Insulin-like Growth Factor 2 Transcript Research Articles

Phaeochromocytomas overexpress insulin transcript and produce insulin.

IntroductionPhaeochromocytomas are tumours originating in the medulla of the adrenal gland. They produce catecholamines, and some tumours also produce ectopic hormones. Two types of glucose imbalances occur in phaeochromocytoma patients, hyperglycaemia and hypoglycaemic attacks. Therefore, we tested whether insulin transcript (INS), insulin, and a hybrid read-through transcript between exons from insulin and insulin-like growth factor 2 (INS-IGF2) were expressed in phaeochromocytomas.MethodsWe measured the expression of insulin using immunohistochemistry. The expression of INS-IGF2 was determined by qRT-PCR in formalin-fixed and paraffin-embedded tissue from 20 phaeochromocytomas. The expression of INS and INS-IGF2 transcriptswas also analysed in 182 phaeochromocytomas and paragangliomas using publicly available datasets in The Cancer Genome Atlas (TCGA) Database.ResultsOf 20 phaeochromocytomas, 16 stained positive for insulin. The distribution of positive cells was mostly scattered, with some focal expression indicating clonal expansion. Nineteen tumours expressed high levels of INS and INS-IGF2 transcripts. The expression of the two transcripts corresponded closely. In the TCGA dataset, phaeochromocytoma expresses higher levels of INS and INS-IGF2 transcripts compared to the normal non-tumour adrenal glands. Thus, the expression of INS and INS-IGF2 seems to be a general phenomenon in phaeochromocytoma.ConclusionMost phaeochromocytomas contain cells that overexpress INS and INS-IGF2 transcripts. Most tumours also display heterogeneous expression of polypeptides immunoreactive to monoclonal anti-insulin antibodies. Clinically this may relate to both hyperglycaemia and hypoglycaemic attacks seen in patients with phaeochromocytoma as well as autocrine tumour growth.

Short Communication: Genetic diversity of the IGF2 gene as a source of genetic marker for halal authentication

Hamdani AD, Madihah, Suryohastari RB, Virgianti DP, Putrie RFW. 2018. Genetic diversity of the IGF2 gene as a source of genetic marker for halal authentication. Nusantara Bioscience 10: 203-209. The main issue of halal authenticity is the availability of reliable and rapid analytical methods to identify animal species in raw and processed food. The two most popular procedures for identifying the source of the meat are protein-based and DNA-based methods, including mass spectroscopy (MS) using a peptide marker or PCR based DNA marker, respectively. This study aims to investigate the genetic diversity of insulin-like growth factor 2 (IGF2) gene, mainly from porcine (Sus scrofa) and bovine (Bos taurus) as a source of genetic marker for halal authentication by in-silico analysis using bioinformatic tools. Multiple sequence alignment and phylogenetic tree construction of IGF2 protein sequences from representative species of mammals, birds, and fishes showed the paraphyletic relationship between the IGF2 protein of S. scrofa and B. taurus. Protein structure analysis revealed differences in helical structures near the carboxyl end of the protein, while gene analysis showed different number of exon and motifs. By in-silico analysis, we have designed a peptide marker from amino acids at position of 93-107 (S. scrofa) and 93-112 (B. taurus) from peptide preptin region that resulted in different pattern of mass spectrum between the two species. We have also identified two DNA markers that can be detected by PCR using two primers sets designed from the IGF2 transcript sequences, to examine the presence of porcine in the sample. Thus, this study provides new genetic predictive markers, derived from the IGF2 gene, to identify the source of meat for halal authentication.

