Growth differentiation factor-15 induces expression of ATP-binding cassette transporter A1 through PI3-K/PKCζ/SP1 pathway in THP-1 macrophages

Role of Specificity Protein 1 (SP1) in Cardiovascular Diseases: Pathological Mechanisms and Therapeutic Potentials

In mammals, specificity protein 1 (SP1) was the first Cys2-His2 zinc finger transcription factor to be isolated within the specificity protein and Krüppel-like factor (Sp/KLF) gene family. SP1 regulates gene expression by binding to Guanine-Cytosine (GC)-rich sequences on promoter regions of target genes, affecting various cellular processes. Additionally, the activity of SP1 is markedly influenced by posttranslational modifications, such as phosphorylation, acetylation, glycosylation, and proteolysis. SP1 is implicated in the regulation of apoptosis, cell hypertrophy, inflammation, oxidative stress, lipid metabolism, plaque stabilization, endothelial dysfunction, fibrosis, calcification, and other pathological processes. These processes impact the onset and progression of numerous cardiovascular disorders, including coronary heart disease, ischemia-reperfusion injury, cardiomyopathy, arrhythmia, and vascular disease. SP1 emerges as a potential target for the prevention and therapeutic intervention of cardiac ailments. In this review, we delve into the biological functions, pathophysiological mechanisms, and potential clinical implications of SP1 in cardiac pathology to offer valuable insights into the regulatory functions of SP1 in heart diseases and unveil novel avenues for the prevention and treatment of cardiovascular conditions.

Role of Sp1 in atherosclerosis

Specificity protein (Sp) is a famous family of transcription factors including Sp1, Sp2 and Sp3. Sp1 is the first one of Sp family proteins to be characterized and cloned in mammalian. It has been proposed that Sp1 acts as a modulator of the expression of target gene through interacting with a series of proteins, especially with transcriptional factors, and thereby contributes to the regulation of diverse biological processes. Notably, growing evidence indicates that Sp1 is involved in the main events in the development of atherosclerosis (AS), such as inflammation, lipid metabolism, plaque stability, vascular smooth muscle cells (VSMCs) proliferation and endothelial dysfunction. This review is designed to provide useful clues to further understanding roles of Sp1 in the pathogenesis of AS, and may be helpful for the design of novel efficacious therapeutics agents targeting Sp1.

Circulating growth differentiation factor 15 levels and apolipoprotein B to apolipoprotein A1 ratio in coronary artery disease patients with type 2 diabetes mellitus

BACKGROUND

Clinical investigations have found that there was a close association between T2DM and adverse cardiovascular events, with possible mechanisms included inflammation, apoptosis, and lipid metabolism disorders. High serum GDF-15 concentration and the apolipoprotein B/apolipoprotein A1 ratio (ApoB/ApoA1) are involved in the above-mentioned mechanisms and are thought to be related to the occurrence of adverse cardiovascular events. However, it remains unclear whether circulating GDF-15 levels and the ApoB/ApoA1 ratio are related to T2DM patients with CAD.

METHODS

T2DM patients with or without CAD were eligible for this study. According to the inclusion and exclusion criteria, 502 T2DM patients were enrolled between January 2021 and December 2021 and were then divided into T2DM group (n = 249) and CAD group (n = 253). The ApoB, ApoA1 and GDF-15 concentrations were measured at hospital admission and the ApoB/ApoA1 ratio was then calculated.

RESULTS

Compared with T2DM group, serum GDF-15 levels and ApoB/ApoA1 ratio increased in CAD group. Furthermore, a positive relationship between the occurrence of CAD in diabetic population and circulating GDF-15 concentrations and ApoB/ApoA1 ratio was observed in logistic regression analysis (p < 0.01). Restrictive cubic spline analysis after adjusted for multiple risky variables showed that serum GDF-15 or ApoB/ApoA1 ratio correlated positively with CAD.

CONCLUSIONS

Circulating GDF-15 levels and serum ApoB/ApoA1 ratio vary in CAD group and T2DM group. ApoB/ApoA1 and GDF-15 may be helpful for predicting the occurrence of CAD in patients with T2DM.

