Molecular scanning for mutations in the insulin receptor substrate-1 (IRS-1) gene in Turkish with type 2 diabetes mellitus

Association of IRS-1 and IRS-2 polymorphisms with predisposition to type-2 diabetes (T2D): a meta-analysis and trial sequential analysis

Background: Insulin Receptor Substrate (IRS) molecules play a major role in insulin signalling, and single nucleotide polymorphisms in the IRS-1 (rs1801278) and IRS-2 (rs1805097) gene has been associated with the predisposition to the development of type-2 diabetes (T2D) in some population. However, the observations remain contradictory. Discrepancies in the results have been attributed to several factors, and consideration of a smaller sample size is one of them. To reach a valid conclusion, we performed a meta-analysis of the genetic association between IRS-1 (rs1801278) and IRS-2 (rs1805097) polymorphism with a predisposition to T2D. Materials and Methods: The literature search was performed in different databases such as PubMed, Science Direct, and Scopus. All relevant articles were screened and based in inclusion and exclusion criteria eligible reports were identified. Baseline characteristics, genotype and allele frequencies were extracted from the eligible reports. The meta-analysis was performed by comprehensive meta-analysis software v3.3.070 and odds ratios, 95% confidence interval and probability values were calculated to find out association of IRS-1 and IRS-2 polymorphisms with rhinitis. Results: A total of seven studies comprising 1287 cases and 1638 control were considered for the present meta-analysis for the association of IRS-1 (rs1801278) polymorphism with T2D, and no significant association was observed. For IRS-2 (rs1805097) polymorphism, data from eight cohorts (cases: 1824, controls: 1786) were considered. The heterozygous genetic comparison models revealed a significant protective association against T2D predisposition (p = 0.017, OR = 0.841, 95% CI = 0.729 to 0.970). The trial sequential analysis revealed the requirement of additional case-control studies to draw a definitive conclusion for IRS-1 polymorphism. Conclusions: IRS-2 rs1805097 heterozygotes are protected from T2D development. However, IRS-1 (rs1801278) is not associated with a subject's proclivity for T2D.

Effect of Carica papaya on IRS-1/Akt Signaling Mechanisms in High-Fat-Diet-Streptozotocin-Induced Type 2 Diabetic Experimental Rats: A Mechanistic Approach

Despite rigorous endeavors, existing attempts to handle type 2 diabetes (T2DM) are still a long way off, as a substantial number of patients do not meet therapeutic targets. Insulin resistance in skeletal muscle is discerned as a forerunner in the pathogenesis of T2DM and can be detected years before its progress. Studies have revealed the antidiabetic properties of Carica papaya (C. papaya), but its molecular mechanism on insulin receptor substrate-1 (IRS-1)/Akt signaling mechanisms is not yet known. The present study aimed to evaluate the role of C. papaya on IRS1 and Akt in high-fat-diet-streptozotocin-induced type 2 diabetic rats and also to analyze the bioactive compounds of C. papaya against IRS-1 and Akt via in silico analysis. Ethanolic extract of the leaves of C. papaya (600 mg/kg of body weight) was given daily for 45 days postinduction of T2DM up to the end of the study. Gluconeogenic enzymes, glycolytic enzymes, gene expression, and immunohistochemical analysis of IRS-1 and Akt in skeletal muscle were evaluated. C. papaya treatment regulated the levels of gluconeogenic and glycolytic enzymes and the levels of IRS-1 and Akt in skeletal muscle of type 2 diabetic animals. In silico studies showed that trans-ferulic acid had the greatest hit rate against the protein targets IRS-1 and Akt. C. papaya restored the normoglycemic effect in diabetic skeletal muscle by accelerating the expression of IRS-1 and Akt.