The complex genetics of human insulin-like growth factor 2 are not reflected in public databases

Recent advances in genetics present unique opportunities for enhancing knowledge about human physiology and disease susceptibility. Understanding this information at the individual gene level is challenging and requires extracting, collating, and interpreting data from a variety of public gene repositories. Here, I illustrate this challenge by analyzing the gene for human insulin-like growth factor 2 (IGF2) through the lens of several databases. IGF2, a 67-amino acid secreted peptide, is essential for normal prenatal growth and is involved in other physiological and pathophysiological processes in humans. Surprisingly, none of the genetic databases accurately described or completely delineated human IGF2 gene structure or transcript expression, even though all relevant information could be found in the published literature. Although IGF2 shares multiple features with the mouse Igf2 gene, it has several unique properties, including transcription from five promoters. Both genes undergo parental imprinting, with IGF2/Igf2 being expressed primarily from the paternal chromosome and the adjacent H19 gene from the maternal chromosome. Unlike mouse Igf2, whose expression declines after birth, human IGF2 remains active throughout life. This characteristic has been attributed to a unique human gene promoter that escapes imprinting, but as shown here, it involves several different promoters with distinct tissue-specific expression patterns. Because new testable hypotheses could lead to critical insights into IGF2 actions in human physiology and disease, it is incumbent that our fundamental understanding is accurate. Similar challenges affecting knowledge of other human genes should promote attempts to critically evaluate, interpret, and correct human genetic data in publicly available databases.

Messenger RNAs and cognate microRNAs in the nucleolus (940.3)

During studies of muscle cell differentiation in a rat myogenic cell line we discovered, to our surprise, that several microRNAs are concentrated in the nucleolus (Politz et al., PNAS 103: 18957‐18962, 2006; RNA 15:1705‐1715, 2009). Since these nucleolus‐localized microRNAs were also present in the cytoplasm, it seemed plausible that their association with nucleoli represented a station on their nuclear export pathway. These findings prompted us to ask whether certain messenger RNAs might also localized in the nucleoli of these cells. Microarray analysis of RNA from highly purified nucleoli revealed a set of mRNAs present at 30 to 650‐fold higher concentrations than in the nucleoplasm and this was confirmed by in situ hybridization for one of these mRNAs, that encoding insulin‐like growth factor 2 (IGF2), an well‐known autocrine regulator of myoblast proliferation and differentiation. RT‐PCR experiments demonstrated that these nucleolus‐localized IGF2 transcripts are spliced mRNAs, suggesting that they arrive from distal sites in the nucleoplasm. Bioinformatics analysis predicted stable interactions between all of the nucleolus‐localized microRNAs and the 5′ or 3′ untranslated regions of IGF2 mRNA. Additional considerations suggest that at least one of the nucleolus‐localized microRNAs, miR‐206, may be involved in the positive regulation of IGF2 mRNA translation and we speculate that transit through the nucleolus commits IGF2 mRNA to this mode of regulation.Grant Funding Source: NSF MCB‐1051398

The IGF2 intronic miR-483 selectively enhances transcription from IGF2 fetal promoters and enhances tumorigenesis

Insulin-like growth factor 2 (IGF2), a developmentally regulated and maternally imprinted gene, is frequently overexpressed in pediatric cancers. Although loss of imprinting (LOI) at fetal promoters contributes to increased IGF2 in tumors, the magnitude of IGF2 expression suggests the involvement of additional regulatory mechanisms. A microRNA (miRNA) screen of primary Wilms' tumors identified specific overexpression of miR-483-5p, which is embedded within the IGF2 gene. Unexpectedly, the IGF2 mRNA itself is transcriptionally up-regulated by miR-483-5p. A nuclear pool of miR-483-5p binds directly to the 5' untranslated region (UTR) of fetal IGF2 mRNA, enhancing the association of the RNA helicase DHX9 to the IGF2 transcript and promoting IGF2 transcription. Ectopic expression of miR-483-5p in IGF2-dependent sarcoma cells is correlated with increased tumorigenesis in vivo. Together, these observations suggest a functional positive feedback loop of an intronic miRNA on transcription of its host gene.

Placental programming of anxiety in adulthood revealed by Igf2-null models

Imprinted, maternally silenced insulin-like growth factor-2 is expressed in both the foetus and placenta and has been shown to have roles in foetal and placental development in animal models. Here we compared mice engineered to be null for the placenta-specific P0 transcript (insulin-like growth factor-2-P0 KO) to mice with disruptions of all four insulin-like growth factor-2 transcripts, and therefore null for insulin-like growth factor-2 in both placenta and foetus (insulin-like growth factor-2-total KO). Both models lead to intrauterine growth restriction but dissociate between a situation where there is an imbalance between foetal demand and placental supply of nutrients (the insulin-like growth factor-2-P0 KO) and one where demand and supply is more balanced (the insulin-like growth factor-2-total KO). Increased reactivity to anxiety-provoking stimuli is manifested later in life only in those animals where there is a mismatch between placental supply and foetal demand for nutrients during gestation. Our findings further distinguish placental dysfunction from intrauterine growth restriction and reveal a role for the placenta in long-term programming of emotional behaviour.

