PTEN influences insulin and lipid metabolism in bovine hepatocytes in vitro

Predictive, preventive, and personalized medicine in breast cancer: targeting the PI3K pathway

Breast cancer (BC) is a multifaceted disease characterized by distinct molecular subtypes and varying responses to treatment. In BC, the phosphatidylinositol 3-kinase (PI3K) pathway has emerged as a crucial contributor to the development, advancement, and resistance to treatment. This review article explores the implications of the PI3K pathway in predictive, preventive, and personalized medicine for BC. It emphasizes the identification of predictive biomarkers, such as PIK3CA mutations, and the utility of molecular profiling in guiding treatment decisions. The review also discusses the potential of targeting the PI3K pathway for preventive strategies and the customization of therapy based on tumor stage, molecular subtypes, and genetic alterations. Overcoming resistance to PI3K inhibitors and exploring combination therapies are addressed as important considerations. While this field holds promise in improving patient outcomes, further research and clinical trials are needed to validate these approaches and translate them into clinical practice.

Protective Effects of Different Selenium Green Tea Polysaccharides on the Development of Type 2 Diabetes in Mice

Selenium polysaccharides have attracted significant interest due to their superior function to that of individual polysaccharides. However, limited research has compared the protective effects of different selenium polysaccharides from different selenization methods on diabetes. This work aims to compare the preventive effects of natural selenium-enriched green tea polysaccharides (NSe-TPS), synthetic selenized green tea polysaccharides (PCSe-TPS), and a mixture of sodium selenite and green tea polysaccharides (ordinary tea polysaccharides (Ord-TPS)+Se) on the development of diabetes. While establishing a diabetes model induced by a high-sugar, high-fat diet combined with streptozotocin, different selenium polysaccharides were administered daily by gavage for nine weeks. Our findings indicate that PCSe-TPS exhibited superior preventive effects on developing type 2 diabetes compared to NSe-TPS and Ord-TPS+Se. PCSe-TPS effectively regulated glucose metabolism and insulin resistance by activating the PI3K/Akt pathway, thereby preventing elevated blood glucose levels. Additionally, PCSe-TPS mitigated oxidative damage and inflammatory responses in liver tissues. Notably, PCSe-TPS intervention reversed the decline in bacterial species richness and the abundance of unclassified_Oscillospiraceae during the development of diabetes in mice. These results provide valuable insights into the protective effects of PCSe-TPS against diabetes development, highlighting its advantages over NSe-TPS and Ord-TPS+Se.

The role of protein kinases as key drivers of metabolic dysfunction-associated fatty liver disease progression: New insights and future directions

Metabolic dysfunction-associated fatty liver disease (MAFLD), proposed in 2020 is a novel term for non-alcoholic fatty liver disease (NAFLD) which was coined for the first time in 1980. It is a leading cause of the most chronic liver disease and hepatic failure all over the world, and unfortunately, with no licensed drugs for treatment yet. The progress of the disease is driven by the triggered inflammatory process, oxidative stress, and insulin resistance in many pathways, starting with simple hepatic steatosis to non-alcoholic steatohepatitis, fibrosis, cirrhosis, and liver cancer. Protein kinases (PKs), such as MAPK, ErbB, PKC, PI3K/Akt, and mTOR, govern most of the pathological pathways by acting on various downstream key points in MAFLD and regulating both hepatic gluco- lipo-neogenesis and inflammation. Therefore, modulating the function of those potential protein kinases that are effectively involved in MAFLD might be a promising therapeutic approach for tackling this disease. In the current review, we have discussed the key role of protein kinases in the pathogenesis of MAFLD and performed a protein-protein interaction (PPI) network among the main proteins of each kinase pathway with MAFLD-related proteins to predict the most likely targets of the PKs in MAFLD. Moreover, we have reported the experimental, pre-clinical, and clinical data for the most recent investigated molecules that are activating p38-MAPK and AMPK proteins and inhibiting the other PKs to improve MAFLD condition by regulating oxidation and inflammation signalling.

IGF-1 ameliorates streptozotocin-induced pancreatic β cell dysfunction and apoptosis via activating IRS1/PI3K/Akt/FOXO1 pathway

BACKGROUND AND OBJECTIVE

Type 2 diabetes mellitus (T2DM) is an endocrine disorder with pancreatic β cell dysfunction and/or reduced insulin sensitivity. IGF-1 is critically involved in pancreatic β cell growth, differentiation, and insulin secretion. Insulin-mediated IRS1/PI3K/Akt/FOXO1 signaling has been proved to be closely associated with pancreatic β cell function, hepatic glucose metabolism, and the development of T2DM. This present work was designed to demonstrate the protective role of IGF-1 against pancreatic β cell dysfunction and to probe into the underlying mechanisms.

