Effects of phycocyanin on INS-1 pancreatic β-cell mediated by PI3K/Akt/FoxO1 signaling pathway

Combined Effects of Spirulina Liquid Extract and Endurance Training on Aerobic Performance and Muscle Metabolism Adaptation in Wistar Rats

BACKGROUND

Physical activity, such as running, protects against cardiovascular disease and obesity but can induce oxidative stress. Athletes often consume antioxidants to counteract the overproduction of reactive oxygen and nitrogen species during exercise. Spirulina, particularly its phycocyanin content, activates the Nrf2 pathway, stimulating antioxidant responses. Studies show that phycocyanin enhances antioxidant defenses and reduces inflammation, potentially improving muscle adaptation and recovery. This study evaluates a Spirulina liquid extract (SLE) supplementation during endurance training, hypothesizing that phycocyanin improves oxidant status and performance in soleus and extensor digitorum longus muscles.

METHODS

Three-week-old male Wistar rats were divided into four groups: a sedentary control group (C), a sedentary group supplemented with SLE (SP), an endurance training group (T), and an endurance training group supplemented with SLE (SPT). After 8 weeks of treadmill training, blood and muscle were collected. Biochemical parameters and gene expression analyses were performed to assess the effects of training and supplementation.

RESULTS

The maximal aerobic speed improved significantly in the SPT group. Plasma lipid profiles showed a reduction in triglyceridemia, cholesterolemia, and atherogenic index in the trained groups, especially with SLE supplementation. Muscle malondialdehyde levels decreased in the SPT group compared to T. Gene expression analysis revealed upregulation of Nrf2 and mitochondrial biogenesis genes in both muscles, with differences between groups for genes related to glycogen storage and β-oxidation.

CONCLUSIONS

This study demonstrated that SLE supplementation enhanced exercise performance and promoted muscle molecular adaptations. These findings suggest SLE as a promising functional food supplement for athletes, optimizing recovery and performance.

C-Phycocyanin: A Phycobiliprotein from Spirulina with Metabolic Syndrome and Oxidative Stress Effects

Spirulina maxima is a cyanobacterium considered a "superfood" due to its metabolites and nutrient content. These include a complex mixture of minerals, vitamins, fatty acids, proteins, and accessory pigments. In recent years, it has positioned itself as a promising source of bioactive molecules for the treatment of several diseases, including metabolic syndrome, coronary diseases, cancer, and the improvement of health modulating oxidative stress. C-Phycocyanin (C-PC) is a photosynthetic pigment from green-blue cyanobacterium and the most abundant phycobiliprotein in the Spirulina genus with various pharmacological properties attributed due to its antioxidant capacity but has no specific cellular target. This has made it a molecule of great interest in biomedical research. This review focuses on the pharmacological effects and the benefits on metabolic syndrome and oxidative stress of C-PC.

Nutraceutical Features of the Phycobiliprotein C-Phycocyanin: Evidence from Arthrospira platensis (Spirulina)

Arthrospira platensis, commonly known as Spirulina, is a photosynthetic filamentous cyanobacterium (blue-green microalga) that has been utilized as a food source since ancient times. More recently, it has gained significant popularity as a dietary supplement due to its rich content of micro- and macro-nutrients. Of particular interest is a water soluble phycobiliprotein derived from Spirulina known as phycocyanin C (C-PC), which stands out as the most abundant protein in this cyanobacterium. C-PC is a fluorescent protein, with its chromophore represented by the tetrapyrrole molecule phycocyanobilin B (PCB-B). While C-PC is commonly employed in food for its coloring properties, it also serves as the molecular basis for numerous nutraceutical features associated with Spirulina. Indeed, the comprehensive C-PC, and to some extent, the isolated PCB-B, has been linked to various health-promoting effects. These benefits encompass conditions triggered by oxidative stress, inflammation, and other pathological conditions. The present review focuses on the bio-pharmacological properties of these molecules, positioning them as promising agents for potential new applications in the expanding nutraceutical market.

