IGF-1 Overexpression Research Articles

Nanoparticle-mediated delivery of placental gene therapy via uterine artery catheterization in a pregnant rhesus macaque

Nanoparticles offer promise as a mechanism to non-invasively deliver targeted placental therapeutics. Our previous studies utilizing intraplacental administration demonstrate efficient nanoparticle uptake into placental trophoblast cells and overexpression of human IGF1 (hIGF1). Nanoparticle-mediated placental overexpression of hIGF1 in small animal models of placental insufficiency and fetal growth restriction improved nutrient transport and restored fetal growth. The objective of this pilot study was to extend these studies to the pregnant nonhuman primate and develop a method for local delivery of nanoparticles to the placenta via maternal blood flow from the uterine artery. Nanoparticles containing hIGF1 plasmid driven by the placenta-specific PLAC1 promoter were delivered to a mid-gestation pregnant rhesus macaque via a catheterization approach that is clinically used for uterine artery embolization. Maternal-fetal interface, fetal and maternal tissues were collected four days post-treatment to evaluate the efficacy of hIGF1 treatment in the placenta. The uterine artery catheterization procedure and nanoparticle treatment was well tolerated by the dam and fetus through the four-day study period following catheterization. Nanoparticles were taken up by the placenta from maternal blood as plasmid-specific hIGF1 expression was detected in multiple regions of the placenta via in situ hybridization and qPCR. The uterine artery catheterization approach enabled successful delivery of nanoparticles to maternal circulation in close proximity to the placenta with no concerns to maternal or fetal health in this short-term feasibility study. In the future, this delivery approach can be used for preclinical evaluation of the long-term safety and efficacy of nanoparticle-mediated placental therapies in a rhesus macaque model.

Compression Promotes the Osteogenic Differentiation of Human Periodontal Ligament Stem Cells by Regulating METTL14-mediated IGF1.

Orthodontic treatment involves the application of mechanical force to induce periodontal tissue remodeling and ultimately promote tooth movement. It is essential to study the response mechanisms of human periodontal ligament stem cells (hPDLSCs) to improve orthodontic treatment. In this study, hPDLSCs treated with compressive force were used to simulate orthodontic treatment. Cell viability and cell death were assessed using the CCK-8 assay and TUNEL staining. Alkaline phosphatase (ALP) and alizarin red staining were performed to evaluate osteogenic differentiation. The binding relationship between IGF1 and METTL14 was assessed using RIP and dual-luciferase reporter assays. The compressive force treatment promoted the viability and osteogenic differentiation of hPDLSCs. Additionally, m6A and METTL14 levels in hPDLSCs increased after compressive force treatment, whereas METTL14 knockdown decreased cell viability and inhibited the osteogenic differentiation of hPDLSCs treated with compressive force. Furthermore, the upregulation of METTL14 increased m6A levels, mRNA stability, and IGF1 expression. RIP and dual-luciferase reporter assays confirmed the interaction between METTL14 and IGF1. Furthermore, rescue experiments demonstrated that IGF1 overexpression reversed the effects of METTL14 knockdown in hPDLSCs treated with compressive force. In conclusion, this study demonstrated that compressive force promotes cell viability and osteogenic differentiation of hPDLSCs by regulating IGF1 levels mediated by METTL14.

The Effect of the Overexpression or Addition of IGF1 and FGF2 in Human Chondrocytes Included in a Fibrin Matrix and Cultivated in a Dynamic Environment.

Hyaline cartilage is a highly specialized tissue. When injured, its repair capacity is low, which results in the massive destruction of the articular surface. Using tissue engineering and genetic engineering techniques, it is possible to provide a suitable microenvironment providing chondrocyte growth factors involved in the development of hyaline cartilage proteins, as well as cell proliferation and differentiation. Our aim was to stimulate the synthesis of an extracellular matrix via the chondrocytes included in a fibrin matrix through the addition or overexpression of IGF1 and/or FGF2, while maintaining a constant agitation of the culture medium. Collagen type II and glycosaminoglycans increased during the entire incubation time. In contrast, collagen type I decreased its expression under the same culture conditions, transfecting or supplementing growth factors to chondrocytes. However, chondrocytes that were not transfected or supplemented showed a general increase in the proteins analyzed in this study. The presence of IGF1 and FGF2 increased the protein synthesis of the hyaline cartilage, regardless of which one was the source of growth factors. Continuous agitation using the spinner flask allows for the adequate nutrition of chondrocytes included in the fibrin matrix. However, they require growth factors to up-regulate or down-regulate collagenous proteins.

