The versatility and paradox of GDF 11

Does Vitamin B6 Act as an Exercise Mimetic in Skeletal Muscle?

Marginal vitamin B6 (B6) deficiency is common in various segments worldwide. In a super-aged society, sarcopenia is a major concern and has gained significant research attention focused on healthy aging. To date, the primary interventions for sarcopenia have been physical exercise therapy. Recent evidence suggests that inadequate B6 status is associated with an increased risk of sarcopenia and mortality among older adults. Our previous study showed that B6 supplementation to a marginal B6-deficient diet up-regulated the expression of various exercise-induced genes in the skeletal muscle of rodents. Notably, a supplemental B6-to-B6-deficient diet stimulates satellite cell-mediated myogenesis in rodents, mirroring the effects of physical exercise. These findings suggest the potential role of B6 as an exercise-mimetic nutrient in skeletal muscle. To test this hypothesis, we reviewed relevant literature and compared the roles of B6 and exercise in muscles. Here, we provide several pieces of evidence supporting this hypothesis and discuss the potential mechanisms behind the similarities between the effects of B6 and exercise on muscle. This research, for the first time, provides insight into the exercise-mimetic roles of B6 in skeletal muscle.

GDF11 protects against mitochondrial-dysfunction-dependent NLRP3 inflammasome activation to attenuate osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a highly prevalent degenerative disease worldwide, and tumor necrosis factor (TNF-α) is closely associated with its development. Growth differentiation factor 11 (GDF11) has demonstrated anti-injury and anti-aging abilities in certain tissues; however, its regulatory role in OA remains unclear and requires further investigation.

OBJECTIVES

To identify whether GDF11 can attenuate osteoarthritis. To exploring the the potential mechanism of GDF11 in alleviating osteoarthritis.

METHODS

In this study, we cultured and stimulated mouse primary chondrocytes with or without TNF-α, analyzing the resulting damage phenotype through microarray analysis. Additionally, we employed GDF11 conditional knockout mice OA model to examine the relationship between GDF11 and OA. To investigate the target of GDF11's function, we utilized NLRP3 knockout mice and its inhibitor to verify the potential involvement of the NLRP3 inflammasome.

RESULTS

Our in vitro experiments demonstrated that endogenous overexpression of GDF11 significantly inhibited TNF-α-induced cartilage matrix degradation and inflammatory expression in chondrocytes. Furthermore, loss of GDF11 led to NLRP3 inflammasome activation, inflammation, and metabolic dysfunction. In an in vivo surgically induced mouse model, intraarticular administration of recombinant human GDF11 alleviated OA pathogenesis, whereas GDF11 conditional knockout reversed this effect. Additionally, findings from the NLRP3-knockout DMM mouse model revealed that GDF11 exerted its protective effect by inhibiting NLRP3.

CONCLUSION

These findings demonstrate the ability of GDF11 to suppress TNF-α-induced inflammation and cartilage degeneration by preventing mitochondrial dysfunction and inhibiting NLRP3 inflammasome activation, suggesting its potential as a promising therapeutic drug for osteoarthritis.

Growth differentiation factor-11 upregulates matrix metalloproteinase 2 expression by inducing Snail in human extravillous trophoblast cells

The human extravillous trophoblast (EVT) cell invasion is an important process during placentation. Although the placenta is normal tissue, the EVT cells exhibit some features common to cancer cells, including high migratory and invasive properties. Snail and Slug are transcription factors that mediate the epithelial-mesenchymal transition (EMT), a crucial event for cancer cell migration and invasion. It has been shown that GDF-11-induced matrix metalloproteinase 2 (MMP2) expression is required for EVT cell invasion. Whether GDF-11 can regulate Snail and Slug expression in human EVT cells remains unknown. If it does, the involvement of Snail and Slug in GDF-11-induced MMP2 expression and EVT cell invasion must also be defined. In the present study, using the immortalized human EVT cell line, HTR-8/SVneo, and primary cultures of human EVT cells as experimental models, our results show that GDF-11 upregulates Snail and Slug expression. ALK4 and ALK5 mediate the stimulatory effects of GDF-11 on Snail and Slug expression. In addition, we demonstrate that SMAD2 and SMAD3 are required for the GDF-11-upregulated Snail expression, while only SMAD3 is involved in GDF-11-induced Slug expression. Moreover, our results reveal that Snail mediates GDF-11-induced MMP2 expression and cell invasion but not Slug. This study increases our understanding of the biological function of GDF-11 in human EVT cells and provides a novel mechanism for regulating MMP2 and EVT cell invasion.

GDF11: An emerging therapeutic target for liver diseases and fibrosis

Growth differentiation factor 11 (GDF11), also known as bone morphogenetic protein 11 (BMP11), has been identified as a key player in various biological processes, including embryonic development, aging, metabolic disorders and cancers. GDF11 has also emerged as a critical component in liver development, injury and fibrosis. However, the effects of GDF11 on liver physiology and pathology have been a subject of debate among researchers due to conflicting reported outcomes. While some studies suggest that GDF11 has anti-aging properties, others have documented its senescence-inducing effects. Similarly, while GDF11 has been implicated in exacerbating liver injury, it has also been shown to have the potential to reduce liver fibrosis. In this narrative review, we present a comprehensive report of recent evidence elucidating the diverse roles of GDF11 in liver development, hepatic injury, regeneration and associated diseases such as non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), liver fibrosis and hepatocellular carcinoma. We also explore the therapeutic potential of GDF11 in managing various liver pathologies.