Phycocyanin as a nature-inspired antidiabetic agent: A systematic review

BACKGROUND

Nutraceuticals have been important for more than two decades for their safety, efficacy, and outstanding effects. Diabetes is a major metabolic syndrome, which may be improved using nutritional pharmaceuticals. Some microalgae species, such as spirulina, stand out by providing biomass with exceptional nutritional properties. Spirulina has a wide range of pharmacological effects, mostly related to phycocyanin. Phycocyanin is a protein compound with antidiabetic properties, known as a nutraceutical.

OBJECTIVE

This review delves into phycocyanin applications in diabetes and its complications and ascertains the mechanisms involved.

METHODS

Scopus, PubMed, Cochrane Library, Web of Science, and ProQuest databases were systematically reviewed (up to April 30, 2023), in which only animal and cellular studies were found.

RESULTS

According to animal studies, the administration of phycocyanin affected biochemical parameters (primary outcome) related to diabetes. These results showed an increase in fasting insulin serum and a decrease in fasting blood glucose, glycosylated serum protein, and glycosylated hemoglobin. In cellular studies, though, phycocyanin prevented methylglyoxal and human islet amyloid polypeptide-induced dysfunction in β-cells and induced apoptosis through different molecular pathways (secondary outcome), including activation of Nrf2, PI3K/Akt, and suppression of JNK and p38. Also, phycocyanin exerted its antidiabetic effect by affecting the pathways regulating hepatic glucose metabolism.

CONCLUSIONS

Thus, based on the available information and literature, targeting these pathways by phycocyanin may unleash an array of benefits, including positive outcomes of the antidiabetic effects of phycocyanin as a nutraceutical.

OTHER

This systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) at the National Institute of Health. The registration number is CRD42022307522.

R-phycocyanin from porphyra haitanensis influences drosophila melanogaster lifespan in a sex-specific manner

Aging has become a major global public health challenge. Our previous research showed that R-phycocyanin (R-PC) possessed anti-aging activity. Notably, studies already revealed that gender may affect the responses to the anti-aging drug. Therefore, it is worth investigating whether the anti-aging effects and their underlying molecular mechanisms of R-PC differ between genders. Firstly, R-PC was isolated from porphyra haitanensis and its anti-aging mechanisms were explored using the nature aging male and female drosophila melanogaster as model. Next, the regulation pathway of longevity was analyzed by KEGG pathway analysis. The longevity pathways-associated molecules were also examined to explore anti-aging mechanisms of R-PC. The results showed that R-PC increased AMPK activity, thus enhanced the key regulatory factors of autophagy (Atg1, Atg8, Atg5), and consequently induced autophagy. Hence, the longevity activity of R-PC life was related with AMPK/mTOR/S6K autophagic signaling pathways in aging female drosophila melanogaster. Meanwhile, R-PC significantly down-regulated TNF-α, MMP3, IL-1β, IL-6, IL-8 expression levels, and the anti-inflammatory and longevity was associated with R-PC-induced regulation of pI3k/AKT/FOXO3 signaling pathway in aging male drosophila melanogaster. These finding showed that R-PC from porphyra haitanensis might exert the anti-aging actions via different mechanisms in male and female drosophila melanogaste.

Sulfated fuco-manno-glucuronogalactan alleviates pancreatic beta cell senescence via PI3K/AKT/FoxO1 pathway

Appearance of senescent beta cells in the pancreas leads to the onset of type 2 diabetes (T2D). The structural analysis of a sulfated fuco-manno-glucuronogalactan (SFGG) indicated SFGG had the backbones of interspersing 1, 3-linked β-D-GlcpA residues, 1, 4-linked α-D-Galp residues, and alternating 1, 2-linked α-D-Manp residues and 1, 4-linked β-D-GlcpA residues, sulfated at C6 of Man residues, C2/C3/C4 of Fuc residues and C3/C6 of Gal residues, and branched at C3 of Man residues. SFGG effectively alleviated senescence-related phenotypes in vitro and in vivo, including cell cycle, senescence-associated β-galactosidase, DNA damage and senescence-associated secretory phenotype (SASP) -associated cytokines and hall markers of senescence. SFGG also alleviated beta cell dysfunction in insulin synthesis and glucose-stimulated insulin secretion. Mechanistically, SFGG attenuated senescence and improved beta cell function via PI3K/AKT/FoxO1 signaling pathway. Therefore, SFGG could be used for beta cell senescence treatment and alleviation of the progression of T2D.

