Follistatin-like 1 Research Articles

Persistent Myocardial Production of Follistatin-like 1 Is Associated With Left Ventricular Adverse Remodeling in Patients With Myocardial Infarction: Myocardial production of FSTL1 in AMI patients

BackgroundAlthough animal studies showed that Follistatin-like 1 (FSTL1) exerts cardioprotective effects against ischemic injury, little is known in humans. We examined whether FSTL1 is secreted in an infarcted myocardium and whether its production is associated with left ventricular (LV) remodeling in survivors of acute myocardial infarction. Methods and ResultsFSTL1 levels were measured by enzyme-linked immunosorbent assay in plasma collected from the aortic root and the anterior interventricular vein in 93 patients with anterior acute myocardial infarction. Measurement of FSTL1 levels and left ventriculography were repeated during the early phase (2 weeks) and the chronic phase (6 months) after MI. A persistent increment in FSTL1 levels from the aortic root to the anterior interventricular vein, reflecting FSTL1 production in the infarcted myocardium at both the early and chronic phases, was seen in 22 patients (24%). A linear regression analysis revealed that a persistent transmyocardial increment in FSTL1 levels was significantly associated with percent changes in LV end-diastolic volume index, LV end-systolic volume index, and LV ejection fraction from the early to the chronic phase (r = 0.44, 0.51, and −0.43, respectively, all P < .001). ConclusionsThe persistent production of FSTL1 in the infarcted myocardium was associated with adverse LV remodeling in survivors of acute myocardial infarction.

Effects of acute endurance exercise on follistatin-like 1 and apelin in the circulation and metabolic organs in rats

Context: Follistatin-like 1 (FSTL1) and apelin exert a favourable effect on energy metabolism. Objective: We examined the effects of acute endurance exercise on the levels of FSTL1 and apelin in the serum and metabolic organs of rats. Methods: Rats were divided into two groups: a sedentary control (CON, n = 8) group and exercise (EX, n = 8) group. The EX group was made to run on a treadmill at 15–30 m/min for 35 min. Immediately after exercise, the blood, skeletal muscles, adipose, heart, and liver were collected; the levels of FSTL1 and apelin were measured. Results: Serum FSTL1 and apelin were significantly increased following acute exercise; in contrast, the levels of FSTL1 and apelin in the tissues were not affected. Conclusions: Acute endurance exercise may stimulate the secretion of FSTL1 and apelin into the circulation, however, the origin of their increased secreted levels may not be the metabolic organs.

OR14-01 FSTL3 Neutralizing Antibodies Restore Function to Diabetic Mouse and Human Islets: A New Approach for Treating Diabetes

Activin, GDF11 and myostatin are structurally related members of the TGFbeta superfamily of growth factors with many biological roles in animal models and humans. Their actions are neutralized by extracellular proteins such as follistatin and follistatin like-3 (FSTL3). We have previously demonstrated that genetic inactivation of Fstl3 results in enlarged pancreatic islets containing increased numbers of beta cells that produce more insulin in response to glucose compared to wild type litter mates. We further discovered that at least some of these new beta cells arise via transdifferentiation from alpha cells. We also demonstrated that functional human islets from normal donors produce very high levels of activin. In contrast, activin biosynthesis is vastly reduced and FSTL3 synthesis is significantly increased in human islets from diabetic donors suggesting that activin is critical for normal insulin production. This was substantiated by direct treatment of human diabetic islets with activin which restored their response to glucose. These observations support the hypothesis that an FSTL3 neutralizing antibody would constitute a novel therapeutic approach to curing diabetes through restoring beta cell function as well as accelerating generation of new beta cells through transdifferentiation. To test this hypothesis, we produced a mouse monoclonal antibody that neutralized hFSTL3 (FP-101), thereby releasing bioactive activin, GDF11, and myostatin. We have now tested this antibody for biological activity in vitro on mouse and human islets. We used islets from high fat diet (HFD) treated mice to model diabetes-inducing effects of obesity as well as 24-hour incubation in hyperglycemic (33 mM glucose) medium to create human islets that lose responsiveness to high glucose as a model for human diabetes. In mouse islets we found that stimulation of normal (chow diet) islets by high glucose produced a stimulation index (SI) of 3.5 that was reduced to 2 in HFD islets. Treatment with activin, FP-101, or a commercial polyclonal antibody to mFSTL3 all increased response of HFD islets to elevated glucose and partially restored SI to normal levels. In human islets, hyperglycemia eliminated the normal (2.5 SI) response to high glucose while activin or FP-101 treatments dose-responsively restored this response. These results demonstrate that anti-FSTL3 therapy can restore function to compromised beta cells from mouse and human diabetes models. The observation that activin has the same action as anti-FSTL3 antibody indicates that FP-101 works through enhancing the activin signaling pathway. Finally, these results demonstrate that the FSTL3-activin pathway is an important regulator of beta cell function in humans as well as mice, supporting further development of this therapy as a diabetes treatment.