CircUSP13 facilitates the fast-to-slow myofiber shift via the MAPK/ERK signaling pathway in goat skeletal muscles.

Understanding how skeletal muscle fiber proportions are regulated is essential for understanding muscle function and improving the quality of mutton. While circular RNA (circRNA) has a critical function in myofiber type transformation, the specific mechanisms are not yet fully understood. Prior evidence indicates that circular ubiquitin-specific peptidase 13 (circUSP13) can promote myoblast differentiation by acting as a ceRNA, but its potential role in myofiber switching is still unknown. Herein, we found that circUSP13 enhanced slow myosin heavy chain (MyHC-slow) and suppressed MyHC-fast expression in goat primary myoblasts (GPMs). Meanwhile, circUSP13 evidently enhanced the remodeling of the mitochondrial network while inhibiting the autophagy of GPMs. We obtained fast-dominated myofibers, via treatment with rotenone, and further demonstrated the positive role of circUSP13 in the fast-to-slow transition. Mechanistically, activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway significantly impaired the slow-to-fast shift in fully differentiated myotubes, which was restored by circUSP13 or IGF1 overexpression. In conclusion, circUSP13 promoted the fast-to-slow myofiber type transition through MAPK/ERK signaling in goat skeletal muscle. These findings provide novel insights into the role of circUSP13 in myofiber type transition and contribute to a better understanding of the genetic mechanisms underlying meat quality.

Urine-derived stem cells genetically modified with IGF1 improve muscle regeneration.

In this study we aimed to determine the impact of human urine derived stem cells (USC) and genetically modified USC that were designed to overexpress myogenic growth factor IGF1 (USCIGF), on the regenerative capacity of cardiotoxin (CTX)-injured murine skeletal muscle. We overexpressed IGF1 in USC and investigated the alterations in myogenic capacity and regenerative function in cardiotoxin-injured muscle tissues. Compared with USC alone, USCIGF1 activated the IGF1-Akt-mTOR signaling pathway, significantly improved myogenic differentiation capacity in vitro, and enhanced the secretion of myogenic growth factors and cytokines. In addition, IGF1 overexpression increased the ability of USC to fuse with skeletal myocytes to form myotubes, regulated the pro-regenerative immune response and inflammatory cytokines, and increased myogenesis in an in vivo model of skeletal muscle injury. Overall, USC genetically modified to overexpress IGF1 significantly enhanced skeletal muscle regeneration by regulating myogenic differentiation, paracrine effects, and cell fusion, as well as by modulating immune responses in injured skeletal muscles in vivo. This study provides a novel perspective for evaluating the myogenic function of USC as a nonmyogenic cell source in skeletal myogenesis. The combination of USC and IGF1 expression has the potential to provide a novel efficient therapy for skeletal muscle injury and associated muscular defects in patients with urinary incontinence.

TREM2-IGF1 Mediated Glucometabolic Enhancement Underlies Microglial Neuroprotective Properties During Ischemic Stroke.

Microglia, the major resident immune cells in the central nervous system, serve as the frontline soldiers against cerebral ischemic injuries, possibly along with metabolic alterations. However, signaling pathways involved in the regulation of microglial immunometabolism in ischemic stroke remain to be further elucidated. In this study, using single-nuclei RNA sequencing, a microglial subcluster up-regulated in ischemic brain tissues is identified, with high expression of Igf1 and Trem2, neuroprotective transcriptional signature and enhanced oxidative phosphorylation. Microglial depletion by PLX3397 exacerbates ischemic brain damage, which is reversed by repopulating the microglia with high Igf1 and Trem2 phenotype. Mechanistically, Igf1 serves as one of the major down-stream molecules of Trem2, and Trem2-Igf1 signaling axis regulates microglial functional and metabolic profiles, exerting neuroprotective effects on ischemic stroke. Overexpression of Igf1 and supplementation of cyclocreatine restore microglial glucometabolic levels and cellular functions even in the absence of Trem2. These findings suggest that Trem2-Igf1 signaling axis reprograms microglial immunometabolic profiles and shifts microglia toward a neuroprotective phenotype, which has promising therapeutic potential in treating ischemic stroke.

