IGF2 promotes alveolar bone regeneration in murine periodontitis via inhibiting cGAS/STING-mediated M1 macrophage polarization

Periodontitis is a chronic inflammatory disease with the destruction of supporting periodontal tissue. This study evaluated the role of insulin-like growth factor 2 (IGF2) in periodontitis by inhibiting the polarization of M1 macrophages via the cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway. IGF2 was enriched in the gingival tissue of murine periodontitis model identified by RNA sequencing. IGF2 application alleviated the expression of pro-inflammatory factors and promoted osteogenesis and the expression of related genes and proteins in a dose-dependent manner in periodontitis. The result of micro-CT verified this finding. Both in vivo and in vitro results revealed that IGF2 decreased the polarization of M1 macrophages and pro-inflammatory factors by immunofluorescence staining, flow cytometry, western blotting and RT-PCR. IGF2 application promoted the osteogenic ability of periodontal ligament fibroblasts (PDLFs) indirectly via its inhibition of M1 polarization evaluated by alkaline phosphatase and alizarin red staining. Then, the cGAS/STING pathway was upregulated in periodontitis and macrophages challenged by LPS, the inhibition of which led to downregulation of M1 polarization. Furthermore, IGF2 could downregulate cGAS, STING and the phosphorylation of P65. Collectively, our study indicates IGF2 can regulate the polarization of M1 macrophages via the cGAS/STING pathway and highlights the promising future of IGF2 as a therapeutic treatment for periodontitis.

The polymorphism of the ovine insulin like growth factor-2 (IGF2) gene and their associations with growth related traits in Tibetan sheep

In the current study, the role of the ovine IGF2 as a potential candidate gene was investigated as though marker-assisted selection in Chinese Tibetan sheep. The Sanger DNA sequencing method explored five single nucleotide polymorphisms (SNPs) in 5'UTR of the ovine IGF2 gene (C15640T, G15801A, G15870A, C15982G and G15991A) in Chinese Tibetan sheep. The frequencies of four SNPs were within the Hardy-Weinberg Equilibrium (chi-square test) except C15982G. The statistical analysis indicated that the C15640T and G15801A were significantly associated with body height, body length, chest circumference, and body weight (P < 0.05 or P < 0.01). Furthermore, C15982G variant exhibited significant correlation with the body weight (P < 0.01). These findings suggests that the promoter variants of IGF2 gene could be used as a candidate gene through marker-assisted selection for the body weight and body measurement traits in Tibetan sheep breeding program.

IGF2 interacts with the imprinted gene Cdkn1c to promote terminal differentiation of neural stem cells

Adult neurogenesis is supported by multipotent neural stem cells (NSCs) with unique properties and growth requirements. Adult NSCs constitute a reversibly quiescent cell population that can be activated by extracellular signals from the microenvironment in which they reside in vivo. Although genomic imprinting plays a role in adult neurogenesis through dose regulation of some relevant signals, the roles of many imprinted genes in the process remain elusive. Insulin-like growth factor 2 (IGF2) is encoded by an imprinted gene that contributes to NSC maintenance in the adult subventricular zone through a biallelic expression in only the vascular compartment. We show here that IGF2 additionally promotes terminal differentiation of NSCs into astrocytes, neurons and oligodendrocytes by inducing the expression of the maternally expressed gene cyclin-dependent kinase inhibitor 1c (Cdkn1c), encoding the cell cycle inhibitor p57. Using intraventricular infusion of recombinant IGF2 in a conditional mutant strain with Cdkn1c-deficient NSCs, we confirm that p57 partially mediates the differentiation effects of IGF2 in NSCs and that this occurs independently of its role in cell-cycle progression, balancing the relationship between astrogliogenesis, neurogenesis and oligodendrogenesis.

IGF-2 mediated hypoglycemia and the paradox of an apparently benign lesion: a case report & review of the literature

BACKGROUND

Non-islet cell tumour hypoglycemia (NICTH) is rarely encountered in clinical practice. Insulin-like growth factor 2 (IGF2) is the most common cause of NICTH observed in the setting of mesenchymal and epithelial neoplasia. This is a paraneoplastic syndrome caused by IGF2 activation of the insulin receptor.

CASE PRESENTATION

An 80 year old female presented with a short history of recurrent episodes of confusion with laboratory confirmed hypoglycemia with a plasma glucose of 2.7 mmol/L on fasting which fulfilled Whipple's triad. Diagnostic clues to the aetiology at presentation include the fasting pattern of hypoglycemia, hypokalaemia and the absence of weight gain. A 72 hour fast with results showed early hypoglycemia and suppression of serum insulin, c-peptide, and proinsulin. Serum insulin antibody was not detected. Subsequent measurement of the serum IGF2:IGF1 ratio was elevated at 22.3 and consistent with IGF-2 mediated hypoglycemia and imaging studies demonstrated a pelvic mass. Dietary intervention and oral prednisolone abated hypoglycemia prior to surgery. Ultimately, hypoglycemia resolved following operative intervention and steroid therapy was successfully withdrawn. Histopathology was remarkable for dual neoplastic processes with uterine solitary fibrous tumour (SFT) confirmed as the source of IGF2 hypersecretion on IGF-2 immunohistochemistry and a coincidental invasive high grade serous carcinoma involving the fimbria of the right fallopian tube.

