Contrasting consequences of podocyte insulin-like growth factor 1 receptor inhibition.

Insulin signaling to the glomerular podocyte via the insulin receptor (IR) is critical for kidney function. In this study we show that near-complete knockout of the closely related insulin-like growth factor 1 receptor (IGF1R) in podocytes is detrimental, resulting in albuminuria and podocyte cell death . In contrast, partial podocyte IGF1R knockdown confers protection against doxorubicin-induced podocyte injury.

Mesenchyme instructs growth while epithelium directs branching in the mouse mammary gland.

The mammary gland is a unique organ that undergoes dynamic alterations throughout a female's reproductive life, making it an ideal model for developmental, stem cell and cancer biology research. Mammary gland development begins in utero and proceeds via a quiescent bud stage before the initial outgrowth and subsequent branching morphogenesis. How mammary epithelial cells transit from quiescence to an actively proliferating and branching tissue during embryogenesis and, importantly, how the branch pattern is determined remain largely unknown.

The developmental basis for scaling of mammalian tooth size.

When evolution leads to differences in body size, organs generally scale along. A well-known example of the tight relationship between organ and body size is the scaling of mammalian molar teeth. To investigate how teeth scale during development and evolution, we compared molar development from initiation through final size in the mouse and the rat.

IGF-1 receptor regulates upward firing rate homeostasis via the mitochondrial calcium uniporter.

Regulation of firing rate homeostasis constitutes a fundamental property of central neural circuits. While intracellular Ca has long been hypothesized to be a feedback control signal, the molecular machinery enabling a network-wide homeostatic response remains largely unknown. We show that deletion of insulin-like growth factor-1 receptor (IGF-1R) limits firing rate homeostasis in response to inactivity, without altering the distribution of baseline firing rates.

PTBP1 promotes hematopoietic stem cell maintenance and red blood cell development by ensuring sufficient availability of ribosomal constituents.

Ribosomopathies constitute a range of disorders associated with defective protein synthesis mainly affecting hematopoietic stem cells (HSCs) and erythroid development. Here, we demonstrate that deletion of poly-pyrimidine-tract-binding protein 1 (PTBP1) in the hematopoietic compartment leads to the development of a ribosomopathy-like condition. Specifically, loss of PTBP1 is associated with decreases in HSC self-renewal, erythroid differentiation, and protein synthesis.

Thyrocyte-specific deletion of insulin and IGF-1 receptors induces papillary thyroid carcinoma-like lesions through EGFR pathway activation.

Insulin and insulin-like growth factor (IGF)-1 signaling in the thyroid are thought to be permissive for the coordinated regulation by thyroid-stimulating hormone (TSH) of thyrocyte proliferation and hormone production. However, the integrated role of insulin receptor (IR) and IGF-1 receptor (IGF-1R) in thyroid development and function has not been explored. Here, we generated thyrocyte-specific IR and IGF-1R double knockout (DTIRKO) mice to precisely evaluate the coordinated functions of these receptors in the thyroid of neonates and adults.

CaMKIIα Expression Defines Two Functionally Distinct Populations of Granule Cells Involved in Different Types of Odor Behavior.

Granule cells (GCs) in the olfactory bulb (OB) play an important role in odor information processing. Although they have been classified into various neurochemical subtypes, the functional roles of these subtypes remain unknown. We used in vivo two-photon Ca imaging combined with cell-type-specific identification of GCs in the mouse OB to examine whether functionally distinct GC subtypes exist in the bulbar network.

Disrupting IGF Signaling in Adult Mice Conditions Leanness, Resilient Energy Metabolism, and High Growth Hormone Pulses.

Growth hormone (GH) and insulinlike growth factor (IGF) promote aging and age-related pathologies. Inhibiting this pathway by targeting IGF receptor (IGF-1R) is a promising strategy to extend life span, alleviate age-related diseases, and reduce tumor growth. Although anti-IGF-1R agents are being developed, long-term effects of IGF-1R blockade remain unknown.

Insulin-like growth factor 1 receptor regulates hypothermia during calorie restriction.

