Biology of insulin-like growth factors in development

Nutrient and Hormonal Effects on Long Bone Growth in Healthy and Obese Children: A Literature Review

Longitudinal bone growth is mediated through several mechanisms including macro- and micronutrients, and endocrine and paracrine hormones. These mechanisms can be affected by childhood obesity as excess adiposity may affect signaling pathways, place undue stress on the body, and affect normal physiology. This review describes the physiology of the epiphyseal growth plate, its regulation under healthy weight and obesity parameters, and bone pathology following obesity. A literature review was performed utilizing PubMed, PMC, NIH, and the Cochrane Database of Systematic Reviews pertinent to hormonal and nutritional effects on bone development, child obesity, and pathologic bone development related to weight. The review indicates a complex network of nutrients, hormones, and multi-system interactions mediates long bone growth. As growth of long bones occurs during childhood and the pubertal growth spurt, pediatric bones require adequate levels of minerals, vitamins, amino acids, and a base caloric supply for energy. Recommendations should focus on a nutrient-dense dietary approach rather than restrictive caloric diets to maintain optimal health. In conclusion, childhood obesity has profound multifaceted effects on the developing musculoskeletal system, ultimately causing poor nutritional status during development. Weight loss, under medical supervision, with proper nutritional guidelines, can help counteract the ill effects of childhood obesity.

Insulin signaling accelerates the anterograde movement of Rab4 vesicles in axons through Klp98A/KIF16B recruitment via Vps34-PI3Kinase

Rab4 GTPase organizes endosomal sorting essential for maintaining the balance between recycling and degradative pathways. Rab4 localizes to many cargos whose transport in neurons is critical for regulating neurotransmission and neuronal health. Furthermore, elevated Rab4 levels in the CNS are associated with synaptic atrophy and neurodegeneration in Drosophila and humans, respectively. However, how the transport of Rab4-associated vesicles is regulated in neurons remains unknown. Using in vivo time-lapse imaging of Drosophila larvae, we show that activation of insulin signaling via Dilp2 and dInR increases the anterograde velocity, run length, and flux of Rab4 vesicles in the axons. Molecularly, we show that activation of neuronal insulin signaling further activates Vps34, elevates the levels of PI(3)P on Rab4-associated vesicles, recruits Klp98A (a PI(3)P-binding kinesin-3 motor) and activates their anterograde transport. Together, these observations delineate the role of insulin signaling in regulating axonal transport and synaptic homeostasis.

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. Here, we provide evidence indicating that epithelial cell proliferation and onset of branching are independent processes, yet partially coordinated by the Eda signaling pathway. Through heterotypic and heterochronic epithelial-mesenchymal recombination experiments between mouse mammary and salivary gland tissues and ex vivo live imaging, we demonstrate that unlike previously concluded, the mode of branching is an intrinsic property of the mammary epithelium whereas the pace of growth and the density of ductal tree are determined by the mesenchyme. Transcriptomic profiling and ex vivo and in vivo functional studies in mice disclose that mesenchymal Wnt/ß-catenin signaling, and in particular IGF-1 downstream of it critically regulate mammary gland growth. These results underscore the general need to carefully deconstruct the different developmental processes producing branched organs.

Transgenic Mouse Models to Study the Development and Maintenance of the Adrenal Cortex

The cortex of the adrenal gland is organized into concentric zones that produce distinct steroid hormones essential for body homeostasis in mammals. Mechanisms leading to the development, zonation and maintenance of the adrenal cortex are complex and have been studied since the 1800s. However, the advent of genetic manipulation and transgenic mouse models over the past 30 years has revolutionized our understanding of these mechanisms. This review lists and details the distinct Cre recombinase mouse strains available to study the adrenal cortex, and the remarkable progress total and conditional knockout mouse models have enabled us to make in our understanding of the molecular mechanisms regulating the development and maintenance of the adrenal cortex.

IPPD-induced growth inhibition and its mechanism in zebrafish

N-isopropyl-N-phenyl-1,4-phenylenediamine (IPPD) is used as a ubiquitous antioxidant worldwide, it is an additive in tire rubber easily discharged into the surrounding environment. At present, there is no study concerning the subacute toxicity of IPPD on fish. We used zebrafish embryos (2 h post-fertilization) exposed to IPPD for 5 days at concentrations of 0, 0.0012, 0.0120 and 0.1200 mg/L to investigate its toxic effects of embryonic development, disruption of growth hormone/insulin-like growth factor (GH/IGF) and hypothalamic-pituitary-thyroid (HPT) axis. The results showed that IPPD exposure decreased hatchability, weakened movement ability, reduced body length, and caused multiple types of deformities in zebrafish embryos. The expression of genes involved to GH/IGF and HPT axis were altered after exposure to IPPD in zebrafish larvae. Meanwhile, exposure to IPPD significantly decreased thyroxine (T4) and 3,5,3'-triiodothyronine (T3) contents in larvae, which indicated that HPT axis was in a disturbed state. Moreover, treatment of IPPD decreased the enzymatic activities of superoxide dismutase (SOD) and catalase (CAT) as well as levels of glutathione (GSH). While the contents of malondialdehyde (MDA) were elevated after exposure to IPPD. The present study thus demonstrated that IPPD induced oxidative stress, caused developmental toxicity and disrupted the GH/IGF and HPT axis of zebrafish, which could be responsible for developmental impairment and growth inhibition.

Costal cartilage overgrowth does not induce pectus‑like deformation in the chest wall of a rat model

Overgrowth of the costal cartilages has been frequently reported to be an etiological factor of chest wall deformities in children. The present study aimed to investigate if induced overgrowth of the costal cartilages could lead to deformation of the chest wall in a rat model. An insulin-like growth factor 1 (IGF1) solution was directly injected under the perichondrium of the last three costal cartilages of 2-week-old rat pups. Two different concentrations, 50 µg/ml (E50) and 100 µg/ml (E100), were applied. This procedure was repeated once per week for 5 consecutive weeks. Subsequently, 14 days after the last injection, all animals were euthanized before the shape of the thoracic cage was assessed, and the diameter was measured. In addition, the last three costal cartilages were dissected before the samples were prepared and examined by light microscopy. Rats that received E100 exhibited larger sagittal and coronal rib cage diameters compared with those in the E50 and control groups. However, no deformation could be observed in the chest wall. Microscopic examinations revealed an anabolic pattern in the E100 group. The present findings suggested that locally administered IGF1 stimulated cell proliferation and tissue growth in coastal cartilages in a dose-dependent manner in vivo. However, this induced overgrowth of the costal cartilages did not result in the deformation of the chest wall.

Insulin-like growth factor signalling and its significance as a biomarker in fish and shellfish research

The insulin-like growth factor signalling system comprises insulin-like growth factors, insulin-like growth factor receptors and insulin-like growth factor-binding proteins. Along with the growth hormones, insulin-like growth factor signalling is very pivotal in the growth and development of all vertebrates. In fishes, insulin-like growth factors play an important role in osmoregulation, besides the neuroendocrine regulation of growth. Insulin-like growth factor concentration in plasma can assess the growth in fishes and shellfishes and therefore widely applied in nutritional research as an indicator to evaluate the performance of selected nutrients. The present review summarizes the role of insulin-like growth factor signalling in fishes and shellfishes, its significance in aquaculture and in evaluating growth, reproduction and development, and discusses the utility of this system as biomarkers for early indication of growth in aquaculture.

Insulin protects acinar cells during pancreatitis by preserving glycolytic ATP supply to calcium pumps

Acute pancreatitis (AP) is serious inflammatory disease of the pancreas. Accumulating evidence links diabetes with severity of AP, suggesting that endogenous insulin may be protective. We investigated this putative protective effect of insulin during cellular and in vivo models of AP in diabetic mice (Ins2^Akita) and Pancreatic Acinar cell-specific Conditional Insulin Receptor Knock Out mice (PACIRKO). Caerulein and palmitoleic acid (POA)/ethanol-induced pancreatitis was more severe in both Ins2^Akita and PACIRKO vs control mice, suggesting that endogenous insulin directly protects acinar cells in vivo. In isolated pancreatic acinar cells, insulin induced Akt-mediated phosphorylation of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2 (PFKFB2) which upregulated glycolysis thereby preventing POA-induced ATP depletion, inhibition of the ATP-dependent plasma membrane Ca²⁺ ATPase (PMCA) and cytotoxic Ca²⁺ overload. These data provide the first mechanistic link between diabetes and severity of AP and suggest that phosphorylation of PFKFB2 may represent a potential therapeutic strategy for treatment of AP.