MiR-524-5p Suppresses Migration, Invasion, and EMT Progression in Breast Cancer Cells Through Targeting FSTL1.

Background: The effects of miR-524-5p on breast cancer (BC) have not been investigated, though studies show that miR-524-5p has an anticancer function. Thus, this study investigated the effects of miR-524-5p on BC cells and its potential molecular mechanism. Materials and Methods: The expression of miR-524-5p from the collected BC samples was determined. Cell counting kit-8 (CCK-8) assay was performed to examine the effect of miR-524-5p on BC cells viability. The target for miR-524-5p was predicted by bioinformatics and further verified by luciferase assay. Wound healing assay and transwell assay were performed to determine cell migration and invasion of BC cells. The expressions of Follistatin-like 1 (FSTL1) and related proteins in epithelial-mesenchymal transition (EMT) were detected by Western blotting and quantitative real-time polymerase chain reaction. Results: MiR-524-5p was low-expressed in BC samples, and upregulation of miR-524-5p suppressed BC cell viability, migration, and invasion. FSTL1 was predicted as a target for miR-524-5p. In addition, overexpressed FSTL1 effectively abolished the effect of miR-524-5p on inhibiting FSTL1 expression, and reversed the inhibitory effects of miR-524-5p on the migration, invasion of BC cells as well as the effect of miR-524-5p on regulating the expressions of matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 9 (MMP9), E-cadherin, and N-cadherin. Conclusions: Our findings suggest that miR-524-5p targeting FSTL1 adversely affects the progression of migration, invasion, and EMT of BC cells, thus, miR-524-5p is possibly a target for BC treatment.

FSTL-1 Attenuation Causes Spontaneous Smoke-Resistant Pulmonary Emphysema.

Rationale: The role of FSTL-1 (follistatin-like 1) in lung homeostasis is unknown.Objectives: We aimed to define the impact of FSTL-1 attenuation on lung structure and function and to identify FSTL-1-regulated transcriptional pathways in the lung. Further, we aimed to analyze the association of FSTL-1 SNPs with lung disease.Methods: FSTL-1 hypomorphic (FSTL-1 Hypo) mice underwent lung morphometry, pulmonary function testing, and micro-computed tomography. Fstl1 expression was determined in wild-type lung cell populations from three independent research groups. RNA sequencing of wild-type and FSTL-1 Hypo mice identified FSTL-1-regulated gene expression, followed by validation and mechanistic in vitro examination. FSTL1 SNP analysis was performed in the COPDGene (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease) cohort.Measurements and Main Results: FSTL-1 Hypo mice developed spontaneous emphysema, independent of smoke exposure. Fstl1 is highly expressed in the lung by mesenchymal and endothelial cells but not immune cells. RNA sequencing of whole lung identified 33 FSTL-1-regulated genes, including Nr4a1, an orphan nuclear hormone receptor that negatively regulates NF-κB (nuclear factor-κB) signaling. In vitro, recombinant FSTL-1 treatment of macrophages attenuated NF-κB p65 phosphorylation in an Nr4a1-dependent manner. Within the COPDGene cohort, several SNPs in the FSTL1 region corresponded to chronic obstructive pulmonary disease and lung function.Conclusions: This work identifies a novel role for FSTL-1 protecting against emphysema development independent of smoke exposure. This FSTL-1-deficient emphysema implicates regulation of immune tolerance in lung macrophages through Nr4a1. Further study of the mechanisms involving FSTL-1 in lung homeostasis, immune regulation, and NF-κB signaling may provide additional insight into the pathophysiology of emphysema and inflammatory lung diseases.

