Knockdown of insulin-like growth factor 2 gene disrupts mitochondrial functions in the liver.
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ABSTRACT:
SUBMITTER: Gui W
PROVIDER: S-EPMC8697341 | biostudies-literature |
REPOSITORIES: biostudies-literature
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| S-EPMC7095259 | biostudies-literature
Project description:BackgroundSerum IGF-I and IGF-II levels decline with age. IGF-I replacement therapy reduces the impact of age in rats. We have recently reported that IGF-II is able to act, in part, as an analogous of IGF-I in aging rats reducing oxidative damage in brain and liver associated with a normalization of antioxidant enzyme activities. Since mitochondria seem to be the most important cellular target of IGF-I, the aim of this work was to investigate whether the cytoprotective actions of IGF-II therapy are mediated by mitochondrial protection.MethodsThree groups of rats were included in the experimental protocol young controls (17 weeks old); untreated old rats (103 weeks old); and aging rats (103 weeks old) treated with IGF-II (2 ?g/100 g body weight and day) for 30 days.ResultsCompared with young controls, untreated old rats showed an increase of oxidative damage in isolated mitochondria with a dysfunction characterized by: reduction of mitochondrial membrane potential (MMP) and ATP synthesis and increase of intramitochondrial free radicals production and proton leak rates. In addition, in untreated old rats mitochondrial respiration was not blocked by atractyloside. In accordance, old rats showed an overexpression of the active fragment of caspases 3 and 9 in liver homogenates. IGF-II therapy corrected all of these parameters of mitochondrial dysfunction and reduced activation of caspases.ConclusionsThe cytoprotective effects of IGF-II are related to mitochondrial protection leading to increased ATP production reducing free radical generation, oxidative damage and apoptosis.
| S-EPMC3162510 | biostudies-literature
Project description:Congenital heart disease (CHD) affects nearly 1% of births annually, and CHD pregnancies carry increased risk of developing pathologies of abnormal placentation. We previously reported significant developmental impacts of disrupting Hand1, a gene associated with CHD, expression in placenta trophoblast and endothelial cells in multiple mouse models. In this study, we aimed to build upon this knowledge and characterize the mechanistic impacts of disrupting HAND1 on human placenta trophoblast and vascular endothelial cell gene expression. HAND1 gene expression was silenced in BeWo cells, a choriocarcinoma model of human cytotrophoblasts, (n = 3-9 passages) and isolated human placental microvascular endothelial cells (HPMVEC; n = 3 passages), with HAND1 siRNA for 96 h. Cells were harvested, mRNA isolated and RNA sequencing performed using the Illumina NextSeq 550 platform. Normalization and differential gene expression analyses were conducted using general linear modeling in edgeR packages. Statistical significance was determined using a log2 fold change of >1.0 or < -1.0 and unadjusted p-value ≤0.05. Panther DB was used for overrepresentation analysis, and String DB for protein association network analysis. There was downregulation of 664 genes, and upregulation of 59 genes in BeWo cells with direct HAND1 knockdown. Overrepresentation analysis identified disruption to pathways including cell differentiation, localization, and cell projection organization. In contrast, only seven genes were changed with direct HAND1 knockdown in HPMVECs. Disruption to HAND1 expression significantly alters gene expression profile in trophoblast but not endothelial cells. This data provides further evidence that future studies on genetic perturbations in CHDs should consider the extra-embryonic tissue in addition to the fetal heart.