Tests of the positive and functional allometry hypotheses for sexually selected traits in the Jamaican field cricket

Sexually selected traits, including threat signals, have been shown to scale steeply positively with body size because their exaggeration maximizes honest signalling. However, the functional allometry hypothesis makes the opposite prediction for some weapons: because the biomechanics of force applied in their use may favor relatively smaller size, sexually selected weapons may exhibit negative allometry. Tests of these ideas in insects have largely focused on holometabolous species, whose adult body size is entirely dependent on nutrients acquired during the larval stage. In contrast, hemimetabolous insects may exhibit different patterns of allometry development because they forage throughout development, between successive moults. Here, we tested complementary and competing predictions made by the positive and functional allometry hypotheses, regarding intrasexually selected trait allometry in a hemimetabolous insect, the Jamaican field cricket (Gryllus assimilis). As expected, head width (a dominance and/or combat trait) was more positively allometric than non-sexually selected traits. In contrast, and consistent with the functional allometry hypothesis, mouthparts (weapons) were either isometric or negatively allometric. We also tested whether trait allometry responded to rearing diet by raising males on either a high protein diet or a high carbohydrate diet; we predicted stronger positive allometry under the high protein diet. However, diet did not influence allometry in the predicted manner. Overall, our results support the functional allometry hypothesis regarding sexually selected trait allometry and raise intriguing possibilities for integrating these ideas with recent paradigms for classifying intrasexually selected traits.

Overwintering conditions impact insulin pathway gene expression in diapausing Megachile rotundata

Diapause is a non-feeding state that many insects undergo to survive the winter months. With fixed resources, overall metabolism and insulin signaling (IIS) are maintained at low levels, but whether those change in response to seasonal temperature fluctuations remains unknown. The focus of this study was to determine 1) how genes in the insulin signaling pathway vary throughout diapause and 2) if that variation changes in response to temperature. To test the hypothesis that expression of IIS pathway genes vary in response to temperature fluctuations during overwintering, alfalfa leafcutting bees, Megachile rotundata, were overwintered at either a constant 4 °C in the lab or in naturally fluctuating temperatures in the field. Expression levels of genes in the IIS pathway, cell cycle regulators, and transcription factors were measured. Overall our findings showed that a few key targets of the insulin signaling pathway, along with growth regulators, change during overwintering, suggesting that only cell cycle regulators, and not the IIS pathway as a whole, change across the phases of diapause. To answer our second question, we compared gene expression levels between temperature treatments at each month for a given gene. We observed significantly more differences in expression of IIS pathway targets, indicating that overwintering conditions impact insulin pathway gene expression and leads to altered expression profiles. With differences seen between temperature treatment groups, these findings indicate that constant temperatures like those used in agricultural storage protocols, lead to different expression profiles and possibly different diapause phenotypes for alfalfa leafcutting bees.

Associations between IGF1, IGFBP2 and TGFß3 Genes Polymorphisms and Growth Performance of Broiler Chicken Lines

Marker-assisted selection based on fast and accurate molecular analysis of individual genes is considered an acceptable tool in the speed-up of the genetic improvement of production performance in chickens. The objective of this study was to detect the single nucleotide polymorphisms (SNPs) in the IGF1, IGFBP2 and TGFß3 genes, and to investigate their associations with growth performance (body weight (BW) and average daily gain (ADG) at 14, 21, 28, 35 and 42 days of age) and carcass traits in broilers. Performance (carcass) data (weight before slaughter; weights of the trunk, giblets, abdominal fat, breast muscle and thigh muscle; slaughter value and slaughter percentage), as well as blood samples for DNA extraction and SNP analysis, were obtained from 97 chickens belonging to two different lines (Hubbard F15 and Cobb E) equally divided between the two sexes. The genotypes were detected using polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) methods with specific primers and restrictase for each gene. The statistical analysis discovered significant associations (p < 0.05) between the TGFβ3 SNP and the following parameters: BW at 21, 28 and 35 days, trunk weight and slaughter value. Association analysis of BWs (at 21, 28 and 35 days) and SNPs was always significant for codominant, dominant and overdominant genetic models, showing a possible path for genomic selection in these chicken lines. Slaughter value was significant for codominant, recessive and overdominant patterns, whereas other carcass traits were not influenced by SNPs. Based on the results of this study, we suggested that the TGFβ3 gene could be used as a candidate gene marker for chicken growth traits in the Hubbard F15 and Cobb E population selection programs, whereas for carcass traits further investigation is needed.

A Comprehensive Cohort Analysis Comparing Growth and GH Therapy Response in IGF1R Mutation Carriers and SGA Children

CONTEXT

IGF1 receptor mutations (IGF1RM) are rare; however, patients exhibit pronounced growth retardation without catch-up. Although several case reports exist, a comprehensive statistical analysis investigating growth profile and benefit of recombinant human growth hormone (rhGH) treatment is still missing.

OBJECTIVE AND METHODS

Here, we compared IGF1RM carriers (n = 23) retrospectively regarding birth parameters, growth response to rhGH therapy, near final height, and glucose/insulin homeostasis to treated children born small for gestational age (SGA) (n = 34). Additionally, health profiles of adult IGF1RM carriers were surveyed by a questionnaire.

RESULTS

IGF1RM carriers were significantly smaller at rhGH initiation and had a diminished first-year response compared to SGA children (Δ height standard deviation score: 0.29 vs. 0.65), resulting in a lower growth response under therapy. Interestingly, the number of poor therapy responders was three times higher for IGF1RM carriers than for SGA patients (53 % vs. 17 %). However, most IGF1RM good responders showed catch-up growth to the levels of SGA patients. Moreover, we observed no differences in homeostasis model assessment of insulin resistance before treatment, but during treatment insulin resistance was significantly increased in IGF1RM carriers compared to SGA children. Analyses in adult mutation carriers indicated no increased occurrence of comorbidities later in life compared to SGA controls.

CONCLUSION

In summary, IGF1RM carriers showed a more pronounced growth retardation and lower response to rhGH therapy compared to non-mutation carriers, with high individual variability. Therefore, a critical reevaluation of success should be performed periodically. In adulthood, we could not observe a significant influence of IGF1RM on metabolism and health of carriers.

Prominence of IL6, IGF, TLR, and Bioenergetics Pathway Perturbation in Lung Tissues of Scleroderma Patients With Pulmonary Fibrosis

Scleroderma-associated pulmonary fibrosis (SSc-PF) and idiopathic pulmonary fibrosis (IPF) are two of many chronic fibroproliferative diseases that are responsible for nearly 45% of all deaths in developed countries. While sharing several pathobiological characteristics, they also have very distinct features. Currently no effective anti-fibrotic treatments exist that can halt the progression of PF or reverse it. Our goal is to uncover potential gene targets for the development of anti-fibrotic therapies efficacious in both diseases, and those specific to SSc-PF, by identifying universal pathways and molecules driving fibrosis in SSc-PF and IPF tissues as well as those unique to SSc-PF. Using DNA microarray data, a meta-analysis of the differentially expressed (DE) genes in SSc-PF and IPF lung tissues (diseased vs. normal) was performed followed by a full systems level analysis of the common and unique transcriptomic signatures obtained. Protein-protein interaction networks were generated to identify hub proteins and explore the data using the centrality principle. Our results suggest that therapeutic strategies targeting IL6 trans-signaling, IGFBP2, IGFL2, and the coagulation cascade may be efficacious in both SSc-PF and IPF. Further, our data suggest that the expression of matrikine-producing collagens is also perturbed in PF. Lastly, an overall perturbation of bioenergetics, specifically between glycolysis and fatty acid metabolism, was uncovered in SSc-PF. Our findings provide insights into potential targets for the development of anti-fibrotic therapies that could be effective in both IPF and SSc-PF.

