Local Insulin-like Growth Factor Research Articles

Locally Directed Recombinant Adeno- Associated Virus–Mediated IGF-1 Gene Therapy Enhances Osteochondral Repair and Counteracts Early Osteoarthritis In Vivo

Background: Restoration of osteochondral defects is critical, because osteoarthritis (OA) can arise. Hypothesis: Overexpression of insulin-like growth factor 1 (IGF-1) via recombinant adeno-associated viral (rAAV) vectors (rAAV-IGF-1) would improve osteochondral repair and reduce parameters of early perifocal OA in sheep after 6 months in vivo. Study Design: Controlled laboratory study. Methods: Osteochondral defects were created in the femoral trochlea of adult sheep and treated with rAAV-IGF-1 or rAAV-lacZ (control) (24 defects in 6 knees per group). After 6 months in vivo, osteochondral repair and perifocal OA were assessed by well-established macroscopic, histological, and immunohistochemical scoring systems as well as biochemical and micro–computed tomography evaluations. Results: Application of rAAV-IGF-1 led to prolonged (6 months) IGF-1 overexpression without adverse effects, maintaining a significantly superior overall cartilage repair, together with significantly improved defect filling, extracellular matrix staining, cellular morphology, and surface architecture compared with rAAV-lacZ. Expression of type II collagen significantly increased and that of type I collagen significantly decreased. Subchondral bone repair and tidemark formation were significantly improved, and subchondral bone plate thickness and subarticular spongiosa mineral density returned to normal. The OA parameters of perifocal structure, cell cloning, and matrix staining were significantly better preserved upon rAAV-IGF-1 compared with rAAV-lacZ. Novel mechanistic associations between parameters of osteochondral repair and OA were identified. Conclusion: Local rAAV-mediated IGF-1 overexpression enhanced osteochondral repair and ameliorated parameters of perifocal early OA. Clinical Relevance: IGF-1 gene therapy may be beneficial in repair of focal osteochondral defects and prevention of perifocal OA.

Association between Expression of Insulin-like Growth Factor-1 (IGF-1), IGF-1 Receptor (IGF-1R), and Hypertension-Mediated Organ Damage (HMOD) Parameters in Leukocytes and Plasma of Children/Adolescents with Primary Hypertension.

A decrease in IGF-1 is often linked to inflammation. Low systemic and local IGF-1 production and downregulation of IGF-1R expression may precede and predict PH development in children/adolescents. Leukocyte mRNA expression of IGF-1 and its receptor (IGF-1R) and plasma IGF-1 were measured in a group of 39 PH children/adolescents (29 boys and 10 girls) and 35 age-matched normotensive children (19 boys and 16 girls) using the RT-PCR and ELISA tests. The expression of the IGF-1R protein was assessed by flow cytometry. Plasma IGF-1 concentration was evaluated with ELISA. The expression of IGF-1 and IGF-1R and plasma concentrations of IGF-1 did not differ between groups. However, the PH children had a decreased percentage in IGF-1R-bearing lymphocytes (p = 0.02) and monocytes (p = 0.0003), as well as a low density of IGF-R in monocytes (p = 0.02). The IGF-1 expression was negatively correlated with pulse-wave velocity (PWV) (r = -0.49), systolic blood pressure (SBP) (-0.44), and carotid intima-media thickness (cIMT) (-0.43). The IGF-1R expression was negatively correlated with PWV (r = -0.42) and SBP (r = -0.41). Our results suggest that early subclinical hypertensive arterial injury is associated with lower activity of IGF-1-IGF-1R expression and loss of protective actions.

The Pregnancy-Associated Plasma Protein-A (PAPP-A) Story.

Pregnancy-associated plasma protein-A PAPP-A) was first identified in the early 1970s as a placental protein of unknown function present at high concentrations in the circulation of pregnant women. In the mid-to-late 1990s, PAPP-A was discovered to be a metzincin metalloproteinase expressed by many non-placental cells that regulates local insulin-like growth factor (IGF) activity through cleavage of high-affinity IGF binding proteins (IGFBPs), in particular IGFBP-4. With PAPP-A as a cell surface-associated enzyme, the reduced affinity of the cleavage fragments results in increased IGF available to bind and activate IGF receptors in the pericellular environment. This proteolytic regulation of IGF activity is important, since the IGFs promote proliferation, differentiation, migration, and survival in various normal and cancer cells. Thus, there has been a steady growth in investigation of PAPP-A structure and function outside of pregnancy. This review provides historical perspective on the discovery of PAPP-A and its structure and cellular function, highlights key studies of the first 50 years in PAPP-A research, and introduces new findings from recent years.