Hapln1 promotes dedifferentiation and proliferation of iPSC-derived cardiomyocytes by promoting versican-based GDF11 trapping

Hyaluronan and proteoglycan link protein 1 (Hapln1) supports active cardiomyogenesis in zebrafish hearts, but its regulation in mammal cardiomyocytes is unclear. This study aimed to explore the potential regulation of Hapln1 in the dedifferentiation and proliferation of cardiomyocytes and its therapeutic value in myocardial infarction with human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) and an adult mouse model of myocardial infarction. HiPSC-CMs and adult mice with myocardial infarction were used as in vitro and in vivo models, respectively. Previous single-cell RNA sequencing data were retrieved for bioinformatic exploration. The results showed that recombinant human Hapln1 (rhHapln1) promotes the proliferation of hiPSC-CMs in a dose-dependent manner. As a physical binding protein of Hapln1, versican interacted with Nodal growth differentiation factor (NODAL) and growth differentiation factor 11 (GDF11). GDF11, but not NODAL, was expressed by hiPSC-CMs. GDF11 expression was unaffected by rhHapln1 treatment. However, this molecule was required for rhHapln1-mediated activation of the transforming growth factor (TGF)-β/Drosophila mothers against decapentaplegic protein (SMAD)2/3 signaling in hiPSC-CMs, which stimulates cell dedifferentiation and proliferation. Recombinant mouse Hapln1 (rmHapln1) could induce cardiac regeneration in the adult mouse model of myocardial infarction. In addition, rmHapln1 induced hiPSC-CM proliferation. In conclusion, Hapln1 can stimulate the dedifferentiation and proliferation of iPSC-derived cardiomyocytes by promoting versican-based GDF11 trapping and subsequent activation of the TGF-β/SMAD2/3 signaling pathway. Hapln1 might be an effective hiPSC-CM dedifferentiation and proliferation agent and a potential reagent for repairing damaged hearts.

Age Is Just a Number: Progress and Obstacles in the Discovery of New Candidate Drugs for Sarcopenia

Sarcopenia is a disease characterized by the progressive loss of skeletal muscle mass and function that occurs with aging. The progression of sarcopenia is correlated with the onset of physical disability, the inability to live independently, and increased mortality. Due to global increases in lifespan and demographic aging in developed countries, sarcopenia has become a major socioeconomic burden. Clinical therapies for sarcopenia are based on physical therapy and nutritional support, although these may suffer from low adherence and variable outcomes. There are currently no clinically approved drugs for sarcopenia. Consequently, there is a large amount of pre-clinical research focusing on discovering new candidate drugs and novel targets. In this review, recent progress in this research will be discussed, along with the challenges that may preclude successful translational research in the clinic. The types of drugs examined include mitochondria-targeting compounds, anti-diabetes agents, small molecules that target non-coding RNAs, protein therapeutics, natural products, and repositioning candidates. In light of the large number of drugs and targets being reported, it can be envisioned that clinically approved pharmaceuticals to prevent the progression or even mitigate sarcopenia may be within reach.

GDF11 as a friend or an enemy in the cancer biology?

The Growth and Differential Factor 11 (GDF11) is a recently discovered representative of Transforming Growth Factor β superfamily. The highest expression of GDF11 is detected in the nervous system, bladder, seminal vesicles and muscles whereas the lowest in the testis, liver or breast. GDF11 role in physiology is still not clear. GDF11 is a crucial factor in embryogenesis, cell cycle control and apoptosis, inasmuch it mainly targets cell retain stemness features, managing to the cell differentiation and the maturation. GDF11 is entangled in lipid metabolism, inflammatory processes and aging. GDF11 is strongly related to carcinogenesis and its expression in tumors is intruded. GDF11 can promote cancer growth in the colon or inhibit the cell proliferation in breast cancer. The aberrated expression is probably allied with the impaired maturation. In this article we summarized an impact of GDF11 on the tumor cells and review the all attitudes connecting GDF11 with carcinogenesis.

The role of GDF11 during inflammation – An overview

GDF11 (Growth differentiation factor 11) is a newly discovered member of family of transforming growth factors-beta. Its crucial role was confirmed in physiology, i.e. embryogenesis due to its involvement in bone formation, skeletogenesis and it is essential to stating skeletal pattern. GDF11 is described as a rejuvenating and anti-aging molecule, that could even restore functions. Beside embryogenesis, GDF11 participates in the process of inflammation and carcinogenesis. In this review, we describe its involvement in regulation of acute and chronic inflammatory disorders. An anti-inflammatory effect of GDF11 was found in experimental colitis, psoriasis and arthritis. Current data regarding liver fibrosis and renal injury indicate that GDF11 may act as pro-inflammatory agent.

GDF11, a target of miR-32-5p, suppresses high-glucose-induced mitochondrial dysfunction and apoptosis in HK-2 cells through PI3K/AKT signaling activation

PURPOSE

To investigate the role and underlying mechanism of GDF11 on diabetic nephropathy (DN)-related mitochondrial dysfunction and apoptosis.

METHODS

A DN model of rats was established in this study. Human Kidney-2 (HK-2) cells were cultured under high-glucose (HG) condition with or without recombinant GDF11 (rGDF11). Mitochondrial morphology of HK-2 cells was analyzed by transmission electron microscope and MitoTracker Red CMXRos staining. Mitochondrial membrane potential (MMP) and ROS production were monitored using JC-1 assay kit and MitoSOX staining, respectively. Cell apoptosis was detected by TUNEL or flow cytometry assays.