GDF-15, a future therapeutic target of glucolipid metabolic disorders and cardiovascular disease

Growth and differentiation factor 15 (GDF-15) was discovered as a member of the transforming growth factor β (TGF-β) superfamily and the serum level of GDF-15 was significantly correlated with glucolipid metabolic disorders (GLMD) and cardiovascular diseases. In 2017, a novel identified receptor of GDF-15-glial-derived neurotrophic factor receptor alpha-like (GFRAL) was found to regulate energy homeostasis (such as obesity, diabetes and non-alcoholic fatty liver disease (NAFLD)). The function of GDF-15/GFRAL in suppressing appetite, enhancing glucose/lipid metabolism and vascular remodeling has been gradually revealed. These effects make it a potential therapeutic target for GLMD and vascular diseases. In this narrative review, we included and reviewed 121 articles by screening 524 articles from literature database. We primarily focused on the function of GDF-15 and its role in GLMD/cardiovascular diseases and discuss its potential clinical application.

Interleukin-5 promotes ATP-binding cassette transporter A1 expression through miR-211/JAK2/STAT3 pathways in THP-1-dervied macrophages

Interleukin-5 (IL-5) is manifested as its involvement in the process of atherosclerosis, but the mechanism is still unknown. In this study, we explored the effect of IL-5 on lipid metabolism and its underlying mechanisms in THP-1-derived macrophages. The quantitative polymerase chain reaction (qPCR) and western blot analysis results showed that IL-5 significantly up-regulated ATP-binding cassette transporter A1 (ABCA1) expression in a dose-dependent and time-dependent manner. [3H]-labeled cholesterol was used to assess the levels of cholesterol efflux, and the results showed that IL-5 increased ABCA1-mediated cholesterol efflux. A high-performance liquid chromatography assay indicated that cellular cholesterol content was decreased by IL-5 treatment in THP-1-derived macrophages. The selective inhibitor and small interfering RNA were used to block the Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathway. The results of the qPCR and western blot analysis showed that IL-5 activated JAK2/STAT3 pathway to up-regulate ABCA1 expression. Meanwhile, IL-5 reduced the expression level of miR-211. Furthermore, we found that JAK2 is a target gene of miR-211 and miR-211 mimic inhibited the expression of JAK2 and reduced the levels of p-STAT3 and ABCA1 as revealed by luciferase reporter assay, qPCR and western blot analysis. In summary, these findings indicated that IL-5 promotes ABCA1 expression and cholesterol efflux through the miR-211/JAK2/STAT3 signaling pathway in THP-1-derived macrophages.

Analysis of Low Molecular Weight Substances and Related Processes Influencing Cellular Cholesterol Efflux

Cholesterol efflux is the key process protecting the vascular system from the development of atherosclerotic lesions. Various extracellular and intracellular events affect the ability of the cell to efflux excess cholesterol. To explore the possible pathways and processes that promote or inhibit cholesterol efflux, we applied a combined cheminformatic and bioinformatic approach. We performed a comprehensive analysis of published data on the various substances influencing cholesterol efflux and found 153 low molecular weight substances that are included in the Chemical Entities of Biological Interest (ChEBI) database. Pathway enrichment was performed for substances identified within the Reactome database, and 45 substances were selected in 93 significant pathways. The most common pathways included the energy-dependent processes related to active cholesterol transport from the cell, lipoprotein metabolism and lipid transport, and signaling pathways. The activators and inhibitors of cholesterol efflux were non-uniformly distributed among the different pathways: the substances influencing ‘biological oxidations’ activate cholesterol efflux and the substances influencing ‘Signaling by GPCR and PTK6’ inhibit efflux. This analysis may be used in the search and design of efflux effectors for therapies targeting structural and functional high-density lipoprotein deficiency.

Functional roles of GDF15 in modulating microenvironment to promote carcinogenesis

Obesity and related metabolic dysregulation are risk factors for many types of cancer. The interactions between a developing tumor and its microenvironment are known to implicate a complex "crosstalk" among the factors produced by the population of cells. Among these factors, Growth and differentiation factor 15 (GDF15) has a functional role in cancer. GDF15 expression is induced in response to the conditions associated with cellular stress and diseases. The GDF15 receptor, a member of the glial-cell-derived neurotropic factor family (GDNF), is a GDNF family receptor α-like (GFRAL) protein. GDF15 induces pro-angiogenic effects in tumors. However, GDF15 could affect tumorigenesis both positively and negatively. With a better understanding of the upstream disease pathways reflected by GDF15, new treatment targets may emerge.