When food resources are scarce, endothermic animals can lower core body temperature (T). This phenomenon is believed to be part of an adaptive mechanism that may have evolved to conserve energy until more food becomes available. Here, we found in the mouse that the insulin-like growth factor 1 receptor (IGF-1R) controls this response in the central nervous system.

The Alzheimer's disease transcriptome mimics the neuroprotective signature of IGF-1 receptor-deficient neurons.

Seminal studies using post-mortem brains of patients with Alzheimer's disease evidenced aberrant insulin-like growth factor 1 receptor (IGF1R) signalling. Addressing causality, work in animal models recently demonstrated that long-term suppression of IGF1R signalling alleviates Alzheimer's disease progression and promotes neuroprotection. However, the underlying mechanisms remain largely elusive.

Igf1r signalling acts on the anagen-to-catagen transition in the hair cycle.

Insulin-like growth factor 1 (Igf1) is important for skin development and homoeostasis. However, overexpression and inactivation studies have produced variable findings regarding its role in hair follicle (HF) biology. Here, we studied a conditional and inducible knockout of the Igf1 receptor (Igf1r) in keratin 15-expressing bulge cells.

Regulatory T cells delay disease progression in Alzheimer-like pathology.

Recent studies highlight the implication of innate and adaptive immunity in the pathophysiology of Alzheimer's disease, and foster immunotherapy as a promising strategy for its treatment. Vaccines targeting amyloid-β peptide provided encouraging results in mouse models, but severe side effects attributed to T cell responses in the first clinical trial AN1792 underlined the need for better understanding adaptive immunity in Alzheimer's disease. We previously showed that regulatory T cells critically control amyloid-β-specific CD4(+) T cell responses in both physiological and pathological settings.

Deleting IGF-1 receptor from forebrain neurons confers neuroprotection during stroke and upregulates endocrine somatotropin.

Insulin-like growth factors control numerous processes, namely somatic growth, metabolism and stress resistance, connecting this pathway to aging and age-related diseases. Insulin-like growth factor signaling also impacts on neurogenesis, neuronal survival and structural plasticity. Recent reports demonstrated that diminished insulin-like growth factor signaling confers increased stress resistance in brain and other tissues.

IGF-1R Reduction Triggers Neuroprotective Signaling Pathways in Spinal Muscular Atrophy Mice.

Unlabelled: Spinal muscular atrophy (SMA) is a neuromuscular disease characterized by the selective loss of spinal motor neurons due to the depletion of the survival of motor neuron (SMN) protein. No therapy is currently available for SMA, which represents the leading genetic cause of death in childhood. In the present study, we report that insulin-like growth factor-1 receptor (Igf-1r) gene expression is enhanced in the spinal cords of SMA-like mice.

Blocking IGF Signaling in Adult Neurons Alleviates Alzheimer's Disease Pathology through Amyloid-β Clearance.

Unlabelled: Alzheimer's disease (AD) is a frequent and irreversible age-related neurodegeneration without efficient treatment. Experimental AD in mice responds positively to decreased insulin-like growth factor I (IGF-I) signaling, a pathway also implicated in aging. Here we aimed to protect the aging brain from devastating amyloid pathology by making specifically adult neurons resistant to IGF signaling.

Suppression of IGF-I signals in neural stem cells enhances neurogenesis and olfactory function during aging.

Downregulation of insulin-like growth factor (IGF) pathways prolongs lifespan in various species, including mammals. Still, the cellular mechanisms by which IGF signaling controls the aging trajectory of individual organs are largely unknown. Here, we asked whether suppression of IGF-I receptor (IGF-1R) in adult stem cells preserves long-term cell replacement, and whether this may prevent age-related functional decline in a regenerating tissue.

Expression of dominant-negative thyroid hormone receptor alpha1 in Leydig and Sertoli cells demonstrates no additional defect compared with expression in Sertoli cells only.

Background: In the testis, thyroid hormone (T3) regulates the number of gametes produced through its action on Sertoli cell proliferation. However, the role of T3 in the regulation of steroidogenesis is still controversial.

