Role of insulin/insulin-like growth factor 1 signaling pathway in longevity

The insulin/insulin-like growth factor 1 (IGF-1) signaling pathway is evolutionary conserved in diverse speciesincluding C.elegans, saccharomyces cerevisiae, Drosophila melanogaster, rodents and humans, which is involved in many interrelated functions that are necessary for metabolism, growth and reproduction. Interestingly, more and more research has revealed that insulin/IGF-1 signaling pathway plays a pivotal role in the regulation of longevity. Generally, disruption of the power of this pathway will extend longevity in species ranging from C.elegansto humans. The role of insulin/IGF-1 in longevit yis probably related to stress resistance. Although the underlying mechanisms of longevity are not fully understood, the Insulin/IGF-1 signaling pathway has attracted substantial attention and it will be a novel target to prevent or postpone age-related diseases and extend life span. In this review, we mainly focus on the similar constitution and role of insulin/IGF-1 signaling pathway in C.elegans, saccharomyces cerevisiae, rodents and humans.

Integrating insulin-like growth factor 1 and sex hormones into neuroprotection:Implications for diabetes

Brain integrity and cognitive aptitude are often impaired in patients with diabetes mellitus, presumably a result of the metabolic complications inherent to the disease. However, an increasing body of evidence has demonstrated the central role of insulin-like growth factor 1(IGF1) and its relation to sex hormones in many neuroprotective processes. Both male and female patients with diabetes display abnormal IGF1 and sexhormone levels but the comparison of these fluctuations is seldom a topic of interest. It is interesting to note that both IGF1 and sex hormones have the ability to regulate phosphoinositide 3-kinase-Akt and mitogen-activated protein kinases-extracellular signal-related kinasesignaling cascades in animal and cell culture models of neuroprotection. Additionally, there is considerable evidence demonstrating the neuroprotective coupling of IGF1 and estrogen. Androgens have also been implicated in many neuroprotective processes that operate on similar signaling cascades as the estrogen-IGF1 relation. Yet, androgens have not been directly linked to the brain IGF1 system and neuroprotection. Despite the sex-specific variations in brain integrity and hormone levels observed in diabetic patients, the IGF1-sex hormone relation in neuroprotection has yet to be fully substantiated in experimental models of diabetes. Taken together, there is a clear need for the comprehensive analysis of sex differences on brain integrity of diabetic patients and the relationship between IGF1 and sex hormones that may influence brain-health outcomes. As such, this review will briefly outline the basic relation of diabetes and IGF1 and its role in neuroprotection. We will also consider the findings on sex hormones and diabetes as a basis for separately analyzing males and females to identify possible hormone-induced brain abnormalities. Finally, we will introduce the neuroprotective interplay of IGF1 and estrogen and how androgen-derived neuroprotection operates through similar signaling cascades. Future research on both neuroprotection and diabetes should include androgens into the interplay of IGF1 and sex hormones.

Preparatory training attenuates drastic response of the insulin-like growth factor binding protein 1 at the point of maximal oxygen consumption in handball players

Background:Intensive exercise changes physiological need for glucose and several biochemical pathways responsible for its metabolism response.Among them are those which involve insulin,insulin-like growth factor(IGF-1),and IGF-binding proteins(IGFBPs).Different types and degrees of exercise,as well as an athlete's fitness,may induce a range of responses regarding concentrations and time needed for the alteration.The idea of the work was to find out whether and how insulin/IGF axis responds to additional physical activity in the already trained subjects and if so,is the adaptation potentially beneficial from the aspect of metabolic control.Methods:The effect of 4-week intensive training on campus(preparatory training) on the levels of insulin,IGF-1,and IGFBPs during maximal progressive exercise test(MPET) on a treadmill was compared to the results obtained during MPET conducted after a regular training season of a female elite handball team(n = 17,age:17 ± 1 years,height:171 ± 8 cm,weight:65 ± 8 kg,body mass index:22 ± 1 kg/m^2 at the beginning of the study;there were no significant changes at the end).Serum samples were obtained from players immediately before the test(basal),at the end of the test after reaching the point of maximal oxygen consumption(VO_(2max)),and after recovery.Results:The concentration of insulin decreased at VO_(2max),but remained higher in players after preparatory training(12.2 ± 2.5 m U/L vs.8.9 ± 4.4 m U/L,p = 0.049).The level of IGFBP-1 decreased in players at VO_(2max) in either case of training,but it remained much higher in tests performed after the preparatory regime than before(p = 0.029).Concentrations of IGF-1,IGFBP-2,-3,and-4 did not change significantly.Conclusion:The inverse relation between insulin and IGFBP-1 was lost during MPET,as these 2 molecules changed in the same direction.The results obtained suggest less severe stress-induced depression of insulin and IGFBP-1 after preparatory training.But another metabolic mechanism cannot be excluded,and that is potentially impaired insulin sensitivity resulting in higher level of IGFBP-1.

