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[Evaluation of IGF1 and IGFBP3 during diet therapy in patients with food allergy with complex nutritional risk].

The seric levels of IGF1 and IGFBP3 and their molar ratio, together with clinical and auxological parameters, have been evaluated in 16 patients (8 males and 8 females), of average age of 11.6 +/- 8.66 months, who were suffering from complex food allergy and were subjected to a balanced diet will excluded the "offending" food. The results, compared with those of a control population of same age and body surface, have shown a significative reduction of IGF1 and an increase of the molar ratio IGFBP3/IGF1. These observations suggest that, in spite of no significative variation of growth in height and weight, an exclusion diet for a food allergy can reduce the biological activity of some hormonal factors of growth.

Female↗

The novel adipokine Placin regulates glucose homeostasis via insulin secretion and IGF1 receptor signaling.

While genome-wide association studies have linked the human PLAC9 gene to body mass index, its physiological function remains largely unexplored. This study identifies PLAC9 as a novel adipokine that is enriched in the stromal vascular fraction of adipose tissue. Its circulating levels correlate with key metabolic dysregulation markers in humans and mice. We utilized gain- and loss-of-function approaches in diet-induced obesity (DIO) and streptozotocin (STZ)-induced diabetic mouse models to demonstrate that PLAC9 is a critical regulator of systemic metabolism. Notably, knockdown of endogenous PLAC9 exacerbated metabolic impairments, while its overexpression significantly mitigated DIO-associated metabolic dysregulation. Additionally, recombinant PLAC9 protein administration alleviated hyperglycemia in insulin-resistant and insulin-deficient models. Mechanistically, PLAC9 potentiated calcium-dependent insulin secretion in pancreatic beta cells, promoted glucose uptake in the liver and skeletal muscle, and upregulated hepatic Ghr and Igf1 levels to facilitate glucose homeostasis. Based on these hormone-like properties, we propose renaming the protein Placin. Collectively, these findings establish Placin as a promising therapeutic target, offering translational potential for the management of both type 2 and type 1 diabetes.

Animals↗

Igf1 gene disruption results in reduced brain size, CNS hypomyelination, and loss of hippocampal granule and striatal parvalbumin-containing neurons.

Homozygous Igf1-/- mice at 2 months of age had reduced brain weights, with reductions evenly affecting all major brain areas. The gross morphology of the CNS was normal, but the size of white matter structures in brain and spinal cord was strongly reduced, owing to decreased numbers of axons and oligodendrocytes. Myelinated axons were more strongly reduced in number than unmyelinated axons. The volume of the dentate gyrus granule cell layer was reduced in excess of the decrease in brain weight. Among populations of calcium-binding protein-containing neurons, there was a selective reduction in the number of striatal parvalbumin-containing cells. Numbers of mesencephalic dopaminergic neurons, striatal and basal forebrain cholinergic neurons, and spinal cord motoneurons were unaffected. Cerebellar morphology was unaltered. Our findings suggest cell type- and region-specific functions for IGF-I and emphasize prominent roles in axon growth and maturation in CNS myelination.

Animals↗

Comparative chromosomal localization of the canine-derived BAC clones containing LEP and IGF1 genes in four species of the family Canidae.

In the present report we show the chromosomal localization of two BAC clones, carrying the leptin (LEP) and insuline-like growth factor 1 (IGF1) genes, respectively, in four species belonging to the family Canidae: the dog, red fox, arctic fox and the Chinese raccoon dog. The assignments are in agreement with earlier data obtained from comparative chromosome painting for the dog, red fox and arctic fox.

Animals↗

Effects of an Igf1 gene null mutation on mouse reproduction.

Both sexes of adult mice homozygous for a targeted mutation of the Igf1 gene, encoding insulin-like growth factor 1, are infertile dwarfs (approximately 30% of normal size). The testes are reduced in size less than expected from the degree of dwarfism but sustain spermatogenesis only at 18% of the normal level. The epididymides are overall nearly allometric to the reduced body weight, but the distal regions of the duct, vas deferens, seminal vesicles, and prostate are vestigial. Despite the mutational impact on the epididymis, capacitated sperm are able to fertilize wild type eggs in vitro. It is hypothesized that the infertility of male mutants is caused by failure of androgenization resulting in absence of mating behavior, due to drastically reduced levels of serum testosterone (18% of normal). This hormonal deficiency was correlated with an ultrastructural analysis of mutant Leydig cells revealing a significant developmental delay, while assays in organ culture showed that the basal and LH-stimulated production of testosterone by testicular parenchyma is reduced in comparison with wild type controls. The female mutants fail to ovulate even after administration of gonadotropins, which is apparently the primary cause of their infertility, and possess an infantile uterus that exhibits a dramatic hypoplasia especially in the myometrium. The phenotypic manifestations of the mutation were correlated with the localization of transcripts for insulin-like growth factor I and its cognate receptor in wild type reproductive tissues by in situ hybridization.