Time-Dependent Changes in Muscle IGF1-IGFBP5-PAPP System after Sciatic Denervation.

Denervation-induced muscle atrophy is a frequent cause of skeletal muscle diseases. However, the role of the most important muscle growth factor, insulin-like growth factor (IGF-1), in this process is poorly understood. IGF-1 activity is controlled by six IGF-1 binding proteins (IGFBPs). In skeletal muscle, IGFBP-5 seems to have an important role in atrophic processes. Furthermore, pappalysins (PAPP-A) modulate muscle growth by increasing IGF-1 bioavailability through IGFBP cleavage. We aimed to study the time-dependent changes in the IGF1-IGFBP5-PAPP system and its regulators in gastrocnemius muscle after sciatic denervation. Gastrocnemius atrophy and overexpression of IGF-1 was observed from day 3 post-denervation. The proteolytic factors measured were elevated from day 1 post-denervation onwards. Expression of both IGFBP-5 and pappalysins were increased on days 1 and 3. Subsequently, on days 7 to 14 pappalysins returned to control levels while IGFBP-5 remained elevated. The ratio IGFBP-5/PAPP-A was correlated with the main proteolytic markers. All data suggest that the initial increase of pappalysins could facilitate the IGF-1 action on muscle growth, whereas their subsequent decrease could lead to further muscle wasting.

Mechanism of myocardial fibrosis regulation by IGF-1R in atrial fibrillation through the PI3K/Akt/FoxO3a pathway.

Atrial structural remodeling takes on a critical significance to the occurrence and maintenance of atrial fibrillation (AF). As revealed by recent data, insulin-like growth factor-1 receptor (IGF-1R) plays a certain role in tissue fibrosis. In this study, the mechanism of IGF-1R in atrial structural remodeling was examined based on in vivo and in vitro experiments. First, cluster analysis of AF hub genes was conducted, and then the molecular mechanism was proposed by which IGF-1R regulates myocardial fibrosis via the PI3K/Akt/FoxO3a pathway. Subsequently, the mentioned mechanism was verified in human cardiac fibroblasts (HCFs) and rats transduced with IGF-1 overexpression type 9 adeno-associated viruses. The results indicated that IGF-1R activation up-regulated collagen Ⅰ protein expression and Akt phosphorylation in HCFs and rat atrium. The administration of LY294002 reversed the above phenomenon, improved the shortening of atrial effective refractory period, and reduced the increased incidence of AF and atrial fibrosis in rats. The transfection of FoxO3a siRNA reduced the anti-fibrotic effect of LY294002 in HCFs. The above data revealed that activation of IGF-1R takes on a vital significance to atrial structural remodeling by facilitating myocardial fibrosis and expediting the occurrence and maintenance of AF through the regulation of the PI3K/Akt/FoxO3a signaling pathway.

β-elemene induced apoptosis and senescence of triple-negative breast cancer cells through IGF1/IGF1R pathway

Purposeβ-elemene has a wide range of anticancer effects and can be used in a variety of cancer types. This study mainly explored its mechanism of action on TNBC cells and provided theoretical basis for the treatment of TNBC. MethodsFirstly, TNBC cells were treated with different concentrations of β-elemene, and screened out an appropriate concentration for subsequent research. Then, through the bioinformatics website, predicted genes that have a binding relationship with β-elemene. Then, the overexpression vector of the selected gene was transfected into the cell. The effects of β-elemene and its target genes on the proliferation and apoptosis of TNBC cells were detected by CCK-8, Edu assay, and flow cytometry, and the senescence of cells was determined by SA-β-gal experiment. Western blotting was used to detect the expression of apoptosis and aging-related proteins. Resultsβ-elemene inhibited TNBC cell viability and proliferation in a concentration-dependent manner, and induces apoptosis and senescence. Through the screening of candidate genes, IGF1 was finally determined to be an effective target gene of β-elemene. The expression level of IGF1 was decreased in cells treated with β-elemene. Overexpression of IGF1 significantly alleviated ability of β-elemene to inhibit cell viability, proliferation, and induced cell apoptosis and senescence. In addition, β-elemene inhibited the expression of IGF1R and Bcl-2, and promoted the expression of Cleaved Caspase-3 and senescence-related proteins (p27, p16, p53 and p21), and these effects were reversed by overexpression of IGF1. Conclusionβ-elemene induced apoptosis and senescence of triple-negative breast cancer cells through IGF1/IGF1R pathway.