CONCLUSION

The paradox in this case is that the benign solitary fibrous tumour accounted for patient morbidity through secretion of IGF2 and without treatment, posed a mortality risk. This is despite the synchronous presence of a highly malignant fallopian tube neoplasm. This case reinforces the need for thorough clinical evaluation of hypoglycemia to allow prompt and definitive management.

A novel model based on interleukin 6 and insulin-like growth factor II for detection of hepatocellular carcinoma associated with hepatitis C virus

BACKGROUND

The coexistence of cirrhosis complicates the early detection of hepatocellular carcinoma (HCC). Thus, novel biomarkers for HCC early detection are needed urgently. Traditionally, HCC detection is carried out by evaluating alpha-fetoprotein (AFP) levels combined with imaging techniques. This work aimed to assess interleukin (IL-6) and insulin-like growth factor 2 (IGF 2) as possible HCC markers in comparison to AFP in patients with and without HCC.

RESULTS

ROC analysis showed that IGF2 had the highest area under the curve (AUC) for discriminating HCC from liver cirrhosis (0.86), followed by IL6 (0.82), AFP (0.72), and platelet count (0.6). A four-marker model was developed and discriminated HCC from liver cirrhosis with an AUC of 0.97. The best cut-off was 1.28, at which sensitivity and specificity were 90% and 85%, respectively. For small tumor (< 2 cm), the model had an AUC of 0.95 compared to AFP (0.72). Also, the model achieved perfect performance with AUC of 0.93, 0.94, and 0.95 for BCLC (0-A), CLIP (0-1), and Okuda (stage I), respectively, compared to AFP (AUC of 0.71, 0.69, and 0.67, respectively).

CONCLUSIONS

The four markers may serve as a diagnostic model for HCC early stages and help overcome AFP poor sensitivity.

Knockdown of insulin-like growth factor 2 gene disrupts mitochondrial functions in the liver

Even though insulin-like growth factor 2 (IGF2) has been reported to be overexpressed in nonalcoholic fatty liver disease (NAFLD), its role in the progression of NAFLD and the potential mechanism remain largely unclear. Using in vitro models, we found that IGF2 was the key overexpressed gene in steatosis, suggesting a possible association between IGF2 and NAFLD. Interestingly, loss-of-function experiments revealed that inhibition of IGF2 protein impaired mitochondrial biogenesis and respiration. It additionally disrupted the expression changes of mitochondrial fusion and fission-related proteins necessary in maintaining mitochondrial homeostasis. Consistently, IGF2 knockdown reduced the mitochondrial membrane potential and increased the production of reactive oxygen species. Mechanistically, IGF2 regulates mitochondrial functions by modulating the expression of SIRT1 and its downstream gene PGC1α. This research opens a new frontier on the role of IGF2 in energy metabolism, which potentially participates in the development of NAFLD. As such, IGF2 is a potential therapeutic target against NAFLD.

IGF2 deficiency causes mitochondrial defects in skeletal muscle

Exercise training improves muscle fitness in many aspects, including induction of mitochondrial biogenesis and maintenance of mitochondrial dynamics. The insulin-like growth factors were recently proposed as key regulators of myogenic factors to regulate muscle development. The present study aimed to investigate the physical exercise impact on insulin-like growth factor 2 (IGF2) and analyzed its functions on skeletal muscle cells in vitro. Using online databases, we stated that IGF2 was relatively highly expressed in skeletal muscle cells and increased after exercise training. Then, IGF2 deficiency in myotubes from C2C12 and primary skeletal muscle cells (PMSCs) led to impaired mitochondrial function, reduced mitochondria-related protein content, and decreased mitochondrial biogenesis. Furthermore, we explored the possible regulatory pathway and found that mitochondrial regulation in skeletal muscle cells might occur through IGF2-Sirtuin 1 (SIRT1)-peroxisome proliferator-activated receptor-γ co-activator-1α (PGC1α) signaling pathway. Therefore, the present study first demonstrated the relationship between IGF2 and mitochondria in skeletal muscle.

Fe (III)@TA@IGF-2 microspheres loaded hydrogel for liver injury treatment

As one of the most commonly used materials in liver tissue engineering, hydrogel has received much attention in recent years. In this work, we prepared a gelatin methacrylate (GelMA)/oxidized hyaluronic acid (OHA)/galactosylated chitosan (Gal-CS)/Fe (III)@TA@IGF-2 200 (TA200) hydrogel loaded with insulin-like growth factor 2 (IGF-2) for regeneration of damaged hepatocytes. Fe (III)@TA microspheres served as carrier to achieve sustained release of IGF-2 to promote hepatocytes regeneration. Galactose ligands could bind to the asialoglycoprotein receptor (ASGPR) on the surface of hepatocytes. Galactosylated chitosan could significantly increase the specific function of hepatocytes. The hydrogel we prepared had a storage modulus of 1100 Pa and was suitable for migration of hepatocytes. The release ratio of IGF-2 could reach up to 90% within 14 days. For carbon tetrachloride (CCl₄) induced human hepatic stellate cell line LX2 damage, GelMA/OHA/Gal-CS/TA200 hydrogel could significantly improve the survival of LX2 cells. The expression of HNF-4α and transferrin was detected in LX2 cells treated with hydrogel, indicating that the specific function of the liver was also restored. In summary, the GelMA/OHA/Gal-CS/TA200 hydrogels could be used as new tissue engineering scaffolds for the construction of artificial livers.