The MIC-1/GDF15-GFRAL Pathway in Energy Homeostasis: Implications for Obesity, Cachexia, and Other Associated Diseases

MIC-1/GDF15 is a stress response cytokine and a distant member of the transforming growth factor beta (TGFb) superfamily, with no close relatives. It acts via a recently identified receptor called glial-derived neurotrophic factor (GDNF) receptor alpha-like (GFRAL), which is a distant orphan member of the GDNF receptor family that signals through the tyrosine kinase receptor Ret. MIC-1/GDF15 expression and serum levels rise in response to many stimuli that initiate cell stress and as part of a wide variety of disease processes, most prominently cancer and cardiovascular disease. The best documented actions of MIC-1/GDF15 are on regulation of energy homeostasis. When MIC-1/GDF15 serum levels are substantially elevated in diseases like cancer, it subverts a physiological pathway of appetite regulation to induce an anorexia/cachexia syndrome initiated by its actions on hindbrain neurons. These effects make it a potential target for the treatment of both obesity and anorexia/cachexia syndromes, disorders lacking any highly effective, readily accessible therapies.

Interferon-stimulated gene 15 promotes cholesterol efflux by activating autophagy via the miR-17-5p/Beclin-1 pathway in THP-1 macrophage-derived foam cells

Macrophage autophagy contributes to the hydrolysis of cholesteryl ester into free cholesterol mainly for ATP-binding cassette transporter A1 (ABCA1)-dependent efflux. Interferon-stimulated gene 15 (ISG15) has been shown to regulate autophagy in multiple types of cells. The present study aimed to examine the effects of ISG15 on autophagy and cholesterol efflux in THP-1 macrophage-derived foam cells and to explore the underlying molecular mechanisms. Our results showed that overexpression of ISG15 promoted autophagy and cholesterol efflux and inhibited lipid accumulation without impact on ABCA1 expression. Inhibition of autophagy by 3-methyladenine (3-MA) abrogated the enhancing effects of ISG15 on cholesterol efflux. Both bioinformatics analysis and dual luciferase reporter assay identified Beclin-1 as a direct target of miR-17-5p. Moreover, ISG15 overexpression markedly decreased miR-17-5p levels and upregulated Beclin-1 expression. ISG15-induced enhancement of autophagy and cholesterol efflux was reversed by pretreatment with either miR-17-5p mimic or Beclin-1 siRNA. In conclusion, these findings suggest that ISG15 reduces miR-17-5p levels and thereby promotes Beclin-1-mediated autophagy, resulting in increased cholesterol efflux from THP-1 macrophage-derived foam cells.

CXXC4 activates apoptosis through up-regulating GDF15 in gastric cancer

Worldwide, gastric cancer is one of the most fatal cancers. Epigenetic alterations in gastric cancer play important roles in silencing of tumor suppressor genes. We previously found that CXXC finger protein 4 (CXXC4) was a novel tumor suppressor in gastric cancer. In this report, we demonstrated that CXXC4 inhibited growth of gastric cancer cells as a pro-apoptotic factor. This inhibition could be reversed by the pan-caspase inhibitor called Z-VAD-FMK. However, CXXC4 with mutations in its DNA binding domain failed to induce apoptosis. Growth differentiation factor 15 (GDF15) was identified as one of potential targets responsible for CXXC4-induced apoptosis. CXXC4 activated GDF15 transcription through enhancing the interaction of transcription factor Sp1 with GDF15 promoter. In summary, the nuclear protein CXXC4 activated apoptosis in gastric cancer through up-regulating its novel potential downstream target GDF15. GDF15 might be a promising target for clinical treatment of gastric cancer with CXXC4 deficiency.

Association between GDF-15 levels and changes in vascular and physical function in older patients with hypertension

BACKGROUND

Growth differentiation factor-15 (GDF-15) may be a biomarker of disease, protective response and/or prognosis, in older people with hypertension.

AIMS

To correlate baseline GDF-15 levels with physical and vascular health data in this population.

METHODS

Baseline blood samples were analysed using a GDF-15 ELISA assay kit. Correlations with baseline and 12-month outcome data, including measures of physical and vascular function, were performed.