Effects of Growth Hormone on Adult Human Gonads: Action on Reproduction and Sexual Function.

Growth hormone (GH), which is commonly considered to be a promoter of growth and development, has direct and indirect effects on adult gonads that influence reproduction and sexual function of humans and nonhumans. GH receptors are expressed in adult gonads in some species including humans. For males, GH can improve the sensitivity of gonadotropins, contribute to testicular steroidogenesis, influence spermatogenesis possibly, and regulate erectile function. For females, GH can modulate ovarian steroidogenesis and ovarian angiogenesis, promote the development of ovarian cells, enhance the metabolism and proliferation of endometrial cells, and ameliorate female sexual function. Insulin-like growth factor-1 (IGF-1) is the main mediator of GH. In vivo, a number of the physiological effects of GH are mediated by GH-induced hepatic IGF-1 and local IGF-1. In this review, we highlight the roles of GH and IGF-1 in adult human gonads, clarify potential mechanisms, and explore the efficacy and the risk of GH supplementation in associated deficiency and assisted reproductive technologies. Besides, the effects of excess GH on adult human gonads are discussed as well.

Pregnancy-associated plasma protein-A (PAPP-A) is a key component of an interactive cellular mechanism promoting pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with few effective treatment options. We found a highly significant correlation between pregnancy-associated plasma protein (PAPP)-A expression in IPF lung tissue and disease severity as measured by various pulmonary and physical function tests. PAPP-A is a metalloproteinase that enhances local insulin-like growth factor (IGF) activity. We used primary cultures of normal adult human lung fibroblasts (NHLF) to test the hypothesis that PAPP-A plays an important role in the development of pulmonary fibrosis.Treatment of NHLF with pro-fibrotic transforming growth factor (TGF)-β stimulated marked increases in IGF-I mRNA expression (>20-fold) and measurable IGF-I levels in 72-hconditioned medium (CM). TGF-β treatment also increased PAPP-A levels in CM fourfold (p = 0.004) and proteolytic activity ~2-fold. There was an indirect effect of TGF-β to stimulate signaling through the PI3K/Akt pathway, which was significantly inhibited by both IGF-I-inactivating and PAPP-A inhibitory antibodies.Induction of senescence in NHLF increased PAPP-A levels in CM 10-fold (p = 0.006) with attendant increased proteolytic activity. Thus, PAPP-A is a novel component of the senescent lung fibroblast secretome. In addition, NHLF secreted extracellular vehicles (EVs) with surface-bound active PAPP-A that were increased fivefold with senescence.Regulation of PAPP-A and IGF signaling by TGF-β and cell senescence suggests an interactive cellular mechanism underlying the resistance to apoptosis and the progression of fibrosis in IPF. Furthermore, PAPP-A-associated EVs may be a means of pro-fibrotic, pro-senescent communication with other cells in the lung and, thus, a potential therapeutic target for IPF.

Effects of Astragalus Extract Mixture HT042 on Circulating IGF-1 Level and Growth Hormone Axis in Rats.

Astragalus extract mixture HT042 is a standardized functional food granted by the Korean FDA for promoting “Children’s Height Growth”. In this study, we determined whether HT042 affects circulatory Insulin-like growth factor-1 (IGF-1) after administration and investigated whether Growth hormone (GH), Growth hormone-releasing hormone receptor (GHRH-R), and Growth hormone secretagogue receptor (GHS-R) mRNAs are expressed in the pituitary, and whether Growth hormone-releasing hormone (GHRH) and Somatostatin (SST) are expressed in the hypothalamus. We also evaluated the growth effect of HT042 on endochondral bone formation. Male Sprague-Dawley rats in the control and HT042 groups were orally administered a single dose of the control and HT042, respectively, and those in the recombinant human GH (rhGH) group were subcutaneously injected with rhGH. Tetracycline was injected intraperitoneally 72 h prior to sacrifice to decide endochondral bone formation. To determine the endocrine or paracrine/autocrine mechanism, we evaluated the expression of local BMP-2 and IGF-1, an immunohistochemical study after HT042 administration. It was confirmed that the growth-promoting effect of HT042 can be contributed to the increase in serum IGF-1, which can be stimulated by GH secretion. Administration of HT042 modulated the activity of GHRH-R and GHR-S in the pituitary gland and promoted GH secretion, thereby changing longitudinal growth through GH/IGF-1 mediation. Results for GHRH and SST expression demonstrated that the hypothalamus can be influenced and mediated by HT042 through a complex neuroendocrine regulatory system. In addition, it was confirmed by oral administration for 10 days that HT042 increased bone formation in cartilage, which is important for height growth. The effect of HT042 could be owing to upregulation of local Bone morphogenetic protein-2 (BMP-2) and IGF-1 expression in the growth plate, which could be regarded as a GH-dependent autocrine/paracrine pathway, as well as circulatory IGF-1.