| S-EPMC9875743 | biostudies-literature
Project description:Podocyte or endothelial cell VEGF-A knockout causes thrombotic microangiopathy in adult mice. To study the mechanism involved in acute and local injury caused by low podocyte VEGF-A we developed an inducible, podocyte-specific VEGF-A knockdown mouse, and we generated an immortalized podocyte cell line (VEGF(KD)) that downregulates VEGF-A upon doxycycline exposure. Tet-O-siVEGF:podocin-rtTA mice express VEGF shRNA in podocytes in a doxycycline-regulated manner, decreasing VEGF-A mRNA and VEGF-A protein levels in isolated glomeruli to ~20% of non-induced controls and urine VEGF-A to ~30% of control values a week after doxycycline induction. Induced tet-O-siVEGF:podocin-rtTA mice developed acute renal failure and proteinuria, associated with mesangiolysis and microaneurisms. Glomerular ultrastructure revealed endothelial cell swelling, GBM lamination and podocyte effacement. VEGF knockdown decreased podocyte fibronectin and glomerular endothelial alpha(V)beta(3) integrin in vivo. VEGF receptor-2 (VEGFR2) interacts with beta(3) integrin and neuropilin-1 in the kidney in vivo and in VEGF(KD) podocytes. Podocyte VEGF knockdown disrupts alpha(V)beta(3) integrin activation in glomeruli, detected by WOW1-Fab. VEGF silencing in cultured VEGF(KD) podocytes downregulates fibronectin and disrupts alpha(V)beta(3) integrin activation cell-autonomously. Collectively, these studies indicate that podocyte VEGF-A regulates alpha(V)beta(3) integrin signaling in the glomerulus, and that podocyte VEGF knockdown disrupts alpha(V)beta(3) integrin activity via decreased VEGFR2 signaling, thereby damaging the three layers of the glomerular filtration barrier, causing proteinuria and acute renal failure.
| S-EPMC3396653 | biostudies-literature
Project description:Insulin-like Growth Factor-1 (IGF-1) has been studied extensively for its ability to promote neuronal growth and excitability. Declining levels of IGF-1 have been correlated with impaired learning and memory as well as an increased risk of neurodegenerative diseases. While neuronal regulation by IGF-1 is well understood, the role of IGF-1 in influencing astrocyte function requires further exploration. Astrocytes regulate many aspects of the brain microenvironment, including controlling glutamate-glutamine cycling, which ultimately supports neuronal metabolism, neurotransmission, and protection from over stimulation. In this study, we examined whether IGF-1 acts through its cognate receptor, IGFR, to alter astrocytic glutamate handling. We utilized both small molecule IGFR inhibitors and Cre-driven genetic approaches to reduce IGFR in vivo and in cultured rodent astrocytes. When IGFR was knocked out of primary astrocytes derived from igfrf/f mice using AAV5-CMV-Cre, significant reductions in glutamate uptake were observed. Similarly, inhibition of IGFR with picropodophyllotoxin for 2 h, as well as 24 h, reduced glutamate uptake in vitro. Mechanistically, short-term inhibition of IGFR resulted in a significant decrease in glutamate transporter availability on the cell surface, as assessed by biotinylation. Long-term inhibition of IGFR led to significant reductions in mRNA expression of glutamate transport machinery, as assessed with qPCR. Reduced glutamate transporter mRNA was also observed in the brains of astrocyte-specific IGFR-deficient mice, three to four months after knock-out was induced with tamoxifen. Interestingly, long-term IGF-1 inhibition also resulted in an increase in adenosine triphosphate-stimulated glutamate release, though no change in adenosine triphosphate-stimulated calcium flux was observed nor were any changes in purinergic receptor protein expression. Together, these data suggest that reduced IGF-1 signaling will favor an accumulation of extrasynaptic glutamate, which may contribute to neurodegeneration in disease states where IGF-1 levels are low. Cover Image for this issue: doi: 10.1111/jnc.14534.