RESULTS

A total of 147 individuals, mean age 76.8 ± 4.7 years, were included. 77 (52 %) were male. Baseline log₁₀GDF-15 showed significant correlations with age (r = 0.37, p < 0.001), total cholesterol (r = -0.33, p < 0.001) and 6-min walking distance (r = -0.37, p < 0.001). Age remained significantly associated with log₁₀GDF-15 in multivariable analysis (beta = -0.29, p = 0.001). Baseline log₁₀GDF-15 was significantly associated with decline in 6-min walk distance over 12 months (beta = -0.27, p = 0.01) in multivariable models. No significant correlations were seen with changes in vascular function over 12 months.

CONCLUSION

Baseline GDF-15 predicts declining physical, but not vascular, function in our population.

Hsp27 promotes ABCA1 expression and cholesterol efflux through the PI3K/PKCζ/Sp1 pathway in THP-1 macrophages

Heat shock protein 27 (Hsp27) is a putative biomarker and therapeutic target in atherosclerosis. This study was to explore the potential mechanisms underlying Hsp27 effects on ATP-binding cassette transporter A1 (ABCA1) expression and cellular cholesterol efflux. THP-1 macrophage-derived foam cells were infected with adenovirus to express wild-type Hsp27, hyper-phosphorylated Hsp27 mimic (3D Hsp27), antisense Hsp27 or hypo-phosphorylated Hsp27 mimic (3A Hsp27). Wild-type and 3D Hsp27 were found to up-regulate ABCA1 mRNA and protein expression and increase cholesterol efflux from cells. Expression of antisense or 3A Hsp27 suppressed the expression of ABCA1 and cholesterol efflux. Furthermore, over-expression of wild-type and 3D Hsp27 significantly increased the levels of phosphorylated specificity protein 1 (Sp1), protein kinase C ζ (PKCζ) and phosphatidylinositol 3-kinase (PI3K). In addition, the up-regulation of ABCA1 expression and cholesterol efflux induced by 3D Hsp27 was suppressed by inhibition of Sp1, PKCζ and PI3K with specific kinase inhibitors. Taken together, our results revealed that Hsp27 may up-regulate the expression of ABCA1 and promotes cholesterol efflux through activation of the PI3K/PKCζ/Sp1 signal pathway in THP-1 macrophage-derived foam cells. Our findings may partly explain the mechanisms underlying the anti-atherogenic effect of Hsp27.

Growth Differentiation Factor 15 Is Associated With Major Amputation and Mortality in Patients With Peripheral Artery Disease

Background

Peripheral artery disease (PAD) is one of the most common clinical presentations of atherosclerosis, and its prevalence is still increasing. Despite improvement of health care, morbidity and mortality risks remain high, including the risk of amputation. GDF15 (growth differentiation factor 15) is a member of the transforming growth factor family that is involved in apoptosis and inflammation; therefore, GDF15 is a potential biomarker to identify patients at high risk of adverse clinical outcomes.

Methods and Results

Circulating GDF15 levels were measured using a multiplex immunoassay in patients with critical limb ischemia and PAD from 2 different patient cohorts that included patients with clinically manifest PAD: the JUVENTAS (Rejuvenating Endothelial Progenitor Cells via Transcutaneous Intra‐Arterial Supplementation) trial (n=160, 67 major events; critical limb ischemia) and the Athero‐Express Biobank (n=386, 64 major events; PAD). Kaplan–Meier curves demonstrated that high levels of GDF15 were associated with increased risk of major events, defined as major amputation (at or above the ankle joint) and all‐cause mortality, in both cohorts (highest versus lowest, JUVENTAS: hazard ratio: 4.01 [95% confidence interval, 2.05–7.84; P<0.0001]; Athero‐Express: hazard ratio: 3.27 [95% confidence interval, 1.64–6.54; P=0.0008]). In the JUVENTAS trial, this was more pronounced in women. Cox proportional multivariable regression models with median follow‐up of 3 years, corrected for common confounders, showed hazard ratios of 1.70 (95% confidence interval, 1.18–2.69; P=0.0053) and 1.57 (95% confidence interval, 1.02–2.41; P=0.041) per 2.78‐fold increase of GDF15 in JUVENTAS and Athero‐Express, respectively.

Conclusions

High GDF15 levels are associated with increased risk of major amputation and/or death in PAD patients. GDF15 levels could be of additive value to identify patients who are at high risk of amputation or death and could help guide treatment choices.