[Effects of down-regulation of IGF2 gene on the biological characteristics of HCT116 colon cancer stem cells]

Objective: To investigate the effect of down-regulation of insulin-like growth factor 2 (IGF2) gene on the biological characteristics of HCT116 colon cancer stem cells (CSCs). Methods: Flow cytometry sorting technology was used to isolate CSCs from colon cancer cell line HCT116 by a monoclonal antibody against CD133; serum free floating culture assay was used for the enrichment of CSCs. The proportion of CD133(+) cells was analyzed by flow cytometry; CSCs were identified by sphere culturing, immunofluorescence analysis and soft agar clone formation. RT-qPCR method was used to examine transcriptional level of IGF2 gene in CSCs. Western blotting was used to examine IGF2 protein expression in CSCs. siRNA was used to establish IGF2 transient knock down model in CSCs. Cell proliferation array, cell cycle and apoptosis analysis, cell invasion array and colony forming assay were used to further examine the role of IGF2 on the biological characteristics of colon CSCs. Results: CSCs were successfully isolated from HCT116 cell lines, which were cultured to form cell spheres in serum-free stem cell culture medium. We found that the morphology of sphere-forming-like cells after several passages maintained the same characteristics as that of the first passage. The results of immunofluorescence showed that CSC markers including CD133 and ALDH continued positively expressing on the cell surface of CSCs, and flow cytometry analysis showed that more than 90% of the spheroid cells remained CD133 positive. The clone formation rate of non-CSCs group and CSCs group were (28.10±2.66)% and (43.73±2.30)% respectively, with significant difference (P<0.01). The RT-qPCR results showed that the transcriptional level IGF2 gene in non-CSCs group and CSCs group were (1.06±0.24) and (2.17±0.51) respectively, with significant difference (P<0.05). The western blot results showed that the protein expression of IGF2 in CSCs group and non-CSCs group were (1.10±0.55) and (2.14±0.23) respectively, with significant difference (P<0.05). Knockdown of IGF2 significantly decreased the percentage of CD133(+) cells in CSCs and cell proliferation (P<0.01). Knockdown of IGF2 increased the percentage of G(2)/M phase (23.46% of siNC group vs 60.14% of siIGF2 group) and cell apoptosis (2.80% of siNC group vs 40.70% of siIGF2 group), while decreased the percentage of G(0)/G(1) phase (40.77% of siNC group vs 17.73% of siIGF2 group). The invasion results showed that the number of cells penetrating into the basement surface in siNC group and siIGF2 group was (109.00±16.37) and (54.00±8.19) respectively, with significant difference (P<0.01). The rate of sphere-forming of colon CSCs in siNC group and siIGF2 group were (51.70±7.42)% and (21.27±2.35)% respectively, with significant difference (P<0.01). The clone formation rate of siNC group and siIGF2 group were (37.20±3.87)% and (18.23±2.25)% respectively, with significant difference (P<0.01). Conclusion: IGF2 gene plays an important role in maintaining the biological characteristics of colon cancer stem cells and promoting self-renewal and stemness of colon CSCs.

Intraoperative glycemic control using an artificial endocrine pancreas in a patient with a recurrent pleural solitary fibrous tumor producing insulin-like growth factor 2: a case report

Background

Non-islet cell tumor producing insulin-like growth factor 2 involves hypoglycemia. During tumor resection, intense fluctuation of blood glucose level may occur. An artificial endocrine pancreas has been reported as beneficial for patients with insulinoma as it maintains stable glycemic levels, although scarcely described with insulin-like growth factor 2-releasing tumor.

Case presentation

An 84-year-old man had a recurrent left pleural solitary fibrous tumor releasing high molecular weight insulin-like growth factor 2 and experienced a frequent syncope accompanied by hypoglycemia. After anesthesia induction, an artificial endocrine pancreas, STG-55, was connected to the patient. Blood glucose level was stable at around 150 mg/dl during the resection surgery. The patient followed an uneventful course and was discharged without any complications.

Conclusions

An artificial endocrine pancreas may have the potential to stabilize the intraoperative blood glucose change in insulin-like growth factor 2-releasing tumor resection.

Associations among IGF-1, IGF2, IGF-1R, IGF-2R, IGFBP-3, insulin genetic polymorphisms and central precocious puberty in girls

BACKGROUND

Insulin and insulin-like growth factor (IGF)-1 coupled with growth hormone helps control timing of sexual maturation. Mutations and variants in multiple genes are associated with development or reduced risk of central precocious puberty (CPP).

METHODS

We assessed single nucleotide polymorphisms (SNPs) in the IGF-1, IGF-2, IGF-3, IGF-1 receptor (IGF1R), IGF-2 receptor (IGF2R), and IGF -binding protein 3 (IGFBP-3) genes, and their association with demographics and metabolic proteins in girls with CPP. Z-scores of height, weight, and body mass index (BMI) were calculated with the WHO reference growth standards for children.