Testosterone protects cardiomyocytes against hydrogen peroxide-induced aging by upregulating IGF1 and SIRT1 pathways.

To investigate the role of IGF1 and SIRT1 pathways in protection of hydrogen peroxide (H2O2)-induced aging in H9c2 rat cardiomyocyte cells by testosterone. The cells were treated with testosterone or up- or down-regulated for the IGF1 and SIRT1 genes and assessed for apoptosis, aging andexpression of relevant genes. Aging was induced and the expression of SIRT1 and IGF1 was down-regulated after H2O2 treatment in H9c2 cells. The aging was attenuated in a dose-dependent manner after the cells were exposed to testosterone. Down-regulation of SIRT1 and IGF1expression was offset inthe H2O2-treated cells co-treated with testosterone. Up- or down-regulation of IGF1 significantly reduced or increased senescence-associated beta-galactosidase (SA-β-gal) cells and the ROS level, respectively. In addition, SIRT1 expression was regulated by IGF1 expression. Down- or up-regulation of SIRT1 significantly decreased or increased the IGF1 levels, respectively. Furthermore, after IGF1 and SIRT1 knockdown, testosterone did not protect the cells from senescence. Testosterone, and overexpression of IGF1 and SIRT1 also up-regulated the expression of the fetal genes SERCA2 and MYH6 and down-regulated the expression of the ACTA1 and MYH7 genes. Our data indicate that testosterone can attenuate cardiomyocyte aging induced by H2O2 and up-regulate SIRT1 and IGF1. The IGF1and SIRT1pathway may be new targets to treat heart aging and heart failure.

Manipulation of Igf‐1 Expression in the Placenta and Impact on the Fetal Brain

The placenta is an essential organ involved in mammalian development in utero. The main function of the placenta is the control of the transfer of nutrients and waste between mother and fetus, and production and delivery of hormones and growth factors. There is a lack of research that investigates the role of maternal and fetal genetics and molecular biology of the placenta’s impact on fetal neurodevelopment. Igf‐1 is a gene involved in mediating fetal development as well as growth of the brain. It is also involved in regulation of placental growth and transport. The placenta is the main source of fetal Igf‐1. Igf‐1 gene expression is altered in some individuals with autism spectrum disorder (ASD) which may reflect a role of Igf‐1 in ASD etiology. We previously found that prenatal stress, a risk factor for ASD, increased placental Igf‐1 expression and increased proliferation of striatal neural progenitors which express Igfreceptors. Developmental striatal changes are found in ASD. We therefore hypothesized that placental alterations in Igf‐1 lead to ASD‐relevant brain changes.MethodsWe examined this through the use of CRISPR Igf‐1 overexpression or control plasmids directly injected in mouse placenta on embryonic day 12, with subsequent tracking of changes in placenta, fetal body, and fetal brain. Igf‐1 overexpression in placenta had a variable trajectory. While placental weight was unaffected by Igf‐1 overexpression at E18, we found developmental and morphological changes of the embryo, including larger body and larger size and altered morphology of the head (macrocephaly) at E18. Brain volume measures demonstrate a range of effects on the primordial cortex and striatum at E14 and E18. One outcome of this work is advancements in methodology for understanding how placental genetics affect the development of the fetal brain. We also conclude that placental Igf‐1 expression does influence offspring growth and ASD‐relevant brain outcomes which suggests a role for placental genetics in neurodevelopmental disorders.

The Overexpression of Insulin-Like Growth Factor-1 and Neurotrophin-3 Promote Functional Recovery and Alleviate Spasticity After Spinal Cord Injury.