Alteration of organ size and allometric scaling by organ-specific targeting of IGF signaling

The size of an organ is proportional to the other body parts or the whole body. This relationship is known as allometry. Understanding how allometry is determined is a fundamental question in biology. Here we tested the hypothesis that local insulin-like growth factor (Igf) signaling is critical in regulating organ size and its allometric scaling by organ-specific expression of Igf binding protein (Igfbp). Overexpression of Igfbp2a or 5b in the developing zebrafish eye, heart, and inner ear resulted in a disproportional reduction in their growth relative to the body. Stable transgenic zebrafish with lens-specific Igfbp5b expression selectively reduced adult eye size. The action is Igf-dependent because an Igf-binding deficient Igfbp5b mutant had no effect. Targeted expression of a dominant-negative Igf1 receptor (dnIgf1r) in the lens caused a similar reduction in relative eye growth. Furthermore, co-expression of IGF-1 with an Igfbp restored the eye size. Finally, co-expression of a constitutively active form of Akt with Igfbp or dnIgf1r restored the relative eye growth. These data suggest that local Igf availability and Igf signaling activity are critical determinants of organ size and allometric scaling in zebrafish.

Gut Microbiota-Derived Short-Chain Fatty Acids Promote Prostate Cancer Growth via IGF1 Signaling.

Excessive intake of animal fat and resultant obesity are major risk factors for prostate cancer. Because the composition of the gut microbiota is known to change with dietary composition and body type, we used prostate-specific Pten knockout mice as a prostate cancer model to investigate whether there is a gut microbiota-mediated connection between animal fat intake and prostate cancer. Oral administration of an antibiotic mixture (Abx) in prostate cancer-bearing mice fed a high-fat diet containing a large proportion of lard drastically altered the composition of the gut microbiota including Rikenellaceae and Clostridiales, inhibited prostate cancer cell proliferation, and reduced prostate Igf1 expression and circulating insulin-like growth factor-1 (IGF1) levels. In prostate cancer tissue, MAPK and PI3K activities, both downstream of the IGF1 receptor, were suppressed by Abx administration. IGF1 directly promoted the proliferation of prostate cancer cell lines DU145 and 22Rv1 in vitro. Abx administration also reduced fecal levels of short-chain fatty acids (SCFA) produced by intestinal bacteria. Supplementation with SCFAs promoted tumor growth by increasing IGF1 levels. In humans, IGF1 was found to be highly expressed in prostate cancer tissue from obese patients. In conclusion, IGF1 production stimulated by SCFAs from gut microbes influences the growth of prostate cancer via activating local prostate MAPK and PI3K signaling, indicating the existence of a gut microbiota-IGF1-prostate axis. Disrupting this axis by modulating the gut microbiota may aid in prostate cancer prevention and treatment. SIGNIFICANCE: These results suggest that intestinal bacteria, acting through short-chain fatty acids, regulate systemic and local prostate IGF1 in the host, which can promote proliferation of prostate cancer cells.

Megakaryocyte progenitor cell function is enhanced upon aging despite the functional decline of aged hematopoietic stem cells.

SummaryAge-related morbidity is associated with a decline in hematopoietic stem cell (HSC) function, but the mechanisms of HSC aging remain unclear. We performed heterochronic HSC transplants followed by quantitative analysis of cell reconstitution. Although young HSCs outperformed old HSCs in young recipients, young HSCs unexpectedly failed to outcompete the old HSCs of aged recipients. Interestingly, despite substantial enrichment of megakaryocyte progenitors (MkPs) in old mice in situ and reported platelet (Plt) priming with age, transplanted old HSCs were deficient in reconstitution of all lineages, including MkPs and Plts. We therefore performed functional analysis of young and old MkPs. Surprisingly, old MkPs displayed unmistakably greater regenerative capacity compared with young MkPs. Transcriptome analysis revealed putative molecular regulators of old MkP expansion. Collectively, these data demonstrated that aging affects HSCs and megakaryopoiesis in fundamentally different ways: whereas old HSCs functionally decline, MkPs gain expansion capacity upon aging.