RESULTS

IGF-1 serum levels of CPP group exhibited a higher correlation with bone age, z-scores of height and weight, and luteinizing hormone (LH) than those of control group, regardless of BMI adjustment. In the CPP group, height was associated with IGF-2(3580), an adenine to guanine (A/G) SNP at position + 3580. BMI in the CPP group was associated with IGF-2(3580), IGF1R, and the combinations of [IGF-2(3580) + IGF2R], and [IGF-2(3580) + IGFBP-3]. Body weight in the CPP group was associated with the combination of [IGF-2(3580) + IGFBP-3] (p = 0.024). Weight and BMI were significantly associated with the combination of [IGF-2(3580) + IGF2R + IGFBP-3] in the CPP group. These associations were not significantly associated with z-scores of weight, height, or BMI. The distribution of these genotypes, haplotypes, and allele frequencies were similar between control and CPP groups.

CONCLUSIONS

These known SNPs of these IGF-1 axis genes appear to play minor roles in the risk for development of CPP.

Black swans - neuroendocrine tumors of rare locations

Neuroendocrine neoplasms (NEN) are rare and heterogeneous. Therefore, they often remain unrecognized for many years, causing significant disease burden. We here report on four unusual NEN presentations including a metastatic NEN of the kidney, hypoglycemia caused by an insulin-like growth factor-2-oma (previously called non-islet-cell tumor hypoglycemia), multifocal pheochromocytoma in von Hippel Lindau syndrome, and ileal NEN metastatic to the heart. One could say that each one of these tumors were "black swans" and learning about them will increase further awareness of the spectrum of NEN.

Effects of Bisphenol-A on proliferation and expression of genes related to synthesis of polyamines, interferon tau and insulin-like growth factor 2 by ovine trophectoderm cells

This study evaluated the effects of bisphenol A (BPA) on proliferation of ovine trophectoderm (oTr1) cells, as well as expression of genes for transport of arginine and synthesis of polyamines. BPA reduced proliferation of oTr1 cells at concentrations of 1 × 10^-6, 1 × 10^-5, 1 × 10^-4 M compared to concentrations of 0, 1 × 10^-9, and 1 × 10^-8 M at 24 and 96 h of culture. Lower concentrations of BPA significantly increased expression of mRNAs for agmatinase (AGMAT), arginine decarboxylase (ADC), ornithine decarboxylase (ODC1) and solute carrier family 7 member 1 (SLC7A1). Similarly, synthesis of polyamines by oTr1 cells was greatest at lower concentrations of BPA and decreased as the dose of BPA increased. Expression of mRNAs for interferon tau (IFNT) and insulin-like growth factor 2 (IGF2) by oTr1 cells was greater than for controls at 1 × 10^-9 M BPA. Overall, the effects of BPA on proliferation and gene expression by oTr1 cells were highly dose-dependent.

Yak IGF2 Promotes Fibroblast Proliferation Via Suppression of IGF1R and PI3KCG Expression

Insulin-like growth factor 2 (IGF2) recapitulates many of the activities of insulin and promotes differentiation of myoblasts and osteoblasts, which likely contribute to genetic variations of growth potential. However, little is known about the functions and signaling properties of IGF2 variants in yaks. The over-expression vector and knockdown sequence of yak IGF2 were transfected into yak fibroblasts, and the effects were detected by a series of assays. IGF2 expression in yak muscle tissues was significantly lower than that of other tissues. In yak fibroblasts, the up-regulated expression of IGF2 inhibits expression of IGF1 and insulin-like growth factor 2 receptor (IGF2R) and significantly up-regulates expression of IGF1R. Inhibition of IGF2 expression caused the up-regulates expression of IGF1, IGF1R and IGF2R. Both over-expression and knockdown of IGF2 resulted in up-regulation of threonine protein kinase 1 (Akt1) expression and down-regulation of phosphatidylinositol 3-kinase, catalytic subunit gamma (PIK3CG). Cell cycle and cell proliferation assays revealed that over-expression of IGF2 enhanced the DNA synthesis phase and promoted yak fibroblasts proliferation. Conversely, knockdown of IGF2 decreased DNA synthesis and inhibited proliferation. These results suggested that IGF2 was negatively correlated with IGF1R and PIK3CG and demonstrated an association with the IGFs-PI3K-Akt (IGFs-phosphatidylinositol 3-kinase- threonine protein kinase) pathway in cell proliferation and provided evidence supporting the functional role of IGF2 for use in improving the production performance of yaks.