Down-regulation of achaete-scute complex homolog 1 (ASCL1) in neuroblastoma cells induces up-regulation of insulin-like growth factor 2 (IGF2)

Neuroblastoma (NB) is the most common extra-cranial solid pediatric tumor. The prognosis of patients with NB has been improved during the last decades. However, treatment results for patients with advanced tumor stages are still unsatisfying. NB cells are characterized by a high tendency for spontaneous or induced differentiation. During differentiation, down-regulation of the basic helix-loop-helix transcription factor achaete-scute complex homolog 1 (ASCL1) has been observed but the consequences of ASCL1 down-regulation have not been elucidated. We used RNA interference to knock-down ASCL1 in NB cells. DNA microarray analysis was used for the identification of ASCL1-regulated genes. Furthermore, conventional and quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used for validation of ASCL1-regulated genes. Down-regulation of ASCL1 influenced the expression of several genes. After down-regulation of ASCL1, we observed very high expression of insulin-like growth factor 2 (IGF2), a factor that is known to be induced during differentiation of NB cells. RT-PCR indicated up-regulation of multiple IGF2 transcript variants after ASCL1 knock-down. Our data suggest that the ASCL1-pathway is responsible for the up-regulation of IGF2 during NB differentiation.

Regulation of IGF2 transcript and protein expression by altered methylation in breast cancer

Breast Cancer is one of the leading causes of cancer deaths among women worldwide. The role of epigenetics as a distinct mechanism to alter gene expression in a tissue-specific manner has emerged as an important mechanism in the pathophysiology of cancer. Present study was carried out to assess the role of methylation in regulating transcription and protein expression of Insulin-like growth factor 2 (IGF2), an oncogene with parental imprinting. Paraffin-embedded archival breast tumor and adjacent normal tissue samples were used for carrying out PCR-based methylation assay, genomic PCR, immunohistochemistry and Real-Time Reverse transcriptase PCR. A significant loss of methylation in exon 9 CpG cluster of IGF2 in breast tumor tissues was observed when compared to normal tissue (P<0.0001). Expression of IGF2 by immunohistochemistry exhibited a mean twofold increase correlating with the hypomethylation of this specific CpG. Real-Time RT PCR showed increased transcripts in the tumor tissue supporting the IHC and methylation results. A total of 33% of tumor samples heterozygous for the ApaI IGF2 polymorphism exhibited biallelic IGF2 expression due to loss of imprinting; this was not seen in any of the normal breast tissues. Altered methylation of exonic CpG plays an important role in the enhanced transcription/expression of IGF2 in breast tumors. Methylation analysis of exon 9 CpG can be used as a biomarker for upregulation of IGF2 in breast tumor tissue and maybe developed as a diagnostic test in future.

Loss of imprinting of IGF2 characterises high IGF2 mRNA-expressing type of fibroblast-like synoviocytes in rheumatoid arthritis

ObjectiveIncreased expression of insulin-like growth factor 2 (IGF2) by fibroblast-like synoviocytes (FLS) was associated with low inflammatory synovium of patients with rheumatoid arthritis (RA). The aim of this study was...

Genetic Imprinting of H19 and IGF2 in Domestic Pigs (Sus scrofa)

The genes insulin-like growth factor 2 (IGF2) and H19 express paternally and maternally, respectively, in humans, mice, sheep, and cattle. Additionally, IGF2 has been shown to be regulated by at least four promoters in a tissue- or development-specific manner. In the domestic pigs, the promoter- and tissue-specific imprinting pattern of IGF2 has not been well characterized, nor is the imprinting pattern of H19. In the present study, we identified two polymorphisms in each of IGF2 (exons 2 and 9) and H19 (exons 1 and 5) and determined the imprinting status of these two genes in 13 organs / tissues of week-old pigs. IGF2 P1 transcript is bi-allelically expressed (not imprinted) in all major organs studied, while the majority of IGF2 transcripts are expressed from promoters 2–4 and are imprinted. H19 is exclusively expressed from the maternal allele in all major organs, concurrent with observations in other species.