Insulin Signal Transduction Perturbations in Insulin Resistance

Type 2 diabetes mellitus is a widespread medical condition, characterized by high blood glucose and inadequate insulin action, which leads to insulin resistance. Insulin resistance in insulin-responsive tissues precedes the onset of pancreatic β-cell dysfunction. Multiple molecular and pathophysiological mechanisms are involved in insulin resistance. Insulin resistance is a consequence of a complex combination of metabolic disorders, lipotoxicity, glucotoxicity, and inflammation. There is ample evidence linking different mechanistic approaches as the cause of insulin resistance, but no central mechanism is yet described as an underlying reason behind this condition. This review combines and interlinks the defects in the insulin signal transduction pathway of the insulin resistance state with special emphasis on the AGE-RAGE-NF-κB axis. Here, we describe important factors that play a crucial role in the pathogenesis of insulin resistance to provide directionality for the events. The interplay of inflammation and oxidative stress that leads to β-cell decline through the IAPP-RAGE induced β-cell toxicity is also addressed. Overall, by generating a comprehensive overview of the plethora of mechanisms involved in insulin resistance, we focus on the establishment of unifying mechanisms to provide new insights for the future interventions of type 2 diabetes mellitus.

Differential expression of insulin receptor substrate-1(IRS-1) in visceral and subcutaneous adipose depots of morbidly obese subjects undergoing bariatric surgery in a tertiary care center in north India; SNP analysis and correlation with metabolic profile

BACKGROUND

/aim: Abdominal obesity and associated metabolic consequences are a burgeoning problem in Asian Indians and studying their genetic predisposition is important. This study is aimed at assessing variations in Insulin receptor substrate-1 (IRS-1), its expression at regional fat-depots (visceral and subcutaneous) in morbidly obese patients, and correlation with genotype-phenotype traits.

METHODS

Gene expression of IRS-1 in paired adipose tissue from 35 morbidly obese subjects (BMI) > 40 kg/m²) with co-morbidities and 15 controls (BMI<25 kg/m²), undergoing bariatric/elective abdominal surgery, respectively was determined by quantitative real time PCR. Genotyping of IRS-1Gly972Arg (n = 436) (rs 1801278) was performed by PCR-RFLP. Metabolic parameters were assessed. Full length sequencing of IRS-1 was performed to identify known/novel variations.

RESULTS

A marked reduction in IRS-1 expression was observed in visceral as compared to subcutaneous adipose tissue of morbidly obese subjects (p = 0.02). Homozygous variant of IRS-1 Gly972Arg was absent and there was no association with obesity or insulin resistance. A salient finding of this study was identification of two new variants in IRS-1 gene, representing G > A (codon 1102) encoding Glu > Lys and a deletion of (A) at codon 658 in morbidly obese subjects with insulin resistance.

CONCLUSIONS

Observation of a substantially lower expression of IRS-1 for first time in visceral adipose tissue of morbidly obese subjects is suggestive of predictive role of IRS-1 expression in insulin responsiveness of visceral adipose tissue. New variants in IRS-1, a non-synonymous mutation and a deletion should be evaluated further for their role in development of obesity and/orT2DM.

Prevalence of Insulin Receptor Substrate-1 Gene (G972R) Polymorphism, Insulin Resistance, and Determination of β-Cell Function among Overweight and Obese Persons with Type 2 Diabetes Mellitus

Background

Type 2 diabetes mellitus (T2DM) is the most common metabolic disorder and its pathogenesis is characterized by a combination of peripheral insulin resistance and impaired insulin secretory capacity of pancreatic β cell. Genetic predisposition interacts with environmental factors including diet, physical activity, and age leading to the development of diabetes.

Objective

To determine the proportion of overweight and obese persons with type 2 diabetes and to compare the fasting blood sugar, fasting serum insulin, insulin resistance and β-cell function in G972R carrier and non-carrier overweight and obese persons with type 2 diabetes.

Methodology

One hundred overweight and obese patients with T2DM were recruited from persons with diabetes attending the Diabetes Outpatient Department of Yangon General Hospital. History taking and physical examination were done and blood samples were collected. Plasma glucose level was determined by the glucose oxidase method and fasting serum insulin was measured by enzyme linked immunoassay (ELISA) kit method. Polymerase chain reaction and Restriction Fragment Length Polymorphism were done for genetic polymorphism.