Identification and expression analysis of cDNA encoding insulin-like growth factor 2 in horses

Insulin-like growth factor 2 (IGF2) is responsible for a broad range of physiological processes during fetal development and adulthood, but genomic analyses of IGF2 containing the 5ʹ- and 3ʹ-untranslated regions (UTRs) in equines have been limited. In this study, we characterized the IGF2 mRNA containing the UTRs, and determined its expression pattern in the fetal tissues of horses. The complete equine IGF2 mRNA sequence harboring another exon approximately 2.8 kb upstream from the canonical transcription start site was identified as a new transcript variant. As this upstream exon did not contain the start codon, the amino acid sequence was identical to the canonical variant. Analysis of the deduced amino acid sequence revealed that the protein possessed two major domains, IlGF and IGF2_C, and analysis of IGF2 sequence polymorphism in fetal tissues of Hokkaido native horse and Thoroughbreds revealed a single nucleotide polymorphism (T to C transition) at position 398 in Thoroughbreds, which caused an amino acid substitution at position 133 in the IGF2 sequence. Furthermore, the expression pattern of the IGF2 mRNA in the fetal tissues of horses was determined for the first time, and was found to be consistent with those of other species. Taken together, these results suggested that the transcriptional and translational products of the IGF2 gene have conserved functions in the fetal development of mammals, including horses.

Premature hippocampus-dependent memory decline in middle-aged females of a genetic rat model of depression

Aging and major depressive disorder are risk factors for dementia, including Alzheimer's Disease (AD), but the mechanism(s) linking depression and dementia are not known. Both AD and depression show greater prevalence in women. We began to investigate this connection using females of the genetic model of depression, the inbred Wistar Kyoto More Immobile (WMI) rat. These rats consistently display depression-like behavior compared to the genetically close control, the Wistar Kyoto Less Immobile (WLI) strain. Hippocampus-dependent contextual fear memory did not differ between young WLI and WMI females, but, by middle-age, female WMIs showed memory deficits compared to same age WLIs. This deficit, measured as duration of freezing in the fear provoking-context was not related to activity differences between the strains prior to fear conditioning. Hippocampal expression of AD-related genes, such as amyloid precursor protein, amyloid beta 42, beta secretase, synucleins, total and dephosphorylated tau, and synaptophysin, did not differ between WLIs and WMIs in either age group. However, hippocampal transcript levels of catalase (Cat) and hippocampal and frontal cortex expression of insulin-like growth factor 2 (Igf2) and Igf2 receptor (Igf2r) paralleled fear memory differences between middle-aged WLIs and WMIs. This data suggests that chronic depression-like behavior that is present in this genetic model is a risk factor for early spatial memory decline in females. The molecular mechanisms of this early memory decline likely involve the interaction of aging processes with the genetic components responsible for the depression-like behavior in this model.

Associations of IGF2 and DRD2 polymorphisms with laying traits in Muscovy duck

Insulin-like growth factor 2 (IGF2) and dopamine receptor 2 (DRD2) play important roles in ovarian follicular development. In this study, we analyzed tissue-specific expression of the Muscovy duck IGF2 and DRD2 genes and cloned those genes transcripts. Polymorphisms in these genes were tightly linked with egg production traits and both genes were highly expressed in the ovary. Moreover, we identified five single nucleotide polymorphisms (SNPs) for IGF1 and 28 for DRD2. Mutations A-1864G and C-1704G of IGF2 were positively correlated with increased egg laying at 59 weeks (E59W) (P < 0.05). The C+7T and C+364G mutations of DRD2 were highly and significantly associated with first-egg age (FEA) and egg numbers at 300 days (E300D) (P < 0.01). Moreover, C+3301G and C+3545G of DRD2 were highly significantly associated with FEA, E59W and E300D (P < 0.01). Other mutations were positively associated with FEA or E300D or E59W (P < 0.05). These data suggest specific roles for IGF1 and DRD2 polymorphisms in egg production in Muscovy ducks.

Population Study Confirms Serum Proteins' Change and Reveals Diagnostic Values in Congenital Ventricular Septal Defect

This study was designed to validate thrombospondin 1 (TSP-1), vascular endothelial-cadherin complex (VE-cad), insulin-like growth factor 2 (IGF-2), and amyloid precursor protein (APP) and assess their diagnostic value in ventricular septal defect (VSD). We investigated the serum levels of TSP-1, VE-cad, IGF-2, and APP by enzyme-linked immunosorbent assay in a hospital-based case-control study that included 40 VSD children and 40 healthy controls. Logistic regression analysis was applied to evaluate the relationship of the proteins and VSD, and receiver operating characteristic (ROC) curve was used to assess the diagnostic value of the significant proteins. The serum levels of TSP-1, VE-cad, and IGF-2 were significantly higher in VSD patients than those in healthy controls (p < 0.05). Multivariate logistic regression analysis demonstrated that high levels of TSP-1, VE-cad, and IGF-2 were significantly associated with an increased risk of VSD [TSP-1 (OR 26.91, 95% CI 6.60-72.66, p < 0.001), VE-cad (OR 11.91, 95% CI 3.90-36.36, p < 0.001), IGF-2 (OR 3.25, 95% CI 1.25-8.43, p = 0.015)]. Areas under the ROC curve for TSP-1, VE-cad, and IGF-2 were 0.985, 0.838, and 0.658, respectively. These data demonstrated that TSP-1, VE-cad, and IGF-2 were significantly associated with risk of VSD and manifested diagnostic values, which may provide new evidence for understanding the etiology and promote the early diagnosis and prevention of VSD.

Detrimental effect of maternal and post-weaning high-fat diet on the reproductive function in the adult female offspring rat: roles of insulin-like growth factor 2 and the ovarian circadian clock

PURPOSE

We evaluate the impact of maternal and post-weaning high-fat (HF) diet on ovarian follicular population, steroidogenesis, and gene expression with a focus on the circadian clock system and insulin-like growth factor 2 (Igf2) in adult offspring ovaries, and to elucidate whether a maternal and post-weaning diet confers similar risks.