Klotho生物学功能与Insulin/IGF-1通路关系的研究进展

Klotho基因是一个与衰老密切相关的基因,他参与维生素K和钙、磷的代谢,保护心血管系统,影响机体的免疫功能,对衰老及衰老相关性疾病进行调节.胰岛素/胰岛素样生长因子-1(insulin/insulin-like growth factor-1,Insulin/IGF-1)信号通路也参与衰老及衰老相关性疾病的调节,其发生改变可以增加寿命,延缓衰老.近年来大量研究发现Klotho发挥其生物学功能与其抑制Insulin/IGF-1信号通路的激活密切相关,本文就此予以综述.

Possible roles of insulin, IGF-1 and IGFBPs in initiation and progression of colorectal cancer

AIM: To investigate the roles of serum insulin, insulin-like growth factor-1 (IGF-1), and insulin-like growth factor binding proteins (IGFBPs) in the initiation and progression of colorectal cancer.

The thermodynamic stability of insulin disulfides is not affected by the C-domain of insulin-like growth factor 1

Both Insulin and insulin-like growth factor 1 are members of insulin superfamily. They share homologous primary and tertiary structure as well as weakly overlapping biological activity. However, their folding behavior is different: insulin and its recombinant precursor (PIP) fold into one unique tertiary structure, while IGF-1 folds into two disulfides isomers with similar thermody-namic stability. To elucidate the molecular mechanism of their different folding behavior, we prepared a single-chain hybrid of insulin and IGF-1, [B10Glu]lns/IGF-1(C), and studied its folding behavior compared with that of PIP and IGF-1. We also separated a major non-native disulfides iso-mer of the hybrid and studied its refolding. The data showed that the C-domain of IGF-1 did not affect the folding thermodynamics of insulin, that is, the primary structure of the hybrid encoded only one thermodynamically stable disulfides linkage. However, the folding kinetics of insulin was affected by the C-domain of IGF-1.

Effect of Kaiyu Qingwei Granule (开郁清胃颗粒) on Insulin Receptor in Liver and Skeletal Muscular Cell Membrane in Diabetes Mellitus Rats

Objective: To investigate the effect of Kaiyu Qingwei granule (KYQWG, on the insulin binding capacity of liver and skeletal muscular cell membrane and serum insulin-like growth factor-1 (IGF-1) in streptozotocin-induced diabetic rats. Methods: Rats in four experimental groups were investigated: the control group, the model group, the KYQWG group and the Metformin group. The insulin binding rate (IBR) of liver and skeletal muscular cell membrane was detected by receptor-ligand ra-diometric method and changes of serum levels of glucose, insulin and IGF-1 were observed before and after 4 weeks of medication. Results: The KYQWG group had a lower blood glucose level and ffiR of liver and muscular cell membrane, as compared with those in the model group (P<0. 01 or P<0.05), and a higher level of IGF-1 than that in the model group(P<0.01), but had no obvious changes in the serum level of insulin. Conclusion: KYQWG may increase the serum level of IGF-1 in diabetic rats, thus to decrease the insulin resistance at ante-receptor sites and improve the sugar metabolic disturbance in rats with diabetes mellitus.