ObjectiveThis study was conducted to investigate the effects of the exogenous overexpression of nerve growth factors NT-3 and IGF-1 on the recovery of nerve function after spinal cord injury (SCI) and identify the potential mechanism involved.MethodsSixty-four female SD rats were randomly divided into four groups: an SCI group, an adeno-associated viral (AAV)-RFP and AAV-GFP injection group, an AAV-IGF-1 and AAV-NT-3 injection group, and a Sham group. After grouping, the rats were subjected to a 10-week electrophysiological and behavioral evaluation to comprehensively evaluate the effects of the intervention on motor function, spasticity, mechanical pain, and thermal pain. Ten weeks later, samples were taken for immunofluorescence (IF) staining and Western blot (WB) detection, focusing on the expression of KCC2, 5-HT2A, and 5-HT2C receptors in motor neurons and the spinal cord.ResultsElectrophysiological and behavioral data indicated that the AAV-IGF-1 and AAV-NT-3 groups showed better recovery of motor function (P < 0.05 from D14 compared with the AAV-RFP + AAV-GFP group; P < 0.05 from D42 compared with SCI group) and less spasticity (4–10 weeks, at 5 Hz all P < 0.05 compared with SCI group and AAV- RFP + AAV-GFP group) but with a trend for more pain sensitivity. Compared with the SCI group, the von Frey value result of the AAV-IGF-1 and AAV-NT-3 groups showed a lower pain threshold (P < 0.05 at 4–8 weeks), and shorter thermal pain threshold (P < 0.05 at 8–10 weeks). IF staining further suggested that compared with the SCI group, the overexpression of NT-3 and IGF-1 in the SCI-R + G group led to increased levels of KCC2 (p < 0.05), 5-HT2A (p < 0.05), and 5-HT2C (p < 0.001) in motor neurons. WB results showed that compared with the SCI group, the SCI-R + G group exhibited higher expression levels of CHAT (p < 0.01), 5-HT2A (p < 0.05), and 5-HT2C (p < 0.05) proteins in the L2-L6 lumbar enlargement.ConclusionData analysis showed that the overexpression of NT-3 and IGF-1 may improve motor function after SCI and alleviate spasms in a rat model; however, these animals were more sensitive to mechanical pain and thermal pain. These behavioral changes may be related to increased numbers of KCC2, 5-HT2A, and 5-HT2C receptors in the spinal cord tissue. The results of this study may provide a new theoretical basis for the clinical treatment of SCI.

IGF-1 Gene Transfer Modifies Inflammatory Environment and Gene Expression in the Caudate-Putamen of Aged Female Rat Brain.

Brain aging is characterized by chronic neuroinflammation caused by activation of glial cells, mainly microglia, leading to alterations in homeostasis of the central nervous system. Microglial cells are constantly surveying their environment to detect and respond to diverse signals. During aging, microglia undergoes a process of senescence, characterized by loss of ramifications, spheroid formation, and fragmented processes, among other abnormalities. Therefore, the study of changes in microglia during is of great relevance to understand age-related declines in cognitive and motor function. We have targeted the deleterious effects of aging by implementing IGF-1 gene transfer, employing recombinant adenoviral vectors (RAds) as a delivery system. In this study, we performed intracerebroventricular (ICV) RAd-IGF-1 or control injection on aged female rats and evaluated its effect on caudate-putamen unit (CPu) gene expression and inflammatory state. Our results demonstrate that IGF-1 overexpression modified aged microglia of the CPu towards an anti-inflammatory condition increasing the proportion of double immuno-positive Iba1+Arg1+ cells. We also observed that phosphorylation of Akt was increased in animals treated with RAd-IGF-1. Moreover, IGF-1 gene transfer was able to regulate CPu pro-inflammatory environment in female aged rats by down-regulating the expression of genes typically overexpressed during aging. RNA-Seq data analysis identified 97 down-modulated DEG in the IGF-1 group as compared to the DsRed one. Interestingly, 12 of these DEG are commonly overexpressed during aging, and 9 out of 12 are expressed in microglia/macrophages and are involved in different processes that lead to neuroinflammation and/or neuronal loss. Finally, we observed that IGF-1 overexpression led to an improvement in motor functions. Although further studies are necessary, with the present results, we conclude that IGF-1 gene transfer is modifying both the pro-inflammatory environment and activation of microglia/macrophages in CPu. In this regard, IGF-1 gene transfer could counteract the neuroinflammatory effects associated with aging and improve motor functions in senile animals.

Overexpression of IGF-1 During Early Development Expands the Number of Mammary Stem Cells and Primes them for Transformation.