METHODS

Virgin Sprague-Dawley rats were fed with normal chow (C) diet or HF diet for 5 weeks before mating, during gestation, and lactation. Female offspring were fed with the C or HF diet from weaning to 6 months of age, resulting in four study groups (n = 6 per group): C/C, C/HF, HF/C, and HF/HF.

RESULTS

Ovaries from offspring exposed to post-weaning HF diet (i.e., the C/HF and HF/HF groups) had a decrease in small follicle numbers, but with similar numbers of antral follicles and corpora lutea. Offspring from HF-fed dams (i.e., the HF/C and HF/HF groups) had increased plasma estradiol concentrations and decreased luteinizing hormone levels at 6 months of age. In addition, Igf2 and each of the circadian rhythm core genes Clock, Per1, Per2, and Per3 were increased in the ovaries of offspring exposed to maternal HF diet (both HF/C and HF/HF groups).

CONCLUSIONS

Maternal and post-weaning HF diet programs the reproductive profile of the female offspring in adult life through different manners. Post-weaning HF intake resulted in the reduction of small follicles in adulthood, whereas maternal HF diet had long-term deleterious consequences on female offspring steroidogenesis and coincided with alteration of the upregulation of the imprinted gene Igf2 and changes in ovarian circadian rhythms.

Up-regulation of insulin-like growth factor 2 by ketamine requires glycogen synthase kinase-3 inhibition

An antidepressant dose of the rapidly-acting ketamine inhibits glycogen synthase kinase-3 (GSK3) in mouse hippocampus, and this inhibition is required for the antidepressant effect of ketamine in learned helplessness depression-like behavior. Here we report that treatment with an antidepressant dose of ketamine (10mg/kg) increased expression of insulin-like growth factor 2 (IGF2) in mouse hippocampus, an effect that required ketamine-induced inhibition of GSK3. Ketamine also inhibited hippocampal GSK3 and increased expression of hippocampal IGF2 in mice when administered after the induction of learned helplessness. Treatment with the specific GSK3 inhibitor L803-mts was sufficient to up-regulate hippocampal IGF2 expression. Administration of IGF2 siRNA reduced ketamine's antidepressant effect in the learned helplessness paradigm. Mice subjected to the learned helplessness paradigm were separated into two groups, those that were resilient (non-depressed) and those that were susceptible (depressed). Non-depressed resilient mice displayed higher expression of IGF2 than susceptible mice. These results indicate that IGF2 contributes to ketamine's antidepressant effect and that IGF2 may confer resilience to depression-like behavior.

Methylation Status of CYP27B1 and IGF2 Correlate to BMI SDS in Children with Obesity

OBJECTIVE

Worldwide increasing childhood obesity is due to interactions between environmental and genetic factors, linked together by epigenetic mechanisms such as DNA methylation.

METHODS

82 obese children (>95th BMI percentile , age: 3-18 years) were included. Anthropometric data, metabolic parameters, 25-OH vitamin D (25OHD), and pubertal status were recorded, 24-hour blood pressure monitoring was performed. BMI standard deviation score (SDS) was calculated. Using candidate gene approach, obesity- (insulin-like growth factor 2 (IGF2), proopiomelanocortin (POMC)) and vitamin D metabolism-related genes (1-alfa-hydroxylase (CYP27B1), VDR) regulated by DNA methylation were selected. After isolating DNA from peripheral blood, bisulfite conversion, bisulfite specific polymerase chain reaction (BS-PCR), and pyrosequencing were carried out.

RESULTS

No significant correlation between 25-OHD and metabolic parameters and DNA methylation status, but a tendency of positive correlation between VDR methylation status and 25-OHD (r = 0.2053,p = 0.066) were observed. Significant positive correlations between BMI SDS and CYP27B1 hypermethylation (r = 0.2371,p = 0.0342) and a significant negative correlation between IGF2 hypomethylation and BMI SDS (r = -0.305,p = 0.0059) were found. Conclusions Rate of obesity shows correlation with DNA methylation. Hypomethylation of IGF2 and hypermethylation of CYP27B1 genes might positively influence the rate of BMI observed in obese children.

Effect of in ovo folic acid injection on hepatic IGF2 expression and embryo growth of broilers

Background

Insulin-like factor 2 (IGF2) plays an important role in embryonic growth process by modulating intermediary metabolism and cell proliferation. Folic acid is involved in one carbon metabolism and contributes to DNA methylation which is related to gene expression. The purpose of this study was to explore whether folic acid could regulate IGF2 expression via epigenetic mechanism and further promote embryonic growth of new-hatched broilers.

Methods

In the present study, 360 fertile eggs were selected and randomly assigned to four treatments. On 11 embryonic day of incubation (E11), 0, 50, 100 and 150 μg folic acid were injected into eggs respectively. After hatched, growth performance of broilers were calculated. Hepatic IGF2 expression, methylation level and chromatin structure of promoter region were analyzed.