Up-Regulation of FSTL3, Regulated by lncRNA DSCAM-AS1/miR-122-5p Axis, Promotes Proliferation and Migration of Non-Small Cell Lung Cancer Cells.

BackgroundFollistatin-like 3 (FSTL3) binds and inactivates activin, a growth factor with cell growth and differentiation. Previous studies reported that it is overexpressed in invasive breast cancers, and its expression and function in non-small cell lung cancer (NSCLC) remain unclear.Materials and MethodsImmunohistochemistry was employed to probe the expression of FSTL3 in NSCLC tissues. Real-time PCR (RT-PCR) was applied to detect the expression of lncRNA DSCAM-AS1 and miR-122-5p. A549 cells and H1299 cells were used as cell models. The biological influence of FSTL3 on cells was studied using CCK-8 assay, wound healing assay and transwell assay in vitro, respectively. In vivo subcutaneous xenotransplanted tumor model and tail vein injection model in mice were also constructed to validate the roles of FSTL3. Interactions between miR-122-5p and FSTL3, DSCAM-AS1 and miR-122-5p were determined by bioinformatics analysis, RT-PCR, and dual-luciferase reporter assay.ResultsFSTL3 and DSCAM-AS1 were remarkably up-regulated in NSCLC samples, and miR-122-5p was down-regulated. FSTL3 was associated with worse prognosis of NSCLC patients. FSTL3 knockdown markedly inhibited the viability, migration and invasion of NSCLCs in vitro and in vivo. DSCAM-AS1 could down-regulate miR-122-5p via sponging it, and FSTL3 was a target gene of miR-122-5p.ConclusionTaken together, our study identified that FSTL3 was a new oncogene of NSCLC, which was regulated by DSCAM-AS1 and miR-122-5p. These findings suggested that FSTL3, DSCAM-AS1 and miR-122-5p might serve as a new valuable therapeutic target for NSCLC.

FSTL3 Promotes Tumor Cell Proliferation, Invasion, Survival and Associates with Poor Prognosis in Colorectal Cancer Patients

Follistatin like‐3 (FSTL3) is a potent inhibitor that antagonizes TGF‐β family ligands including activin, myostatin and bone morphogenetic proteins. Though usually a secreted glycoprotein, nuclear FSTL3 expression had been noted in several cell types, suggesting the existence of specific intracellular functions of this protein. Colorectal cancer (CRC) is one of the leading malignant tumors worldwide. Its strong metastatic ability and chemoresistance tendency is a major obstacle in clinical treatment. In large cohort survival analyses, we have found that FSTL3 has a significant prognostic predictive power in colorectal cancer at both RNA and protein level. Immunohistochemistry staining of CRC specimens revealed that patients with high FSTL3 expression are significantly associated with poor survival. Our study further showed that knockdown of FSTL3 inhibited the migration and invasion of colon cancer cells and reduced tumorigenesis in vivo. Conversely, ectopic over‐expression of FSTL3 elicited the opposite effects in CRC cells. In addition, the overexpression of FSTL3 was found to confer the resistance to 5‐fluorouracil in CRC cells. mRNA profiling analyses suggested that FSTL3 drives CRC tumorigenesis through various carcinogenesis‐related pathways. Our results unveil the significance of FSTL3 in the oncogenesis of CRC, with implications for its potential use as a diagnostic or prognostic biomarker and also a candidate for therapeutic target in this disease.Support or Funding InformationThis research was supported by Academia Sinica [AS‐SUMMIT‐108].

Myokines as potential indirect biomarkers of myostatin abuse in sport doping: reference ranges in elite athletes