Comparative Study of Two Common In Vitro Models for the Pancreatic Islet with MIN6

BACKGROUND

Islet transplantation is currently considered the most promising method for treating insulin-dependent diabetes. The two most-studied artificial islets are alginate-encapsulated β cells or β cell spheroids. As three-dimensional (3D) models, both artificial islets have better insulin secretory functions and transplantation efficiencies than cells in two-dimensional (2D) monolayer culture. However, the effects of these two methods have not been compared yet. Therefore, in this study, cells from the mouse islet β cell line Min6 were constructed as scaffold-free spheroids or alginate-encapsulated dispersed cells.

METHODS

MIN6 cell spheroids were prepared by using Agarose-base microwell arrays. The insulin secretion level was determined by mouse insulin ELISA kit, and the gene and protein expression status of the MIN6 were performed by Quantitative polymerase chain reaction and immunoblot, respectively.

RESULTS

Both 3D cultures effectively promoted the proliferation and glucose-stimulated insulin release (GSIS) of MIN6 cells compared to 2D adherent cells. Furthermore, 1% alginate-encapsulated MIN6 cells demonstrated more significant effects than the spheroids. In general, three pancreatic genes were expressed at higher levels in response to the 3D culture than to the 2D culture, and pancreatic/duodenal homeobox-1 (PDX1) expression was higher in the cells encapsulated in 1% alginate than that in the spheroids. A western blot analysis showed that 1% alginate-encapsulated MIN6 cells activated the phosphoinositide 3-kinase (PI3K)/serine/threonine protein kinase (AKT)/forkhead transcription factor FKHR (FoxO1) pathway more than the spheroids, 0.5% alginate-, or 2% alginate-encapsulated cells did. The 3D MIN6 culture, therefore, showed improved effects compared to the 2D culture, and the 1% alginate-encapsulated MIN6 cells exhibited better effects than the spheroids. The upregulation of PDX1 expression through the activation of the PI3K/AKT/FoxO1 pathway may mediate the improved cell proliferation and GSIS in 1% alginate-encapsulated MIN6 cells.

CONCLUSION

This study may contribute to the construction of in vitro culture systems for pancreatic islets to meet clinical requirements.

The m6A Methyltransferase METTL3 Ameliorates Methylglyoxal-Induced Impairment of Insulin Secretion in Pancreatic β Cells by Regulating MafA Expression

Methylglyoxal, a major precursor of advanced glycation end products, is elevated in the plasma of patients with type 2 diabetes mellitus. Islet β-cell function was recently shown to be regulated by N⁶-methyladenosine (m⁶A), an RNA modification consisting of methylation at the N6 position of adenosine. However, the role of m⁶A methylation modification in methylglyoxal-induced impairment of insulin secretion in pancreatic β cells has not been clarified. In this study, we showed that treatment of two β-cell lines, NIT-1 and β-TC-6, with methylglyoxal reduced m⁶A RNA content and methyltransferase-like 3 (METTL3) expression levels. We also showed that silencing of METTL3 inhibited glucose-stimulated insulin secretion (GSIS) from NIT-1 cells, whereas upregulation of METTL3 significantly reversed the methylglyoxal-induced decrease in GSIS. The methylglyoxal-induced decreases in m⁶A RNA levels and METTL3 expression were not altered by knockdown of the receptor for the advanced glycation end product but were further decreased by silencing of glyoxalase 1. Mechanistic investigations revealed that silencing of METTL3 reduced m⁶A levels, mRNA stability, and the mRNA and protein expression levels of musculoaponeurotic fibrosarcoma oncogene family A (MafA). Overexpression of MafA greatly improved the decrease in GSIS induced by METTL3 silencing; silencing of MafA blocked the reversal of the MG-induced decrease in GSIS caused by METTL3 overexpression. The current study demonstrated that METTL3 ameliorates MG-induced impairment of insulin secretion in pancreatic β cells by regulating MafA.

