestinal inflammation via ROS-NLRP3 inflammasome pathway

BACKGROUND

Inflammation and oxidative stress play an important role in the pathophysiology of inflammatory bowel disease (IBD). This study aimed to explore the effects of copper chaperone Antioxidant-1 (Atox1) on macrophages in a mouse model of intestinal inflammation.

METHODS

A mouse model of TNBS-induced colitis was established and verified using the disease activity index. Atox1 conditional knockout mice were applied. The proportion of macrophages in colonic lamina propria mononuclear cells and ROS production were analyzed using flow cytometry. Inflammatory cytokines were measured using ELISA. Expression of macrophage M1/M2 polarization markers, p47phox, NLRP3, and Caspase-1 p20 was measured using quantitative RT-PCR and Western blotting.

RESULTS

Atox1 expression was up-regulated in colon tissues of TNBS-induced colitis mice. Macrophages isolated from TNBS-induced colitis mice showed M1 polarization and nuclear translocation of Atox1. Inhibiting copper chaperone activity decreased p47phox, ROS production, and M1 polarization induced by CuCl2 in macrophages. TNBS induced up-regulation of inflammatory cytokines, M1 polarization markers, and p47phox expression in mice, an effect which was preempted by Atox1 knockout. Inflammatory cytokines and expression of M1 polarization markers, p47phox, NLRP3, Caspase-1 p20 were also increased in macrophages isolated from TNBS-induced colitis mice. These changes were alleviated in mice with Atox1 knockout. The effects of Atox1 on macrophage polarization were mediated via the ROS-NLRP3 inflammasome pathway.

CONCLUSION

Atox1 plays a pro-inflammatory role, promotes M1 polarization of macrophages, and increases the concentrations of pro-inflammatory cytokines in intestinal tissue by regulating the ROS-NLRP3 inflammasome pathway. Atox1 is a potential therapeutic target in IBD.

Tat-CIAPIN1 Prevents Pancreatic β-Cell Death in hIAPP-Induced RINm5F Cells and T2DM Animal Model

It is well known that the cytokine-induced apoptosis inhibitor 1 (CIAPIN1) protein plays an important role in biological progresses as an anti-apoptotic protein. Human islet amyloid peptide (hIAPP), known as amylin, is caused to pancreatic β-cell death in type 2 diabetes mellitus (T2DM). However, the function of CIAPIN1 protein on T2DM is not yet well studied. Therefore, we investigated the effects of CIAPIN1 protein on a hIAPP-induced RINm5F cell and T2DM animal model induced by a high-fat diet (HFD) and streptozotocin (STZ). The Tat-CIAPIN1 protein reduced the activation of mitogen-activated protein kinase (MAPK) and regulated the apoptosis-related protein expression levels including COX-2, iNOS, Bcl-2, Bax, and Caspase-3 in hIAPP-induced RINm5F cells. In a T2DM mice model, the Tat-CIAPIN1 protein ameliorated the pathological changes of pancreatic β-cells and reduced the fasting blood glucose, body weight and hemoglobin Alc (HbAlc) levels. In conclusion, the Tat-CIAPIN1 protein showed protective effects against T2DM by protection of β-cells via inhibition of hIAPP toxicity and by regulation of a MAPK signal pathway, suggesting CIAPIN1 protein can be a therapeutic protein drug candidate by beneficial regulation of T2DM.

The oxidative aging model integrated various risk factors in type 2 diabetes mellitus at system level

Background

Type 2 diabetes mellitus (T2DM) is a chronic endocrine metabolic disease caused by insulin dysregulation. Studies have shown that aging-related oxidative stress (as "oxidative aging") play a critical role in the onset and progression of T2DM, by leading to an energy metabolism imbalance. However, the precise mechanisms through which oxidative aging lead to T2DM are yet to be fully comprehended. Thus, it is urgent to integrate the underlying mechanisms between oxidative aging and T2DM, where meaningful prediction models based on relative profiles are needed.

Methods

First, machine learning was used to build the aging model and disease model. Next, an integrated oxidative aging model was employed to identify crucial oxidative aging risk factors. Finally, a series of bioinformatic analyses (including network, enrichment, sensitivity, and pan-cancer analyses) were used to explore potential mechanisms underlying oxidative aging and T2DM.

Results

The study revealed a close relationship between oxidative aging and T2DM. Our results indicate that nutritional metabolism, inflammation response, mitochondrial function, and protein homeostasis are key factors involved in the interplay between oxidative aging and T2DM, even indicating key indices across different cancer types. Therefore, various risk factors in T2DM were integrated, and the theories of oxi-inflamm-aging and cellular senescence were also confirmed.

Conclusion

In sum, our study successfully integrated the underlying mechanisms linking oxidative aging and T2DM through a series of computational methodologies.