BackgroundMyokines are a class of small proteins mainly produced and released from muscle cells and involved in muscle contractions, exercise‐associated metabolic changes and myogenesis. Among them, myostatin (MYO) is one of the key negative regulators of skeletal muscle cell growth and differentiation. As a consequence, the abuse of myostatin inhibitors as performance‐enhancing agents in sport, and/or the use of pharmaceutical agents or genetic methods blocking myostatin function are presently prohibited by the World Anti‐doping Agency (WADA). No direct method is currently available for the detection of all the many possible strategies of myostatin inhibition. We are here exploring the potential application of human serum myokines as indirect markers of doping. We are here reporting the results of a pilot study aimed to asses baseline serum levels of the principal myokines, and their variability as a function of sex, age and sport discipline.MethodsWe have assayed MYO in human serum, together with a variety of myokines: follistatin‐like 1 (FSTL‐1), musclin (MUS), oncostatin (ONC), osteonectin (OST), irisin (IRI), brain‐derived neurotrophic factor (BDNF), some interleukins (IL‐6 and IL‐15) and the main inhibitor of the members of the TGF‐β superfamily follistatin (FST). Serum samples from elite athletes were assayed through various immunological assays using antibodies specifically directed against the proteins of interest. More specifically, MYO and FST levels were measured by enzyme‐linked immunosorbent assay (ELISA); IRI serum levels by radioimmunoassays (RIA), while the analysis of the other peptides by multiplex cytometric beads array (CBA).ResultsAll analytes resulted measurable in human serum, with the exception of few samples relatively to MUS and IRI. The myokines analyzed showed levels of serum concentration of different order in magnitude: OST and MUS had a concentration lower than 1ng/mL; FST, MYO and IRI reached very few ng/mL of concentration, while BDNF and FSTL‐1 were highly expressed in serum (10–50 ng/mL). No significant differences in myokines serum levels were found between female and male subjects. Our results showed significantly lower levels of FST in subjects under the age of 25 compared to the older ones, but no differences were found for the other proteins. Interestingly the ratio between MYO and FST is higher in the great majority of all the sample analyzed.ConclusionsIn this pilot study we examined a pool of human myokines to assess their variability in serum samples of athletes and their potential feasibility as biomarkers to reveal the manipulation of muscle cells regulators for doping purpose. In general, there were no strong correlations among the myokines studied, despite a PCA analysis showed that a group of 4 myokines (MUS, FSTL‐1, ONC, MYO) were more closely related. These preliminary results suggest that the identification of a range of baseline levels, especially for these 4 myokines, and their longitudinal monitoring, may represent an innovative strategy to reveal the illicit recourse to doping strategies aimed to myostatin inhibition.Support or Funding InformationFederazione Medico Sportiva Italiana

Hsa_circ_0011290 regulates proliferation, apoptosis and glycolytic phenotype in papillary thyroid cancer via miR-1252/ FSTL1 signal pathway

ObjectiveDespite of previous report regarding the aberrant overexpression of hsa_circ_0011290 in thyroid cancer, the regulatory mechanism and mechanistic involvements of which were still elusive currently in papillary thyroid cancer (PTC). Here we set out to characterize expression status and functional contributions of hsa_circ_0011290 in this disease especially through mode-of-action of sponging RNA. MethodsRelative expression of hsa_circ_0011290, microRNA (miR)-1252 and FSTL1 was quantified by real-time polymerase chain reaction. Glucose metabolism was determined by examination of glucose uptake, lactate production and ATP contents. The regulatory effects of miR-1252 on both hsa_circ_0011290 and Follistatin Like 1 (FSTL1) were interrogated by luciferase reporter assay. Direct binding between miR-1252 with hsa_circ_0011290 and FSTL1 transcripts were analyzed by RNA pulldown assay. Protein levels of FSTL1 was examined by Western blots. ResultsAberrant over-expression of hsa_circ_0011290 was associated with advanced stage and unfavorable prognosis of PTC. Knockdown of hsa_circ_0011290 greatly inhibited cell viability, proliferation and stimulated cell apoptosis in PTC cells. Meanwhile, glucose metabolism was significantly switched with decreased glucose uptake and lactate production, and increased ATP contents. We identified miR-1252 as target miR of hsa_circ_0011290, and miR-1252 evidently inhibited expressions of both luciferase reporter and endogenous hsa_circ_0011290, and miR-1252 was negatively regulated by hsa_circ_0011290 vice versa. We further suggested that FSTL1 as direct target of miR-1252, and provided direct evidences in support of binding between miR-1252 with both hsa_circ_0011290 and FSTL1. Through sponging miR-1252, hsa_circ_0011290 was capable of positively modulate FSTL1 expression. Notably, inhibition of miR-1252 completely reversed phenotypic effects of hsa_circ_0011290 knockdown including cell viability, proliferation, apoptosis and glucose metabolisms. ConclusionOur study uncovered the oncogenic contributions of hsa_circ_0011290-miR-1252-FSTL1 in PTCs.