Insulin-Like Growth Factor Dysregulation Both Preceding and Following Type 1 Diabetes Diagnosis

Insulin-like growth factors (IGFs), specifically IGF1 and IGF2, promote glucose metabolism, with their availability regulated by IGF-binding proteins (IGFBPs). We hypothesized that IGF1 and IGF2 levels, or their bioavailability, are reduced during type 1 diabetes development. Total serum IGF1, IGF2, and IGFBP1-7 levels were measured in an age-matched, cross-sectional cohort at varying stages of progression to type 1 diabetes. IGF1 and IGF2 levels were significantly lower in autoantibody (AAb)⁺ compared with AAb^- relatives of subjects with type 1 diabetes. Most high-affinity IGFBPs were unchanged in individuals with pre-type 1 diabetes, suggesting that total IGF levels may reflect bioactivity. We also measured serum IGFs from a cohort of fasted subjects with type 1 diabetes. IGF1 levels significantly decreased with disease duration, in parallel with declining β-cell function. Additionally, plasma IGF levels were assessed in an AAb⁺ cohort monthly for a year. IGF1 and IGF2 showed longitudinal stability in single AAb⁺ subjects, but IGF1 levels decreased over time in subjects with multiple AAb and those who progressed to type 1 diabetes, particularly postdiagnosis. In sum, IGFs are dysregulated both before and after the clinical diagnosis of type 1 diabetes and may serve as novel biomarkers to improve disease prediction.

Mechanism and Functions of Identified miRNAs in Poultry Skeletal Muscle Development – A Review

Development of the skeletal muscle goes through several complex processes regulated by numerous genetic factors. Although much efforts have been made to understand the mechanisms involved in increased muscle yield, little work is done about the miRNAs and candidate genes that are involved in the skeletal muscle development in poultry. Comprehensive research of candidate genes and single nucleotide related to poultry muscle growth is yet to be experimentally unraveled. However, over a few periods, studies in miRNA have disclosed that they actively participate in muscle formation, differentiation, and determination in poultry. Specifically, miR-1, miR-133, and miR-206 influence tissue development, and they are highly expressed in the skeletal muscles. Candidate genes such as CEBPB, MUSTN1, MSTN, IGF1, FOXO3, mTOR, and NFKB1, have also been identified to express in the poultry skeletal muscles development. However, further researches, analysis, and comprehensive studies should be made on the various miRNAs and gene regulatory factors that influence the skeletal muscle development in poultry. The objective of this review is to summarize recent knowledge in miRNAs and their mode of action as well as transcription and candidate genes identified to regulate poultry skeletal muscle development.

The Insulin/IGF System in Mammalian Sexual Development and Reproduction

Persistent research over the past few decades has clearly established that the insulin-like family of growth factors, which is composed of insulin and insulin-like growth factors 1 (IGF1) and 2 (IGF2), plays essential roles in sexual development and reproduction of both males and females. Within the male and female reproductive organs, ligands of the family act in an autocrine/paracrine manner, in order to guide different aspects of gonadogenesis, sex determination, sex-specific development or reproductive performance. Although our knowledge has greatly improved over the last years, there are still several facets that remain to be deciphered. In this review, we first briefly outline the principles of sexual development and insulin/IGF signaling, and then present our current knowledge, both in rodents and humans, about the involvement of insulin/IGFs in sexual development and reproductive functions. We conclude by highlighting some interesting remarks and delineating certain unanswered questions that need to be addressed in future studies.

The ventral epithelium of Trichoplax adhaerens deploys in distinct patterns cells that secrete digestive enzymes, mucus or diverse neuropeptides

The disk-shaped millimeter-sized marine animal, Trichoplax adhaerens, is notable because of its small number of cell types and primitive mode of feeding. It glides on substrates propelled by beating cilia on its lower surface and periodically pauses to feed on underlying microorganisms, which it digests externally. Here, a combination of advanced electron and light microscopic techniques are used to take a closer look at its secretory cell types and their roles in locomotion and feeding. We identify digestive enzymes in lipophils, a cell type implicated in external digestion and distributed uniformly throughout the ventral epithelium except for a narrow zone near its edge. We find three morphologically distinct types of gland cell. The most prevalent contains and secretes mucus, which is shown to be involved in adhesion and gliding. Half of the mucocytes are arrayed in a tight row around the edge of the ventral epithelium while the rest are scattered further inside, in the region containing lipophils. The secretory granules in mucocytes at the edge label with an antibody against a neuropeptide that was reported to arrest ciliary beating during feeding. A second type of gland cell is arrayed in a narrow row just inside the row of mucocytes while a third is located more centrally. Our maps of the positions of the structurally distinct secretory cell types provide a foundation for further characterization of the multiple peptidergic cell types in Trichoplax and the microscopic techniques we introduce provide tools for carrying out these studies.

Pleiotropic roles of the insulin-like growth factor axis in type 1 diabetes

PURPOSE OF REVIEW

We review studies demonstrating lowered levels of insulin-like growth factors (IGFs) in patients with recent-onset type 1 diabetes (T1D) and discuss their potential roles in the disorder's pathogenesis.

RECENT FINDINGS

IGFs have long been recognized as a class of hormones that promote growth, development, and cellular metabolism throughout the human body. More recently, studies have noted an association between reduced pancreatic weight/volume and T1D. Thus, we believe it is important to understand pancreatic regulation of IGF expression and bioavailability, as well as the impact of IGFs on pancreatic growth and islet health. Additional studies of IGFs have been extended to their influence on the inflammatory/regulatory balance of monocytes, B cells, and T cells; features which have been previously established to show dysregulation in settings of T1D.

SUMMARY

These data suggest that IGFs may prevent known impairments in the pancreas and immune system in T1D and underscore the need to extend these studies, some of which were performed in health or other autoimmune diseases, toward T1D specifically. Collectively, the work emphasized here support the potential therapeutic use of IGFs in T1D prevention efforts as pancreatic growth factors and/or immunoregulatory agents.

Effects of Insulin on Porcine Neonatal Sertoli Cell Responsiveness to FSH In Vitro

There is ongoing debate as to whether the decline of sperm production in recent times may be related to a parallel increase in the rate of obesity and diabetes. Lower anti-Müllerian hormone (AMH) and inhibin B secretion have been observed in young hyperinsulinemic patients compared to healthy controls, suggesting a Sertoli cell (SC) dysfunction. The pathophysiological mechanisms underlying SC dysfunction in these patients are poorly understood. To the best of our knowledge, no evidence is available on the effects of insulin on SC function. Therefore, this study was undertaken to assess the effects of insulin on basal and follicle-stimulating hormone (FSH)-stimulated SC function in vitro. To accomplish this, we evaluated the expression of AMH, inhibin B and FSHR genes, the secretion of AMH and inhibin B and the phosphorylation of AKT473 and SC proliferation on neonatal porcine SC after incubation with FSH and/or insulin. We found that similar to FSH, the expression and secretion of AMH is suppressed by insulin. Co-incubation with FSH and insulin decreased AMH secretion significantly more than with FSH alone. Insulin had no effect on the expression and secretion of the inhibin B gene, but co-incubation with FSH and insulin had a lower effect on inhibin B secretion than that found with FSH alone. FSH and/or insulin increased AKT473 phosphorylation and SC proliferation. In conclusion, the results of this study showed that insulin modulates SC function. We hypothesize that hyperinsulinemia may therefore influence testicular function even before puberty begins. Therefore, particular care should be taken to avoid the onset of hyperinsulinemia in children to prevent a future deleterious effect on fertility.

Insulin and Insulin Receptors in Adipose Tissue Development

Insulin is a major endocrine hormone also involved in the regulation of energy and lipid metabolism via the activation of an intracellular signaling cascade involving the insulin receptor (INSR), insulin receptor substrate (IRS) proteins, phosphoinositol 3-kinase (PI3K) and protein kinase B (AKT). Specifically, insulin regulates several aspects of the development and function of adipose tissue and stimulates the differentiation program of adipose cells. Insulin can activate its responses in adipose tissue through two INSR splicing variants: INSR-A, which is predominantly expressed in mesenchymal and less-differentiated cells and mainly linked to cell proliferation, and INSR-B, which is more expressed in terminally differentiated cells and coupled to metabolic effects. Recent findings have revealed that different distributions of INSR and an altered INSR-A:INSR-B ratio may contribute to metabolic abnormalities during the onset of insulin resistance and the progression to type 2 diabetes. In this review, we discuss the role of insulin and the INSR in the development and endocrine activity of adipose tissue and the pharmacological implications for the management of obesity and type 2 diabetes.