Animals↗

Kermit 2/XGIPC, an IGF1 receptor interacting protein, is required for IGF signaling in Xenopus eye development.

GIPC is a PDZ-domain-containing protein identified in vertebrate and invertebrate organisms through its interaction with a variety of binding partners including many membrane proteins. Despite the multiple reports identifying GIPC, its endogenous function and the physiological significance of these interactions are much less studied. We have previously identified the Xenopus GIPC homolog kermit as a frizzled 3 interacting protein that is required for frizzled 3 induction of neural crest in ectodermal explants. We identified a second Xenopus GIPC homolog, named kermit 2 (also recently described as an IGF receptor interacting protein and named XGIPC). Despite its high amino acid similarity with kermit, kermit 2/XGIPC has a distinct function in Xenopus embryos. Loss-of-function analysis indicates that kermit 2/XGIPC is specifically required for Xenopus eye development. Kermit 2/XGIPC functions downstream of IGF in eye formation and is required for maintaining IGF-induced AKT activation. A constitutively active PI3 kinase partially rescues the Kermit 2/XGIPC loss-of-function phenotype. Our results provide the first in vivo loss of function analysis of GIPC in embryonic development and also indicate that kermit 2/XGIPC is a novel component of the IGF pathway, potentially functioning through modulation of the IGF1 receptor.

Adaptor Proteins, Signal Transducing↗

Synteny mapping of the bovine IGHG2, CRC and IGF1 genes.

A panel of bovine-murine hybrid cell lines was analysed for 10 loci, including three (IGF1, IGHG2 and the calcium release channel gene [CRC]) that have previously been mapped in man, but not in cattle. The IGF and CRC genes were indirectly mapped to chromosomes 5 and 18 respectively and the syntenies of the HOX2 and GH genes and of the NP and FOS genes were confirmed. The results also show that the IGHG2 locus, which is linked to NP and FOS on human chromosome 14, is separated from these genes in cattle. By showing synteny of the IGHG2 and MPI loci, the IGHG2 locus has been indirectly mapped to chromosome 21.

Animals↗

Role of the insulin-like growth factor 1 (IGF1)/phosphoinositide-3-kinase (PI3K) pathway mediating physiological cardiac hypertrophy.

Growth of the heart can be induced by physiological stimuli (e.g. postnatal development or chronic exercise training: 'the athlete's heart') or pathological stimuli (e.g. pressure or volume overload). Physiological hypertrophy is characterized by the normal organization of sarcomeres and fibres, normal or enhanced cardiac function and a relatively normal pattern of cardiac gene expression; whereas pathological hypertrophy is associated with an altered pattern of cardiac gene expression, fibrosis, cardiac dysfunction and increased mortality. Previously, an unresolved question in cardiac biology was whether distinct signalling pathways are responsible for the development of pathological and physiological cardiac hypertrophy. Recent studies have identified several signalling pathways that play unique roles in the regulation of pathological and physiological cardiac hypertrophy. This review focuses largely on the role of the insulin-like growth factor 1 (IGF1)/phosphoinositide-3-kinase (PI3K) pathway in mediating physiological cardiac growth.

Animals↗

Autosomal-recessive syndrome with alopecia, hypogonadism, progressive extra-pyramidal disorder, white matter disease, sensory neural deafness, diabetes mellitus, and low IGF1.