Copper chaperone antioxidant 1: multiple roles and a potential therapeutic target

Copper (Cu) was recently demonstrated to play a critical role in cellular physiological and biochemical processes, including energy production and maintenance, antioxidation and enzymatic activity, and signal transduction. Antioxidant 1 (ATOX1), a chaperone of Cu previously named human ATX1 homologue (HAH1), has been found to play an indispensable role in maintaining cellular Cu homeostasis, antioxidative stress, and transcriptional regulation. In the past decade, it has also been found to be involved in a variety of diseases, including numerous neurodegenerative diseases, cancers, and metabolic diseases. Recently, increasing evidence has revealed that ATOX1 is involved in the regulation of cell migration, proliferation, autophagy, DNA damage repair (DDR), and death, as well as in organism development and reproduction. This review summarizes recent advances in the research on the diverse physiological and cytological functions of ATOX1 and the underlying mechanisms of its action in human health and diseases. The potential of ATOX1 as a therapeutic target is also discussed. This review aims to pose unanswered questions related to ATOX1 biology and explore the potential use of ATOX1 as a therapeutic target.

A discovery-based proteomics approach identifies protein disulphide isomerase (PDIA1) as a biomarker of β cell stress in type 1 diabetes

BACKGROUND

Stress responses within the β cell have been linked with both increased β cell death and accelerated immune activation in type 1 diabetes (T1D). At present, information on the timing and scope of these responses as well as disease-related changes in islet β cell protein expression during T1D development is lacking.

METHODS

Data independent acquisition-mass spectrometry was performed on islets collected longitudinally from NOD mice and NOD-SCID mice rendered diabetic through T cell adoptive transfer.

FINDINGS

In islets collected from female NOD mice at 10, 12, and 14 weeks of age, we found a time-restricted upregulation of proteins involved in stress mitigation and maintenance of β cell function, followed by loss of expression of protective proteins that heralded diabetes onset. EIF2 signalling and the unfolded protein response, mTOR signalling, mitochondrial function, and oxidative phosphorylation were commonly modulated pathways in both NOD mice and NOD-SCID mice rendered acutely diabetic by T cell adoptive transfer. Protein disulphide isomerase A1 (PDIA1) was upregulated in NOD islets and pancreatic sections from human organ donors with autoantibody positivity or T1D. Moreover, PDIA1 plasma levels were increased in pre-diabetic NOD mice and in the serum of children with recent-onset T1D compared to non-diabetic controls.

INTERPRETATION

We identified a core set of modulated pathways across distinct mouse models of T1D and identified PDIA1 as a potential human biomarker of β cell stress in T1D.

FUNDING

NIH (R01DK093954, DK127308, U01DK127786, UC4DK104166, R01DK060581, R01GM118470, and 5T32DK101001-09). VA Merit Award I01BX001733. JDRF (2-SRA-2019-834-S-B, 2-SRA-2018-493-A-B, 3-PDF-20016-199-A-N, 5-CDA-2022-1176-A-N, and 3-PDF-2017-385-A-N).

Cell-penetrating peptide-mediated delivery of therapeutic peptides/proteins to manage the diseases involving oxidative stress, inflammatory response and apoptosis

OBJECTIVES

Peptides and proteins represent great potential for modulating various cellular processes including oxidative stress, inflammatory response, apoptosis and consequently the treatment of related diseases. However, their therapeutic effects are limited by their inability to cross cellular barriers. Cell-penetrating peptides (CPPs), which can transport cargoes into the cell, could resolve this issue, as would be discussed in this review.

KEY FINDINGS

CPPs have been successfully exploited in vitro and in vivo for peptide/protein delivery to treat a wide range of diseases involving oxidative stress, inflammatory processes and apoptosis. Their in vivo applications are still limited due to some fundamental issues of CPPs, including nonspecificity, proteolytic instability, potential toxicity and immunogenicity.

SUMMARY

Totally, CPPs could potentially help to manage the diseases involving oxidative stress, inflammatory response and apoptosis by delivering peptides/proteins that could selectively reach proper intracellular targets. More studies to overcome related CPP limitations and confirm the efficacy and safety of this strategy are needed before their clinical usage.

Camel whey protein (CWP) ameliorates liver injury in type 2 diabetes mellitus rats and insulin resistance (IR) in HepG2 cells via activation of the PI3K/Akt signaling pathway