RESULTS

Herein, we observed that GDF11 was down-regulated in renal cortex and serum of DN rats, which was accompanied by renal mitochondrial morphological abnormalities. In line with the findings in vivo, HK-2 cells exposed to HG presented with mitochondrial morphological alterations and further apoptosis accompanied by GDF11 reduction. In addition, HG promoted a decrease in MMP while an increase in mitochondrial ROS production. Conversely, rGDF11 treatment significantly alleviated these HG-induced mitochondrial defects in HK-2 cells. Meanwhile, HK-2 cell apoptosis induced by HG was simultaneously suppressed by rGDF11. Mechanistically, the decreased levels of p-AKT induced by HG were attenuated after rGDF11 administration. Inhibition of the PI3K/AKT pathway resisted the effects of rGDF11 on the MMP and apoptosis of HK-2 cells. In addition, we identified that GDF11 is a target of miR-32-5p. Up-regulation of miR-32-5p could inhibit the expression of GDF11.

CONCLUSION

rGDF11 treatment rescued HG-induced HK-2 cell mitochondrial dysfunction and apoptosis, which may be dependent on the activation of the PI3K/AKT pathway.

Insights into bone morphogenetic proteins in cardiovascular diseases

Bone morphogenetic proteins (BMPs) are secretory proteins belonging to the transforming growth factor-β (TGF-β) superfamily. These proteins play important roles in embryogenesis, bone morphogenesis, blood vessel remodeling and the development of various organs. In recent years, as research has progressed, BMPs have been found to be closely related to cardiovascular diseases, especially atherosclerosis, vascular calcification, cardiac remodeling, pulmonary arterial hypertension (PAH) and hereditary hemorrhagic telangiectasia (HHT). In this review, we summarized the potential roles and related mechanisms of the BMP family in the cardiovascular system and focused on atherosclerosis and PAH.

GDF-11 promotes human trophoblast cell invasion by increasing ID2-mediated MMP2 expression

BACKGROUND

Growth differentiation factor-11 (GDF-11), also known as bone morphogenetic protein-11, belongs to the transforming growth factor-beta superfamily. GDF-11 was first identified as an important regulator during embryonic development. Increasing evidence has demonstrated that GDF-11 regulates the development of various organs and its aberrant expressions are associated with the risk of cardiovascular diseases and cancers. Extravillous trophoblast (EVT) cells invasion is a critical event for placenta development and needs to be finely regulated. However, to date, the biological function of GDF-11 in the human EVT cells remains unknown.

METHODS

HTR-8/SVneo, a human EVT cell line, and primary cultures of human EVT cells were used to examine the effect of GDF-11 on matrix metalloproteinase 2 (MMP2) expression. Matrigel-coated transwell invasion assay was used to examine cell invasiveness. A series of in vitro experiments were applied to explore the underlying mechanisms that mediate the effect of GDF-11 on MMP2 expression and cell invasion.

RESULTS

Treatment with GDF-11 stimulates MMP2 expression, in the HTR-8/SVneo and primary human EVT cells. Using a pharmacological inhibitor and siRNA-mediated knockdown approaches, our results demonstrated that the stimulatory effect of GDF-11 on MMP2 expression was mediated by the ALK4/5-SMAD2/3 signaling pathways. In addition, the expression of inhibitor of DNA-binding protein 2 (ID2) was upregulated by GDF-11 and that was required for the GDF-11-stimulated MMP2 expression and EVT cell invasion.

CONCLUSIONS

These findings discover a new biological function and underlying molecular mechanisms of GDF-11 in the regulation of human EVT cell invasion. Video Abstract.

Potential role of recombinant growth differentiation factor 11 in Alzheimer’s disease treatment

Alzheimer's disease (AD) is a neurodegenerative disease closely related to the accumulation of beta-amyloid (Aβ) plaques. Growth differentiation factor 11 (GDF11) is one of the proteins that play a role in the aggravation of AD. Decreased concentration of GDF11 disrupts regenerative nervous system, blood vessels, and various vital systems. Low levels of GDF11 with age can be overcome with recombinant GDF11 (rGDF11) to rejuvenate the regenerative effect. Based on research results, rGDF11 enhance the proliferation rate of neuronal precursor cells as well as angiogenesis. rGDF11 can replace lost levels of GDF11, overcome astrogliosis and activation of nerve cell microglia. Therapeutic effect of rGDF11 leads to an improved prognosis in AD patients by neurogenesis and angiogenesis. The prospects of rGDF11 in the treatment of AD have great potential for further research in the future.

Growth differentiation factor-11 downregulates steroidogenic acute regulatory protein expression through ALK5-mediated SMAD3 signaling pathway in human granulosa-lutein cells

BACKGROUND

Growth differentiation factor-11 (GDF-11) belongs to the transforming growth factor-β (TGF-β) superfamily. To date, the expression of GDF-11 in the ovary and its role in regulating ovarian function are completely unknown. Ovarian granulosa cell-mediated steroidogenesis plays a pivotal role in maintaining normal female reproductive function. GDF-11 and GDF-8 share high sequence similarity and exhibit many similar features and functions. Steroidogenic acute regulatory protein (StAR) regulates the rate-limiting step in steroidogenesis and its expression can be downregulated by GDF-8. Polycystic ovary syndrome (PCOS) is the most common cause of female infertility. The expression levels of GDF-8 are upregulated in the human follicular fluid and granulosa-lutein (hGL) cells of PCOS patients. However, whether similar results can be observed for the GDF-11 needs to be determined.