Integration of transcriptome-wide association study and messenger RNA expression profile to identify genes associated with osteoarthritis.

AimsOsteoarthritis (OA) is the most prevalent joint disease. However, the specific and definitive genetic mechanisms of OA are still unclear.MethodsTissue-related transcriptome-wide association studies (TWAS) of hip OA and knee OA were performed utilizing the genome-wide association study (GWAS) data of hip OA and knee OA (including 2,396 hospital-diagnosed hip OA patients versus 9,593 controls, and 4,462 hospital-diagnosed knee OA patients versus 17,885 controls) and gene expression reference to skeletal muscle and blood. The OA-associated genes identified by TWAS were further compared with the differentially expressed genes detected by the messenger RNA (mRNA) expression profiles of hip OA and knee OA. Functional enrichment and annotation analysis of identified genes was performed by the DAVID and FUMAGWAS tools.ResultsWe detected 33 common genes, eight common gene ontology (GO) terms, and one common pathway for hip OA, such as calcium and integrin-binding protein 1 (CIB1) (PTWAS = 0.025, FCmRNA = -1.575 for skeletal muscle), adrenomedullin (ADM) (PTWAS = 0.022, FCmRNA = -4.644 for blood), Golgi apparatus (PTWAS <0.001, PmRNA = 0.012 for blood), and phosphatidylinositol 3' -kinase-protein kinase B (PI3K-Akt) signalling pathway (PTWAS = 0.033, PmRNA = 0.005 for blood). For knee OA, we detected 24 common genes, eight common GO terms, and two common pathways, such as histocompatibility complex, class II, DR beta 1 (HLA-DRB1) (PTWAS = 0.040, FCmRNA = 4.062 for skeletal muscle), Follistatin-like 1 (FSTL1) (PTWAS = 0.048, FCmRNA = 3.000 for blood), cytoplasm (PTWAS < 0.001, PmRNA = 0.005 for blood), and complement and coagulation cascades (PTWAS = 0.017, PmRNA = 0.001 for skeletal muscle).ConclusionWe identified a group of OA-associated genes and pathways, providing novel clues for understanding the genetic mechanism of OA.Cite this article: Bone Joint Res. 2020;9(3):130–138.

Follistatin-like 1: A dual regulator that promotes cardiomyocyte proliferation and fibrosis.

Follistatin-like 1 (FSTL1) is a key factor in maintaining cardiac growth and development. It can be activated by exercise training and has a dual role in promoting cardiomyocyte proliferation and fibrosis, but its underlying mechanism is not fully understood. To elucidate the dual mechanism and target of FSTL1 regulating of cardiomyocyte proliferation and myocardial fibrosis, and the mechanism by which exercise-regulated FSTL1 improves cardiovascular disease, we explored the signal transduction pathway of FSTL1 promoting cardiomyocyte proliferation and fibrosis, and compared the effects of different modes of exercise on the dual role of FSTL1. We believe that the dual role of promoting cardiomyocyte proliferation and fibrosis may be related to the ratio of cardiomyocyte and myocardial interstitial cell proliferation, different stages of the disease, different degrees of fibrosis, immune repair process, and transforming growth factor-β activation. Compared with long-term excessive endurance exercise, moderate resistance exercise can activate cardiomyocyte proliferation pathway through FSTL1, which is one of the effective ways to prevent cardiovascular disease.

Characterization of Mesenchymal Stem Cells Derived from Patients with Cerebellar Ataxia: Downregulation of the Anti-Inflammatory Secretome Profile.