Tumor Suppressor PTEN Regulates Negatively Sertoli Cell Proliferation, Testis Size, and Sperm Production In Vivo

The IGFs are the major intratesticular factors regulating immature Sertoli cell proliferation and are, therefore, critical to establish the magnitude of sperm production. However, the intratesticular source of IGF production and the downstream signaling pathway mediating IGF-dependent Sertoli cell proliferation remain unclear. Single-cell RNA sequencing on mouse embryonic testis revealed a robust expression of Igf1 and Igf2 in interstitial steroidogenic progenitors, suggesting that IGFs exert paracrine actions on immature Sertoli cells. To elucidate the intracellular signaling mechanism that underlies the proliferative effects of IGFs on immature Sertoli cells, we have generated mice with Sertoli cell-specific deletion of the Pten gene, a negative regulator of the phosphatidylinositol-3 kinase (PI3K)/AKT pathway, alone or together with the insulin receptor (Insr) and the IGF1 receptor (Igf1r). Although ablation of Pten appears dispensable for Sertoli cell proliferation and spermatogenesis, inactivation of Pten in the absence of Insr and Igf1r rescued the Sertoli cell proliferation rate during late fetal development, testis size, and sperm production. Overall, these findings suggest that IGFs secreted by interstitial progenitor cells act in a paracrine fashion to promote the proliferation of immature Sertoli cells through the IGF/PTEN/PI3K pathway.

Pathobiology and genetics of adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare malignancy with an incidence worldwide of 0.7-2.0 cases/million/year. Initial staging is the most important factor in determining prognosis. If diagnosed early, complete surgical resection +/- adjuvant treatment can lead to 5-year survival of up to 80%. However, often it is diagnosed late and in advanced disease, 5-year survival is <15% with a high recurrence rate even after radical surgery. The mainstay of adjuvant treatment is with the drug mitotane. Mitotane has a specific cytotoxic effect on steroidogenic cells of the adrenal cortex, but despite this, progression through treatment is common. Developments in genetic analysis in the form of next-generation sequencing, aided by bioinformatics, have enabled high-throughput molecular characterisation of these tumours. This, in addition to a better appreciation of the processes of physiological, homeostatic self-renewal of the adrenal cortex, has furthered our understanding of the pathogenesis of this malignancy. In this review, we have detailed the pathobiology and genetic alterations in adrenocortical carcinoma by integrating current understanding of homeostasis and self-renewal in the normal adrenal cortex with molecular profiling of tumours from recent genetic analyses. Improved understanding of the mechanisms involved in self-renewal and stem cell hierarchy in normal human adrenal cortices, together with the identification of cell populations likely to be co-opted by oncogenic mutations, will enable further progress in the definition of the molecular pathways involved in the pathogenesis of ACC. The combination of these advances eventually will lead to the development of novel, effective and personalised strategies to eradicate molecularly annotated ACCs.

Molecular evolution and functional characterisation of insulin related peptides in molluscs: Contributions of Crassostrea gigas genomic and transcriptomic-wide screening

Insulin Related Peptides (IRPs) belong to the insulin superfamily and possess a typical structure with two chains, B and A, linked by disulphide bonds. As the sequence conservation is usually low between members, IRPs are classified according to the number and position of their disulphide bonds. In molluscan species, the first IRPs identified, named Molluscan Insulin-related Peptides (MIPs), exhibit four disulphide bonds. The genomic and transcriptomic data screening in the Pacific oyster Crassostrea gigas (Mollusc, Bivalvia) allowed us to identify six IRP sequences belonging to three structural groups. Cg-MIP1 to 4 have the typical structure of MIPs with four disulphide bonds. Cg-ILP has three disulphide bonds like vertebrate Insulin-Like Peptides (ILPs). The last one, Cg-MILP7 has a significant homology with Drosophila ILP7 (DILP7) associated with two additional cysteines allowing the formation of a fourth disulphide bond. The phylogenetic analysis points out that ILPs may be the most ancestral form. Moreover, it appears that ILP7 orthologs are probably anterior to lophotrochozoa and ecdysozoa segregation. In order to investigate the diversity of physiological functions of the oyster IRPs, we combine in silico expression data, qPCR measurements and in situ hybridization. The Cg-ilp transcript, mainly detected in the digestive gland and in the gonadal area, is potentially involved in the control of digestion and gametogenesis. The expression of Cg-mip4 is mainly associated with the larval development. The Cg-mip transcript shared by the Cg-MIP1, 2 and 3, is mainly expressed in visceral ganglia but its expression was also observed in the gonads of mature males. This pattern suggested the key roles of IRPs in the control of sexual reproduction in molluscan species.

Intestinal epithelial cell-specific IGF1 promotes the expansion of intestinal stem cells during epithelial regeneration and functions on the intestinal immune homeostasis

It is well known that insulin-like growth factor 1 (IGF1) acts as a trophic factor in small intestine under both physiological and pathophysiological conditions. However, it still lacks direct in vivo evidence of the functions of intestinal epithelial cell (IEC)-specific IGF1 under both normal and pathological conditions. Using IEC-specific IGF1-knockout (cKO) mice and Lgr5-eGFP-CreERT mice, we demonstrate that IEC-specific IGF1 can enhance nutrient uptake, reduce protein catabolism and energy consumption, and promote the proliferation and expansion of intestinal epithelial cells, including intestinal epithelial stem cells and intestinal secretory cells. Next, we showed that IEC-specific IGF1 renders IECs resistant to irradiation and promotes epithelial regeneration. Strikingly, transcriptome profiling assay revealed that many differentially expressed genes involved in the differentiation and maturation of lymphoid lineages were significantly suppressed in the cKO mice as compared with the control mice. We demonstrated that deletion of IGF1 in IECs enhances bacterial translocation to the mesenteric lymph nodes and liver. Furthermore, high-throughput sequencing of 16S ribosomal RNA genes of gut microbiota revealed that IEC-specific IGF1 loss profoundly affected the gut microbial composition at various levels of classification. Therefore, our findings shed light on the in vivo roles of IEC-specific IGF1 in intestinal homeostasis, epithelial regeneration, and immunity, broadening our current insights on IGF1 functions.

Roles of insulin-like growth factors in metamorphic development of turbot (Scophthalmus maximus)

Larval turbot (Scophthalmus maximus) undergo metamorphosis, a late post-embryonic developmental event that precedes juvenile transition. Insulin-like growth factors (IGFs) are important endocrine/autocrine/paracrine factors that provide essential signals to control of the embryonic and postnatal development of vertebrate species, including fish. Accumulating evidence suggests that IGFs are involved in regulating the metamorphic development of flatfish. This mini review focus on the functions of all known IGFs (IGF-I and IGF-II) during the metamorphic development of turbot. Information about IGFs and insulin-like growth factors binding proteins (IGFBPs) from other teleosts is also included in this review to provide an overview of IGFs functions in the metamorphic development of turbot. These findings may enhance our understanding of the potential roles of the IGFs system in controlling of flatfish metamorphosis and contributing to the improvement of broodstock management strategies for larval turbot.

