Long-term p110α PI3K inactivation exerts a beneficial effect on metabolism (original) (raw)
Related papers
Aging Cell, 2013
Caloric restriction (CR) and down-regulation of the insulin/IGF pathway are the most robust interventions known to increase longevity in lower organisms. However, little is known about the molecular adaptations induced by CR in humans. Here we report that long-term CR in humans inhibits the IGF-1/insulin pathway in skeletal muscle, a key metabolic tissue. We also demonstrate that CR-induced dramatic changes of the skeletal muscle transcriptional profile that resemble those of younger individuals. Finally, in both rats and humans CR evoked similar responses in the transcriptional profiles of skeletal muscle. This common signature consisted of three key pathways typically associated with longevity: IGF-1/insulin signaling, mitochondrial biogenesis and inflammation. Furthermore, our data identifies promising pathways for therapeutic targets to combat age-related diseases and promote health in humans.
The Role of PIK3R1 in Metabolic Function and Insulin Sensitivity
International Journal of Molecular Sciences
PIK3R1 (also known as p85α) is a regulatory subunit of phosphoinositide 3-kinases (PI3Ks). PI3K, a heterodimer of a regulatory subunit and a catalytic subunit, phosphorylates phosphatidylinositol into secondary signaling molecules involved in regulating metabolic homeostasis. PI3K converts phosphatidylinositol 4,5-bisphosphate (PIP2) to phosphatidylinositol 3,4,5-triphosphate (PIP3), which recruits protein kinase AKT to the inner leaflet of the cell membrane to be activated and to participate in various metabolic functions. PIK3R1 stabilizes and inhibits p110 catalytic activity and serves as an adaptor to interact with insulin receptor substrate (IRS) proteins and growth factor receptors. Thus, mutations in PIK3R1 or altered expression of PIK3R1 could modulate the activity of PI3K and result in significant metabolic outcomes. Interestingly, recent studies also found PI3K-independent functions of PIK3R1. Overall, in this article, we will provide an updated review of the metabolic fun...
Cardiac PI3K p110α attenuation delays aging and extends lifespan
Cell Stress
Phosphoinositide 3-kinase (PI3K) is a key component of the insulin signaling pathway that controls cellular metabolism and growth. Loss-of-function mutations in PI3K signaling and other downstream effectors of the insulin signaling pathway extend the lifespan of various model organisms. However, the pro-longevity effect appears to be sex-specific and young mice with reduced PI3K signaling have increased risk of cardiac disease. Hence, it remains elusive as to whether PI3K inhibition is a valid strategy to delay aging and extend healthspan in humans. We recently demonstrated that reduced PI3K activity in cardiomyocytes delays cardiac growth, causing subnormal contractility and cardiopulmonary functional capacity, as well as increased risk of mortality at young age. In stark contrast, in aged mice, experimental attenuation of PI3K signaling reduced the age-dependent decline in cardiac function and extended maximal lifespan, suggesting a biphasic effect of PI3K on cardiac health and su...
PI3K keeps the balance between metabolism and cancer
Advances in biological regulation, 2012
Epidemiological studies have established a positive correlation between cancer and metabolic disorders, suggesting that aberrant cell metabolism is a common feature of nearly all tumors. To meet their demand of building block molecules, cancer cells switch to a heavily glucose-dependent metabolism. As insulin triggers glucose uptake, most tumors are or become insulin-dependent. However, the effects of insulin and of other similar growth factors are not only limited to metabolic control but also favor tumor growth by stimulating proliferation and survival. A key signaling event mediating these metabolic and proliferative responses is the activation of the phosphatidylinositol-3 kinases (PI3K) pathway. In this review, we will thus discuss the current concepts of tumor metabolism and the opportunity of PI3K-targeted therapies to exploit the "sweet tooth" of cancer cells.
Insulin/IGF-1 paradox of aging: Regulation via AKT/IKK/NF-κB signaling
Cellular Signalling, 2010
GH/insulin/IGF-1 signaling is a vital pathway e.g. in the regulation of protein synthesis and glucose metabolism. However, mouse dwarf strains which exhibit reduced GH secretion and subsequently a decline in IGF-1 signaling can live longer than their wild type counterparts. There is striking evidence indicating that the IGF-1/PI-3K/AKT signaling enhances growth of animals during development but later in life can potentiate the aging process. This conserved pleiotropy has been called the insulin/IGF-1 paradox. In Caenorhabditis elegans, the decline in this pathway activates the DAF-16 gene, an ortholog of mammalian FoxO genes, which regulate stress resistance and longevity. The mammalian PI-3K/AKT pathway also activates the NF-κB signaling that inhibits apoptosis and triggers inflammatory responses. Many longevity genes, e.g. FoxOs and SIRT1, are inhibitors of NF-κB signaling. We will discuss the evidence that insulin/IGF-1 signaling can enhance the NF-κB signaling and subsequently potentiate the aging process and aggravate age-related degenerative diseases.
