Microproteomic-Based Analysis of the Goat Milk Protein Synthesis Network and Casein Production Evaluation

Goat milk has been consumed by humans since ancient times and is highly nutritious. Its quality is mainly determined by its casein content. Milk protein synthesis is controlled by a complex network with many signal pathways. Therefore, the aim of our study is to clearly depict the signal pathways involved in milk protein synthesis in goat mammary epithelial cells (GMECs) using state-of-the-art microproteomic techniques and to identify the key genes involved in the signal pathway. The microproteomic analysis identified more than 2253 proteins, with 323 pathways annotated from the identified proteins. Knockdown of IRS1 expression significantly influenced goat casein composition (α, β, and κ); therefore, this study also examined the insulin receptor substrate 1 (IRS1) gene more closely. A total of 12 differential expression proteins (DEPs) were characterized as upregulated or downregulated in the IRS1-silenced sample compared to the negative control. The enrichment and signal pathways of these DEPs in GMECs were identified using GO annotation and KEGG, as well as KOG analysis. Our findings expand our understanding of the functional genes involved in milk protein synthesis in goats, paving the way for new approaches for modifying casein content for the dairy goat industry and milk product development.

Insulin receptor substrate 1 gene variations and lipid profile characteristics in the type 2 diabetic patients with comorbid obesity and chronic pancreatitis

Objective. Type 2 diabetes mellitus (T2DM) is one of diseases that develops in a setting of polymorbid processes or more often promotes their development, forming in this spectrum the phenomenon of comorbidity. The aim of this study was to evaluate changes in the lipid panel data in T2DM patients with comorbid obesity and chronic pancreatitis (CP) taking into account the C/A polymorphism of the insulin receptor substrate 1 (IRS1) gene (rs2943640). Methods. The study involved 34 T2DM patients and 10 healthy individuals. The rs2943640 IRS1 gene polymorphism was genotyped using the TaqMan real-time polymerase chain reaction (PCR) method. Blood serum lipid panel data were determined with commercially available kits on a Cobas 6000 analyzer. Results. In patients with only T2DM and T2DM + comorbid obesity, an association between IRS1 gene polymorphism (rs2943640) and lipid profile abnormalities with maximum changes of the lipid characteristics recorded in C/C genotype carriers was found. Within the C/C genotype of the IRS1 gene (rs2943640) in type 2 diabetic patients with comorbid obesity and CP, significantly lower high-density lipoprotein cholesterol (HDL-C) levels and significantly higher levels of triglycerides (TG), non-HDL-C and remnant cholesterol (RC) in relation to type 2 diabetic patients with comorbid obesity were found. At the same time, within the C/A genotype of the IRS1 gene (rs2943640), significant changes of lipid panel data were found in type 2 diabetic patients with comorbid obesity relative to the control group (p<0.001). Conclusions. Our data indicate that the presence of the C allele of IRS1 gene (rs2943640) in both homozygous and heterozygous states may indicate increased risk of dyslipidemia in type 2 diabetic patients with comorbidities.

Insulin Receptor Substrate 1 Gene and Glucose Metabolism Characteristics in Type 2 Diabetes Mellitus with Comorbidities

BACKGROUND

Genetic variants that affect insulin signaling play an important role in insulin resistance (IR) in type 2 diabetes mellitus (T2DM). This study aimed to evaluate changes of the glycemic profile and IR in T2DM with comorbid obesity and chronic pancreatitis (CP) considering the allele status of the IRS1 gene (rs2943640).

METHODS

The study involved 33 type-2 diabetic patients and 10 healthy individuals. The IRS-1 gene rs2943640 C>A polymorphism was genotyped using the TaqMan real-time PCR method.

RESULTS

In type 2 diabetic patients regardless of the presence/absence of comorbid obesity and CP glycemic profile parameters significantly did not differ between carriers of allele C or allele A of the IRS1 gene (rs2943640). At the same time significantly higher HOMA-IR (by 2.25 times) was established in carriers of the C allele. In type 2 diabetic patients with both comorbidities (carriers of the C allele) the maximum HOMA-IR was established, which significantly differed from the data of patients with only T2DM and patients with comorbid obesity. In carriers of the A allele significantly higher level of HOMA-IR was found in patients with comorbid obesity and CP vs patients with only T2DM, and also in patients with comorbid obesity vs patients with only T2DM.

CONCLUSIONS

Presence of the C allele of the IRS1 gene (rs2943640) may indicate risk of high IR in type 2 diabetic patients regardless of the presence/absence of comorbid obesity and CP; here with CP is a more important factor in IR progression then obesity.