Region-specific effects of blocking estrogen receptors on longitudinal bone growth.

Estrogen receptors (ERs) regulate the development of the growth plate (GP) by binding to estrogen, a phenomenon that determines the growth of skeletal bone. However, the exact mechanisms underlying the regulatory effects of ERs on axial and appendicular growth plates during puberty remain unclear. In the present study, the strategy of ERβ blocking resulted in increased longitudinal elongation of the appendicular bone (P < 0.01), whereas ERα blocking suppressed appendicular elongation (P < 0.05). Blocking both ERs did not have opposite effects on axial longitudinal growth. The expression of chondrocyte proliferation genes including collagen II, aggrecan, and Sox9 and hypertrophic marker genes including collagen X, MMP13, and Runx2 was significantly increased in the growth plate of female mice treated with ERβ antagonist compared with that in the GP of control mice (P < 0.05). There were no significant differences in local insulin-like growth factor 1 (IGF-1) expression among these groups (P > 0.05), and Indian hedgehog protein (Ihh) and parathyroid-related protein (PTHrP) expressions differed among these groups (P < 0.05). ERs appeared not to affect axial bone growth during puberty in female mice (P > 0.05). Our data show that the blocking of different ER subtypes might have a region-specific influence on longitudinal appendicular and axial growth.

High-fat diet-fed ovariectomized mice are susceptible to accelerated subcutaneous tumor growth potentially through adipose tissue inflammation, local insulin-like growth factor release, and tumor associated macrophages.

Background: The association between obesity and colorectal cancer (CRC) risk has been well established. This relationship appears to be more significant in men than in women, which may be attributable to sex hormones. However, controlled animal studies to substantiate these claims and the mechanisms involved are lacking.Materials and Methods: MC38 murine colon adenocarcinoma cells were injected subcutaneously into high-fat diet (HFD) fed male, female and ovariectomized (OVX) female C57BL/6 mice.Results: HFD increased tumor growth (main effect) that was consistent with metabolic perturbations (P < 0.01). HFD OVX mice exhibited the most significant tumor growth compared to HFD male and female mice (p < 0.05) and this was associated with increased subcutaneous adipose tissue (p < 0.05). Further, the subcutaneous adipose tissue depots within HFD OVX mice exhibited more severe macrophage associated inflammation compared to female (P < 0.01), but not male mice. Conditioned media from subcutaneous adipose tissue of HFD OVX contained higher IGF-1 levels compared to male (P < 0.01), but not female mice. Finally, HFD OVX mice had increased M2-like gene expression in their tumor-associated macrophages (TAMs) compared to female mice (P < 0.01).Conclusions: This work provides evidences suggesting adiposity, adipose specific IGF-1, macrophage associated adipose inflammation, and TAMs as potential mechanisms driving obesity-enhanced CRC in females lacking ovarian hormones.

SUN-608 Juvenile Toxicity Study of Livoletide: A Peptide Analogue of Unacylated Ghrelin for the Treatment of Hyperphagia in Prader-Willi Syndrome