METHODS

The effect of GDF-11 on StAR expression and the underlying molecular mechanisms were explored by a series of in vitro experiments in a primary culture of hGL cells obtained from patients undergoing in vitro fertilization (IVF) treatment. Human follicular fluid samples were obtained from 36 non-PCOS patients and 36 PCOS patients. GDF-11 levels in follicular fluid were measured by ELISA.

RESULTS

GDF-11 downregulates StAR expression, whereas the expression levels of the P450 side-chain cleavage enzyme (P450scc) and 3β-hydroxysteroid dehydrogenase (3β-HSD) are not affected by GDF-11 in hGL cells. Using pharmacological inhibitors and a siRNA-mediated approach, we reveal that ALK5 but not ALK4 mediates the suppressive effect of GDF-11 on StAR expression. Although GDF-11 activates both SMAD2 and SMAD3 signaling pathways, only SMAD3 is involved in the GDF-11-induced downregulation of StAR expression. In addition, we show that SMAD1/5/8, ERK1/2, and PI3K/AKT signaling pathways are not activated by GDF-11 in hGL cells. RT-qPCR and ELISA detect GDF-11 mRNA expression in hGL cells and GDF-11 protein expression in human follicular fluid, respectively. Interestingly, unlike GDF-8, the expression levels of GDF-11 are not varied in hGL cells and follicular fluid between non-PCOS and PCOS patients.

CONCLUSIONS

This study increases the understanding of the biological function of GDF-11 and provides important insights into the regulation of ovarian steroidogenesis.

Growth Differentiation Factor-15 in Immunity and Aging

Aging increases susceptibility to and severity of a variety of chronic and infectious diseases. Underlying this is dysfunction of the immune system, including chronic increases in low-grade inflammation (inflammaging) and age-related immunosuppression (immunosenescence). Growth differentiation factor-15 (GDF-15) is a stress-, infection-, and inflammation-induced cytokine which is increased in aging and suppresses immune responses. This mini review briefly covers existing knowledge on the immunoregulatory and anti-inflammatory roles of GDF-15, as well as its potential importance in aging and immune function.

Single-cell Transcriptomic Profiling of the Hypothalamic Median Eminence during Aging

Aging is a slow and progressive natural process that compromises the normal functions of cells, tissues, organs and systems. The aging of the hypothalamic median eminence (ME), a structural gate linking neural and endocrine systems, may impair hormone release, energy homeostasis and central sensing of circulating molecules, leading to systemic and reproductive aging. However, the molecular and cellular features of ME aging remain largely unknown. Here we describe the transcriptional landscape of young and middle-aged mouse ME at single-cell resolution, revealing the common and cell-type-specific transcriptional changes with age. The transcriptional changes in cell-intrinsic programs, cell-cell crosstalk and cell-extrinsic factors highlight five molecular features of ME aging and also implicate several potentially druggable targets at cellular, signaling and molecular levels. Importantly, our results suggest that vascular and leptomeningeal cells (VLMCs) may lead the asynchronized aging process among diverse cell types and drive local inflammation and cellular senescence via a unique secretome. Together, our study uncovers how intrinsic and extrinsic features of each cell type in the hypothalamic ME are changed by the aging process, which will facilitate our understanding of brain aging and provide clues for efficient anti-aging intervention at the middle-aged stage.

Reduced leukocyte telomere lengths and sirtuin 1 gene expression in long-term survivors of type 1 diabetes: A Dialong substudy

AIMS/INTRODUCTION

The shortening of leukocyte telomere length with age has been associated with coronary disease, whereas the association with type 1 diabetes is unclear. We aimed to explore telomere lengths in diabetes patients with regard to coronary artery disease, compared with healthy controls. The longevity factors sirtuin 1 and growth-differentiating factor 11 were investigated accordingly.

MATERIALS AND METHODS

We carried out a cross-sectional study of 102 participants with long-term type 1 diabetes and 75 controls (mean age 62 and 63 years, respectively), where 88 cases and 60 controls without diagnosed coronary artery disease completed computed tomography coronary angiography. Telomere lengths and gene expression of sirtuin 1 and growth-differentiating factor 11 were quantified in leukocytes.

RESULTS

Telomere lengths and sirtuin 1 were reduced in diabetes patients versus controls, medians (25th to 75th percentiles): 0.97 (0.82-1.15) versus 1.08 (0.85-1.29) and 0.88 (0.65-1.14) vs 1.01 (0.78-1.36), respectively, adjusted P < 0.05, both. Previous coronary artery disease in diabetes patients (n = 15) was associated with lower sirtuin 1 and growth-differentiating factor 11 messenger ribonucleic acid expression (adjusted P < 0.03, both). In the combined diabetes and control group, previous artery coronary disease (n = 18) presented with significantly shorter telomeres (adjusted P = 0.038). Newly diagnosed obstructive coronary artery disease, defined as >50% stenosis, was not associated with the investigated variables.

CONCLUSIONS

Long-term type 1 diabetes presented with reduced telomeres and sirtuin 1 expression, with additional reduction in diabetes patients with previous coronary artery disease, showing their importance for cardiovascular disease development with potential as novel biomarkers in diabetes and coronary artery disease.