Results

Among 100 overweight and obese subjects with T2DM, 81 patients were of homozygous (G/G) genotype, 18 patients were of heterozygous (G/A) and only one patient of homozygous (A/A) genotype. There was no statistically significant difference in the proportion of genotypes between overweight and obese subjects with T2DM.

There was no significant difference in fasting blood sugar (FBS), fasting serum insulin, HOMA-IR, β-cell function, lipid parameters between IRS-1 (G972R) carriers and non-carriers. There is significant negative correlation between insulin resistance and TG level (r²=0.0529, p=0.01).

Conclusion

It was concluded that IRS-1 G972R polymorphism was not important in insulin resistance, β-cell function and lipid parameters in overweight and obese T2DM. There could be a number of candidate genes in the pathophysiology of diabetes mellitus, genetic sequencing of IRS-1 and other genes in the insulin signaling pathway, and finding out the alteration in their genetic patterns would provide clues for the association of the site-specific polymorphisms of these genes with insulin resistance in T2DM.

ASSOCIATION OF IRS1 GLY971ARG GENE POLYMORPHISM WITH INSULIN RESISTANCE IN IRANIAN NEWLY DIAGNOSED DIABETIC ADULTS

Context

Insulin receptor substrate-1 (IRS-1) has an important role in insulin signaling and the common Gly971Arg polymorphism is related to type 2 diabetes (T2D). IRS-1 Gly971Arg polymorphism can modify tyrosine phosphorylation at a specific site of IRS-1 and may have a critical role in the development of insulin resistance (IR).

Objective

The purpose of this study was to investigate the association between this polymorphism and IR in Iranian patients with newly-diagnosed type 2 diabetes.

Design

The study was conducted on 114 individuals with newly-diagnosed T2D and 118 healthy matched controls, aged 20-80 years. Fasting blood glucose and insulin were measured by the enzymatic method and enzyme-linked immunosorbent assay, respectively. Insulin-resistance was calculated by homeostasis model assessment estimated-insulin resistance (HOMA-IR). The gene polymorphism was examined by polymerase chain reaction-restriction fragment length polymorphism.

Results

There are significant differences between IRS1 Gly971Arg polymorphism and studied individuals (P<0.0001). The findings showed that the risk of developing T2D in individuals who had R-alleles was 3.74 folds higher than those without R-alleles. However, IRS1 Gly971Arg polymorphism was not associated with high HOMA-IR, high BMI and familial history of diabetes.

Conclusions

Even though there was not a significant relationship between IRS-1 G971R polymorphism with insulin resistance and high BMI, this polymorphism was correlated to newly-diagnosed diabetic patients. Thus, the evaluation of IRS-1 G971R polymorphism may be helpful for predicting T2D new cases.

A Missense Mutation in IRS1 is Associated with the Development of Early-Onset Type 2 Diabetes

There could be an overlap of monogenic diabetes and early-onset type 2 diabetes mellitus. Precise diagnosis of early-onset diabetes has proven valuable for understanding the mechanism of diabetes and selecting optimal therapy. The majority of maturity onset diabetes of the young (MODY) pathogenic genes in China is still unknown. In this study, a family with suspected MODY was enrolled. Whole-exome sequencing (WES) was used to analyze the variants of the proband. Variants were filtered according to their frequency, location, functional consequences, and bioinformatics software. Candidate pathogenic variants were validated by Sanger sequencing and tested for cosegregation in other members of the family and nonrelated healthy controls. KEGG (Kyoto Encyclopedia of Genes and Genomes) and PPI (protein-protein interaction) analysis were conducted using the DAVID (Database for Annotation, Visualization, and Integrated Discovery) and the STRING online analysis tools for the candidate pathogenic gene. A total of 123291 variants including 105344 SNPs and 17947 InDels were found in WES. A likely pathogenic rare missense heterozygous mutation in diabetes genes (c.2137C > T, p.His713Tyr in IRS1) was identified, which was a cosegregate in this family and not in nonrelated healthy controls. The position of the mutation in the aminoacid sequence of the gene is highly conserved among the species. 2 significantly enriched KEGG pathways were identified including bta04930, type II diabetes mellitus (GCK, INS, PDX1, ABCC8, and IRS1), and bta04910, insulin signaling pathway (GCK, INS, and IRS1). PPI analysis displayed that IRS1 interacts with 3 known pathogenic proteins including INS, KCNJ11, and GCK. We conclude that WES could be an initial option for genetic testing in patients with early-onset diabetes. IRS1 p.His713Tyr is implicated as a possible pathogenic mutation in monogenic diabetes, which might require further validation, and the precise molecular mechanism underlying the influence of IRS1 p.His713Tyr on the development of diabetes remains to be determined in the further prospective studies.