Results

Results have showed that IGF2 expression was up-regulated in 150 μg folic acid group (P < 0.05) and other two dose of folic acid did not affect gene expression (P > 0.05). Meanwhile, methylation level of IGF2 promoter were lower in 100 and 150 μg groups, which was consistent with lower expression of DNA methyltransferase 1 (DNMT1) (P < 0.05). What’s more, chromatin looseness of IGF2 promoter was higher in 150 μg group than control group (P < 0.05). Further, birth weight (BW), liver and bursa index of new-hatched chickens in 150 μg folic acid group were higher than the other groups (P < 0.05). There were positive correlations between hepatic IGF2 expression and BW and organs index (P < 0.05).

Conclusion

In conclusion, our data have demonstrated that 150 μg folic acid injection on E11 could up-regulate IGF2 expression by modulating DNA hypomethylation and improving chromatin accessibility in the gene promoter region, and ulteriorly facilitate embryonic growth and organ development of broilers.

Electronic supplementary material

The online version of this article (doi:10.1186/s40104-016-0099-3) contains supplementary material, which is available to authorized users.

Decreased IDE and IGF2 expression but increased Aβ40 in the cerebral cortex of mouse pups by early life lead exposure

As the abbreviation of plumbum and a chemical symbol for lead, Pb produces neurotoxic effects, which result into an impairment of learning and memory and other neurological dysfunctions. However, the mechanism of neurotoxicity of Pb exposure is unclear. The present study was undertaken to investigate the effects of maternal lead exposure on expression of insulin-degrading enzyme (IDE),insulin-like growth factor 2 (IGF2) and beta amyloid protein 40 (Aβ40) in the cerebral cortex of mice offspring. Lead exposure initiated from beginning of gestation to weaning. Lead acetate administered in drinking solutions was dissolved in distilled deionized water at the concentrations of 0.1%, 0.2% and 0.5% groups respectively. On the 21st postnatal day, On the PND21, the learning and memory ability were tested by water maze test and the Pb levels were also determined by graphite furnace atomic absorption spectrometry. The expression of IDE, IGF2 and Aβ40 in cerebral cortex was examined by immunohistochemistry, immunofluorescence and western blotting. The lead levels in blood and cerebral cortex of all lead exposure groups were significantly higher than that of the control group (P<0.05). In water maze test, the performances of 0.5% and 1% lead exposure groups were worse than that of the control group (P<0.05).The expression of IDE and IGF2 was decreased, but Aβ40 was increased in lead exposed groups than that of the control group (P<0.05). The decreased expression of IDE and IGF2 and increased expression of Aβ40 in the cerebral cortex of pups may contribute to the neurotoxicity associated with maternal Pb exposure.

Seborrheic keratoses and severe hypoinsulinemic hypoglycemia associated with insulin grow factor 2 secretion by a malignant solitary fibrous tumor

A rare sign of some malignant tumors is a sudden eruption of multiple seborrheic keratoses called Leser-Trélat sign. Overproduction of insulin-like growth factor-2 (IGF2) or its precursor is the main mechanism related to non-islet cell tumor hypoglycemia. Doege-Potter syndrome is the name given to paraneoplastic hypoinsulinemic hypoglycemia in presence of a solitary fibrous tumor. This report describes a case of a patient with hypoinsulinemic hypoglycemia and Leser-Trélat sign associated with a malignant solitary fibrous tumor with IGF2 secretion. Both conditions have improved after tumor excision.

Exogenous insulin-like growth factor 2 administration enhances memory consolidation and persistence in a time-dependent manner

Memory consolidation is an important process for the formation of long-term memory. We have previously reported that mature brain-derived neurotrophic factor enhances memory consolidation within 9h after initial learning. Recent studies suggest that insulin-like growth factor 2 (IGF2) significantly enhances memory consolidation and prevents forgetting. Thus, we hypothesized that IGF2 exerts its activity on cognitive performance in a time-dependent manner as observed in our previous study. In the one-trial step-through inhibitory avoidance task, we demonstrate that a bilateral injection of IGF2 into the dorsal hippocampus 6 or 9 h after training significantly enhanced the step-through latencies compared with the vehicle-treated controls in the retention trial, which was conducted 24 h after the acquisition trial. However, 12h post-training, IGF2 injection did not increase the step-through latencies. Intriguingly, in the retention trial at 21 days after the training, hippocampal IGF2 injection 6, 9 or 12 h after the acquisition trial significantly increased the step-through latencies compared with the vehicle-treated controls. IGF2 administration at 9 h and 12 h after the acquisition trial significantly increased discrimination index and exploration time on the novel-located object in the test trial at 24 h and 21 days, respectively, after the acquisition trial in the novel location recognition task. In addition, IGF2-induced an increase in the step-through latencies in the retention trial 24 h or 21 days, respectively, after the initial learning was completely abolished by co-injected anti-IGF2 receptor antibody. These results suggest that IGF2 enhances memory consolidation within 9h after initial learning, and increased IGF2 within the 12 h after the acquisition trial, which represents a delayed consolidation phase, is also critical for memory persistence.