Insulin-like growth factor I (IGF-1) has been implicated in breast cancer due to its mitogenic and anti-apoptotic effects. Despite substantial research on the role of IGF-1 in tumor progression, the relationship of IGF-1 to tissue stem cells, particularly in mammary tissue, and the resulting tumor susceptibility has not been elucidated. Previous studies with the BK5.IGF-1 transgenic (Tg) mouse model reveals that IGF-1 does not act as a classical, post-carcinogen tumor promoter in the mammary gland. Pre-pubertal Tg mammary glands display increased numbers and enlarged sizes of terminal end buds, a niche for mammary stem cells (MaSCs). Here we show that MaSCs from both wild-type (WT) and Tg mice expressed IGF-1R and that overexpression of Tg IGF-1 increased numbers of MaSCs by undergoing symmetric division, resulting in an expansion of the MaSC and luminal progenitor (LP) compartments in pre-pubertal female mice. This expansion was maintained post-pubertally and validated by mammosphere assays in vitro and transplantation assays in vivo. The addition of recombinant IGF-1 promoted, and IGF-1R downstream inhibitors decreased mammosphere formation. Single-cell transcriptomic profiles generated from 2 related platforms reveal that IGF-1 stimulated quiescent MaSCs to enter the cell cycle and increased their expression of genes involved in proliferation, plasticity, tumorigenesis, invasion, and metastasis. This study identifies a novel, pro-tumorigenic mechanism, where IGF-1 increases the number of transformation-susceptible carcinogen targets during the early stages of mammary tissue development, and "primes" their gene expression profiles for transformation.

Let-7b-5p suppresses the proliferation and migration of pulmonary artery smooth muscle cells via down-regulating IGF1

ObjectivesSome previous studies indicated that the excessive proliferation and migration of Pulmonary Artery Smooth Muscle Cells (PASMCs) could be observed in pulmonary artery intima after Pulmonary Embolism (PE) occurred. In addition, recent studies identified some miRNAs that are differentially expressed in the blood of PE patients, which might be used as a diagnostic biomarker for PE, including let-7a-5p, let-7b-5p, and miR-150-5p. Hence, the authors sought to explore the effects of let-7b-5p in PASMC proliferation and migration and the corresponding regulatory mechanism. MethodsPlatelet-Derived Growth Factor (PDGF) was utilized to induce the hyper-proliferation model in PASMCs. The mRNA and protein expression levels were detected by RT-qPCR and western blot, respectively. The proliferation of PASMCs was evaluated by the detection of PCNA expression, as well as CCK-8 and Edu assays. Wound healing and Transwell assays were exploited to assess the migration ability of PASMCs. The targets of let-7b-5p were predicted based on two bioinformatics online tools. Dual-luciferase and Ago2 pull-down assays were applied to confirm the interaction between let-7b-5p and IGF1. Results40 ng/mL PDGF was selected as the optimal concentration to induce PASMCs. let-7b-5p mimics suppressed the proliferation and migration of PDGF-induced PASMCs, while let-7b-5p inhibitor led to the opposite result. In further mechanism exploration, IGF1 was predicted and confirmed as the direct target gene of let-7b-5p. The promotion role of IGF1 overexpression on the proliferation and migration of PDGF-induced PASMCs was dramatically countered by let-7b-5p mimics. Conclusionlet-7b-5p prohibits the proliferation and migration of PDGF-induced PASMCs by modulating IGF1.

Skeletal stem cell fate defects caused by Pdgfrb activating mutation.

Autosomal dominant PDGFRβ gain-of-function mutations in mice and humans cause a spectrum of wasting and overgrowth disorders afflicting the skeleton and other connective tissues, but the cellular origin of these disorders remains unknown. We demonstrate that skeletal stem cells (SSCs) isolated from mice with a gain-of-function D849V point mutation in PDGFRβ exhibit colony formation defects that parallel the wasting or overgrowth phenotypes of the mice. Single-cell RNA transcriptomics with SSC-derived polyclonal colonies demonstrates alterations in osteogenic and chondrogenic precursors caused by PDGFRβD849V. Mutant cells undergo poor osteogenesis in vitro with increased expression of Sox9 and other chondrogenic markers. Mice with PDGFRβD849V exhibit osteopenia. Increased STAT5 phosphorylation and overexpression of Igf1 and Socs2 in PDGFRβD849V cells suggests that overgrowth in mice involves PDGFRβD849V activating the STAT5-IGF1 axis locally in the skeleton. Our study establishes that PDGFRβD849V causes osteopenic skeletal phenotypes that are associated with intrinsic changes in SSCs, promoting chondrogenesis over osteogenesis.