We explored the manifestations of an autosomal-recessive multisystemic disorder in several Saudi families. Recognized causes of progressive extra-pyramidal disorder and white matter disease were excluded and the neurological, imaging, endocrine, and skin manifestations of this syndrome described. The onset of these symptoms in these patients began in early adolescence and progressed more rapidly in males. All affected patients had total or partial alopecia, clinical and chemical evidence of hypogonadism (low levels of estradiol and testosterone); females had clear evidence of hypogonadism (streak or absent ovaries), and some patients had diabetes mellitus and/or sensorineural deafness. The constant biochemical abnormality was the low IGF-1. The neurological manifestations included moderate to severe intellectual decline and abnormality of muscle tone and posture with choreo-athetoid and dystonic movements resulting in gait difficulty, dysarthria, difficulty swallowing, and scoliosis. The MRI of brain demonstrated white matter involving cerebellum, brain stem, and cerebral structures, as well as abnormal decreased signal intensity in the basal ganglia with involvement of the substantia nigra. We conclude that the association of hypogonadism, alopecia, and persistent low IGF-1 is a significant autosomal recessive syndrome; it is prevalent in Saudi Arabia. We also demonstrate that the progressive extra-pyramidal disorder, white matter disease, and abnormal signals of the basal ganglia are common features of this syndrome. Sensorineural deafness and diabetes mellitus were recognized features.

Adolescent↗

Prenatal overgrowth and mosaic trisomy 15q25-qter including the IGF1 receptor gene.

Overgrowth is rarely associated with chromosomal imbalances. Here, we report on a male foetus presenting with overgrowth and additional material on the short arm of one of the chromosome 15 in 12% of lymphocytes and 50% of amniotic cells. Parents' karyotypes were normal, indicating a de novo origin for this unbalanced rearrangement. Complementary studies using cytogenetic and FISH studies showed that this additional material resulted in a 15q25-qter trisomy and confirmed the presence of three copies of the insulin-like growth factor 1 receptor (IGF1R) gene, included in the trisomic region. Autopsy performed after termination of pregnancy revealed isolated overgrowth and absence of visceral malformations. The possible mechanisms and origins for the formation of this mosaic pure trisomy are complex. The present observation emphasises the hypothesis that the overgrowth phenotype, frequently reported in patients with trisomy including the 15q26 region, might be causally related to a dosage effect of the IGF1R gene, as well as the importance of chromosome analysis in patients with overgrowth. It also confirms that the overgrowth is of prenatal onset in those observations.

Abortion, Induced↗

Genetic variation in IGF1, IGF-1R, IGFALS, and IGFBP3 in breast cancer survival among Chinese women: a report from the Shanghai Breast Cancer Study.

Disruption of the balance of IGF (Insulin like growth factor) pathway constituents has been implicated in the etiology and progression of breast and other cancers. We hypothesized that genetic polymorphisms in IGF system members may be associated with breast cancer survival and evaluated this hypothesis in a cohort of 1,455 women diagnosed with breast cancer between 1996 and 1998 in Shanghai, China. Nineteen functional or potentially functional polymorphisms were evaluated in the IGF-1, IGF-1R, IGFALS, and IGFBP3 genes. Disease recurrence and vital status were obtained with a median follow-up time of 7.1 years. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI). Overall, no significant association was noted between any of the 19 polymorphisms and survival. However, subgroup analyses demonstrated apparent interactions between menopausal status and survival for several (Single nucleotide polymorphism) SNPs in the IGF-1R and IGFBP3 genes. Carriers of the A/G or G/G genotypes (rs951715) in the IGF-1R gene had an increased risk of death among post-menopausal women (HR = 1.7, 95% CI = 1.1-2.7). Significant associations with breast cancer survival in pre-menopausal women were found for two IGFBP3 polymorphisms (rs2854744 and rs3110697), with an additional polymorphism (rs6413441) reaching borderline significance (P = 0.05). Hazard ratios for overall survival among pre-menopausal women were 1.5 (95% CI = 1.1-2.0) for the C/T-T/T genotypes (rs3110697), 1.4 (95% CI = 1.0-1.9) for the A/C-C/C genotypes (rs2854744), and 1.4 (95% CI = 1.0-1.9) for the N/A-A/A genotypes (rs6413441). Taken together, these data suggest that polymorphisms in the IGF-1R and IGFBP3 genes may be associated with altered survival among subgroups of breast cancer patients defined by menopausal status.

Adult↗

The role of the IGF1 receptor in the regulation of cdc2 mRNA levels in fibroblasts.