CRNDE, a long non-coding RNA responsive to insulin/IGF signaling, regulates genes involved in central metabolism

Colorectal neoplasia differentially expressed (CRNDE) is a novel gene that is activated early in colorectal cancer but whose regulation and functions are unknown. CRNDE transcripts are recognized as long non-coding RNAs (lncRNAs), which potentially interact with chromatin-modifying complexes to regulate gene expression via epigenetic changes. Complex alternative splicing results in numerous transcripts from this gene, and we have identified novel transcripts containing a highly-conserved sequence within intron 4 ("gVC-In4"). In colorectal cancer cells, we demonstrate that treatment with insulin and insulin-like growth factors (IGF) repressed CRNDE nuclear transcripts, including those encompassing gVC-In4. These repressive effects were negated by use of inhibitors against either the PI3K/Akt/mTOR pathway or Raf/MAPK pathway, suggesting CRNDE is a downstream target of both signaling cascades. Expression array analyses revealed that siRNA-mediated knockdown of gVC-In4 transcripts affected the expression of many genes, which showed correlation with insulin/IGF signaling pathway components and responses, including glucose and lipid metabolism. Some of the genes are identical to those affected by insulin treatment in the same cell line. The results suggest that CRNDE expression promotes the metabolic changes by which cancer cells switch to aerobic glycolysis (Warburg effect). This is the first report of a lncRNA regulated by insulin/IGFs, and our findings indicate a role for CRNDE nuclear transcripts in regulating cellular metabolism which may correlate with their upregulation in colorectal cancer.

Intragenic DNA methylation status down-regulates bovine IGF2 gene expression in different developmental stages

DNA methylation is a key epigenetic modification in mammals and has an essential and important role in muscle development. Insulin-like growth factor 2 (IGF2) is a fetal growth and differentiation factor that plays an important role in muscle growth and in myoblast proliferation and differentiation. The aim of this study was to evaluate the expression of IGF2 and the methylation pattern on the differentially methylated region (DMR) of the last exon of IGF2 in six tissues with two different developmental stages. The DNA methylation pattern was compared using bisulfite sequencing polymerase chain reaction (BSP) and combined bisulfite restriction analysis (COBRA). The quantitative real-time PCR (qPCR) analysis indicated that IGF2 has a broad tissue distribution and the adult bovine group showed significant lower mRNA expression levels than that in the fetal bovine group (P<0.05 or P<0.01). Moreover, the DNA methylation level analysis showed that the adult bovine group exhibited a significantly higher DNA methylation levels than that in the fetal bovine group (P<0.05 or P<0.01). These results indicate that IGF2 expression levels were negatively associated with the methylation status of the IGF2 DMR during the two developmental stages. Our results suggest that the methylation pattern in this DMR may be a useful parameter to investigate as a marker-assisted selection for muscle developmental in beef cattle breeding program and as a model for studies in other species.

Assessment of association between variants and haplotypes of the IGF2 gene in beef cattle

Insulin-like growth factor 2 (IGF2) is a fetal growth and differentiation factor that plays an important role in muscle growth and in myoblast proliferation and differentiation. The aim of this study was to examine the association of the IGF2 polymorphism with growth traits in beef cattle breed. Four single nucleotide polymorphisms (SNPs: 1-4) were identified in the bovine IGF2 by sequencing pooled DNA samples (Pool-Seq) and forced polymerase chain reaction-restriction fragment length polymorphism (Forced PCR-RFLP) methods. The result of haplotype analysis of four SNPs showed that eight haplotypes and eighteen combined genotypes were revealed, and the linkage disequilibrium and evolutionary relationship were assessed in 1522 individuals representing four purebred cattle breeds from China. The statistical analyses indicated that the 4 SNPs and 18 combined genotypes or haplotypes are associated with the body weight at 18 and 24 months in Jiaxian cattle population (P<0.05 or P<0.01). Our results provide evidence that polymorphisms in the IGF2 gene are associated with growth traits, and may be used for marker-assisted selection in beef cattle breeding program.

Construction of expression plasmids carrying miRNA targeting IGF-II and detection of their inhibitory effect on IGF-II expression in human HepG2 cells

AIM: To investigate inhibitory effect of transfection of eukaryotic expression plasmids carrying specific microRNA (miRNA) on insulin-like growth factor II (IGF-II) gene and protein expression in human HepG2 cells.

METHODS: Four miRNAs targeting the IGF-II gene were synthesized and inserted into the pcDNATM6.2-GW/EmGFPmiR vector. The recombinant plasmids were identified and transiently transfected into HepG2 cells. Their inhibitory efficiency on IGF-II expression was determined at gene level by real time-PCR and at protein level by ELISA.

RESULTS: Four eukaryotic expression plasmids carrying miRNA targeting IGF-II were constructed successfully and confirmed by sequencing. HepG2 cells were then transfected with these plasmids (MR-IGF-II-1 to 4). The highest transfection efficiency was up to 50%. The reduced rates of IGF-II gene expression were 33%, 43%, 0% and 3% in cells transfected with MR-IGF-II-1 to 4, respectively. Transfection of the MR-IGF-II-2 plasmid for 72 h reduced IGF-II protein expression by 44% in HepG2 cells.

CONCLUSION: The expression plasmids carrying miRNA targeting IGF-II have been successfully constructed. Transfection of these plamsids can efficiently inhibit IGF-II expression in HepG2 cells.