F1000Research
Background: Class IA phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) is an integral mediator of insulin signaling. The p110 catalytic and p85 regulatory subunits of PI3K are the products of separate genes, and while they come together to make the active heterodimer, they have opposing roles in insulin signaling and action. Deletion of hepatic p110α results in an impaired insulin signal and severe insulin resistance, whereas deletion of hepatic p85α results in improved insulin sensitivity due to sustained levels of phosphatidylinositol (3,4,5)-trisphosphate. Here, we created mice with combined hepatic deletion of p110α and p85α (L-DKO) to study the impact on insulin signaling and whole body glucose homeostasis. Methods: Six-week old male flox control and L-DKO mice were studied over a period of 18 weeks, during which weight and glucose levels were monitored, and glucose tolerance tests, insulin tolerance test and pyruvate tolerance test were performed. Fasting insulin, insulin ...
Integrating Metabolism and Longevity Through Insulin and IGF1 Signaling
Endocrinology and Metabolism Clinics of North America, 2013
Understanding how metabolism integrates nutrient homeostasis with life span is a complicated undertaking. The insulin pathway coordinates growth, development, metabolic homoeostasis, fertility and stress resistance, which ultimately influence lifespan. From a clinical perspective, compensatory hyperinsulinemia to overcome systemic insulin resistance is thought to be a healthy goal, because it circumvents to immediate catastrophic consequences of hyperglycemia; however, work in flies, nematodes and mice indicate that excess insulin signaling ultimately damages cellular function and accelerates aging. Maintenance of the central nervous system (CNS) has particular importance for lifespan. Depending upon the exact site, reduced insulin/IGF1 signaling in the CNS can dysregulate peripheral energy homeostasis and metabolism, promote obesity, and extend lifespan. In this review, we explore how genetic manipulations of insulin/IGF1 signaling components are beginning to reveal neuronal circuits which might resolve the central regulation of systemic metabolism from organism longevity. Keywords Aging; central nervous system; insulin/IGF signaling; lifespan; neurodegeneration; metabolism; leptin; energy balance; glucose homeostasis disease (2). By comparison, genetic strategies to reduce insulin/IGF1 signaling in Caenorhabditis elegans, Drosophila melanogaster, and rodents has emerged as a reliable means of extending lifespan (3-7). Understanding the relation between insulin 'resistance' and 'reduced' insulin/IGF signaling might provide important insight into the pathology of metabolic disease, its sequelae, and strategies for treatment.
2019
Oncogenes and tumor suppressor genes play a key role in cancer induction and progression. They directly or indirectly regulate critical metabolic pathways, phosphatidylinositol-3 kinase pathway being frequently activated pathway in cancer. The catalytic subunit of phosphatidylinositol-4,5bisphosphate 3-kinase (PI3K), p110α, is the most frequently mutated kinase in human cancer, E542K, E545K, and H1047R mutations being the most common. Expression of hepatic E545K and H1047R p110α mutants in vivo shows marked and rapid increase in hepatic lipid and glycogen accumulation in mice with developmental (chronic) liver-specific deletion of p110α, which was not seen in mice when wildtype p110α is overexpressed. To investigate the logical pathways that could explain the lipid accumulation in mutant expressing mice, RNA sequencing from wildtype, knockout and mutated mouse livers was performed. Read alignment and count quantification was done using the Rsubread package and the statistical analys...
Critical role for the p110α phosphoinositide-3-OH kinase in growth and metabolic regulation
Nature, 2006
The eight catalytic subunits of the mammalian phosphoinositide-3-OH kinase (PI(3)K) family form the backbone of an evolutionarily conserved signalling pathway; however, the roles of most PI(3)K isoforms in organismal physiology and disease are unknown. To delineate the role of p110a, a ubiquitously expressed PI(3)K involved in tyrosine kinase and Ras signalling, here we generated mice carrying a knockin mutation (D933A) that abrogates p110a kinase activity. Homozygosity for this kinase-dead p110a led to embryonic lethality. Mice heterozygous for this mutation were viable and fertile, but displayed severely blunted signalling via insulin-receptor substrate (IRS) proteins, key mediators of insulin, insulin-like growth factor-1 and leptin action. Defective responsiveness to these hormones led to reduced somatic growth, hyperinsulinaemia, glucose intolerance, hyperphagia and increased adiposity in mice heterozygous for the D933A mutation. This signalling function of p110a derives from its highly selective recruitment and activation to IRS signalling complexes compared to p110b, the other broadly expressed PI(3)K isoform, which did not contribute to IRS-associated PI(3)K activity. p110a was the principal IRS-associated PI(3)K in cancer cell lines. These findings demonstrate a critical role for p110a in growth factor and metabolic signalling and also suggest an explanation for selective mutation or overexpression of p110a in a variety of cancers 1,2 .