Genetic association of insulin receptor substrate-1 (IRS-1, rs1801278) gene with insulin resistant of type 2 diabetes mellitus in a Pakistani population

Insulin resistance (IR), a pathological condition of type 2 diabetes mellitus (T2DM) is characterized by an inability of body's tissue to respond the secreted or administered insulin, a necessary step for cellular glucose transportation. The prevalence of insulin resistance progresses with age, especially in overweight people with central obesity. Insulin receptor substrates (IRS) are important molecular proteins in the insulin signalling pathway, where IRS-1 plays a key function in cells insulin sensitivity. The common mutation (rs1801278; r.2963G > A: Gly972Arg) of the IRS-1 gene occurs when residue glycine changes to arginine at codon 972. The objective of this study was to detect the genetic association of rs1801278 polymorphism of the IRS-1 gene with insulin resistance in type 2 diabetes from the Lahore region of Pakistan. A total of 322 subjects (161 cases and 161 healthy individuals) were included. DNA was isolated for detection of the genotype distribution and allele frequencies by PCR-RFLP. The results showed a significant difference in the genotype distribution and allele frequency between the T2DM cases and controls for single nucleotide polymorphism (SNP) rs1801278 (OR 17.61, 95% CI 8.06-38.4, p < 0.001). In conclusion, association between rs1801278 polymorphism of the IRS-1 gene and insulin resistance in T2DM has been established in a Pakistani population.

Effects of the Tangningtongluo formula as an alternative strategy for diabetics via upregulation of insulin receptor substrate-1

Tangningtongluo (TNTL), a traditional Chinese medicine, has been widely used in clinics for decades in southwest China. Its pharmacological properties and underlying molecular mechanisms remain unclear. The main goal of ethnopharmacology is to identify novel bioactive compounds derived from plants for use in indigenous medical practice. This knowledge can be used to develop novel pharmaceuticals. In the present study, hyperglycemic C57BL/KsJ-db/db (db/db) mice were used to test the effect of TNTL on microvasculature of the retina and hypoglycemia. Metformin (Met) was selected as a positive control. 26-week-old mice were randomly assigned to receive either the anti-diabetic agent Met [140 mg/kg body weight (BW)], 1.8, 0.9 or 0.45 g/kg BW TNTL, or a placebo. The fasting blood glucose, serum insulin and glycated hemoglobin levels were measured. Histopathologic examination of the pancreas was performed to confirm the hypoglycemic effect. Fluorescein angiography was applied to detect diabetes-induced retinal angioma in the db/db mice. TNTL intake significantly decreased the fasting blood glucose level in a dose-dependent manner. Additionally, TNTL intervention resulted in a significant decrease in the insulin resistance index. Notably, TNTL treatment markedly reduced the speed of retinal degeneration and mildly reversed microvascular caliber degeneration. Western blot analysis indicated that upregulation of phosphorylated insulin receptor substrate-1 (p-IRS-1) by the administration of TNTL may be strongly involved in the improvement of insulin resistance. In conclusion, TNTL exerted a strong hypoglycemic effect and reversed retinal degeneration via upregulation of ISR-1. The present findings provide important scientific evidence supporting TNTL as an effective alternative approach for the management of Type 2 diabetes mellitus.