A 3'-untranslated region variant (rs2289046) of insulin receptor substrate 2 gene is associated with susceptibility to nonalcoholic fatty liver disease

PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is an increasing global health concern defined by excessive hepatic fat content in the absence of excessive alcohol consumption. Regarding the key role of insulin and insulin resistance in NAFLD, we investigated whether insulin receptor substrate 1 (IRS1) and insulin receptor substrate 2 (IRS2) gene variants were associated with NAFLD risk.

METHODS

In this case-control study, 305 subjects including 151 cases with biopsy-proven NAFLD and 154 controls were enrolled. All the subjects were genotyped for IRS1 (rs1801278) and IRS2 (rs2289046) gene variants using PCR-RFLP method.

RESULTS

Our findings showed that the IRS2 rs2289046 "GG+AG" genotype compared with "AA" genotype to be a marker of decreased NAFLD susceptibility and the difference remained significant even after adjustment for confounding factors including age, BMI, sex, smoking status, systolic blood pressure, and diastolic blood pressure (P=0.014; OR=0.50, 95%CI= 0.29-0.87). Furthermore, the IRS2 "G" allele was significantly underrepresented in the cases with NAFLD than controls (P=0.026 ; OR=0.62, 95%CI=0.41-0.94). However, no significant difference was found for IRS1 rs1801278 gene variant.

CONCLUSIONS

This study suggests, for the first time, that the IRS2 gene rs2289046 variant may play a role in NAFLD susceptibility. Nevertheless, this observation warrants further investigations in other populations.

Physical activity attenuates the association between the IRS1 genotype and childhood obesity in Chinese children

BACKGROUND AND AIMS

The insulin receptor substrate 1 (IRS1) rs2943650 was found to be associated with obesity in adults, but the association has not been evaluated in children. The present study aimed to examine whether IRS1 rs2943650 was associated with obesity in Chinese children and investigate the interaction between rs2943650 and physical activity.

METHODS AND RESULTS

IRS1 rs2943650 was genotyped in 3303 Chinese children aged 6-18 years recruited from four independent studies. Logistic regression and linear regression were performed to examine associations. Meta-analyses were conducted to pool the results of the four independent studies. The C-allele carriers of rs2943650 showed a 29% higher risk of obesity than noncarriers (OR (95% CI) = 1.29 (1.05, 1.58), P = 0.02) and a 0.41 kg/m² increase in BMI (β (95% CI) = 0.41 (0.05, 0.78) kg/m², P = 0.02). We also observed significant interactions between rs2943650 and physical activity/sedentary behaviors on obesity (P_{forinteraction}<0.05). Compared with the physically active children (physical activity ≥1 h/d and sedentary behaviors <2 h/d), the risk allele (C) of rs2943650 was significantly associated with a 241% increased risk of obesity among inactive children who participated in physical activity <1 h/d and sedentary behaviors ≥2 h/d (OR (95% CI) = 3.41 (1.45, 8.01), P = 0.005).

CONCLUSIONS

We found that IRS1 rs2943650 was significantly associated with BMI and risk of childhood obesity. Additionally, we also found significant interaction between IRS1 rs2943650 polymorphism and physical activity/sedentary behaviors on childhood obesity. Our study would provide novel insights into the function of the IRS1 gene and the implementation of effective intervention strategies of childhood obesity.

IRS1 gene polymorphisms Gly972Arg and Ala513Pro are not associated with insulin resistance and type 2 diabetes risk in non-obese Turkish population

Insulin receptor substrate 1 (IRS1), plays a critical role in insulin signaling and its control has an important place in the development of insulin resistance. The tyrosine phosphorylation of IRS1 serves as docking molecules for downstream effectors such as Phosphatidylinositol 3-kinase and phosphotyrosine phosphatase-2. We focused on the Gly972Arg and Ala513Pro variants of the IRS1 gene, since these specific allelic variants are located near the Tyr-Met-X-Met (YMXM) motifs around Tyr987 and Tyr612. Thus, we aimed to investigate the effects of Gly972Arg/Ala513Pro polymorphisms in IRS1 gene on development of insulin resistance and the risk of type 2 diabetes in a non-obese Turkish population. This work included 306 individuals comprising 178 subjects with type 2 diabetes and 128 healthy subjects matched for body mass index. Gly972Arg/Ala513Pro polymorphisms had no effect on type 2 diabetes risk and its phenotypes (P > 0.05). Although IRS1 gene and its variants are associated with type 2 diabetes and insulin resistance in several studies worldwide, our data showed that there is no association between Gly972Arg and Ala513Pro variants in IRS1 and disease in Turkish population.