| S-EPMC7416791 | biostudies-literature
Project description:SHANK2 is a scaffold protein that serves as a protein anchor at the postsynaptic density in neurons. Genetic variants of SHANK2 are strongly associated with synaptic dysfunction and the pathophysiology of autism spectrum disorder. Recent studies indicate that early neuronal developmental defects play a role in the pathogenesis of autism spectrum disorder, and that insulin-like growth factor 1 has a positive effect on neurite development. To investigate the effects of SHANK2 knockdown on early neuronal development, we generated a sparse culture system using human induced pluripotent stem cells, which then differentiated into neural progenitor cells after 3-14 days in culture, and which were dissociated into single neurons. Neurons in the experimental group were infected with shSHANK2 lentivirus carrying a red fluorescent protein reporter (shSHANK2 group). Control neurons were infected with scrambled shControl lentivirus carrying a red fluorescent protein reporter (shControl group). Neuronal somata and neurites were reconstructed based on the lentiviral red fluorescent protein signal. Developmental dendritic and motility changes in VGLUT1+ glutamatergic neurons and TH+ dopaminergic neurons were then evaluated in both groups. Compared with shControl VGLUT1+ neurons, the dendritic length and arborizations of shSHANK2 VGLUT1+ neurons were shorter and fewer, while cell soma speed was higher. Furthermore, dendritic length and arborization were significantly increased after insulin-like growth factor 1 treatment of shSHANK2 neurons, while cell soma speed remained unaffected. These results suggest that insulin-like growth factor 1 can rescue morphological defects, but not the change in neuronal motility. Collectively, our findings demonstrate that SHANK2 deficiency perturbs early neuronal development, and that IGF1 can partially rescue the neuronal defects caused by SHANK2 knockdown. All experimental procedures and protocols were approved by the Laboratory Animal Ethics Committee of Jinan University, China (approval No. 20170228010) on February 28, 2017.
| S-EPMC7749486 | biostudies-literature
Project description:Regulatory B cells (Bregs) are important in immune regulation. The factors that regulate Breg functions are less clear. Insulin-like growth factor 2 (IGF2) is capable of inducing hematopoietic stem cell differentiation. This study aimed to investigate the role of IGF2 in the development of Bregs and the enhancement of their function. In this study, the expression of IGF1 receptor (IGF1R) and IGF2R in ovalbumin (OVA)-specific B cells (OVAsBCs) was assessed by real time RT-PCR and Western blotting. The release of interleukin (IL)-10 from OVAsBCs and OVAsBC proliferation were assessed by enzyme-linked immunoassay and proliferation assay. The role of IGF2 in enhancing the function of OVAsBCs was tested with an intestinal allergic inflammation mouse model. The results showed that OVAsBCs expressed high levels of IGF2R. Exposure to both IGF2 and a specific antigen (Ag), OVA, markedly enhanced the expression of IL-10 in OVAsBCs as well as enhanced the IL-10(+) OVAsBC proliferation. The concurrent exposure to IGF2 and specific Ag markedly induced the IL-10 promoter DNA demethylation via activating the STAT5 pathway. IGF2 also enhanced both the OVAsBC proliferation in vivo and the effect of Ag-specific immunotherapy on inhibiting allergic inflammation in the intestine. We conclude that OVAsBCs express high levels of IGF2R and that IGF2 increases the expression of IL-10 in OVAsBCs and enhances OVAsBC proliferation and the inhibitory effect on allergic inflammation.
| S-EPMC4067224 | biostudies-literature
Project description:Background and aimAlcohol-related liver disease (ALD) is mediated in part by insulin resistance. Attendant dysregulation of lipid metabolism increases accumulation of hepatic ceramides that worsen insulin resistance and compromise the structural and functional integrity of the liver. Insulin and insulin growth factor (IGF) stimulate aspartyl-asparaginyl-β-hydroxylase (AAH), which promotes cell motility needed for structural maintenance and remodeling of the liver. AAH mediates its effects by activating Notch, and in ALD, insulin/IGF signaling, AAH, and Notch are inhibited.MethodTo test the hypothesis that in ALD, hepatic ceramide load contributes to impairments in insulin, AAH, and Notch signaling, control and chronic ethanol-fed adult Long-Evans rats were treated with myriocin, an inhibitor of serine palmitoyl transferase. Livers were used to assess steatohepatitis, insulin/IGF pathway activation, and expression of AAH-Notch signaling molecules.ResultsChronic ethanol-fed rats had steatohepatitis with increased ceramide levels; impairments in signaling through the insulin receptor, insulin receptor substrate, and Akt; and decreased expression of AAH, Notch, Jagged, Hairy-Enhancer of Split-1, hypoxia-inducible factor 1α, and proliferating cell nuclear antigen. Myriocin abrogated many of these adverse effects of ethanol, particularly hepatic ceramide accumulation, steatohepatitis, and impairments of insulin signaling through Akt, AAH, and Notch.ConclusionsIn ALD, the histopathology and impairments in insulin/IGF responsiveness can be substantially resolved by ceramide inhibitor treatments, even in the context of continued chronic ethanol exposure.