Mesenchymal stem cell (MSC) therapy is a promising alternative approach for the treatment of neurodegenerative diseases, according to its neuroprotective and immunomodulatory potential. Despite numerous clinical trials involving autologous MSCs, their outcomes have often been unsuccessful. Several reports have indicated that MSCs from patients have low capacities in terms of the secretion of neurotrophic or anti-inflammatory factors, which might be associated with cell senescence or disease severity. Therefore, a new strategy to improve their capacities is required for optimal efficacy of autologous MSC therapy. In this study, we compared the secretory potential of MSCs among cerebellar ataxia patients (CA-MSCs) and healthy individuals (H-MSCs). Our results, including secretome analysis findings, revealed that CA-MSCs have lower capacities in terms of proliferation, oxidative stress response, motility, and immunomodulatory functions when compared with H-MSCs. The functional differences were validated in a scratch wound healing assay and neuron-glia co-cultures. In addition, the neuroprotective and immunoregulatory protein follistatin-like 1 (FSTL1) was identified as one of the downregulated proteins in the CA-MSC secretome, with suppressive effects on proinflammatory microglial activation. Our study findings suggest that targeting aspects of the downregulated anti-inflammatory secretome, such as FSTL1, might improve the efficacy of autologous MSC therapy for CA.

BIOMARKERS OF DISEASE ACTIVITY IN SYSTEMIC SCLEROSIS

Systemic sclerosis (SSc) is an autoimmune disease characterized by vasculopathy and uncontrolled cutaneous and internal organs fibrosis. Diagnosis of SSc in an early phase can be difficult because of a lack of typical symptoms. The delay in diagnosis and treatment of SSc may lead to uncontrolled progression of the disease, thus identification of possible early indicators of skin and organ involvement to prevent their further damage is necessary. The aim of this study is to review the latest biomarkers of organ involvement in SSc. In patients with lung fibrosis lung-epithelial-derived surfactant protein (SP-D), the glycoprotein Krebs von den Lungen-6 (KL-6), and chemokine ligands 2, 4 and 18 (CCL2, CXCL4, CCL18) are elevated, while in patients with skin fibrosis serum levels of heat shock protein 27 (Hsp27), interleukin 16 (IL-16), and IgG-galactosylation ratio are increased. Adiponectin concentration is inversely correlated with the intensity of cutaneous fibrosis. Skin gene profiling also seems very promising. In patients with heart involvement increased serum levels of brain natriuretic peptide (BNP) are present, as well as raised Midkine and Follistatin-like 3 (FSTL3) proteins, ratios of Cu/Se and ceruloplasmin(CP) /Circulating selenoprotein P(SELENOP) and higher whole blood viscosity level. Elevated calprotectin levels are found in individuals with gastrointestinal involvement. Increased levels of chemerin and ARA autoantibodies are associated with renal involvement, whereas high levels of adhesion molecules are found in patients with scleroderma renal crisis (SRC). Currently there are no biomarkers in use that can specifically identify the early involvement of organs.

Follistatin-like 3, an activin A binding protein, is involved in early pregnancy loss

BackgroundEarly pregnancy loss (EPL), a common and severe complication in pregnancy, has a long-term personal and social impact. It was previously reported that follistatin-like 3(FSTL3), an activin A binding protein, contributes to the invasion and migration of trophoblast. Simultaneously, activin A induces the release of FSTL3 and the elevated activin A is found to be associated with pregnancy loss in women. This study aimed to identify the roles of FSTL3 in the establishment and maintenance of pregnancy, and to determine whether FSTL3 is involved in the pathophysiology of EPL. MethodsEndometrial Ishikawa cells and JAR cells were cultured and FSTL3 siRNA was used to silence FSTL3. The trophoblast spheroids mimicking embryos were used in an embryonic adhesion system. The system aimed to investigate the role of FSTL3 silence on embryonic adhesion onto endometrial cell in vitro. The ICR mice model in vivo was used to investigate whether the FSTL3 works in embryonic implantation. The western blotting was used to determine the expression of FSTL3 and activin A. ResultsIn the in vitro study, silence of FSTL3 in JAR cells significantly reduced the number of trophoblast spheroids adhered onto Ishikawa cells compared with the scramble siRNA. For the in vivo study, the number of embryos implanted in the uterine horn injected with FATL3 siRNA mixture was significantly less than that in control group. In the case control study, both the expression of FSTL3 and activin A in EPL women were significantly higher than that in controls. ConclusionsFSTL3 plays a biological role in the establishment and maintenance of normal pregnancy. Moreover, FSTL3 may be involved in the early pregnancy loss via neutralizing the elevated activin A.

Follistatin-like 1 in Cardiovascular Disease and Inflammation.