The growth factor BMP11 is required for the development and evolution of a male exaggerated weapon and its associated fighting behavior in a water strider

Exaggerated sexually selected traits, often carried by males, are characterized by the evolution of hyperallometry, resulting in their disproportionate growth relative to the rest of the body among individuals of the same population. While the evolution of allometry has attracted much attention for centuries, our understanding of the developmental genetic mechanisms underlying its emergence remains fragmented. Here we conduct comparative transcriptomics of the legs followed by an RNA interference (RNAi) screen to identify genes that play a role in the hyperallometric growth of the third legs in the males of the water strider Microvelia longipes. We demonstrate that a broadly expressed growth factor, Bone Morphogenetic Protein 11 (BMP11, also known as Growth Differentiation Factor 11), regulates leg allometries through increasing the allometric slope and mean body size in males. In contrast, BMP11 RNAi reduced mean body size but did not affect slope either in the females of M. longipes or in the males and females of other closely related Microvelia species. Furthermore, our data show that a tissue-specific factor, Ultrabithorax (Ubx), increases intercept without affecting mean body size. This indicates a genetic correlation between mean body size and variation in allometric slope, but not intercept. Strikingly, males treated with BMP11 RNAi exhibited a severe reduction in fighting frequency compared to both controls and Ubx RNAi-treated males. Therefore, male body size, the exaggerated weapon, and the intense fighting behavior associated with it are genetically correlated in M. longipes. Our results support a possible role of pleiotropy in the evolution of allometric slope.

Skin Immunomodulation during Regeneration: Emerging New Targets

Adipose-Derived Stem Cells (ADSC) are present within the hypodermis and are also expected to play a pivotal role in wound healing, immunomodulation, and rejuvenation activities. They orchestrate, through their exosome, the mechanisms associated to cell differentiation, proliferation, and cell migration by upregulating genes implicated in different functions including skin barrier, immunomodulation, cell proliferation, and epidermal regeneration. ADSCs directly interact with their microenvironment and specifically the immune cells, including macrophages and T and B cells, resulting in differential inflammatory and anti-inflammatory mechanisms impacting, in return, ADSCs microenvironment and thus skin function. These useful features of ADSCs are involved in tissue repair, where the required cell proliferation, angiogenesis, and anti-inflammatory responses should occur rapidly in damaged sites. Different pathways involved have been reported such as Growth Differentiation Factor-11 (GDF11), Tumor Growth Factor (TGF)-β, Metalloproteinase (MMP), microRNA, and inflammatory cytokines that might serve as specific biomarkers of their immunomodulating capacity. In this review, we try to highlight ADSCs’ network and explore the potential indicators of their immunomodulatory effect in skin regeneration and aging. Assessment of these biomarkers might be useful and should be considered when designing new clinical therapies using ADSCs or their specific exosomes focusing on their immunomodulation activity.

Systemic blockade of ACVR2B ligands attenuates muscle wasting in ischemic heart failure without compromising cardiac function

Signaling through activin receptors regulates skeletal muscle mass and activin receptor 2B (ACVR2B) ligands are also suggested to participate in myocardial infarction (MI) pathology in the heart. In this study, we determined the effect of systemic blockade of ACVR2B ligands on cardiac function in experimental MI, and defined its efficacy to revert muscle wasting in ischemic heart failure (HF). Mice were treated with soluble ACVR2B decoy receptor (ACVR2B-Fc) to study its effect on post-MI cardiac remodeling and on later HF. Cardiac function was determined with echocardiography, and myocardium analyzed with histological and biochemical methods for hypertrophy and fibrosis. Pharmacological blockade of ACVR2B ligands did not rescue the heart from ischemic injury or alleviate post-MI remodeling and ischemic HF. Collectively, ACVR2B-Fc did not affect cardiomyocyte hypertrophy, fibrosis, angiogenesis, nor factors associated with cardiac regeneration except modification of certain genes involved in metabolism or cell growth/survival. ACVR2B-Fc, however, was able to reduce skeletal muscle wasting in chronic ischemic HF, accompanied by reduced LC3II as a marker of autophagy and increased mTOR signaling and Cited4 expression as markers of physiological hypertrophy in quadriceps muscle. Our results ascertain pharmacological blockade of ACVR2B ligands as a possible therapy for skeletal muscle wasting in ischemic HF. Pharmacological blockade of ACVR2B ligands preserved myofiber size in ischemic HF, but did not compromise cardiac function nor exacerbate cardiac remodeling after ischemic injury.

Significance of 125I radioactive seed implantation on growth differentiation factor and programmed death receptor-1 during treatment of oral cancer

BACKGROUND

Oral cancer (OC) is the most common malignant tumor in the oral cavity, and is mainly seen in middle-aged and elderly men. At present, OC is mainly treated clinically by surgery or combined with radiotherapy and chemotherapy; but recently, more and more studies have shown that the stress trauma caused by surgery and the side effects of radiotherapy and chemotherapy seriously affect the prognosis of patients.

AIM

To determine the significance of ¹²⁵I radioactive seed implantation on growth differentiation factor 11 (GDF11) and programmed death receptor-1 (PD-1) during treatment of OC.

METHODS

A total of 184 OC patients admitted to The Second Affiliated Hospital of Jiamusi University from May 2015 to May 2017 were selected as the research subjects for prospective analysis. Of these patients, 89 who received ¹²⁵I radioactive seed implantation therapy were regarded as the research group (RG) and 95 patients who received surgical treatment were regarded as the control group (CG). The clinical efficacy, incidence of adverse reactions and changes in GDF11 and PD-1 before treatment (T0), 2 wk after treatment (T1), 4 wk after treatment (T2) and 6 wk after treatment (T3) were compared between the two groups.