Background: Prader-Willi syndrome (PWS) is a rare endocrine disorder characterized by hyperphagia and abnormal food-related behaviors that contribute to severe morbidity, early mortality, and significant burdens for patients and caregivers. Dysregulation of acylated ghrelin (AG) and unacylated ghrelin (UAG) in people with PWS and hyperphagia has led to the hypothesis that replacing the relative deficit of UAG observed in this population will reduce hyperphagia. Livoletide is a cyclic, 8 amino acid analogue of UAG being developed as a potential treatment for hyperphagia and food-related behaviors associated with PWS. In a previous Phase 2a study (n=47) in people with PWS, livoletide improved food-related behaviors and hyperphagia scores relative to placebo. An extensive nonclinical safety program to support clinical development of livoletide has been conducted. Here we report the results of study of livoletide in juvenile rats. Methods: Male and female juvenile Wistar rats were administered livoletide (10, 25, or 75 mg/kg/day, subcutaneous) once daily from the age of weaning (postnatal day 21) until 12 weeks of age (n=32/sex/group). Subgroups were sacrificed at the end of the dosing period or after a recovery period. Toxicity was assessed based on local tolerance, clinical observations, body weights, food consumption, tibia length, bone densitometry, behavioral tests, IGF1 (insulin-like growth factor-1), LH (luteinizing hormone), and other endpoints. Macroscopic (necropsy), microscopic/histopathological, and caesarean examinations were also performed. Toxicokinetic (TK) evaluations were performed at various time-points after dosing to assess exposure. Results: Livoletide was not associated with treatment-related clinical signs or any relevant changes in hematological, coagulation, clinical chemistry parameters or urine analysis. Body weight and food consumption were unaffected. Livoletide did not affect systemic concentrations of IGF-1 or LH. No adverse effects of livoletide on bone growth, mating performance, or fertility were observed. Pups delivered by caesarian section did not exhibit abnormalities. Results were consistent with a lack of effect of livoletide on growth hormone signaling. Histological changes were limited to minimal local reversible reactions at injection sites that were non-adverse and observed at low incidence and severity. Conclusions: Livoletide was well-tolerated and not associated with evidence of overt systemic toxicity. The no observed adverse effect level (NOAEL) of 75 mg/kg/day was associated with Cmax and AUC0-24h values of 72.6/83.2 μg/mL and 169/144 μg.h/mL (males/females), respectively. These exposures are >100-fold above the anticipated clinical exposures in the Phase 2b/3 ZEPHYR study, which is enrolling people ages 4 to 65 with PWS.

Decline in Insulin-like Growth Factor-1 (IGF1) from Aged Mesenchymal Stromal Cells Is a Targetable Mechanism to Rescue Hematopoietic Stem Cell Aging

Hematopoietic stem cells (HSCs) are responsible for long-term maintenance and regeneration of the hematopoietic system. Loss of long-term (LT)-HSC function is a major contributor to decline in hematopoietic function with aging, leading to increased risk of infection, poor vaccination response, and increased susceptibility to hematologic malignancies. A number of LT-HSC-intrinsic alterations and LT-HSC-extrinsic changes in the bone marrow (BM) microenvironment have been associated with functional decline in aged LT-HSCs. Outstanding questions in the field are which of these mechanisms cause, rather than are a consequence of, physiological aging and what mechanism(s) represent key therapeutic targets to extend healthy LT-HSC function in older age? Previously, we took the novel approach of examining LT-HSC frequency and function in mice at a wide array of ages with the rationale that interventions to extend LT-HSC function will be most effective starting at or before the age of onset of functional hematopoietic decline. We found that canonical markers of LT-HSC aging significantly accumulate by middle age (9-12mo) in C57BL/6 mice, including increased phenotypic LT-HSC frequency, reduced regenerative capacity, myeloid lineage bias at both transcriptional and functional levels, increased gH2.AX staining, and loss of polarity of CDC42 and tubulin. Furthermore, we found by reciprocal transplantation studies of young LT-HSCs into middle-aged recipient mice and middle-aged LT-HSCs into young recipient mice that LT-HSC-extrinsic changes in the middle-aged BM microenvironment were necessary and sufficient to cause LT-HSC aging. By transcriptome analysis, we identified decreased IGF1 signaling in LT-HSCs as a candidate mechanism causing LT-HSC aging. Here, we systematically identify mesenchymal stromal cells (MSCs) as the major local producer of IGF1 in the BM of young mice and determine that this production is diminished by middle age. To evaluate the specific effect of MSC-produced IGF1 on LT-HSCs, we co-cultured LT-HSCs with Igf1conditional knockout MSCs, which was found to cause increased differentiation of LT-HSCs toward myeloid progenitor cells. In vivo, reduced IGF signaling in the BM microenvironment was modeled by transplantation of wild-type BM cells into Igf1 conditional knockout recipients, which phenocopied myeloid-biased hematopoiesis as observed in middle-aged mice. A similar myeloid-biased hematopoiesis phenotype was observed upon transplant of Igf1r conditional knockout LT-HSCs into wild-type recipients, supporting a model of direct communication between MSCs and LT-HSCs via IGF1 signaling. To determine whether restoration of IGF1 signaling had the capacity to rejuvenate middle-aged LT-HSCs, we applied short-term (24hr) in vitro treatment of recombinant IGF1. IGF1 treatment restored polarity of CDC42 and tubulin, decreased gH2.AX staining, increased in vivo regenerative capacity, and increased lymphoid differentiation potential of middle-aged LT-HSCs at the transcriptional and functional levels. Furthermore, increasing local IGF1 levels in the middle-aged BM microenvironment by transient intrafemoral injection (once per week for 4 wks) restored mature B cell frequency and decreased mature myeloid cell frequency in the BM and peripheral blood, rebalancing the composition of hematopoietic cells to that observed in young mice. At a mechanistic level, short-term IGF1 stimulation of middle-aged LT-HSCs was found to induce phosphorylation of IGF1R and the downstream signaling mediator AKT, and transcriptionally activate PI3K/AKT target genes. Open chromatin profiling by ATAC-seq revealed altered chromatin organization in middle-aged LT-HSCs in response to IGF1 stimulation, altering chromatin accessibility at promoters of genes enriched in intracellular and protein localization, regulation of transport and sequence-specific DNA binding, and enrichment of regulatory regions containing E2F2 binding sites. In summary, our data strongly support that decreased local production of IGF1 in the BM microenvironment causes many hallmarks of LT-HSC aging. We propose that restoration of local IGF1 signaling, or its downstream target pathways, represents an attractive prophylactic strategy for extending hematopoietic healthspan into older age. Disclosures Trowbridge: Fate Therapeutics: Patents &amp; Royalties: patent license.