Type 2 Diabetes Susceptibility in the Greek-Cypriot Population: Replication of Associations with TCF7L2, FTO, HHEX, SLC30A8 and IGF2BP2 Polymorphisms

Type 2 diabetes (T2D) has been the subject of numerous genetic studies in recent years which revealed associations of the disease with a large number of susceptibility loci. We hereby initiate the evaluation of T2D susceptibility loci in the Greek-Cypriot population by performing a replication case-control study. One thousand and eighteen individuals (528 T2D patients, 490 controls) were genotyped at 21 T2D susceptibility loci, using the allelic discrimination method. Statistically significant associations of T2D with five of the tested single nucleotide polymorphisms (SNPs) (TCF7L2 rs7901695, FTO rs8050136, HHEX rs5015480, SLC30A8 rs13266634 and IGF2BP2 rs4402960) were observed in this study population. Furthermore, 14 of the tested SNPs had odds ratios (ORs) in the same direction as the previously published studies, suggesting that these variants can potentially be used in the Greek-Cypriot population for predictive testing of T2D. In conclusion, our findings expand the genetic assessment of T2D susceptibility loci and reconfirm five of the worldwide established loci in a distinct, relatively small, newly investigated population.

Associations between two single-nucleotide polymorphisms (rs1801278 and rs2943641) of insulin receptor substrate 1 gene and type 2 diabetes susceptibility: a meta-analysis

The objective of the study is to assess the association between rs1801278 and rs2943641 of insulin receptor substrate 1 gene (IRS1) and the susceptibility to type 2 diabetes. A literature search strategy was conducted to identify all references lists of relevant studies. The fixed or random effect model was used to calculate the pooled ORs on the basis of heterogeneity. Further analyses were performed to explore the sources of heterogeneity by sensitivity analysis, meta-regression analysis, and subgroup analysis. There was significant association between rs1801278 and type 2 diabetes risk in recessive model (AA vs. GA + GG, p = 0.043) and codominant model (AA vs. GG, p = 0.007). Subgroup analysis showed that the association between rs1801278 and type 2 diabetes risk was significant in dominant model (GA + AA vs. GG, p = 0.044), codominant model (GA vs. GG, p = 0.039), codominant model (AA vs. GG, p = 0.044), overdominant model (GG + AA vs. GA, p = 0.037) in Asian and codominant model (AA vs. GG, p = 0.039) in Caucasian of rs1801278. The association between rs2943641 and type 2 diabetes risk was significant in codominant model (CT vs. CC, p = 0.023) in Caucasian. This meta-analysis suggests that rs1801278 may play a role in type 2 diabetes risk, especially in Asian. It also indicates that rs2943641 may be associated with type 2 diabetes risk in Caucasian. Further larger studies should be performed to warrant confirmation.

IRS-1 gene polymorphism and DNA damage in pregnant women with diabetes or mild gestational hyperglycemia

BACKGROUND

Pregnant women with mild gestational hyperglycemia present a high risk for hypertension and obesity, and appear to reproduce the model of metabolic syndrome in pregnancy, including hyperinsulinemia and insulin resistance. Diabetic patients have a higher frequency of the IRS-1 Gly972Arg variant and this polymorphism is directly related to insulin resistance and subsequent hyperglycemia. In diabetes, hyperglycemia and other associated factors generate reactive oxygen species that increase DNA damage. The aims of this study were to evaluate the presence of the IRS-1 Arg972 polymorphism in pregnant women with diabetes or mild gestational hyperglycemia, and in their newborns. Additionally, we evaluated the level of primary DNA damage in lymphocytes of Brazilian pregnant women and the relationship between the amount of genetic damage and presence of the polymorphism.

METHODS

A based on the oral glucose tolerance test (OGTT) results and on glycemic profiles (GP), as follows: non-diabetic group, mild gestational hyperglycemia (MGH) and diabetic group. Eighty-five newborns were included in the study. Maternal peripheral blood samples and umbilical cord blood samples (5-10 mL) were collected for genotyping by PCR-RFLP and for comet assays.

RESULTS

The prevalence of genotype Gly/Arg in pregnant women groups was not statistically significant. In newborns, the frequency of Gly/Arg was significantly higher in the MGH and diabetic groups than in the non-diabetic group. Taken together, groups IIA and IIB (IIA + IIB; diabetes) presented lower amounts of DNA damage than the non-diabetic group (p = 0.064). No significant association was detected between genetic damage and the presence of the Arg972 genotype in pregnant women.