W2476 represses TXNIP transcription via dephosphorylation of FOXO1 at Ser319

Thioredoxin-interacting protein (TXNIP) overexpression is implicated in the pathogenesis of type 2 diabetes. Previous studies have shown that a small molecule compound (W2476) was able to improve β-cell dysfunction and exert therapeutic effects in diabetic mice via repression of TXNIP signaling pathway. The impact of W2476 on TXNIP transcription was thus investigated using the chromatin immunoprecipitation method. It was found that W2476 promotes competitive binding of forkhead box O1 transcription factor (FOXO1) to the carbohydrate response element (ChoRE) sequence associated with ChoRE-binding protein (ChREBP)/Mlx interacting protein-like(Mlx) complexes. This interaction hinders the attachment of histone acetyltransferase p300 and reduces histone H4 acetylation on the TXNIP promoter, leading to decreasing TXNIP transcription.

The Chemical Constituents from Fruits of Catalpa bignonioides Walt. and Their α-Glucosidase Inhibitory Activity and Insulin Secretion Effect

Catalpa pod has been used in traditional medicine for the treatment of diabetes mellitus in South America. Studies on the constituents of Catalpa species have shown that it is rich in iridoids. In the present study, three previously undescribed compounds (2–4), including two secoiridoid derivatives along with twelve known compounds, were isolated from the fruits of Catalpa bignonioides Walt. In addition, fully assigned ¹³C-NMR of 5,6-dihydroxy-7,4’-dimethoxyflavone-6-O-sophoroside (1) is reported for the first time in the present study. The structures of compounds were determined on the basis of extensive spectroscopic methods, including UV, IR, 1D, and 2D NMR, mass spectroscopy, and CD spectroscopic data. All the isolated compounds were evaluated for α-glucosidase inhibitory activity. Among the tested compounds, compounds 2, 3, and 9 exhibited significant inhibitory activity against α-glucosidase enzyme assay. Meanwhile, the effect of compounds 2, 3, and 9 on glucose-stimulated insulin secretion (GSIS) was measured using pancreatic β-cells. Compounds 2, 3, and 9 exhibited non-cytotoxicity-stimulated insulin secretion in INS-1 cells. The expression levels of proteins associated with β-cell function and insulin secretion such as phosphorylation of total insulin receptor substrate-2 (IRS-2), phosphatidylinositol 3-kinase (PI3K), Akt, activated pancreatic duodenal homeobox-1 (PDX-1), and peroxisome proliferator-activated receptor-γ (PPAR-γ) were increased in INS-1 cells after treatment with compounds 2, 3, and 9. The findings of the present study could provide a scientific warrant for their application as a potential antidiabetic agent.

Phycobiliproteins from Arthrospira Platensis (Spirulina): A New Source of Peptides with Dipeptidyl Peptidase-IV Inhibitory Activity

Arthrospira platensis (spirulina) is a cyanobacterium, which contains mainly two phycobiliproteins (PBP), i.e., C-phycocyanin (C-PC) and allophycocyanin (APC). In this study, PBP were hydrolyzed using trypsin, and the composition of the hydrolysate was characterized by HPLC-ESI-MS/MS. Furthermore, the potential anti-diabetic activity was assessed by using either biochemical or cellular techniques. Findings suggest that PBP peptides inhibit DPP-IV activity in vitro with a dose-response trend and an IC₅₀ value falling in the range between 0.5 and 1.0 mg/mL. A lower inhibition of the DPP-IV activity expressed by Caco-2 cells was observed, which was explained by a secondary metabolic degradation exerted by the same cells.

Association of the polymorphisms in FOXO1 gene and diabetic nephropathy risk

PURPOSE

This study was aimed to study the hypothesis that forkhead box O1 (FOXO1) gene rs17446614 and rs17592236 single nucleotide polymorphisms (SNPs) influenced the development of diabetic nephropathy (DN).

METHODS

This study included 138 DN patients and 149 healthy controls. Controls were matched with the patients in age and gender. The method of polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) was used to detect FOXO1 gene polymorphisms. Haploview software was conducted to analyze the linkage disequilibrium and haplotypes of FOXO1 gene polymorphisms. Relative risk of DN was expressed by odds ratios (ORs) and 95% confidence intervals (95% CIs), then the results were adjusted by clinical characteristics of the study subjects using logistic regression analysis. Subgroup analysis was performed according to gender.