Lin28a regulates neurogliogenesis in mammalian retina through the Igf signaling

In the developing central nervous system (CNS) the majority of neurons are born before the generation of glia. Emerging evidence implicates heterochronic gene, Lin28 in the temporal switch between two distinct lineages. However, the respective contributions of Lin28a and Lin28b in neurogliogenesis remain poorly understood. Here, we have examined the relative involvement of Lin28a and Lin28b in mammalian retina, a simple and accessible CNS model where neurogliogenic decision largely occurs postnatally. Examination of Lin28a/b involvement during late histogenesis by the perturbation of function approaches revealed that while Lin28b did not influence differentiation in general Lin28a facilitated and antagonized the generation of neurons and glia, respectively. Silencing of Lin28a expression in vitro and its conditional deletion in vivo during early histogenesis led to premature generation of glia. The instructive role of Lin28a on neuronal differentiation was revealed by its influence to suppress glial-specific genes and directly differentiate glia along the neuronal lineage. This function of Lin28a is likely mediated through the Igf signaling, as inhibition of the pathway abrogated Lin28a-mediated neurogliogenesis. Thus, our observations suggest that Lin28a is an important intrinsic factor that acts in concert with cell-extrinsic factors like Igfs, coordinating the developmental bias of the progenitors and niche, respectively, for the successive generation of neurons and glia.

Identification of a unique loss-of-function mutation in IGF1R and a crosstalk between IGF1R and Wnt/β-catenin signaling pathways

IGF1R is a ubiquitous receptor tyrosine kinase that plays critical roles in cell proliferation, growth and survival. Clinical studies have demonstrated upregulation of IGF1R mediated signaling in a number of malignancies including colon, breast, and lung cancers. Overexpression of the IGF1R in these malignancies is associated with a poor prognosis and overall survival. IGF1R specific kinase inhibitors have failed in multiple clinical trials partly because of the complex nature of IGF1R signaling. Thus identifying new binding partners and allosteric sites on IGF1R are emerging areas of research. More recently, IGF1R has been shown to translocate into the nucleus and perform many functions. In this study, we generated a library of IGF1R deletion and point mutants to examine IGF1R subcellular localization and activation of downstream signaling pathways. We show that the nuclear localization of IGF1R is primarily defined by its cytoplasmic domain. We identified a cross-talk between IGF1R and Wnt/β-catenin signaling pathways and showed, for the first time, that IGF1R is associated with upregulation of TCF-mediated β-catenin transcriptional activity. Using loss-of-function mutants, deletion analysis and IGF1R specific inhibitor(s), we show that cytoplasmic and nuclear activities are two independent functions of IGF1R. Furthermore, we identified a unique loss-of-function mutation in IGF1R. This unique loss-of-function mutant retains only nuclear functions and sits in a pocket, outside ATP and substrate binding region, that is suited for designing allosteric inhibitors of IGF1R.

Cargo-selective SNX-BAR proteins mediate retromer trimer independent retrograde transport

Kvainickas et al. show that the retromer cargo CI-MPR does not recycle from endosomes to the trans-Golgi network through interactions with the core retromer trimer. Instead, CI-MPR depends on cargo-selective SNX-BAR proteins, which function independently of the core retromer trimer.

The retromer complex, which recycles the cation-independent mannose 6-phosphate receptor (CI-MPR) from endosomes to the trans-Golgi network (TGN), is thought to consist of a cargo-selective VPS26–VPS29–VPS35 trimer and a membrane-deforming subunit of sorting nexin (SNX)–Bin, Amphyphysin, and Rvs (BAR; SNX-BAR) proteins. In this study, we demonstrate that heterodimers of the SNX-BAR proteins, SNX1, SNX2, SNX5, and SNX6, are the cargo-selective elements that mediate the retrograde transport of CI-MPR from endosomes to the TGN independently of the core retromer trimer. Using quantitative proteomics, we also identify the IGF1R, among more potential cargo, as another SNX5 and SNX6 binding receptor that recycles through SNX-BAR heterodimers, but not via the retromer trimer, in a ligand- and activation-dependent manner. Overall, our data redefine the mechanics of retromer-based sorting and call into question whether retromer indeed functions as a complex of SNX-BAR proteins and the VPS26–VPS29–VPS35 trimer.

Investigating the role of the IGF axis as a predictor of biochemical recurrence in prostate cancer patients post-surgery

BACKGROUND

Between 20% and 35% of prostate cancer (PCa) patients who undergo treatment with curative intent (ie, surgery or radiation therapy) for localized disease will experience biochemical recurrence (BCR). Alterations in the insulin-like growth factor (IGF) axis and PTEN expression have been implicated in the development and progression of several human tumors including PCa. We examined the expression of the insulin receptor (INSR), IGF-1 receptor (IGF-1R), PTEN, and AKT in radical prostatectomy tissue of patients who developed BCR post-surgery.

METHODS

Tissue microarrays (TMA) of 130 patients post-radical prostatectomy (65 = BCR, 65 = non-BCR) were stained by immunohistochemistry for INSR, IGF-1R, PTEN, and AKT using optimized antibody protocols. INSR, IGF1-R, PTEN, and AKT expression between benign and cancerous tissue, and different Gleason grades was assessed. Kaplan-Meier survival curves were used to examine the relationship between proteins expression and BCR.

RESULTS

INSR (P < 0.001), IGF-1R (P < 0.001), and AKT (P < 0.05) expression was significantly increased and PTEN (P < 0.001) was significantly decreased in cancerous versus benign tissue. There was no significant difference in INSR, IGF-1R, or AKT expression in the cancerous tissue of non-BCR versus BCR patients (P = 0.149, P = 0.990, P = 0.399, respectively). There was a significant decrease in PTEN expression in the malignant tissue of BCR versus non-BCR patients (P = 0.011). Combinational analysis of the tissue proteins identified a combination of decreased PTEN and increased AKT or increased INSR was associated with worst outcome. We found that in each case, our hypothesized worst group was most likely to experience BCR and this was significant for combinations of PTEN+INSR and PTEN+AKT but not PTEN+IGF-1R (P = 0.023, P = 0.028, P = 0.078, respectively).

CONCLUSIONS

Low PTEN is associated with BCR and this association is strongly modified by high INSR and high AKT expression. Measurement of these proteins could help inform appropriate patient selection for postoperative adjuvant therapy and prevent BCR.

Macrophage-derived insulin-like growth factor-1 affects influenza vaccine efficacy through the regulation of immune cell homeostasis

The level of antibody production induced by a vaccine involves a variety of host factors. One of these, insulin-like growth factor-1 (IGF-1), plays an important role in lymphocyte maturation and antibody expression. Here, we investigated the role of macrophage-derived IGF-1 in the induction of influenza vaccine-specific antibodies using macrophage-derived IGF-1 gene knockout (MIKO) mice. The titers of vaccine-specific total immunoglobulin G (IgG) and IgG1 after immunization were about two- to fourfold lower in MIKO mice than in WT mice. Moreover, MIKO mice showed a relatively weak booster effect of repeated immunization. In contrast, antigen-nonspecific total IgG was about threefold higher in MIKO mice than in WT mice. After viral challenge, the viral titer and the pathological damage in lungs of MIKO mice were higher than those in WT mice despite vaccination. Interestingly, the proportions of proinflammatory immune cells including M1 macrophages, Th1 and Th17 cells was higher in unvaccinated MIKO mice than in unvaccinated WT mice. This suggests that nonspecific activation of immune cells may paradoxically impair the response to the vaccine. In addition, although the proportions of T follicular helper (Tfh) cells and GL-7⁺ germinal center (GC) B cells were higher in MIKO mice than in WT mice, the population of CD138⁺B220⁺ antibody-secreting plasmablasts was lower in MIKO mice, which may be a cause of the low influenza-specific antibody titer in MIKO mice. Taken together, these results suggest that macrophage-derived IGF-1 might play an important role in the vaccine-triggered immune response by regulating immune cell homeostasis.

Insulin-like growth factor signaling regulates developmental trajectory associated with diapause in embryos of the annual killifish Austrofundulus limnaeus

Annual killifishes exhibit a number of unique life history characters including the occurrence of embryonic diapause, unique cell movements associated with dispersion and subsequent reaggregation of the embryonic blastomeres, and a short post-embryonic life span. Insulin-like growth factor (IGF) signaling is known to play a role in the regulation of metabolic dormancy in a number of animals but has not been explored in annual killifishes. The abundance of IGF proteins during development and the developmental effects of blocking IGF signaling by pharmacological inhibition of the insulin-like growth factor I receptor (IGF1R) were explored in embryos of the annual killifish Austrofundulus limnaeus Blocking of IGF signaling in embryos that would normally escape entrance into diapause resulted in a phenotype that was remarkably similar to that of embryos entering diapause. IGF-I protein abundance spikes during early development in embryos that will not enter diapause. In contrast, IGF-I levels remain low during early development in embryos that will enter diapause II. IGF-II protein is packaged at higher levels in escape-bound embryos compared with diapause-bound embryos. However, IGF-II levels quickly decrease and remain low during early development and only increase substantially during late development in both developmental trajectories. Developmental patterns of IGF-I and IGF-II protein abundance under conditions that would either induce or bypass entrance into diapause are consistent with a role for IGF signaling in the regulation of developmental trajectory and entrance into diapause in this species. We propose that IGF signaling may be a unifying regulatory pathway that explains the larger suite of characters that are associated with the complex life history of annual killifishes.