RESULTS

The efficacy and recurrence rate in the RG were better than those in the CG (P < 0.05), while the incidence of adverse reactions and survival rate were not different. There was no difference in GDF11 and PD-1 between the two groups at T0 and T1, but these factors were lower in the RG than in the CG at T2 and T3 (P < 0.05). Using receiver operating characteristic (ROC) curve analysis, GDF11 and PD-1 had good predictive value for efficacy and recurrence (P < 0.001).

CONCLUSION

¹²⁵I radioactive seed implantation has clinical efficacy and can reduce the recurrence rate in patients with OC. This therapy has marked potential in clinical application. The detection of GDF11 and PD-1 in patients during treatment showed good predictive value for treatment efficacy and recurrence in OC patients, and may be potential targets for future OC treatment.

Targeting Unique Epitopes on Highly Similar Proteins GDF-11 and GDF-8 with Modified DNA Aptamers

The mature forms of the TGF-β family members GDF-11 and GDF-8 are highly similar 25 kDa homodimers with 90% amino acid sequence identity and 99% similarity. Cross-reactivity of GDF-11 and GDF-8 binding reagents is common, making it difficult to attribute distinct roles of these two proteins in biology. We report the selection of GDF-11 and GDF-8 specific SOMAmer (Slow Off-rate Modified Aptamer) reagents aided by a combination of positive selection for one protein coupled with counter-selection against the other. We identified GDF-11 specific SOMAmer reagents from four modified DNA libraries that showed a high affinity (K_d range 0.05-1.2 nM) for GDF-11 but did not bind to GDF-8 (K_d > 1 μM). Conversely, we identified one SOMAmer reagent for GDF-8 from one of the modified libraries that demonstrated excellent affinity (K_d = 0.23 nM) and specificity. In contrast, standard protocols that utilized only positive selection produced binding reagents with similar affinity for both proteins. High affinity and specificity were efficiently encoded in minimal sequences of 21 nucleotides for GDF-11 and 24 nucleotides for GDF-8. Further characterization in pull-down, competition, sandwich-binding, and kinetic studies revealed robust binding under a wide range of buffer and assay conditions. For highly similar proteins like GDF-11 and GDF-8, our method of selection coupled with counter-selection was essential for identification of high-affinity, specific reagents that have the potential to elucidate the fundamental distinction of these growth factors in biology.

GDF11 Implications in Cancer Biology and Metabolism. Facts and Controversies

Growth Differentiation Factor 11 (GDF11), a member of the super family of the Transforming Growth Factor β, has gained more attention in the last few years due to numerous reports regarding its functions in other systems, which are different to those related to differentiation and embryonic development, such as age-related muscle dysfunction, skin biology, metabolism, and cancer. GDF11 is expressed in many tissues, including skeletal muscle, pancreas, kidney, nervous system, and retina, among others. GDF11 circulating levels and protein content in tissues are quite variable and are affected by pathological conditions or age. Although, GDF11 biology had a lot of controversies, must of them are only misunderstandings regarding the variability of its responses, which are independent of the tissue, grade of cellular differentiation or pathologies. A blunt fact regarding GDF11 biology is that its target cells have stemness feature, a property that could be found in certain adult cells in health and in disease, such as cancer cells. This review is focused to present and analyze the recent findings in the emerging research field of GDF11 function in cancer and metabolism, and discusses the controversies surrounding the biology of this atypical growth factor.

MiR-92a regulates endothelial progenitor cells (EPCs) by targeting GDF11 via activate SMAD2/3/FAK/Akt/eNOS pathway

Background

The effects of miR-92a on EPCs are still poorly elucidated. This study aimed to investigate the effects of miR-92a on EPCs (Endothelial progenitor cells) in a model of hypoxia (HO) or high glucose (HG)-induced EPCs injury by targeting GDF11 (Differentiation growth factor 11).

Methods

The effects of miR-92a on EPCs subjected to HO or HG were investigated firstly. Subsequently, the action mechanism of miR-92a on EPCs by targeting GDF11 was elucidated. Proliferation, apoptosis, migration, angiogenesis was measured with MTT, flow cytometry, transwell, tube formation respectively. After 24 h, levels of reactive oxygen species (ROS) were measured by fluorescence intensity. LDH and NO (nitric oxide) levels were determined by ELISA. The expression of FLK-1 (fetal liver kinase 1) and vWF (von Willebrand factor) was detected by immunofluorescence. mRNA and protein expression levels were examined using PCR and western blotting respectively. The interaction between miR-92a and GDF11 was evaluated by dual-luciferase reporter assay.

Results

Our results showed that HO or HG increased apoptosis, production of LDH and generation of ROS, but decreased the ability of migration and tube formation and generation of NO in EPCs; inhibiting of miR-92a decreased HO or HG-induced injury of EPCs, whereas miR-92a over-expression had the opposite effect; the protective effects induced by inhibiting of miR-92a on EPCs could be reversed by GDF11 siRNA and the harmful effects induced by over-expression of miR-92a could be rescued by over-expression of GDF11, which showed that the harmful effects of miR-92a be related to its inhibition of GDF11 and subsequent inactivation of the SMAD2/3/FAK/Akt/eNOS signaling pathway.