METHODS

Herein, cell viability, cell apoptosis, insulin secretion, oxidative stress, and glycolysis in STZ-treated INS-1 cells were measured, so as to determine the biological function of IGF-1 against pancreatic β cell dysfunction in T2DM. Additionally, whether IGF-1 could activate IRS1/PI3K/Akt/FOXO1 signaling pathway to manipulate the progression of T2DM was also investigated.

RESULTS

It was discovered that IGF-1 treatment enhanced the viability and suppressed the apoptosis of STZ-treated INS-1 cells. Besides, IGF-1 treatment augmented insulin secretion of INS-1 cells in response to STZ. Moreover, IGF-1 exerted protective role against oxidative damage and displayed inhibitory effect on glycolysis in STZ-treated INS-1 cells. Mechanistically, IGF-1 treatment markedly boosted the activation of IRS1/PI3K/Akt/FOXO1 pathway. Furthermore, treatment with AG1024 (an inhibitor of IGF-1R) partially abolished the actions of IGF-1 on cell viability, cell apoptosis, insulin secretion, oxidative stress, and glycolysis in STZ-treated INS-1 cells.

CONCLUSION

To conclude, IGF-1 could improve the viability and inhibit the apoptosis of STZ-treated pancreatic β cells, induce insulin secretion, alleviate oxidative damage, as well as arrest glycolysis by activating IRS1/PI3K/Akt/FOXO1 pathway.

NEFAs Influence the Inflammatory and Insulin Signaling Pathways Through TLR4 in Primary Calf Hepatocytes in vitro

Transition dairy cows are often in a state of negative energy balance because of decreased dry matter intake and increased energy requirements, initiating lipid mobilization and leading to high serum β-hydroxybutyrate (BHBA) and non-esterified fatty acid (NEFAs) levels, which can induce ketosis and fatty liver in dairy cows. Inflammation and insulin resistance are also common diseases in the perinatal period of dairy cows. What is the relationship between negative energy balance, insulin resistance and inflammation in dairy cows? To study the role of non-esterified fatty acids in the nuclear factor kappa beta (NF-κB) inflammatory and insulin signaling pathways through Toll-like receptor 4 (TLR4), we cultured primary calf hepatocytes and added different concentrations of NEFAs to assess the mRNA and protein levels of inflammatory and insulin signaling pathways. Our experiments indicated that NEFAs could activate the NF-κB inflammatory signaling pathway and influence insulin resistance through TLR4. However, an inhibitor of TLR4 alleviated the inhibitory effects of NEFAs on the insulin pathway. In conclusion, all of these results indicate that high-dose NEFAs (2.4 mM) can activate the TLR4/NF-κB inflammatory signaling pathway and reduce the sensitivity of the insulin pathway through the TLR4/PI3K/AKT metabolic axis.

Metformin alleviates inflammation through suppressing FASN-dependent palmitoylation of Akt

Metformin, traditionally regarded as a hypoglycemic drug, has been studied in other various fields including inflammation. The specific mechanism of metformin’s effect on immune cells remains unclear. Herein, it is verified that LPS-induced macrophages are characterized by enhanced endogenous fatty acid synthesis and the inhibition of fatty acid synthase (FASN) downregulates proinflammatory responses. We further show that metformin could suppress such elevation of FASN as well as proinflammatory activation in macrophages. In vivo, metformin treatment ameliorates dextran sulfate sodium (DSS)-induced colitis through impairing proinflammatory activation of colonic lamina propria mononuclear cells (LPMCs). The reduction of FASN by metformin hinders Akt palmitoylation, which further disturbs Akt membrane attachment and its phosphorylation. Metformin-mediated suppression of FASN/Akt pathway and its downstream MAPK signaling contributes to its anti-inflammatory role in macrophages. From the perspective of immunometabolism, our work points towards metformin utilization as an effective and potential intervention against macrophages-involved inflammatory diseases.