Effects of ad libitum milk replacer feeding and butyrate supplementation on the epithelial growth and development of the gastrointestinal tract in Holstein calves

Intensive milk feeding and butyrate supplementation in calves stimulate body growth and affect gastrointestinal development. The aim of the present study was to investigate the synergistic effects of ad libitum milk replacer (MR) feeding and butyrate supplementation of MR on rumen and small intestinal growth and on gene expression in the small intestine related to growth and energy metabolism at weaning. Male Holstein calves (n = 32) received colostrum from birth to d 3 of age and MR either ad libitum (Adl) or restrictively (Res; 6 L of MR/d; 12.5% solids) with (AdlB+, ResB+) or without (AdlB-, ResB-) 0.24% butyrate from d 4 until wk 8 of age. From wk 9 to 10, all calves were weaned and were fed 2 L/d until the end of the trial. Concentrate, hay, and water were freely available. At d 80, calves were slaughtered, volatile fatty acids were measured in rumen fluid, and rumen and small intestine samples were taken for histomorphometric measurements. The expression of mRNA associated with the local insulin-like growth factor (IGF) system and glucose metabolism as well as lactase and maltase activities were measured in the intestinal mucosa. The small intestine was 3 m longer in Adl than in Res. In the atrium ruminis, papilla width was greater in Res than in Adl. Villus circumference, cut surface, and height in the duodenum, proximal jejunum, and ileum were greater in Adl than in Res and in the proximal, mid, and distal jejunum and ileum were greater in calves treated with butyrate. Crypt depth in the duodenum and proximal jejunum was greater in Adl than in Res and in the ileum was smaller in calves treated with butyrate. The villus height:crypt depth ratio was greatest in AdlB+ calves. In the proximal and mid jejunum, IGF1 mRNA abundance was lower in calves treated with butyrate. In the proximal jejunum, INSR mRNA abundance was greater in Res than in Adl. The abundance of PCK2 mRNA was greater in Res than in Adl in the duodenum and was greatest in ResB- in the mid jejunum. Lactase activity tended to be greater in Res than in Adl and after butyrate treatment in the proximal jejunum. The results indicated an elevated growth of the small intestinal mucosa at weaning due to intensive milk feeding and butyrate supplementation, and the local IGF system was involved in intestinal growth regulation. Rumen development was not affected by butyrate supplementation of MR and was slightly delayed due to ad libitum MR feeding.

Effects of Eleutherococcus Extract Mixture on Endochondral Bone Formation in Rats.

Eleutherococcus extract mixture (EEM) is an herbal mixture of dried stem of Eleutherococcus sessiliflorus and germinated barley, which has been highly effective, in previous screening and among the traditional medicines to tonify innate qi and acquired qi, respectively. In this study, we investigate the effects of EEM on endochondral bone formation. Female adolescent rats were given EEM, growth hormone or vehicle for 10 days. Tetracycline was intraperitoneally injected to light the fluorescent band 72 h before sacrifice to determine endochondral bone formation. In order to evaluate endocrine or paracrine/autocrine mechanisms, expressions of insulin-like growth factor 1 (IGF1), insulin-like growth factor binding protein 3 (IGFBP3), or bone morphogenetic protein 2 (BMP2) were evaluated after EEM administration in liver or growth plate (GP). EEM oral administration significantly increased endochondral bone formation and proliferative and hypertrophic zonal heights of tibial GP. EEM also upregulated hepatic IGF1 and IGFBP3 mRNA expressions, and IGF1 and BMP2 expressions in GP. Taken together, EEM increases endochondral bone formation through stimulating proliferation and hypertrophy with upregulation of hepatic IGF1 and IGFBP3 expressions. Considering immunohistochemical studies, the effect of EEM may be due to increased local IGF1 and BMP2 expression in GP, which may be considered growth hormone (GH)-dependent endocrine and autocrine/paracrine pathways.