CONCLUSION

The polymorphism was more prevalent in newborns of diabetic and MGH women. We believe that it is necessary to increase the number of subjects to be examined in order to better determine the biological role of the Arg972 polymorphism in these patients. Despite being classified as low-risk, pregnant women with mild gestational hyperglycemia characterize a population of maternal and perinatal adverse outcomes, and that, together with their newborns, require better monitoring by professionals and health services.

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.

Genetic variants of the insulin receptor substrate-1 are influencing the therapeutic efficacy of oral antidiabetics

AIM

The therapeutic efficacy of oral hypoglycaemic drugs varies between individuals, and pharmacogenetic factors contribute to this variability. The Gly972Arg polymorphism in the insulin receptor substrate-1 (IRS-1) has been shown to play a role in insulin signal transduction and therapeutic failure to sulphonylurea drugs.

METHODS

We studied the association between the IRS-1 polymorphism and the haemoglobin A1c (HbA1c) level in diabetic patients treated with insulinotropic versus non-insulinotropic hypoglycaemic drugs as a marker for the efficacy of an antidiabetic treatment. Genotyping of the IRS-1 Arg(972) variant was performed in type 2 diabetes patients treated with either sulphonylurea drugs, glinides or insulin or with metformin, acarbose or glitazones using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

Significantly higher HbA1c levels were observed in carriers of the Arg(972) variant after treatment with insulinotropic drugs compared to wild-type carriers (8.3 vs. 7.6%, p = 0.005, independent t-test). Furthermore, patients with secondary failure to insulinotropic hypoglycaemic drugs switching finally to insulin showed even higher HbA1c levels in carriers of Arg(972) compared to wild-type (8.7 vs. 7.6%, p = 0.005, independent t-test).

CONCLUSIONS

Thus, we were able to replicate the earlier findings of an association between the IRS-1 Arg(972) variant and secondary failure to sulphonylurea drugs, and further observed a general association between HbA1c and this polymorphism in type 2 diabetes patients treated with insulinotropic hypoglycaemic drugs but not with metformin.

IRS1 G972R polymorphism and type 2 diabetes: a paradigm for the difficult ascertainment of the contribution to disease susceptibility of 'low-frequency-low-risk' variants

AIMS/HYPOTHESIS

The aim of the study was to determine the association between IRS1 G972R polymorphism and type 2 diabetes; published data concerning this association have been conflicting. To obtain further insight into this topic, we performed a meta-analysis of all available case-control studies.

METHODS

We performed a meta-analysis of 32 studies (12,076 cases and 11,285 controls).

RESULTS

The relatively infrequent R972 variant was not significantly associated with type 2 diabetes (OR 1.09, 95% CI 0.96-1.23, p = 0.184 under a dominant model). Some evidence of heterogeneity was observed across studies (p = 0.1). In the 14 studies (9,713 individuals) in which the mean age at type 2 diabetes diagnosis was available, this variable explained 52% of the heterogeneity (p = 0.03). When these studies were subdivided into tertiles of mean age at diagnosis, the OR for diabetes was 1.48 (95% CI 1.17-1.87), 1.22 (95% CI 0.97-1.53) and 0.88 (95% CI 0.68-1.13) in the youngest, intermediate and oldest tertile, respectively (p = 0.0022 for trend of ORs).

CONCLUSIONS/INTERPRETATION

Our findings illustrate the difficulties of ascertaining the contribution of 'low-frequency-low-risk' variants to type 2 diabetes susceptibility. In the specific context of the R972 variant, approximately 200,000 study individuals would be needed to have 80% power to identify a 9% increase in diabetes risk at a genome-wide significance level. Under these circumstances, a strategy aimed at improving outcome definition and decreasing its heterogeneity may critically enhance our ability to detect genetic effects, thereby decreasing the required sample size. Our data suggest that focusing on early-onset diabetes, which is characterised by a stronger genetic background, may be part of such a strategy.