Phosphatase and tensin homolog (PTEN) suppresses triacylglycerol accumulation and monounsaturated fatty acid synthesis in goat mammary epithelial cells

Phosphatase and tensin homolog (PTEN) is a well-known tumor suppressor in nonruminants and regulates various cellular processes including growth through dephosphorylation of phosphoinositide substrates. Although studies with bovine mammary tissue suggested a role for PTEN during lactation, its potential role in lipid metabolism remains unknown. Objectives of the present study were to determine PTEN abundance in goat mammary tissue at 2 stages of lactation (n = 6 Xinong Saanen dairy goats per stage), and to use gene-silencing and adenoviral transfections in vitro with isolated goat mammary epithelial cells (GMEC) to evaluate the role of PTEN abundance of lipid metabolism-related genes. Abundance of PTEN decreased by 51.5% at peak lactation compared with the dry period. The PTEN was overexpressed in isolated GMEC through adenoviral transfection using an adenovirus system with Ad-GFP (recombinant adenovirus of green fluorescent protein) as control, and silenced via targeted small interfering RNA (siRNA) transfection with a scrambled small interfering RNA as a negative control. Cell culture was performed for 48 h before RNA extraction, triacylglycerol (TAG) analysis, and fatty acid analysis. Overexpression of PTEN downregulated abundance of acetyl-coenzyme A carboxylase α (ACACA), fatty acid synthase (FASN), sterol regulatory element binding transcription factor1 (SREBF1), stearoyl-coenzyme A desaturase 1 (SCD1), diacylglycerol acytransferase 1 (DGAT1), 1-acylglycerol-3-phosphate O-acyltransferase 6 (AGPAT6) coupled with an increase in patatin-like-phospholipase domain containing 2 (PNPLA2), hormone-sensitive lipase (LIPE), and carnitine palmitoyltransferase 1 β (CPT1B). Furthermore, overexpressing PTEN in vitro resulted in a significant decrease in TAG concentration and concentration of C16:1. In contrast, interference of PTEN led to an opposite effect on lipid metabolism in GMEC. These changes suggested a shift from lipogenesis and esterification to lipolysis and fatty acid oxidation. Collectively, PTEN seems to play a role in monounsaturated fatty acids synthesis and lipid accumulation in GMEC.

miR-141-3p is Poorly Expressed in Polycystic Ovary Syndrome and Correlates with Glucose and Lipid Metabolism

Polycystic ovary syndrome (PCOS) is a common endocrinopathy with high prevalence. miR-141-3p downregulation was reported in PCOS rats. This study intended to investigate miR-141-3p expression in serum of PCOS patients and its correlation with glucose and lipid metabolism. A total of 100 PCOS patients and 100 healthy controls were enrolled in this study. Clinical parameters and glucose and lipid indexes were analyzed. A 3-month fat reduction intervention was conducted to PCOS-obese patients. Expressions of miR-141-3p and PTEN were detected. WHR and levels of TG, HDL-C, FBG, FINS, HOMA-β, and HOMA-IR showed significant differences in PCOS patients. miR-141-3p was downregulated in PCOS patients. Area under ROC curve of miR-141-3p diagnosing PCOS-obese patients was 0.985 with specificity 95.35% and flexibility 93.33%. Levels of glucose and lipid metabolism indexes were increased while HDL-C level was decreased in miR-141-3p low expression group. Indexes of PCOS-obese patients were improved and miR-141-3p was upregulated after fat reduction intervention. PTEN was upregulated in PCOS patients and negatively correlated with miR-141-3p. In conclusion, miR-141-3p was downregulated in PCOS patients and had higher diagnostic value on PCOS and associated with glucose and lipid metabolism. miR-141-3p might play a role in glucose and lipid metabolism in PCOS-obese patients by targeting PTEN.

Knockdown of phosphatase and tensin homolog (PTEN) inhibits fatty acid oxidation and reduces very low density lipoprotein assembly and secretion in calf hepatocytes