261 PHENOTYPIC CHARACTERISTICS AND TISSUE-SPECIFIC IGF2R/IGF2 EXPRESSION PARTITION BOVINE FETAL OVERGROWTH ASSOCIATED WITH IN VITRO FERTILIZATION AND SOMATIC CELL NUCLEAR TRANSFER CLONING

Large offspring syndrome (LOS) in ruminants refers to various poorly defined organ pathologies that are associated with fetal overgrowth and are encountered after a range of embryo manipulations (Rhind et al. 2003 Nat. Rev. Genet. 4, 855–864). We have explored the effects of somatic cell nuclear transfer (NT) and in vitro fertilization (IVF) on phenotype and relative expression levels of 2 imprinted genes important for fetal growth, insulin-like growth factor 2 (IGF2) and its receptor (IGF2R). Viable bovine fetuses were recovered near the end of the first trimester of pregnancy, and skeletal muscle, liver, and lung were sampled for real-time RT-PCR analyses. We compared NT-fetuses (n = 23), IVF-fetuses (n = 24), and fetuses generated by artificial insemination (controls, n = 24) in order to separate abnormalities specific to cloning from effects of in vitro gamete and embryo manipulation. Nuclear transfer and IVF-fetuses, both derived from embryos cultured with 10% estrous cow serum, demonstrated significant fetal overgrowth. The increase in body weight relative to controls was similar for both groups (+22%, P &amp;lt; 0.001, and +19%, P &amp;lt; 0.001, respectively), but further analyses clearly separated the NT phenotype from the IVF phenotype. The NT-fetuses were characterized by a shorter crown-rump length but larger thorax circumference, which consequently produced a significantly reduced fetus length-to-thorax circumference ratio in comparison with IVF-fetuses and controls (-9% each, P &amp;lt; 0.0001). Absolute liver weight was significantly increased in NT- and IVF-fetuses (+62%, P &amp;lt; 0.0001, and +20%, P &amp;lt; 0.0001, respectively), but relative liver weight was increased only in NT-fetuses (+30%, P &amp;lt; 0.0001). Heart (P&amp;lt; 0.0001) and kidney (P = 0.0003) mass also showed disproportionate organomegaly in NT-fetuses only, but relative lung weight (NT, P = 0.263; IVF, P = 0.317) was not affected by either embryo technique. Transcript abundance for IGF2 and IGF2R genes were strongly correlated in muscle (r = 0.835, P &amp;lt; 0.0001), liver (r = 0.922, P &amp;lt; 0.0001), and lung (r = 0.772, P &amp;lt; 0.0001). The IGF2 and IGF2R transcript levels in muscle tissue from NT-fetuses were markedly reduced in comparison with both IVF-fetuses (-31%, P &amp;lt; 0.0001, and -41%, P &amp;lt; 0.0001, respectively) and controls (-31%, P &amp;lt; 0.0001, and -41%, P &amp;lt; 0.0001, respectively). In liver tissue, however, transcript levels for NT-fetuses were similar to those of controls, and IVF-fetuses showed markedly elevated, albeit non-significant, IGF2 (+86%, P = 0.0591) and IGF2R (+54%, P = 0.1305) mRNA levels relative to controls. Our data demonstrate that seemingly similar syndromes caused by NT or IVF procedures can be clearly partitioned with respect to phenotype and IGF2/IGF2R expression.

Thymic neuroendocrine self-antigens. Role in T-cell development and central T-cell self-tolerance.