The levels of cdc2 mRNA increase when quiescent cells are stimulated by growth factors. In BALB/c 3T3, both platelet-derived growth factor and insulin-like growth factor 1 (IGF-1) are required to increase cdc2 mRNA levels. In p6 cells, which constitutively overexpress the IGF-1 receptor, IGF-1 is sufficient. The importance of the IGF-1/IGF-1 receptor interaction in regulating the levels of cdc2 mRNA was further confirmed by showing that an antisense oligodeoxynucleotide to the IGF-1 receptor RNA inhibited the IGF-1-mediated increase.

3T3 Cells↗

Phenotypic improvement of dystrophic muscles by rAAV/microdystrophin vectors is augmented by Igf1 codelivery.

The absence of dystrophin in Duchenne muscular dystrophy (DMD) leads to sarcolemmal instability and enhances the susceptibility of muscle fibers to contraction-induced injury. Various viral vectors have been used to deliver mini- and microdystrophin expression cassettes to muscles of dystrophin-deficient mdx mice, significantly increasing both the morphological and the functional properties of the muscles. However, dystrophin delivery to adult mdx mice has not yielded a complete rescue of the dystrophic phenotype. Here we investigated a novel strategy involving dual gene transfer of recombinant adeno-associated viral vectors expressing either microdystrophin (rAAV-muDys) or a muscle-specific isoform of Igf-1 (rAAV-mIgf-1). Injection of mdx muscles with rAAV-muDys reduced myofiber degeneration and turnover and increased their resistance to mechanical injury, but did not increase muscle mass or force generation. Injection of mdx muscles with rAAV-mIgf-1 led to increased muscle mass, but did not provide protection against mechanical injury or halt myofiber degeneration, leading to loss of the vector over time. In contrast, co-injection of the rAAV-muDys and rAAV-mIgf-1 vectors resulted in increased muscle mass and strength, reduced myofiber degeneration, and increased protection against contraction-induced injury. These results suggest that a dual-gene, combinatorial strategy could enhance the efficacy of gene therapy of DMD.

Animals↗

Physicochemical characteristics of LR3-IGF1 protein inclusion bodies: electrophoretic mobility studies.

A knowledge of the physicochemical properties of inclusion bodies is important for the rational design of potential recovery processes such as flotation and precipitation. In this study, measurement of the size and electrophoretic mobility of protein inclusion bodies and cell debris was undertaken. SDS-PAGE analysis of protein inclusion bodies subjected to different cleaning regimes suggested that electrophoretic mobility provides a qualitative measure of protein inclusion body purity. Electrophoretic mobility as a function of electrolyte type and ionic strength was investigated. The presence of divalent ions produced a stronger effect on electrophoretic mobility compared with monovalent ions. The isoelectric point of cell debris was significantly lower than that for the inclusion bodies. Hence, the contaminating cell debris may be separated from inclusion bodies using flotation by exploiting this difference in isoelectric points. Separation by this method is simple, convenient, and a possible alternative to the conventional route of centrifugation.

Electrophoresis, Polyacrylamide Gel↗

Overgrowth and trisomy 15q26.1-qter including the IGF1 receptor gene: report of two families and review of the literature.

Overgrowth is rarely associated with chromosomal imbalances. Here we report on four children from two unrelated families presenting with overgrowth and a terminal duplication of the long arm of chromosome 15 diagnosed using cytogenetic and FISH studies. In both cases, chromosome analysis of the parents showed a balanced translocation involving 15q26.1-qter. Molecular and cytogenetic studies showed three copies of the insulin-like growth factor 1 receptor (IGF1R) gene. This finding suggests that overgrowth observed in our patients might be causally related to a dosage effect of the IGF1R gene, in contrast to severe growth retardation observed in patients with terminal deletion of 15q. The present observation emphasises the importance of chromosome analysis in patients with overgrowth and mental retardation. Moreover, it further delineates a specific phenotype related to trisomy 15q26.1-qter with macrosomia at birth, overgrowth, macrocephaly and mild developmental delay being the major clinical features.

Abnormalities, Multiple↗

Cloning of porcine IGF1 receptor cDNA and detection of sequence polymorphisms using RT-PCR.

A cDNA encoding the porcine type 1 insulin-like growth factor receptor (IGF1R) was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR). The sequence of a 4.2-kb product was determined and had an open reading frame, encoding 1367 amino acids with 98.1 and 95.2% sequence similarity to the human and rat IGF1R, respectively. In the comparison of RT-PCR derived IGF1R sequences from 12 unrelated pigs, 12 silent sequence variants were found.

Animals↗