Methods: The TRαAMI knock-in allele allows the generation of transgenic mice expressing a dominant-negative TRα1 (thyroid receptor α1) isoform restricted to specific target cells after Cre-loxP recombination.

IGF-IR determines the fates of BCR/ABL leukemia.

Background: The tyrosine kinase receptor insulin-like growth factor 1 receptor (IGF-IR) contributes to the initiation and progression of many types of malignancies. We previously showed that IGF-2, which binds IGF-IR, is an extrinsic factor that supports the ex vivo expansion of hematopoietic stem cells (HSCs). We also demonstrated that IGF-IR is not required for HSC activity in vivo.

The intestinal epithelial insulin-like growth factor-1 receptor links glucagon-like peptide-2 action to gut barrier function.

Glucagon-like peptide-2 (GLP-2) is an intestinal growth-promoting hormone used to treat short bowel syndrome. GLP-2 promotes intestinal growth through a mechanism that involves both IGF-1 and the intestinal-epithelial IGF-1 receptor (IE-IGF-1R). GLP-2 also enhances intestinal barrier function, but through an unknown mechanism.

Longevity effect of IGF-1R(+/-) mutation depends on genetic background-specific receptor activation.

Growth hormone (GH) and insulin-like growth factor (IGF) signaling regulates lifespan in mice. The modulating effects of genetic background gained much attention because it was shown that life-prolonging effects in Snell dwarf and GH receptor knockout vary between mouse strains. We previously reported that heterozygous IGF-1R inactivation (IGF-1R(+/-) ) extends lifespan in female mice on 129/SvPas background, but it remained unclear whether this mutation produces a similar effect in other genetic backgrounds and which molecules possibly modify this effect.

Knockout of insulin-like growth factor-1 receptor impairs distal lung morphogenesis.

Background: Insulin-like growth factors (IGF-I and -II) are pleiotropic regulators of somatic growth and development in vertebrate species. Endocrine and paracrine effects of both hormones are mediated by a common IGF type 1 receptor (IGF-1R). Lethal respiratory failure in neonatal IGF-1R knockout mice suggested a particular role for this receptor in pulmonary development, and we therefore investigated the consequences of IGF-1R inactivation in lung tissue.

IGF signaling contributes to malignant transformation of hematopoietic progenitors by the MLL-AF9 oncoprotein.

Malignant transformation of normal hematopoietic progenitors is a multistep process that likely requires interaction between collaborating oncogenic signals at critical junctures. For instance, the MLL-AF9 fusion oncogene is thought to contribute to myeloid leukemogenesis by driving a hematopoietic stem cell-like "self-renewal" gene expression signature in committed myeloid progenitors. In addition, insulin-like growth factor (IGF) signaling has been implicated in self-renewal/pluripotency in hematopoietic and embryonic stem cell contexts and supports cell growth/survival by activation of downstream pathways, including phosphatidylinositol 3-kinase/Akt and Ras/Raf/extracellular signal-regulated kinase.

Proinflammatory actions of visfatin/nicotinamide phosphoribosyltransferase (Nampt) involve regulation of insulin signaling pathway and Nampt enzymatic activity.

Visfatin (also termed pre-B-cell colony-enhancing factor (PBEF) or nicotinamide phosphoribosyltransferase (Nampt)) is a pleiotropic mediator acting on many inflammatory processes including osteoarthritis. Visfatin exhibits both an intracellular enzymatic activity (nicotinamide phosphoribosyltransferase, Nampt) leading to NAD synthesis and a cytokine function via the binding to its hypothetical receptor. We recently reported the role of visfatin in prostaglandin E(2) (PGE(2)) synthesis in chondrocytes.

Igf-I signaling and effects on longevity.

Insulin and insulin-like signaling regulate survival and lifespan in a variety of animal species, from nematodes and flies to higher vertebrates and mammals. Recently, it was shown that brain IGF-I receptor and brain IRS2 control mammalian lifespan, and that this occurs through neuroendocrine mechanisms, control of energy metabolism and modified stress resistance. Furthermore, it was demonstrated that insulin receptor substrate molecules are implicated downstream of insulin and IGF receptors in the extension of lifespan.