Conclusions

Inhibiting miR-92a can protect EPCs from HO or HG-induced injury. The effect of miR-92a on EPCs are mediated by regulating of GDF11 and downstream SMAD2/3/FAK/Akt/eNOS signaling pathway.

GDF11 Decreases Pressure Overload-Induced Hypertrophy, but Can Cause Severe Cachexia and Premature Death

RATIONALE

Possible beneficial effects of GDF11 (growth differentiation factor 11) on the normal, diseased, and aging heart have been reported, including reversing aging-induced hypertrophy. These effects have not been well validated. High levels of GDF11 have also been shown to cause cardiac and skeletal muscle wasting. These controversies could be resolved if dose-dependent effects of GDF11 were defined in normal and aged animals as well as in pressure overload-induced pathological hypertrophy.

OBJECTIVE

To determine dose-dependent effects of GDF11 on normal hearts and those with pressure overload-induced cardiac hypertrophy.

METHODS AND RESULTS

Twelve- to 13-week-old C57BL/6 mice underwent transverse aortic constriction (TAC) surgery. One-week post-TAC, these mice received rGDF11 (recombinant GDF11) at 1 of 3 doses: 0.5, 1.0, or 5.0 mg/kg for up to 14 days. Treatment with GDF11 increased plasma concentrations of GDF11 and p-SMAD2 in the heart. There were no significant differences in the peak pressure gradients across the aortic constriction between treatment groups at 1 week post-TAC. Two weeks of GDF11 treatment caused dose-dependent decreases in cardiac hypertrophy as measured by heart weight/tibia length ratio, myocyte cross-sectional area, and left ventricular mass. GDF11 improved cardiac pump function while preventing TAC-induced ventricular dilation and caused a dose-dependent decrease in interstitial fibrosis (in vivo), despite increasing markers of fibroblast activation and myofibroblast transdifferentiation (in vitro). Treatment with the highest dose (5.0 mg/kg) of GDF11 caused severe body weight loss, with significant decreases in both muscle and organ weights and death in both sham and TAC mice.

CONCLUSIONS

Although GDF11 treatment can reduce pathological cardiac hypertrophy and associated fibrosis while improving cardiac pump function in pressure overload, high doses of GDF11 cause severe cachexia and death. Use of GDF11 as a therapy could have potentially devastating actions on the heart and other tissues.

GDF11 contributes to hepatic hepcidin (HAMP) inhibition through SMURF1-mediated BMP-SMAD signalling suppression

Hepcidin (HAMP) synthesis is suppressed by erythropoiesis to increase iron availability for red blood cell production. This effect is thought to result from factors secreted by erythroid precursors. Growth differentiation factor 11 (GDF11) expression was recently shown to increase in erythroid cells of β-thalassaemia, and decrease with improvement in anaemia. Whether GDF11 regulates hepatic HAMP production has never been experimentally studied. Here, we explore GDF11 function during erythropoiesis-triggered HAMP suppression. Our results confirm that exogenous erythropoietin significantly increases Gdf11 as well as Erfe (erythroferrone) expression, and Gdf11 is also increased, albeit at a lower degree than Erfe, in phlebotomized wild type and β-thalassaemic mice. GDF11 is expressed predominantly in erythroid burst forming unit- and erythroid colony-forming unit- cells during erythropoiesis. Exogeneous GDF11 administration results in HAMP suppression in vivo and in vitro. Furthermore, exogenous GDF11 decreases BMP-SMAD signalling, enhances SMAD ubiquitin regulatory factor 1 (SMURF1) expression and induces ERK1/2 (MAPK3/1) signalling. ERK1/2 signalling activation is required for GDF11 or SMURF1-mediated suppression in BMP-SMAD signalling and HAMP expression. This research newly characterizes GDF11 in erythropoiesis-mediated HAMP suppression, in addition to ERFE.

Low plasma adropin concentrations increase risks of weight gain and metabolic dysregulation in response to a high-sugar diet in male nonhuman primates

Mouse studies linking adropin, a peptide hormone encoded by the energy homeostasis-associated (ENHO) gene, to biological clocks and to glucose and lipid metabolism suggest a potential therapeutic target for managing diseases of metabolism. However, adropin's roles in human metabolism are unclear. In silico expression profiling in a nonhuman primate diurnal transcriptome atlas (GSE98965) revealed a dynamic and diurnal pattern of ENHO expression. ENHO expression is abundant in brain, including ventromedial and lateral hypothalamic nuclei regulating appetite and autonomic function. Lower ENHO expression is present in liver, lung, kidney, ileum, and some endocrine glands. Hepatic ENHO expression associates with genes involved in glucose and lipid metabolism. Unsupervised hierarchical clustering identified 426 genes co-regulated with ENHO in liver, ileum, kidney medulla, and lung. Gene Ontology analysis of this cluster revealed enrichment for epigenetic silencing by histone H3K27 trimethylation and biological processes related to neural function. Dietary intervention experiments with 59 adult male rhesus macaques indicated low plasma adropin concentrations were positively correlated with fasting glucose, plasma leptin, and apolipoprotein C3 (APOC3) concentrations. During consumption of a high-sugar (fructose) diet, which induced 10% weight gain, animals with low adropin had larger increases of plasma leptin and more severe hyperglycemia. Declining adropin concentrations were correlated with increases of plasma APOC3 and triglycerides. In summary, peripheral ENHO expression associates with pathways related to epigenetic and neural functions, and carbohydrate and lipid metabolism, suggesting co-regulation in nonhuman primates. Low circulating adropin predicts increased weight gain and metabolic dysregulation during consumption of a high-sugar diet.