RESULTS

AA genotype of rs17446614 SNPs was significantly associated with the risk of DN (P = .037, adjusted OR = 5.412, 95% CI = 1.103-26.559), especially in female (OR = 8.700, 95% CI = 1.008-75.062, P = .021). FOXO1 rs17446614 A allele positively associated with the development of DN (P = .027, adjusted OR = 1.680, 95% CI = 1.060-2.662), particularly in women (OR = 2.003, 95% CI = 1.070-3.749, P = .028). A-C haplotype formed by FOXO1 gene rs17446614 and rs17592236 SNPs was significantly associated with the increased risk of DN (P = .011, OR = 1.850, 95% CI = 1.146-2.986).

CONCLUSION

FOXO1 gene rs17446614 SNP, and the A-C haplotype of rs17446614 and rs17592236 polymorphisms were risk factors for the development of DN.

C-Phycocyanin elicited antitumor efficacy via cell-cycle arrest, apoptosis induction, and invasion inhibition in esophageal squamous cell carcinoma

Objectives: Mounting evidence has demonstrated that C-Phycocyanin (C-PC) exhibits marked antitumor activity in a wide type of tumors, such as pancreas cancer, breast carcinoma, lung cancer, and colon cancer. The current study aimed to confirm the antitumor efficacy of C-PC in esophageal squamous cell carcinoma (ESCC). Methods: The efficacy of C-PC was evaluated against the proliferation of ESCC cell lines EC9706 and EC1 by CCK-8 kit and in a mice model of ESCC EC9706. Cell cycle and apoptosis were investigated by flow cytometry, and cell invasion was determined via transwell chamber. Protein expression was examined by Western blots. Results: We found that C-PC exhibited anti-proliferation ability in a time-dependent manner and a dose-dependent manner in ESCC EC9706 and EC1 cells. Besides, C-PC markedly arrested cell cycle in the G0/G1 phase, induced cell apoptosis and suppressed cell invasion ability in both EC9706 and EC1 cells (p < .01). Notably, C-PC evoked the elevations of Bax, PARP, and cleaved-caspase-3 protein, but reduced cyclin D1, CDK4, Bcl-2, MMP-2, and MMP-9 expression levels. Further investigation from in vivo experiment revealed that C-PC displayed significant antitumor efficacy in the xenografted EC9706 model. Conclusions: Our data presented herein suggest C-PC exerts antitumor efficacy in ESCC.

Cellular signaling pathways regulating β-cell proliferation as a promising therapeutic target in the treatment of diabetes

It is established that a decrease in β-cell number and deficiency in the function of existing β-cells contribute to type 1 and type 2 diabetes mellitus. Therefore, a major focus of current research is to identify novel methods of improving the number and function of β-cells, so as to prevent and/or postpone the development of diabetes mellitus and potentially reverse diabetes mellitus. Based on prior knowledge of the above-mentioned causes, promising therapeutic approaches may include direct transplantation of islets, implantation and subsequent induced differentiation of progenitors/stem cells to β-cells, replication of pre-existing β-cells, or activation of endogenous β-cell progenitors. More recently, with regards to cell replacement and regenerative treatment for diabetes patients, the identification of cellular signaling pathways with related genes or corresponding proteins involved in diabetes has become a topic of interest. However, the majority of pathways and molecules associated with β-cells remain unresolved, and the specialized functions of known pathways remain unclear, particularly in humans. The current article has evaluated the progress of research on pivotal cellular signaling pathways involved with β-cell proliferation and survival, and their validity for therapeutic adult β-cell regeneration in diabetes. More efforts are required to elucidate the cellular events involved in human β-cell proliferation in terms of the underlying mechanisms and functions.