Effects of Siwu decoction on chondrocyte proliferation of growth plate in adolescent rats

Ethnopharmacological relevanceAccording to traditional Korean medicine theory in which children's growth retardation is attributed to blood deficiency, Siwu decoction (SWD), a representative treatment for blood deficiency, was chosen as a sample.Aim of the study: To evaluate the effects of SWD on chondrocyte proliferation of growth plate in adolescent female rats. Materials and methodsFemale adolescent rats were allocated to one of the following four groups; SWD 100 and 300 mg/kg, recombinant human growth hormone, and vehicle for 4 days. Tetracycline was intraperitoneally injected at 48 h before sacrifice to obtain a band exhibiting fluorescence by binding newly formed bone. Bromodeoxyuridine was injected at day 2–4 to mark proliferating chondrocytes. To evaluate possible mechanisms of SWD, expressions of insulin-like growth factor-1 (IGF-1) and bone morphogenetic protein-2 (BMP-2) in the growth plate were examined by immunohistochemistry. ResultsTreatment with SWD significantly increased the number of BrdU-positive chondrocytes and the new bone formation in the proximal growth plate of tibia compared to the vehicle treated control group. SWD also increased the expression of IGF-1 and BMP-2 in the proliferative and hypertrophic zones of the growth plate. ConclusionsSWD 300 mg/kg stimulates chondrocyte proliferation and new bone formation in the growth plate. Immunohistochemical studies indicate that the effects of SWD may be due to upregulation of local IGF-1 and BMP-2 expression in the growth plate, which may be considered as a GH-dependent paracrine-autocrine pathway.

Characterization of mouse pericardial fat: regulation by PAPP-A

Although implicated in cardiovascular disease, little is known about the fat surrounding the heart. In humans, epicardial fat is the visceral fat depot of the heart, which directly contacts the myocardium. This strategically placed fat depot is thought to produce bioactive molecules that could affect cardiac function. A major limitation in understanding the biology of epicardial fat is its restricted access in humans and its seeming absence in commonly-used experimental animal models. Although laboratory mice do not have epicardial fat per se, they do have a fat depot around the heart. In this study, we found that mouse pericardial fat has the molecular signature, small adipocyte size, and resistance to differentiation consistent with visceral fat. In addition, we show that mouse pericardial fat is regulated by pregnancy-associated plasma protein-A (PAPP-A), a key modulator of local insulin-like growth factor bioavailability. PAPP-A is highly expressed in mouse pericardial fat at levels equivalent to those in mesenteric visceral fat and 10-fold higher than in subcutaneous inguinal fat (P = .0003). Cultured pre-adipocytes isolated from pericardial fat show 2-fold increased PAPP-A secretion compared to pre-adipocytes isolated from inguinal fat. Furthermore, PAPP-A knock-out mice fed a high fat diet for 20 weeks have significantly reduced pericardial fat (by 60%; P < .0001) compared to wild-type littermates. There was no significant difference in inguinal fat between wild-type and PAPP-A knock-out mice. These data characterize a new mouse model of visceral-like pericardial fat and lay a foundation for understanding its role in human heart disease.

PAPP-A and cancer.

The zinc metalloproteinase, PAPP-A, enhances local insulin-like growth factor (IGF) action through cleavage of inhibitory IGF-binding proteins, thereby increasing IGF available for IGF receptor-mediated cell proliferation, migration and survival. In many tumors, enhanced IGF receptor signaling is associated with tumor growth, invasion and metastasis. We will first discuss PAPP-A structure and function, and post-translational inhibitors of PAPP-A expression or proteolytic activity. We will then review the evidence supporting an important role for PAPP-A in many cancers, including breast, ovarian and lung cancer, and Ewing sarcoma.