Regulation of Glucose Uptake and Enteroendocrine Function by the Intestinal Epithelial Insulin Receptor

Insulin receptors (IRs) and IGF-I receptors (IGF-IR) are major regulators of metabolism and cell growth throughout the body; however, their roles in the intestine remain controversial. Here we show that genetic ablation of the IR or IGF-IR in intestinal epithelial cells of mice does not impair intestinal growth or development or the composition of the gut microbiome. However, the loss of IRs alters intestinal epithelial gene expression, especially in pathways related to glucose uptake and metabolism. More importantly, the loss of IRs reduces intestinal glucose uptake. As a result, mice lacking the IR in intestinal epithelium retain normal glucose tolerance during aging compared with controls, which show an age-dependent decline in glucose tolerance. Loss of the IR also results in a reduction of glucose-dependent insulinotropic polypeptide (GIP) expression from enteroendocrine K-cells and decreased GIP release in vivo after glucose ingestion but has no effect on glucagon-like peptide 1 expression or secretion. Thus, the IR in the intestinal epithelium plays important roles in intestinal gene expression, glucose uptake, and GIP production, which may contribute to pathophysiological changes in individuals with diabetes, metabolic syndrome, and other insulin-resistant states.

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. To better understand the role of neuronal insulin-like growth factor signaling in neuroprotection, we inactivated insulin-like growth factor type-1-receptor in forebrain neurons using conditional Cre-LoxP-mediated gene targeting. We found that brain structure and function, including memory performance, were preserved in insulin-like growth factor receptor mutants, and that certain characteristics improved, notably synaptic transmission in hippocampal neurons. To reveal stress-related roles of insulin-like growth factor signaling, we challenged the brain using a stroke-like insult. Importantly, when charged with hypoxia-ischemia, mutant brains were broadly protected from cell damage, neuroinflammation and cerebral edema. We also found that in mice with insulin-like growth factor receptor knockout specifically in forebrain neurons, a substantial systemic upregulation of growth hormone and insulin-like growth factor-I occurred, which was associated with significant somatic overgrowth. Collectively, we found strong evidence that blocking neuronal insulin-like growth factor signaling increases peripheral somatotropic tone and simultaneously protects the brain against hypoxic-ischemic injury, findings that may contribute to developing new therapeutic concepts preventing the disabling consequences of stroke.

Cryptochromes regulate IGF-1 production and signaling through control of JAK2-dependent STAT5B phosphorylation

The circadian clock regulates IGF-1 production and signaling through proteins called cryptochromes, which regulate the activity of transcriptional factor STAT5B and control mouse body and organ size.

Insulin-like growth factor (IGF) signaling plays an important role in cell growth and proliferation and is implicated in regulation of cancer, metabolism, and aging. Here we report that IGF-1 level in blood and IGF-1 signaling demonstrates circadian rhythms. Circadian control occurs through cryptochromes (CRYs)—transcriptional repressors and components of the circadian clock. IGF-1 rhythms are disrupted in Cry-deficient mice, and IGF-1 level is reduced by 80% in these mice, which leads to reduced IGF signaling. In agreement, Cry-deficient mice have reduced body (∼30% reduction) and organ size. Down-regulation of IGF-1 upon Cry deficiency correlates with reduced Igf-1 mRNA expression in the liver and skeletal muscles. Igf-1 transcription is regulated through growth hormone–induced, JAK2 kinase–mediated phosphorylation of transcriptional factor STAT5B. The phosphorylation of STAT5B on the JAK2-dependent Y699 site is significantly reduced in the liver and skeletal muscles of Cry-deficient mice. At the same time, phosphorylation of JAK2 kinase was not reduced upon Cry deficiency, which places CRY activity downstream from JAK2. Thus CRYs link the circadian clock and JAK-STAT signaling through control of STAT5B phosphorylation, which provides the mechanism for circadian rhythms in IGF signaling in vivo.

Equine Chorionic Gonadotropin Modulates the Expression of Genes Related to the Structure and Function of the Bovine Corpus Luteum

We hypothesized that stimulatory and superovulatory treatments, using equine chorionic gonadotropin (eCG), modulate the expression of genes related to insulin, cellular modelling and angiogenesis signaling pathways in the bovine corpus luteum (CL). Therefore, we investigated: 1—the effect of these treatments on circulating insulin and somatomedin C concentrations and on gene and protein expression of INSR, IGF1 and IGFR1, as well as other insulin signaling molecules; 2—the effects of eCG on gene and protein expression of INSR, IGF1, GLUT4 and NFKB1A in bovine luteal cells; and 3—the effect of stimulatory and superovulatory treatments on gene and protein expression of ANG, ANGPT1, NOS2, ADM, PRSS2, MMP9 and PLAU. Serum insulin did not differ among groups (P = 0.96). However, serum somatomedin C levels were higher in both stimulated and superovulated groups compared to the control (P = 0.01). In stimulated cows, lower expression of INSR mRNA and higher expression of NFKB1A mRNA and IGF1 protein were observed. In superovulated cows, lower INSR mRNA expression, but higher INSR protein expression and higher IGF1, IGFR1 and NFKB1A gene and protein expression were observed. Expression of angiogenesis and cellular modelling pathway-related factors were as follows: ANGPT1 and PLAU protein expression were higher and MMP9 gene and protein expression were lower in stimulated animals. In superovulated cows, ANGPT1 mRNA expression was higher and ANG mRNA expression was lower. PRSS2 gene and protein expression were lower in both stimulated and superovulated animals related to the control. In vitro, eCG stimulated luteal cells P4 production as well as INSR and GLUT4 protein expression. In summary, our results suggest that superovulatory treatment induced ovarian proliferative changes accompanied by increased expression of genes providing the CL more energy substrate, whereas stimulatory treatment increased lipogenic activity, angiogenesis and plasticity of the extracellular matrix (ECM).

Expression of insulin-like growth factors at mRNA levels during the metamorphic development of turbot (Scophthalmus maximus)

Insulin-like growth factors I and II (IGF-I and IGF-II) are important regulators of vertebrate growth and development. This study characterized the mRNA expressions of igf-i and igf-ii during turbot (Scophthalmus maximus) metamorphosis to elucidate the possible regulatory role of the IGF system in flatfish metamorphosis. Results showed that the mRNA levels of igf-i significantly increased at the early-metamorphosis stage and then gradually decreased until metamorphosis was completed. By contrast, mRNA levels of igf-ii significantly increased at the pre-metamorphosis stage and then substantially decreased during metamorphosis. Meanwhile, the whole-body thyroxine (T4) levels varied during larval metamorphosis, and the highest value was observed in the climax-metamorphosis. The mRNA levels of igf-i significantly increased and decreased by T4 and thiourea (TU, inhibitor of endogenous thyroid hormone) during metamorphosis, respectively. Conversely, the mRNA levels of igf-ii remained unchanged. Furthermore, TU significantly inhibited the T4-induced mRNA up-regulation of igf-i during metamorphosis. The whole-body thyroxine (T4) levels were significantly increased and decreased by T4 and TU during metamorphosis, respectively. These results suggested that igf-i and igf-ii may play different functional roles in larval development stages, and igf-i may have a crucial function in regulating the early metamorphic development of turbot. These findings may enhance our understanding of the potential roles of the IGF system to control flatfish metamorphosis and contribute to the improvement of broodstock management for larvae.