Mulberry Leaf Regulates Differentially Expressed Genes in Diabetic Mice Liver Based on RNA-Seq Analysis

The pathogenesis of diabetes mellitus is a complicated process involving much gene regulation. The molecular mechanism of mulberry (Morus alba L.) leaf in the treatment of diabetes is not fully understood. In this study, we used the Illumina HiSeq™ 2,500 platform to explore the liver transcriptome of normal mice, STZ-induced diabetic mice, and mulberry leaf-treated diabetic mice, and we obtained 52,542,956, 52,626,414, and 52,780,196 clean reads, respectively. We identified differentially expressed genes (DEGs) during the pathogenesis of diabetes in mice. The functional properties of DEGs were characterized by comparison with the GO and KEGG databases, and the results show that DEGs are mainly involved in the metabolic pathway. qRT-PCR was used to analyse 27 differential genes involved in liver expression in different groups of diabetic mice. Among the DEGs, the expression of Scube1, Spns3, Ly6a, Igf2, and other genes between the control (C) and diabetic control (DC) groups was significantly upregulated; the expression of Grb10, Mup2, and Fasn was significantly downregulated; the expression of the Sqle, Lss, and Irs2 genes between the C group and diabetic group treated with mulberry (DD) was significantly upregulated; the expression of Fabp2, Ly6a, and Grb10 was significantly downregulated; and the expression of Sqle and Lss was significantly upregulated in the DC and DD groups, but Tap1, Igf2, and Spns3 were significantly downregulated. The results of Western blot validation showed that dynamic changes in proteins, such as IGF2, Ly6a, Grb10, and UBD, occurred to regulate the incidence of diabetes by influencing the insulin receptor substrate (IRS) signaling pathway.

Mulberry Leaf Regulates Differentially Expressed Genes in Diabetic Mice Liver Based on RNA-Seq Analysis

The pathogenesis of diabetes mellitus is a complicated process involving much gene regulation. The molecular mechanism of mulberry (Morus alba L.) leaf in the treatment of diabetes is not fully understood. In this study, we used the Illumina HiSeq™ 2,500 platform to explore the liver transcriptome of normal mice, STZ-induced diabetic mice, and mulberry leaf-treated diabetic mice, and we obtained 52,542,956, 52,626,414, and 52,780,196 clean reads, respectively. We identified differentially expressed genes (DEGs) during the pathogenesis of diabetes in mice. The functional properties of DEGs were characterized by comparison with the GO and KEGG databases, and the results show that DEGs are mainly involved in the metabolic pathway. qRT-PCR was used to analyse 27 differential genes involved in liver expression in different groups of diabetic mice. Among the DEGs, the expression of Scube1, Spns3, Ly6a, Igf2, and other genes between the control (C) and diabetic control (DC) groups was significantly upregulated; the expression of Grb10, Mup2, and Fasn was significantly downregulated; the expression of the Sqle, Lss, and Irs2 genes between the C group and diabetic group treated with mulberry (DD) was significantly upregulated; the expression of Fabp2, Ly6a, and Grb10 was significantly downregulated; and the expression of Sqle and Lss was significantly upregulated in the DC and DD groups, but Tap1, Igf2, and Spns3 were significantly downregulated. The results of Western blot validation showed that dynamic changes in proteins, such as IGF2, Ly6a, Grb10, and UBD, occurred to regulate the incidence of diabetes by influencing the insulin receptor substrate (IRS) signaling pathway.

C-Phycocyanin inhibits hepatic gluconeogenesis and increases glycogen synthesis via activating Akt and AMPK in insulin resistance hepatocytes

The mechanism of C-PC in improving glucose homoeostasis is to activate the IRS/PI3 K/Akt and SIRT1/LKB1/AMPK signaling pathway in insulin resistant hepatocytes.

C-Phycocyanin protects against mitochondrial dysfunction and oxidative stress in parthenogenetic porcine embryos

C-Phycocyanin (CP) is a biliprotein enriched in blue-green algae that is known to possess antioxidant, anti-apoptosis, anti-inflammatory, and radical-scavenging properties in somatic cells. However, the protective effect of CP on porcine embryo developmental competence in vitro remains unclear. In the present study, we investigated the effect of CP on the development of early porcine embryos as well as its underlying mechanisms. Different concentrations of CP (2, 5, 8, 10 μg/mL) were added to porcine zygote medium 5 during in vitro culture. The results showed that 5 μg/mL CP significantly increased blastocyst formation and hatching rate. Blastocyst formation and quality were significantly increased in the 50 μM H₂O₂ treatment group following 5 μg/mL CP addition. CP prevented the H₂O₂-induced compromise of mitochondrial membrane potential, release of cytochrome c from the mitochondria, and reactive oxygen species generation. Furthermore, apoptosis, DNA damage level, and autophagy in the blastocysts were attenuated by supplementation of CP in the H₂O₂-induced oxidative injury group compared to in controls. These results suggest that CP has beneficial effects on the development of porcine parthenotes by attenuating mitochondrial dysfunction and oxidative stress.