Growth differentiation factor 11 is involved in isoproterenol‑induced heart failure

The present study aimed to investigate the potential effects of growth differentiation factor 11 (GDF11) on isoproterenol (ISO)-induced heart failure (HF) and identify the underlying molecular mechanisms. A rat model of HF was induced in vivo by intraperitoneally administering ISO (5 mg/kg/day) for 7 days. After 4 weeks following establishment of the HF model, hemodynamic analysis demonstrated that ISO induced a significant increase in the left ventricular end-diastolic pressure and a decrease in the left ventricular systolic pressure and maximum contraction velocity. The plasma levels of myocardial injury markers, including lactate dehydrogenase (LDH), creatine kinase (CK), CK-muscle/brain which were determined using the corresponding assay kits and plasma brain natriuretic peptide which was detected by an ELISA kit, an important biomarker of HF, increased following ISO treatment. Furthermore, levels of GDF11 expression and protein, which were estimated using reverse transcription-quantitative polymerase chain reaction and an ELISA kit in plasma and western blotting in the heart tissue, respectively, significantly increased following ISO treatment. To demonstrate the effects of ISO on GDF11 production in cardiomyocytes, H9C2 cells (a cardiomyoblast cell line derived from embryonic rat heart tissue) were treated with ISO (50 nM) for 24 h in vitro; it was revealed that GDF11 protein and mRNA expression levels significantly increased following ISO treatment. In addition, recombinant GDF11 (rGDF11) administered to ISO-treated H9C2 cells resulted in decreased proliferation, which was detected via a CCK-8 assay, and increased LDH levels and cell apoptosis of cells, which was determined using Caspase-3 activity and Hoechst 33258 staining. Additionally, rGDF11 increased the levels of reactive oxygen species and malondialdehyde due to the upregulation of nicotinamide adenine dinucleotide phosphate oxidase 4 (Nox4) following rGDF11 treatment. Conversely, GDF11 knockdown reduced ISO-induced apoptosis by inhibiting oxidative stress injury. The results suggested that GDF11 production was upregulated in ISO-induced rats with HF and in ISO-treated H9C2 cells, and that rGDF11 treatment increased ISO-induced oxidative stress injury by upregulating Nox4 in H9C2 cells.

Inhibitory effects of growth differentiation factor 11 on autophagy deficiency-induced dedifferentiation of arterial smooth muscle cells

Growth differentiation factor (GDF)11 has been reported to reverse age-related cardiac hypertrophy in mice and cause youthful regeneration of cardiomyocytes. The present study attempted to test a hypothesis that GDF11 counteracts the pathologic dedifferentiation of mouse carotid arterial smooth muscle cells (CASMCs) due to deficient autophagy. By real-time RT-PCR and Western blot analysis, exogenously administrated GDF11 was found to promote CASMC differentiation with increased expression of various differentiation markers (α-smooth muscle actin, myogenin, myogenic differentiation, and myosin heavy chain) as well as decreased expression of dedifferentiation markers (vimentin and proliferating cell nuclear antigen). Upregulation of the GDF11 gene by trichostatin A (TSA) or CRISPR-cas9 activating plasmids also stimulated the differentiation of CASMCs. Either GDF11 or TSA treatment blocked 7-ketocholesterol-induced CASMC dedifferentiation and autophagosome accumulation as well as lysosome inhibitor bafilomycin-induced dedifferentiation and autophagosome accumulation. Moreover, in CASMCs from mice lacking the CD38 gene, an autophagy deficiency model in CASMCs, GDF11 also inhibited its phenotypic transition to dedifferentiation status. Correspondingly, TSA treatment was shown to decrease GDF11 expression and reverse CASMC dedifferentiation in the partial ligated carotid artery of mice. The inhibitory effects of TSA on dedifferentiation of CASMCs were accompanied by reduced autophagosome accumulation in the arterial wall, which was accompanied by attenuated neointima formation in partial ligated carotid arteries. We concluded that GDF11 promotes CASMC differentiation and prevents the phenotypic transition of these cells induced by autophagosome accumulation during different pathological stimulations, such as Western diet, lysosome function deficiency, and inflammation. NEW & NOTEWORTHY The present study demonstrates that growth differentiation factor (GDF)11 promotes autophagy and subsequent differentiation in carotid arterial smooth muscle cells. Upregulation of GDF11 counteracts dedifferentiation under different pathological conditions. These findings provide novel insights into the regulatory role of GDF11 in the counteracting of sclerotic arterial diseases and also suggest that activation or induction of GDF11 may be a new therapeutic strategy for the treatment or prevention of these diseases.

Recent Advances: Decoding Alzheimer's Disease With Stem Cells

Alzheimer’s disease (AD) is an irreversible neurodegenerative disorder that destroys cognitive functions. Recently, a number of high-profile clinical trials based on the amyloid cascade hypothesis have encountered disappointing results. The failure of these trials indicates the necessity for novel therapeutic strategies and disease models. In this review, we will describe how recent advances in stem cell technology have shed light on a novel treatment strategy and revolutionized the mechanistic investigation of AD pathogenesis. Current advances in promoting endogenous neurogenesis and transplanting exogenous stem cells from both bench research and clinical translation perspectives will be thoroughly summarized. In addition, reprogramming technology-based disease modeling, which has shown improved efficacy in recapitulating pathological features in human patients, will be discussed.