Follistatin-like 1 (FSTL1), a secreted glycoprotein, has been shown to participate in regulating developmental processes and to be involved in states of disease and injury. Spatiotemporal regulation and posttranslational modifications contribute to its specific functions and make it an intriguing candidate to study disease mechanisms and potentially develop new therapies. With cardiovascular diseases as the primary cause of death worldwide, clarification of mechanisms underlying cardiac regeneration and revascularization remains essential. Recent findings on FSTL1 in both acute coronary syndrome and heart failure emphasize its potential as a target for cardiac regenerative therapy. With this review, we aim to shed light on the role of FSTL1 specifically in cardiovascular disease and inflammation.

Data-independent acquisition of the proteomics of spleens from chickens infected by avian leukosis virus.

Immunosuppression caused by avian leukemia virus J subgroup (ALV-J) infection includes atrophy or regeneration disorders of the lymphoid organs, decreased immune response, and termination of B lymphocyte maturation process and inhibition of T-lymphocyte development. The regulatory mechanism of the related resistance genes and protein expression is not clear. While searching for a molecular marker for the immune response to ALV-J infection, we detected differentially expressed proteins (DEPs) of spleens from chicken infected by ALV-J at 15th day and 30th day by the data-independent acquisition technique. Approximately 220 DEPs from the spleens of chickens infected by ALV-J were detected. To find a relatively stable biomarker molecule, we summarized the DEPs at two timepoints and selected activating signal cointegrator 1 complex subunit 3 (ASCC3), TBC1 domain family member 2 (TBC1D2), MHC class II beta chain 1 (BLB2), ensconsin (MAP7), complement component 1 Q subcomponent B chain (C1QB), and Follistatin-like 1 (FSTL1) from both comparisons for protein interaction network analysis. ASCC3, BLB2, C1QB, and FSTL1 were potential biomarkers for the complex infection mechanism of ALV-J and the dynamic immune mechanism of the body.

Effects of acute sprint interval exercise on follistatin-like 1 and apelin secretions

Context Insulin resistance is the main triggering factor for type 2 diabetes. Recently, it has been reported that high-intensity sprint interval training (SIT) was effective for improving glucose metabolism and insulin sensitivity despite lower training volume. However, the mechanisms underlying the SIT-induced increases in glucose metabolism and insulin sensitivity have not been well-understood. Follistatin-like 1 (FSTL1) and apelin, which are novel myokines, have a favourable effect on glucose metabolism. Objective We examined the impact of acute SIT on FSTL1 and apelin secretions. Methods Eight healthy men were enrolled in this study. The subjects performed acute SIT consisting of four 30-s all-out cycling efforts with 4-min rest periods. Blood samples were obtained before and after the acute SIT to measure FSTL1 and apelin concentrations. Results FSTL1 and apelin both significantly increased following acute SIT. Conclusion Acute SIT may be an effective stimulus for increasing of FSTL1 and apelin secretions.

312-OR: Functional Decline in Brown Adipose Progenitors during BAT Remodeling

In humans, there is a striking decrease in the prevalence and activity of brown adipose tissue (BAT) with age and obesity; however, the cellular and molecular mechanisms of BAT remodeling are almost completely unknown. Rodent models have been widely used to study BAT but they possess constitutively active BAT throughout life even at thermoneutrality; therefore, complementary animal models that possess characteristics of human BAT remodeling are needed. Here, we found that BAT progressively whitened in rabbits in a similar manner as in humans. As rabbits mature, preadipocytes in BAT displayed reduced capacity to be differentiated into brown adipocytes, when transplanted into immune-deficient mice. RNA-sequencing of brown preadipocytes identified that, during BAT remodeling, genes enriched for muscle contraction and mitochondrial function were down-regulated, while genes involved in lipid and amino acid metabolism were up-regulated. Single-cell RNA sequencing discovered a unique population of stromal vascular fraction cells specifically expressing genes regulating muscle and mitochondrial function. Knocking down these genes in rabbit brown preadipocytes blunted their ability to become mature brown adipocytes. We also identified follistatin like 1 (FSTL1) as a novel “batokine” that is specifically expressed by brown preadipocytes but not mature brown adipocytes. FSTL1 gradually reduced its expression when BAT whitens in rabbits, but was stably expressed in mouse BAT during life. Deleting FSTL1 specifically in the Myf5 lineage in mice reduced BAT size, UCP1 expression, and body temperature in newborns, suggesting the constitutive expression of FSTL1 prevents BAT whitening in mice. Taken together, we identify potential molecular mechanisms underlying functional decline in the browning ability of preadipocytes that contribute to BAT remodeling in rabbits and possibly humans. Disclosure Z. Huang: None. Z. Zhang: None. H. Ruan: None. Funding American Diabetes Association (1-18-IBS-167 to H-B.R.)