Abstract 13092: Macrophage Specific IGF1 Overexpression on ApoE Deficient Mice Decreases Atherosclerosis, Reduces CXCL12 Chemokine Expression, and Increases Cholesterol Efflux

Increased bioavailability of Insulin Like Growth Factor I (IGF1) has been shown to reduce cardiovascular events. Systemic IGF1 administration in ApoE deficient (Apoe -/- ) mice fed a high fat diet reduced atherosclerosis and reduced plaque macrophages. Results of our previous in vitro experiments suggest that macrophages play a predominant role in mediating IGF1 effects in atherosclerotic plaque. We hypothesized that increasing IGF1 levels strictly in macrophages will prevent atherosclerosis. After breeding a novel macrophage-specific IGF1 overexpressing transgenic mouse to an Apoe -/- background (MF-IGF1 mice), we assessed atherosclerotic plaque burden, stability, and monocyte recruitment. Macrophage IGF1 overexpression downregulated plaque burden by 30% (P&lt;0.01), reduced plaque macrophages by 47% (P&lt;0.001) and promoted a stable plaque phenotype. Monocyte recruitment was reduced by 70% (P&lt;0.05) in MF-IGF1 mice and was associated with a decrease in circulating levels of CXC Chemokine Ligand 12 (CXCL12) (27% reduction, P&lt;0.05). CXCL12 protein levels were reduced in plaque and peritoneal macrophages in MF-IGF1 mice. IGF1 completely blocked oxidized low-density lipoprotein (oxLDL)-dependent increase of CXCL12 mRNA transcription (98% reduction, P&lt;0.01) and IGF1 treatment reduced CXCL12 protein (56% decrease, P&lt;0.001) in vitro. ATP-binding cassette transporter A1 (ABCA1) is the key cholesterol transporter mediating macrophage cholesterol efflux and CXCL12 reduces its expression. We found that peritoneal macrophages isolated from MF-IGF1 mice have a 2 fold increase in ABCA1 protein levels. We loaded peritoneal macrophages with oxLDL to measure changes in cholesterol efflux and found that MF-IGF1 mice have a 42% increase in efflux (P&lt;0.01). We also found a 27% increase in cholesterol efflux in IGF1 (100 ng/mL) treated THP-1 cells (P&lt;0.01) with Apolipoprotein AI as a cholesterol acceptor. Overall, our results indicate that macrophage IGF1 reduces atherosclerosis and decreases CXCL12, a chemokine newly implicated in atheroprogression. IGF1 potentially exerts its atheroprotective effect via this reduction in CXCL12 by reducing monocyte recruitment and by increasing ABCA1, thereby increasing cholesterol efflux capacity.

Insulin-like growth factor 1 promotes neural differentiation of human stem cells from the apical papilla

ObjectiveInsulin-like growth factor 1 (IGF1) is one of the vital factors in regenerative endodontics. Previous studies have focused on the role of IGF1 in the mineralization of dental tissues. However, the role of IGF1 in the neural differentiation of dental stem cells was little discussed. DesignIGF1 was overexpressed in human stem cells from the apical papilla (hSCAPs) by lentivirus and knocked down in hSCAPs by small interfering RNA. The neural differentiation level of hSCAPs was investigated histologically by HE staining and Nissl staining after neural induction for 3 days. The expression of proteins was examined by western blot and immunofluorescence. ResultsIGF1 promoted neural differentiation of hSCAPs, more cell processes and Nissl-positive body stained cells. IGF1 overexpression could both promote glial differentiation in hSCAPs, characterized by the increase of S100β and GFAP proteins, and neuronal differentiation, characterized by the increase of βIII-tubulin and functional GAD67/vGLUT1 proteins. Conversely, IGF1 knockdown suppressed both glial and neuronal differentiation. IGF1 activated AKT to regulate the early neural differentiation of hSCAPs. ConclusionsThe results indicate IGF1 could promote neural differentiation of hSCAPs by activating AKT signaling and provide a cue for the candidate of induced neural seeding cells in regenerative endodontics.