The repertoire of thymic neuroendocrine precursors plays a dual role in T-cell differentiation as the source of either cryptocrine accessory signals in T-cell development or neuroendocrine self-antigens presented by the thymic major histocompatibility complex (MHC) machinery. Thymic neuroendocrine self-antigens usually correspond to peptide sequences highly conserved during the evolution of one family. The thymic presentation of some neuroendocrine self-antigens is not restricted by MHC alleles. Oxytocin (OT) is the dominant peptide of the neurohypophysial family. It is expressed by thymic epithelial and nurse cells (TEC/TNCs) of different species. Ontogenetic studies have shown that the thymic expression of the OT gene precedes the hypothalamic one. Both OT and VP stimulate the phosphorylation of p125FAK and other focal adhesion-related proteins in murine immature T cells. These early cell activation events could play a role in the promotion of close interactions between thymic stromal cells and developing T cells. It is established that such interactions are fundamental for the progression of thymic T-cell differentiation. Insulin-like growth factor 2 (IGF-2) is the dominant thymic polypeptide of the insulin family. Using fetal thymic organ cultures (FTOCs), the inhibition of thymic IGF-2-mediated signaling was shown to block the early stages of T-cell differentiation. The treatment of FTOCs with an mAb anti-(pro)insulin had no effect on T-cell development. In an animal model of autoimmune type 1 diabetes (BB rat), thymic levels of (pro)insulin and IGF-1 mRNAs were normal both in diabetes-resistant and diabetes-prone BB rats. IGF-2 transcripts were clearly identified in all thymuses from diabetes-resistant adult (5-week) and young (2- and 5-days) BB rats. In marked contrast, the IGF-2 transcripts were absent and the IGF-2 protein was almost undetectable in +/- 80% of the thymuses from diabetes-prone adult and young BB rats. These data show that a defect of the thymic IGF-2-mediated tolerogenic function might play an important role in the pathophysiology of autoimmune Type 1 diabetes.

Insulin-like growth factor 2 gene imprinting in clear cell sarcoma of the kidney

We examined the expression of insulin-like growth factor 2 ( IGF2) transcripts and allelic-specificity in four cases of clear cell sarcoma of the kidney (CCSK). All cases contained abundant IGF2 transcripts in the cytoplasm of tumor cells detected by in situ mRNA hybridization. The level of IGF2 expression was comparable with that of Wilms tumor. The IGF2 gene imprinting status was analysed by using DNA/RNA extracted from one frozen tumor tissue and three archival tumor and kidney tissue. The allele-specific analysis using Apal polymorphism in the 5′-untranslated region of the IGF2 gene showed that two out of four tumors were heterozygous at the IGF2 locus. The result showed that one of two informative heterozygous tumors showed biallelic IGF2 expression whereas the other showed monoallelic expression. The data show that disruption of IGF2 gene imprinting occurs in CCSK.

Insulin-like growth factor 2 and insulin-like growth factor binding protein 2 expression in hepatoblastoma

The expression of insulin-like growth factor 2 (IGF2) and insulin-like growth factor binding protein 2 (IGFBP2) in 11 cases of hepatoblastoma was studied by means of in situ mRNA hybridization using digoxigenin (DIG)-labeled riboprobes. The results showed that both IGF2 and IGFBP2 transcripts are present in hepatoblastoma and that their expression is inversely correlated with the degree of tumor cell differentiation. The data suggested that IGF2 and IGFBP2 gene expression could be regarded as a marker for assessment of the degree of differentiation in hepatoblastoma.

Insulin-like growth factor 2 and short-range stimulatory loops in control of human placental growth.

Substructures of the first-trimester human placenta (within 3 months post-conception) display 'pseudo-malignant' properties. We show here, by in situ hybridization, that the insulin-like growth factor 2 (IGF-2) gene expression is particularly active in the cytotrophoblasts, which dominate these structures. Because the majority of placental IGF-2 mRNA is polysomal in extracts of first-trimester placenta, the spatial pattern of IGF-2 transcripts generally also defines the pattern of IGF-2 production. In primary trophoblast cultures, rendered quiescent by serum starvation. IGF-2 performs as a human embryonic growth factor by activating cell cycle entry/progression. Although both type 1 and 2 IGF receptor mRNAs can be found co-distributed with IGF-2 mRNA during placental development (supporting an autocrine role for IGF-2), these occasional patterns are confined to cytotrophoblasts with low proliferative potential. The reciprocity in ligand and receptor expression patterns are discussed in terms of rate-limiting steps in the involvement of IGF-2 in the proliferative phenotype of the early human placenta.