Pregnancy-Associated Plasma Protein-aa Regulates Photoreceptor Synaptic Development to Mediate Visually Guided Behavior.

To guide behavior, sensory systems detect the onset and offset of stimuli and process these distinct inputs via parallel pathways. In the retina, this strategy is implemented by splitting neural signals for light onset and offset via synapses connecting photoreceptors to ON and OFF bipolar cells, respectively. It remains poorly understood which molecular cues establish the architecture of this synaptic configuration to split light-onset and light-offset signals. A mutant with reduced synapses between photoreceptors and one bipolar cell type, but not the other, could reveal a critical cue. From this approach, we report a novel synaptic role for pregnancy-associated plasma protein aa (pappaa) in promoting the structure and function of cone synapses that transmit light-offset information. Electrophysiological and behavioral analyses indicated pappaa mutant zebrafish have dysfunctional cone-to-OFF bipolar cell synapses and impaired responses to light offset, but intact cone-to-ON bipolar cell synapses and light-onset responses. Ultrastructural analyses of pappaa mutant cones showed a lack of presynaptic domains at synapses with OFF bipolar cells. pappaa is expressed postsynaptically to the cones during retinal synaptogenesis and encodes a secreted metalloprotease known to stimulate insulin-like growth factor 1 (IGF1) signaling. Induction of dominant-negative IGF1 receptor expression during synaptogenesis reduced light-offset responses. Conversely, stimulating IGF1 signaling at this time improved pappaa mutants' light-offset responses and cone presynaptic structures. Together, our results indicate Pappaa-regulated IGF1 signaling as a novel pathway that establishes how cone synapses convey light-offset signals to guide behavior.SIGNIFICANCE STATEMENT Distinct sensory inputs, like stimulus onset and offset, are often split at distinct synapses into parallel circuits for processing. In the retina, photoreceptors and ON and OFF bipolar cells form discrete synapses to split neural signals coding light onset and offset, respectively. The molecular cues that establish this synaptic configuration to specifically convey light onset or offset remain unclear. Our work reveals a novel cue: pregnancy-associated plasma protein aa (pappaa), which regulates photoreceptor synaptic structure and function to specifically transmit light-offset information. Pappaa is a metalloprotease that stimulates local insulin-like growth factor 1 (IGF1) signaling. IGF1 promotes various aspects of synaptic development and function and is broadly expressed, thus requiring local regulators, like Pappaa, to govern its specificity.

Changes of insulin-like growth factor 1 axis in chronic kidney disease and its role in skeletal muscle atrophy

Objective: To investigate the changes of insulin-like growth factor 1 (IGF-1) axis in chronic kidney disease (CKD) and its role in skeletal muscle atrophy. Methods: A total of 240 patients with CKD stage 1-5 (without dialysis treatment) were included between August 2016 and February 2017. Serum IGF-1 and IGF-1 binding protein-3 (IGFBP-3) were measured using chemiluminescence, and the influencing factors of serum IGF-1 and IGFBP-3 were analyzed. Besides, male Sprague-Dawley rats (200-250 g) were randomly assigned to the sham-operated control group (Control, n=15) and the 5/6 nephrectomy group (n=15) as CKD animal model. The expressions of local IGF-1 and IGF-1 receptor (IGF-1R) of skeletal muscles were evaluated at the level of transcription and protein by real-time PCR and Western blotting. Results: There was no significant correlation between changes of serum IGF-1 level and estimated glomerular filtration rate (eGFR) (r=-0.066, P=0.307). However, after multivariable adjustment, serum IGFBP-3 increased with decreasing of eGFR (r=-0.181, P=0.005) in adult CKD patients. In multivariate analysis, age, eGFR, serum cholesterol level and 24 h urinary protein quantification were independent factors of serum IGFBP-3 in patients with CKD (R2=0.243, P<0.001). Animal experiments showed that the expression of IGF-1 mRNA and protein decreased in skeletal muscles of CKD rats. Expressions of IGF-1R mRNA and protein were slightly reduced and phosphorylation of IGF-1R was severely impaired in skeletal muscles of CKD rats. Conclusions: IGF-1 levels seem to be independent of renal function, but IGFBP-3 levels increased with decreasing of eGFR, which may cause a low affinity of IGF-1 with IGF-1R in skeletal muscles. Low affinity of IGF-1 with IGF-1R, as well as the decreasing of IGF-1 synthesis could lead to disorders of IGF-1R phosphorylation, and thus cause atrophy of skeletal muscles.