Applications of Chondrocyte-Based Cartilage Engineering: An Overview

Chondrocytes are the exclusive cells residing in cartilage and maintain the functionality of cartilage tissue. Series of biocomponents such as different growth factors, cytokines, and transcriptional factors regulate the mesenchymal stem cells (MSCs) differentiation to chondrocytes. The number of chondrocytes and dedifferentiation are the key limitations in subsequent clinical application of the chondrocytes. Different culture methods are being developed to overcome such issues. Using tissue engineering and cell based approaches, chondrocytes offer prominent therapeutic option specifically in orthopedics for cartilage repair and to treat ailments such as tracheal defects, facial reconstruction, and urinary incontinence. Matrix-assisted autologous chondrocyte transplantation/implantation is an improved version of traditional autologous chondrocyte transplantation (ACT) method. An increasing number of studies show the clinical significance of this technique for the chondral lesions treatment. Literature survey was carried out to address clinical and functional findings by using various ACT procedures. The current study was conducted to study the pharmacological significance and biomedical application of chondrocytes. Furthermore, it is inferred from the present study that long term follow-up studies are required to evaluate the potential of these methods and specific positive outcomes.

Developmental changes of Insulin-like growth factors in the liver and muscle of chick embryos

The insulin-like growth factors ( IGFS: ) are synthesized in tissues and play an important role in embryonic development of avian via autocrine/paracrine mechanisms. In the study, mRNA expression of IGFs were detected by real-time PCR in the muscle and liver from d 10 to 20 of chick embryo ( E10: to E20: ). Methylation of IGF1 promoter in the muscle was analyzed by bisulfite sequencing PCR as well as IGF2 promoter in the liver. These results showed that there was obviously IGF1 expression in liver at E19 and E20. The higher IGF1 expression in muscle was found during E15 to E18 with the peak on E17, and then declined. Correspondingly, the lowest methylation level of IGF1 promoter was detectable on the same embryonic d 17. Expression of IGF2 in muscle increased gradually during embryonic growth and showed higher level in the later stages (E17 to E20) when IGF1 expression began to decrease. IGF2 expression in liver reached the first peak on E14, then declined but gradually elevated from E17. IGF2 promoter methylation in liver showed gradual decline on d 12, 15, 17 and 19 of incubation, meanwhile IGF2 expression of liver increased gradually. These results suggested that IGF1 and IGF2 might separately be more important for muscle and liver growth in chick embryonic development. Variation of IGFs expression during the incubation might be concerned with the methylation of gene promoter. The profile of IGFs expression in chick embryonic tissues may be meaningful for understanding organ growth and embryonic development in chick.

The role of selenium in insulin-like growth factor I receptor (IGF-IR) expression and regulation of apoptosis in mouse osteoblasts

Selenium (Se) is an essential component for animals and human beings. The chemoprotective role of Se, via the regulation of the cell cycle, stimulation of apoptosis and activation of some cytokines among others, is well known; however, the comprehensive effects of Se on the expression of IGF-IR and its regulation of apoptosis have not been investigated. Thus the aim of this study was to report on the effects that different concentrations of Se extert on body weight, blood serum IGF-IR levels and histopathology in mice; and on IGF-IR expression, proliferation and apoptosis in mouse osteoblasts. In vivo experiments showed a significant decrease in body weight, serum levels of IGF-IR and prominent toxicant effects on the liver, kidney, heart and spleen following the administration of defined concentrations of Se for 30 d. However, moderate levels (0.1 mg/kg) of Se gradually improved weight and serum IGF-IR. In vitro osteoblast experiments revealed that at concentrations of 5 × 10(-6) and 10(-5) mol/L Se, MTT activity decreased in comparison with control cells. Cell cycle, TEM and caspase-3 activity supported these observations including an increase in the sub-G1 phase and notable apoptosis in osteoblasts, along with a decrease in the expression of mRNA and protein levels of IGF-IR. Moreover, the MTT activity, mRNA and protein levels of IGF-IR in osteoblasts were decreased and caspase-3 activity was increased in siRNA groups as compared with non-siRNA groups. These data suggest that Se significantly affects IGF-IR expression, and that it contributes to the proliferation and regulation of apoptosis in osteoblasts.

The cartilage extracellular matrix as a transient developmental scaffold for growth plate maturation

The cartilage growth plate is a specialized developmental tissue containing characteristic zonal arrangements of chondrocytes. The proliferative and differentiative states of chondrocytes are tightly regulated at all stages including the initial limb bud and rudiment cartilage stages of development, the establishment of the primary and secondary ossification centers, development of the growth plates and laying down of bone. A multitude of spatio-temporal signals, including transcription factors, growth factors, morphogens and hormones, control chondrocyte maturation and terminal chondrocyte differentiation/hypertrophy, cell death/differentiation, calcification and vascular invasion of the growth plate and bone formation during morphogenetic transition of the growth plate. This involves hierarchical, integrated signaling from growth and factors, transcription factors, mechanosensory cues and proteases in the extracellular matrix to regulate these developmental processes to facilitate progressive changes in the growth plate culminating in bone formation and endochondral ossification. This review provides an overview of selected components which have particularly important roles in growth plate biology including collagens, proteoglycans, glycosaminoglycans, growth factors, proteases and enzymes.

Two-Dimensional Differential Gel Electrophoresis to Identify Protein Biomarkers in Amniotic Fluid of Edwards Syndrome (Trisomy 18) Pregnancies

BACKGROUND

Edwards syndrome (ES) is a severe chromosomal abnormality with a prevalence of about 0.8 in 10,000 infants born alive. The aims of this study were to identify candidate proteins associated with ES pregnancies from amniotic fluid supernatant (AFS) using proteomics, and to explore the role of biological networks in the pathophysiology of ES.

METHODS

AFS from six second trimester pregnancies with ES fetuses and six normal cases were included in this study. Fluorescence-based two-dimensional difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) were used for comparative proteomic analysis. The identified proteins were further validated by Western blotting and the role of biological networks was analyzed.

RESULTS

Twelve protein spots were differentially expressed by more than 1.5-fold in the AFS of the ES pregnancies. MALDI-TOF/MS identified one up-regulated protein: apolipoprotein A1 (ApoA1), and four under-regulated proteins: vitamin D binding protein (VDBP), alpha-1-antitrypsin (A1AT), insulin-like growth factor-binding protein 1 (IGFBP-1), and transthyretin (TTR). Western blot and densitometric analysis of ApoA1, A1AT, IGFBP-1, and TTR confirmed the alteration of these proteins in the amniotic fluid samples. Biological network analysis revealed that the proteins of the ES AFS were involved mainly in lipid and hormone metabolism, immune response, and cardiovascular disease.

CONCLUSIONS

These five proteins may be involved in the pathogenesis of ES. Further studies are needed to explore.

The effects of in utero bisphenol A exposure on the ovaries in multiple generations of mice

Bisphenol A is used in polycarbonate plastics and epoxy resins. Previous studies show that in utero BPA exposure inhibits germ cell nest breakdown in the F1 generation of mice, but its effects on germ cell nest breakdown and on the ovary in the F2-F3 generations were unknown. Thus, we tested the hypothesis that BPA has transgenerational effects on the ovary. Mice were exposed to BPA in utero (BPA 0.5, 20, or 50μg/kg/day), and ovaries were collected at postnatal days (PND) 4 and 21 from the F1-F3 generations and subjected to histological evaluation and gene expression analyses. In utero BPA exposure did not have transgenerational effects on germ cell nest breakdown and gene expression on PND 4, but it caused transgenerational changes in expression in multiple genes on PND 21. Collectively, these data indicate that in utero BPA exposure has some transgenerational effects in mice.

Role of peptide growth factors in the rhythm of change hair

The article presents current data on the role growth factors play in hair physiology. Based on a review of literature, the authors described the role growth factors play for initiating, suppressing the growth and differentiating hair follicles. According to them, each morphologic development stage of hair follicles is characterized by its own factor expression pattern. Referring to experimental and clinical studies, the authors describe the role some growth factors play for mechanisms promoting the development of androgynous and focal alopecia.