| S-EPMC4551508 | biostudies-literature
Project description:The aim of the study was to analyze whether the proliferative effects of insulin in rat liver involve cross-signaling toward the epidermal growth factor receptor (EGFR) and whether this is mediated by insulin-induced hepatocyte swelling. Studies were performed in the perfused rat liver and in primary rat hepatocytes. Insulin (35 nmol/liter) induced phosphorylation of the EGFR at position Tyr(845) and Tyr(1173), but not at Tyr(1045), suggesting that EGF is not involved in insulin-induced EGFR activation. Insulin-induced EGFR phosphorylation and subsequent ERK1/2 phosphorylation were sensitive to bumetanide, indicating an involvement of insulin-induced hepatocyte swelling. In line with this, hypoosmotic (225 mosmol/liter) hepatocyte swelling also induced EGFR and ERK1/2 activation. Insulin- and hypoosmolarity-induced EGFR activation were sensitive to inhibition by an integrin-antagonistic RGD peptide, an integrin beta1 subtype-blocking antibody, and the c-Src inhibitor PP-2, indicating the involvement of the recently described integrin-dependent osmosensing/signaling pathway (Schliess, F., Reissmann, R., Reinehr, R., vom Dahl, S., and Häussinger, D. (2004) J. Biol. Chem. 279, 21294-21301). As shown by immunoprecipitation studies, insulin and hypoosmolarity induced a rapid, RGD peptide-, integrin beta1-blocking antibody and PP-2-sensitive association of c-Src with the EGFR. As for control, insulin-induced insulin receptor substrate-1 phosphorylation remained unaffected by the RGD peptide, PP-2, or inhibition of the EGFR tyrosine kinase activity by AG1478. Both insulin and hypoosmolarity induced a significant increase in BrdU uptake in primary rat hepatocytes, which was sensitive to RGD peptide-, integrin beta1-blocking antibody, PP-2, AG1478, and PD098059. It is concluded that insulin- or hypoosmolarity-induced hepatocyte swelling triggers an integrin- and c-Src kinase-dependent EGFR activation, which may explain the proliferative effects of insulin.
| S-EPMC2923979 | biostudies-literature
Project description:Hepatocyte transplantation holds great promise as an alternative to orthotopic organ transplantation in the treatment of liver diseases. However, obtaining clinically meaningful levels of liver repopulation has not been achieved because the mechanisms regulating hepatocyte proliferation in recipient livers have not yet been well characterized. In the mouse model of Hereditary Tyrosinemia Type I, the fumarylacetoacetate hydrolase-deficient (Fah-/-) mouse, we found gradually increasing expression level of insulin-like growth factor 2 (IGF2) in the hepatocytes of host livers. Similarly, high levels of IGF2 were found in the livers of patients with deficient FAH activity. Recombinant IGF2 directly promotes proliferation of primary hepatocytes in vitro. Inhibition on IGF2 expression through the interruption of PI3K/Akt and MAPK pathways significantly reduced the level of liver repopulation in Fah-/- mice. Interestingly, treatment with IGF2 before hepatocyte transplantation generally improved the amount of liver repopulation seen in various mice models of liver injury. Altogether, these findings underscore the underlying mechanisms of therapeutic liver repopulation in Fah-/- mice, and indicate that IGF2 is a potential hepatocyte mitogen for liver cell transplantation therapies.
| S-EPMC5833551 | biostudies-literature