The regulation of FOXO1 and its role in disease progression

Cell proliferation, apoptosis, autophagy, oxidative stress and metabolic dysregulation are the basis of many diseases. Forkhead box transcription factor O1 (FOXO1) changes in response to cellular stimulation and maintains tissue homeostasis during the above-mentioned physiological and pathological processes. Substantial evidences indicate that FOXO1's function depends on the modulation of downstream targets such as apoptosis- and autophagy-associated genes, anti-oxidative stress enzymes, cell cycle arrest genes, and metabolic and immune regulators. In addition, oxidative stress, high glucose and other stimulations induce the regulation of FOXO1 activity via PI3k-Akt, JNK, CBP, Sirtuins, ubiquitin E3 ligases, etc., which mediate multiple signalling pathways. Subsequent post-transcriptional modifications, including phosphorylation, ubiquitination, acetylation, deacetylation, arginine methylation and O-GlcNAcylation, activate or inhibit FOXO1. The regulation of FOXO1 and its role might provide a significant avenue for the prevention and treatment of diseases. However, the subtle mechanisms of the post-transcriptional modifications and the effect of FOXO1 remain elusive and even conflicting in the development of many diseases. The determination of these questions potentially has implications for further research regarding FOXO1 signalling and the identification of targeted drugs.

Jiang Tang Xiao Ke Granule Play an Anti-diabetic Role in Diabetic Mice Pancreatic Tissue by Regulating the mRNAs and MicroRNAs Associated with PI3K-Akt Signaling Pathway

Purpose: To investigate the effect of JTXK granule on the expression pattern of miRNA in pancreatic tissue of KKAy diabetic mice, and to explore the molecular mechanism and pathways of JTXK granule in anti-diabetic effect.

Methods: We used high fat diet (HFD) to induce the KKAy diabetic mice and screened the differentially expressed miRNAs (DEMs) between JTXK-treated group (n = 6) and the diabetic group (n = 6) using MicroRNA (miRNA) Microarray. C57BL/6J mice were given a normal diet as the control group (n = 6). Subsequently, miRNA target gene prediction, GO and Pathway analysis were used to explore the function of DEMs. Finally, the mechanism of anti-diabetic effects of JTXK granule was tested by in vitro INS-1 pancreatic β-cell experiment.

Results: The blood glucose and body weight of JTXK-treated group was significantly lower compared with the model group. Moreover, a total of 45 miRNAs with significant differences were detected in the model group and the JTXK-treated group (P ≤ 0.05, Fold Change > 2). Further, miRNA-mRNA analysis showed that the differential expression of mmu-miR-192-5p, mmu-miR-291a-3p, mmu-miR-320-3p, mmu-miR-139-5p and mmu-miR-378a-3p are closely related to pancreatic histological changes. In addition, pathway analysis showed that the DEMs were closely related to PI3K-Akt Signaling Pathway. Furthermore, the levels of serine/threonine-protein kinase (Akt), phosphorylated Akt (p-Akt) and phosphorylated forkhead transcription factor O1 (p-Foxo1) in INS-1-FOXO1 overexpressing model cells were lower than those in normal group, while JTXK granules could increase the expression of Akt, p-Akt and p-Foxo1.

Conclusions: The results showed that JTXK granule could play an anti-diabetic role by regulating the mRNA and miRNAs associated with PI3K-Akt pathway in diabetic mice pancreatic tissue.

Phycocyanin prevents methylglyoxal-induced mitochondrial-dependent apoptosis in INS-1 cells by Nrf2

Phycocyanin prevents mitochondrial-dependent apoptosis in methylgiyoxal-induced INS-1 cells by activating Nrf2.