Aerobic Training-induced Increase In Follistatin-like 1 Secretion Is Associated With eNOS Phosphorylation In Diabetic Rats.

INTRODUCTIN: Aerobic exercise training reduces arterial stiffness via elevation of nitric oxide (NO) production in type 2 diabetes. Follistatin-like 1 (FSTL1) is a muscle-derived myokine and stimulates protein kinase B (Akt)/endothelial nitric oxide synthase (eNOS) signaling via binding to receptor (DIP2A) in endothelial cells. However, it is unclear whether FSTL1 secretion induced by aerobic exercise training is related to a reduction of arterial stiffness in type 2 diabetic rats. PURPOSE: This study aimed to investigate whether FSTL1 secretion induced by aerobic exercise training is related to a reduction of arterial stiffness with activation of aortic eNOS phosphorylation in type 2 diabetic rats. METHODS: Twenty-week-old male type 2 diabetic (OLETF) rats were randomly divided into sedentary control (OLETF-Con: n=7) and aerobic exercise training (OLETF-Ex: treadmill running for 60min at 25m/min, 5days/week: n=7) groups. In addition, 7 male LETO rats were used as healthy sedentary control. After 8-week experiment, we measured carotid-femoral pulse wave velocity (cfPWV: as an index of arterial stiffness), and thoracic aorta was isolated after collection of blood. RESULTS: Fasting blood glucose and cfPWV significantly increased (p<0.05) and aortic Akt and eNOS phosphorylation levels, plasma nitrate/nitrite (NOx) level, and serum FSTL1 protein level significantly decreased (p<0.05) in OLETF-Con as compared to LETO. OLETF-Ex showed significant decrease in fasting blood glucose and cfPWV (p<0.05), and significant increase in aortic Akt and eNOS phosphorylation, plasma NOx, and serum FSTL1 protein levels (p<0.05) as compared to OLETF-Con. However, no significant difference in aortic DIP2A protein level among three groups was seen. Serum FSTL1 protein level was positively correlated with aortic eNOS phosphorylation level (p<0.05, r=0.630), and plasma NOx level was negatively correlated with cfPWV (p<0.05, r=-0.546). CONCLUSION: The results suggest that the increase in FSTL1 secretion induced by aerobic exercise training is associated with the reduction of arterial stiffness via activation of arterial NO production-related signaling pathway in type 2 diabetic rats. Supported by Grants-in-Aid for Scientific Research (#17H02182, #16K13059, M. Iemitsu)

The glycoprotein follistatin-like 1 promotes brown adipose thermogenesis

ObjectivesThe thermogenic brown adipose tissue (BAT) has been proposed as a potential target to prevent or treat obesity and related metabolic diseases. BAT secretes adipokines to regulate the thermogenic program in an autocrine or paracrine manner. Follistatin-like 1 (FSTL1), a glycoprotein involved in adipogenesis and obesity, however, the function of FSTL1 in BAT thermogenesis and in the regulation of systemic energy homeostasis are not fully understood. MethodsWhole-body ablation Fstl1 heterozygous mice (Fstl1+/−) and its littermates control were injected with CL316,243 to assess energy balance. A series of FSTL1 overexpression and knockdown experiments were carried out to evaluate its function in regulating thermogenic gene expression in brown adipocytes. ResultsFSTL1 expression was induced upon BAT activation during cold challenge or β3-adrenergic activation. FSTL1 haploinsufficiency in mice led to reduced thermogenic gene expression, impaired BAT recruitment, and decreased heat production. FSTL1 cell-autonomously promoted the β3-adrenergic signaling, which was required to upregulate PPARγ and UCP1 in brown adipocytes. Furthermore, only glycosylated FSTL1 could be secreted from brown adipocytes to induce the β3-adrenergic activation. ConclusionsOur results suggest FSTL1 as a novel stimulator of the β-adrenergic signaling and BAT thermogenesis.