This research investigated the effects of camel whey protein (CWP) treatment on type 2 diabetes mellitus (T2DM) rats and insulin resistance (IR) HepG2 cell models. Body weight and fasting blood glucose were observed in type 2 diabetes mellitus (T2DM) rats every week, and biochemical parameters in serum samples were evaluated after 6 weeks. Antioxidant activity in the liver was estimated, and histological examination of the liver tissues was conducted. After CWP treatment, the glucose uptake and lipid accumulation were examined in insulin-resistant HepG2 cells. Our results indicated that CWP mitigated the body weight loss, reversed dyslipidemia, and inhibited the inflammatory response, in T2DM rats. Meanwhile, it protected the liver from being injured by reducing the level of oxidative stress. In the CWP group, the pathological changes were significantly reduced, while the liver lobule structure, liver cell arrangement, as well as congestion, edema, and vacuolization were improved. Our results from quantitative real-time PCR and western blot analyses showed that CWP could up-regulate the expression levels of insulin receptor substrate-2 (IRS-2), phosphoinositide3-kinase (PI3K), protein kinase B (AKT), and glycogen synthase (GS). An active protein component CWP8 was isolated and identified, which was shown to be able to stimulate glycogen synthesis and ameliorate lipid accumulation in IR HepG2 cells. These data indicate that CWP and CWP8 might act as potential natural products regulating glucose and lipid metabolism in T2DM.

Tat-ATOX1 inhibits inflammatory responses via regulation of MAPK and NF-κB pathways

Antioxidant 1 (ATOX1) protein has been reported to exhibit various protective functions, including antioxidant and chaperone. However, the effects of ATOX1 on the inflammatory response has not been fully elucidated. Thus, we prepared cell permeable Tat-ATOX1 and studied the effects on lipopolysaccharide (LPS)- and 12-O-tetradecanoyl phorbol-13-acetate (TPA)-induced inflammation. Experimental results showed that transduced Tat-ATOX1 protein significantly suppressed LPS-induced intracellular reactive oxygen species (ROS). Also, Tat-ATOX1 protein markedly inhibited LPS- and TPA-induced inflammatory responses by decreasing cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) and further inhibited phosphorylation of mitogen activated protein kinases (MAPKs; JNK, ERK and p38) and the nuclear factor-kappaB (NF-κB) signaling pathway. These results indicate that the Tat-ATOX1 protein has a pivotal role in inflammation via inhibition of inflammatory responses, suggesting Tat-ATOX1 protein may offer a therapeutic strategy for inflammation.

Protective effects of Tat-DJ-1 protein against streptozotocin-induced diabetes in a mice model

A major feature of type 1 diabetes mellitus (T1DM) is hyperglycemia and dysfunction of pancreatic β-cells. In a previous study, we have shown that Tat-DJ-1 protein inhibits pancreatic RINm5F β-cell death caused by oxidative stress. In this study, we examined effects of Tat-DJ-1 protein on streptozotocin (STZ)-induced diabetic mice. Wild type (WT) Tat-DJ-1 protein transduced into pancreas where it markedly inhibited pancreatic β-cell destruction and regulated levels of serum parameters including insulin, alkaline phosphatase (ALP), and free fatty acid (FFA) secretion. In addition, transduced WT Tat-DJ-1 protein significantly inhibited the activation of NF-κB and MAPK (ERK and p38) expression as well as expression of COX-2 and iNOS in STZ exposed pancreas. In contrast, treatment with C106A mutant Tat-DJ-1 protein showed no protective effects. Collectively, our results indicate that WT Tat-DJ-1 protein can significantly ameliorate pancreatic tissues in STZ-induced diabetes in mice. [BMB Reports 2018; 51(7): 362-367].

Liraglutide Enhances Autophagy and Promotes Pancreatic β Cell Proliferation to Ameliorate Type 2 Diabetes in High-Fat-Fed and Streptozotocin-Treated Mice

Background

Clinical and experimental studies have revealed that liraglutide has multiple anti-diabetes biological effects. However, little is known about its role in autophagy and pancreatic β cell proliferation. This study aimed to assessed the effects of liraglutide on pancreatic β cell proliferation and autophagy in a mouse model of type 2 diabetes.

Material/Methods

The effect of liraglutide on autophagy and proliferation in pancreatic β cells was investigated using a high-fat-fed and streptozotocin-induced mouse model of type 2 diabetes.

Results

Liraglutide significantly improved the symptoms of high-fat-fed (HFD) and streptozotocin (STZ)-induced type 2 diabetic mice, as indicated by body weight gain, reduction of blood glucose and plasma insulin, and enhanced sensitivity to insulin. The results of quantitative real-time polymerase chain reaction and Western blot analysis showed that liraglutide upregulated AGT5 expression and promoted the conversion of LC3-I to LC3-II, thus improving the defective autophagy. In addition, we observed that both mRNA and protein expressions of PCNA and Ki-67 were upregulated by liraglutide treatment. Immunocytochemical staining results showed that the number of PCNA- or Ki-67-positive cells in pancreatic islet tissues in the HFD + STZ + liraglutide group were increased compared with the HFD + STZ group.

Conclusions

These results strongly suggest that liraglutide is able to enhance autophagy and promote pancreatic β cell proliferation. This study improves our insights into the mechanism by which liraglutide treatment relieves diabetes, and provides experimental evidence for clinical utilization of liraglutide in type 2 diabetes treatment.