Macrophage Specific IGF‐1 Overexpression Decreases Atherosclerosis, CXCL12 Chemokine, And Increases Cholesterol Efflux In ApoE Deficient Mice

Increased bioavailability of Insulin Like Growth Factor (IGF-1) has been shown to decrease cardiovascular event risk. We have shown that systemic IGF-1 administration reduced atherosclerosis in ApoE deficient (Apoe-/-) mice fed a high fat diet and that those animals have reduced plaque macrophages. Thus, we have shown that IGF-1 is atheroprotective, but cell-specific mechanism(s) mediating IGF-1's effect need to be identified. IGF-1 interacts with major cell types in atherosclerotic plaque: macrophages, smooth muscle cells, and endothelial cells. Results of our previous in vitro experiments suggest that macrophages play a predominant role in mediating IGF-1 effects. We hypothesized that increasing IGF-1 levels strictly in macrophages will prevent atherosclerosis. Using a novel macrophage-specific IGF-1 overexpressing transgenic mouse bred to an Apoe-/- background (MF-IGF1 mice), we assessed atherosclerotic plaque burden, stability, and monocyte recruitment. We isolated plaque using laser capture microdissection and we analyzed monocyte recruitment via intravenous injection of fluorescent red beads among other traditional techniques. Macrophage IGF-1 overexpression downregulated plaque burden by 30% (P<0.01), reduced plaque macrophages by 47% (P<0.001) and promoted a stable plaque phenotype. Monocyte recruitment was reduced by 70% (P<0.05) in MF-IGF1 mice and was associated with a decrease in circulating levels of CXC Chemokine Ligand 12 (CXCL12) (27% reduction compared to control, P<0.05). CXCL12 protein levels were reduced in plaque and peritoneal macrophages in MF-IGF1 mice. IGF-1 completely blocked oxidized low-density lipoprotein (oxLDL)-dependent increase of CXCL12 mRNA transcription (98% reduction vs. control, P<0.01) and IGF-1 treatment reduced CXCL12 protein (56% decrease vs. control, P<0.001)in vitro. ATP-binding cassette transporter A1 (ABCA1) is the key cholesterol transporter mediating macrophage cholesterol efflux. We found that peritoneal macrophages isolated from MF-IGF1 mice have a 2-fold increase in ABCA1 protein levels. To study whether IGF-1 changes macrophage cholesterol efflux, we loaded THP-1 cells with oxLDL and then attached a fluorescent label to measure changes in efflux. We found a 27% increase in cholesterol efflux in IGF-1 (100ng/mL)-treated cells (P<0.01) when using Apolipoprotein A I as a cholesterol acceptor. Overall, our results indicate that macrophage IGF-1 reduces atherosclerosis and decreases CXCL12, a chemokine newly implicated in atheroprogression. CXCL12 downregulates ABCA1 expression. IGF-1 potentially exerts its atheroprotective effect via this reduction in CXCL12 by reducing monocyte recruitment and by increasing ABCA1 and thereby increasing cholesterol efflux capacity.

Insulin-like growth factor-1 alleviates hepatocyte senescence by regulating intranuclear p53-progerin pathway

To construct cellular senescence model by stimulating primary hepatocytes with hydrogen peroxide (H(2)O(2)). Primary hepatocytes were transfected with p53 siRNA, progerin siRNA or IGF-1 adenovirus vector. The number of SA-β-Gal stained positive cells and the expression of p53 and progerin were detected. The results showed that p53 siRNA and progerin siRNA had knocked-down the expression of p53 and progerin, and had alleviated the hepatocyte senescence. Transfection of insulin-like growth factor (IGF)-1 adenovirus vector into primary hepatocytes had overexpressed IGF-1, and had alleviated the number of SA-β-Gal-positive cells. The expression of p53 and progerin was down-regulated in the nucleus, while the expression of p53 was up-regulated in the cytoplasm. The co-precipitation and co-localization of p53 and progerin was decreased in the nuclear region of hepatocytes. IGF-1 overexpression can inhibit intranuclear p53 translocation, alleviate the interaction between p53-progerin, and alleviate hepatocyte senescence.