Expression profile of IGF-I-calcineurin-NFATc3-dependent pathway genes in skeletal muscle during early development between duck breeds differing in growth rates

The insulin-like growth factor I (IGF-I)-calcineurin (CaN)-NFATc signaling pathways have been implicated in the regulation of myocyte hypertrophy and fiber-type specificity. In the present study, the expression of the CnAα, NFATc3, and IGF-I genes was quantified by RT-PCR for the first time in the breast muscle (BM) and leg muscle (LM) on days 13, 17, 21, 25, and 27 of embryonic development, as well as at 7 days posthatching (PH), in Gaoyou and Jinding ducks, which differ in their muscle growth rates. Consistent expression patterns of CnAα, NFATc3, and IGF-I were found in the same anatomical location at different development stages in both duck breeds, showing significant differences in an age-specific fashion. However, the three genes were differentially expressed in the two different anatomical locations (BM and LM). CnAα, NFATc3, and IGF-I messenger RNA (mRNA) could be detected as early as embryonic day 13 (ED13), and the highest level appeared at this stage in both BM and LM. Significant positive relationships were observed in the expression of the studied genes in the BM and LM of both duck breeds. Also, the expression of these three genes showed a positive relationship with the percentage of type IIb fibers and a negative relationship with the percentage of type I fibers and type IIa fibers. Our data indicate differential expression and coordinated developmental regulation of the selected genes involved in the IGF-I-calcineurin-NFATc3 pathway in duck skeletal muscle during embryonic and early PH growth and development; these data also indicate that this signaling pathway might play a role in the regulation of myofiber type transition.

Comparative Meta-Analysis of Transcriptomics Data during Cellular Senescence and In Vivo Tissue Ageing

Several studies have employed DNA microarrays to identify gene expression signatures that mark human ageing; yet the features underlying this complicated phenomenon remain elusive. We thus conducted a bioinformatics meta-analysis on transcriptomics data from human cell- and biopsy-based microarrays experiments studying cellular senescence or in vivo tissue ageing, respectively. We report that coregulated genes in the postmitotic muscle and nervous tissues are classified into pathways involved in cancer, focal adhesion, actin cytoskeleton, MAPK signalling, and metabolism regulation. Genes that are differentially regulated during cellular senescence refer to pathways involved in neurodegeneration, focal adhesion, actin cytoskeleton, proteasome, cell cycle, DNA replication, and oxidative phosphorylation. Finally, we revealed genes and pathways (referring to cancer, Huntington's disease, MAPK signalling, focal adhesion, actin cytoskeleton, oxidative phosphorylation, and metabolic signalling) that are coregulated during cellular senescence and in vivo tissue ageing. The molecular commonalities between cellular senescence and tissue ageing are also highlighted by the fact that pathways that were overrepresented exclusively in the biopsy- or cell-based datasets are modules either of the same reference pathway (e.g., metabolism) or of closely interrelated pathways (e.g., thyroid cancer and melanoma). Our reported meta-analysis has revealed novel age-related genes, setting thus the basis for more detailed future functional studies.

Epithelial-to-mesenchymal transition in breast cancer: a role for insulin-like growth factor I and insulin-like growth factor-binding protein 3?

Evidence indicates that for most human cancers the problem is not that gene mutations occur but is more dependent upon how the body deals with damaged cells. It has been estimated that only about 1% of human cancers can be accounted for by unmistakable hereditary cancer syndromes, only up to 5% can be accounted for due to high-penetrance, single-gene mutations, and in total only 5%-15% of all cancers may have a major genetic component. The predominant contribution to the causation of most sporadic cancers is considered to be environmental factors contributing between 58% and 82% toward different cancers. A nutritionally poor lifestyle is associated with increased risk of many cancers, including those of the breast. As nutrition, energy balance, macronutrient composition of the diet, and physical activity levels are major determinants of insulin-like growth factor (IGF-I) bioactivity, it has been proposed that, at least in part, these increases in cancer risk and progression may be mediated by alterations in the IGF axis, related to nutritional lifestyle. Localized breast cancer is a manageable disease, and death from breast cancer predominantly occurs due to the development of metastatic disease as treatment becomes more complicated with poorer outcomes. In recent years, epithelial-to-mesenchymal transition has emerged as an important contributor to breast cancer progression and malignant transformation resulting in tumor cells with increased potential for migration and invasion. Furthermore, accumulating evidence suggests a strong link between components of the IGF pathway, epithelial-to-mesenchymal transition, and breast cancer mortality. Here, we highlight some recent studies highlighting the relationship between IGFs, IGF-binding protein 3, and epithelial-to-mesenchymal transition.

The Novel Functions of High-Molecular-Mass Complexes Containing Insulin Receptor Substrates in Mediation and Modulation of Insulin-Like Activities: Emerging Concept of Diverse Functions by IRS-Associated Proteins

Insulin-like peptides, such as insulin-like growth factors (IGFs) and insulin, induce a variety of bioactivities, such as growth, differentiation, survival, increased anabolism, and decreased catabolism in many cell types and in vivo. In general, IGFs or insulin bind to IGF-I receptor (IGF-IR) or insulin receptor (IR), activating the receptor tyrosine kinase. Insulin receptor substrates (IRSs) are known to be major substrates of receptor kinases, mediating IGF/insulin signals to direct bioactivities. Recently, we discovered that IRSs form high-molecular-mass complexes (referred to here as IRSomes) even without IGF/insulin stimulation. These complexes contain proteins (referred to here as IRSAPs; IRS-associated proteins), which modulate tyrosine phosphorylation of IRSs by receptor kinases, control IRS stability, and determine intracellular localization of IRSs. In addition, in these complexes, we found not only proteins that are involved in RNA metabolism but also RNAs themselves. Thus, IRSAPs possibly contribute to modulation of IGF/insulin bioactivities. Since it is established that disorder of modulation of insulin-like activities causes various age-related diseases including cancer, we could propose that the IRSome is an important target for treatment of these diseases.

The amazing ubiquitin-proteasome system: structural components and implication in aging

Proteome quality control (PQC) is critical for the maintenance of cellular functionality and it is assured by the curating activity of the proteostasis network (PN). PN is constituted of several complex protein machines that under conditions of proteome instability aim to, firstly identify, and then, either rescue or degrade nonnative polypeptides. Central to the PN functionality is the ubiquitin-proteasome system (UPS) which is composed from the ubiquitin-conjugating enzymes and the proteasome; the latter is a sophisticated multi-subunit molecular machine that functions in a bimodal way as it degrades both short-lived ubiquitinated normal proteins and nonfunctional polypeptides. UPS is also involved in PQC of the nucleus, the endoplasmic reticulum and the mitochondria and it also interacts with the other main cellular degradation axis, namely the autophagy-lysosome system. UPS functionality is optimum in the young organism but it is gradually compromised during aging resulting in increasing proteotoxic stress; these effects correlate not only with aging but also with most age-related diseases. Herein, we present a synopsis of the UPS components and of their functional alterations during cellular senescence or in vivo aging. We propose that mild UPS activation in the young organism will, likely, promote antiaging effects and/or suppress age-related diseases.

Tissue-engineered cartilage: the crossroads of biomaterials, cells and stimulating factors

Damage to cartilage represents one of the most challenging tasks of musculoskeletal therapeutics due to its limited propensity for healing and regenerative capabilities. Lack of current treatments to restore cartilage tissue function has prompted research in this rapidly emerging field of tissue regeneration of functional cartilage tissue substitutes. The development of cartilaginous tissue largely depends on the combination of appropriate biomaterials, cell source, and stimulating factors. Over the years, various biomaterials have been utilized for cartilage repair, but outcomes are far from achieving native cartilage architecture and function. This highlights the need for exploration of suitable biomaterials and stimulating factors for cartilage regeneration. With these perspectives, we aim to present an overview of cartilage tissue engineering with recent progress, development, and major steps taken toward the generation of functional cartilage tissue. In this review, we have discussed the advances and problems in tissue engineering of cartilage with strong emphasis on the utilization of natural polymeric biomaterials, various cell sources, and stimulating factors such as biophysical stimuli, mechanical stimuli, dynamic culture, and growth factors used so far in cartilage regeneration. Finally, we have focused on clinical trials, recent innovations, and future prospects related to cartilage engineering.