Dairy cows with fatty liver exhibit hepatic lipid accumulation and disturbances in fatty acid oxidation and lipid transport. Phosphatase and tensin homolog (PTEN), a lipid phosphatase, regulates intrahepatic fatty acid oxidation and lipid transport in mice. Whether PTEN play a role in fatty acid oxidation and very low density lipoprotein (VLDL) assembly in calf hepatocytes are unknown. Hepatocytes isolated from 3 healthy female Holstein calves (1 d old, 30-40 kg) were infected with empty adenovirus with green fluorescent protein for 48 h (Ad-GFP group) or infected with PTEN knockdown adenovirus for 48 h (Ad-shPTEN group), or cultured in RPMI-1640 without Ad-shPTEN or Ad-GFP (control group). Compared with the Ad-GFP group, PTEN knockdown decreased mRNA and protein abundance and the activity of fatty acid oxidation-related molecules, including acyl-coA synthetase long-chain 1, carnitine palmitoyltransferase 1, carnitine palmitoyltransferase 2, and 3-hydroxy acyl-coA dehydrogenase. Furthermore, PTEN knockdown decreased mRNA and protein abundance of VLDL assembly-related molecules, including apolipoprotein B100, apolipoprotein E, microsomal triglyceride transfer protein, and low density lipoprotein receptor. Importantly, PTEN knockdown promoted triglyceride accumulation in hepatocytes and reduced the VLDL content in culture medium. A subsequent study was conducted on the following 4 groups: cells infected with Ad-GFP for 48 h and then treated with 2% BSA for another 24 h (Ad-GFP + BSA); cells infected with Ad-GFP for 48 h and then treated with 1.2 mM free fatty acids (FFA) and 2% BSA for another 24 h (Ad-GFP + 1.2 mM FFA); cells infected with Ad-shPTEN for 48 h and then treated with 2% BSA for another 24 h (Ad-shPTEN + BSA); cells infected with Ad-shPTEN for 48 h and then treated with 1.2 mM FFA and 2% BSA for another 24 h (Ad-shPTEN + 1.2 mM FFA). Compared with Ad-GFP + BSA, the abundances of PTEN and of fatty acid oxidation- and VLDL assembly-related proteins were lower in the Ad-GFP + 1.2 mM FFA group. Importantly, PTEN knockdown heightened the increase in triglyceride accumulation of hepatocytes and the decrease in VLDL content in culture medium induced by FFA. Overall, these in vitro data indicate that FFA inhibits PTEN expression, leading to triglyceride accumulation and the inhibition of VLDL assembly in calf hepatocytes. These findings suggest that PTEN may be a potential therapeutic target for FFA-induced hepatic steatosis in dairy cows.

Frequent and mild scrotal heat stress in mice epigenetically alters glucose metabolism in the male offspring

Several studies have reported that health problems occur in assisted reproductive technology (ART)-conceived offspring. Recently, investigations have demonstrated that paternal environmental conditions influence offspring health. However, it is unclear whether the factors that cause male infertility per se affect offspring health and contribute to health problems in ART-born children. Scrotal heat stress represents a common cause for oligoasthenozoospermia, and in these cases, in vitro fertilization-embryo transfer (IVF-ET) is typically recommended for those individuals trying to conceive. We exposed C57BL/6J male mice to frequent and mild scrotal heat stress (fmSHS) (39°C for 30 min once weekly for 5 consecutive wk). Sperm was subjected to IVF-ET with oocytes of untreated C57BL/6J females to produce offspring mice. Glucose intolerance and insulin resistance was observed in the male offspring mice derived from fmSHS-exposed fathers. Islets, after evaluation, remained unchanged. Genes involved in glucose metabolism, especially, those in insulin signaling pathways, showed dysregulation in the liver of the fmSHS-derived male offspring. Differentially methylated regions were found in the sperm of fmSHS-exposed mice by whole genome bisulfite sequencing. Interestingly, abnormal methylation of some genes with altered expression in offspring was observed in both the sperm of fmSHS fathers and the liver of their male offspring. Our results suggest that the factors that cause male infertility can affect male offspring health by an epigenetic mechanism.

Molecular Characteristics, Phylogeny and Expression Profile of the PTEN Gene in Goats

Phosphatase and the tensin homologue deleted on chromosome ten (PTEN) has pleiotropic effects on cell growth, organ development, glucose metabolism and insulin resistance in mammals. In the present study, we investigated the molecular characteristics, phylogeny and expression profile of the PTEN gene in different tissues of Jianzhou Daer goats. In this study, eight different tissues from E90, E135 and D90 female goats were collected to quantify the expression pattern of the PTEN gene using quantitative real-time PCR (qPCR), western blotting and FISH. In addition, the dynamic expression of PTEN was also determined during the differentiation of goat precursor adipose cells. A 1212-bp fragment (accession number MG923848), encoding a 403-amino acid protein with a putative molecular weight of 47.14 kDa, was identified in Jianzhou Daer goats by reverse-transcription polymerase chain reaction (RT-PCR). The phylogenetic tree showed that caprine PTEN had a relatively close relationship with ovine PTEN and bovine PTEN. qPCR revealed that PTEN was highly expressed in the liver, lung and spleen, while the lowest expression levels were observed in muscle tissues (P < 0.05). Moreover, the expression of the PTEN gene showed a decreasing trend during the differentiation of goat precursor adipose cells. RNA in situ hybridization yielded a consistent result with the qPCR data. Indeed, low protein expression was found in psoas major muscle and longissimus dorsi muscle, as well as in kidney and liver. However, PTEN protein was expressed at the highest level in the brain. The expression levels of PTEN mRNA and protein were inconsistent with each other, possibly because of post-transcriptional regulation. The findings obtained in our study lay a foundation for further investigations examining the caprine PTEN gene in embryo and organ development.