Catestatin (chromogranin A(352-372)) and novel effects on mobilization of fat from adipose tissue through regulation of adrenergic and leptin signaling

Chromogranin A deficiency attenuates tauopathy by altering epinephrine-alpha-adrenergic receptor signaling in PS19 mice

Metabolic disorders such as insulin resistance and hypertension are potential risk factors for aging and neurodegenerative diseases. These conditions are reversed in Chromogranin A (CgA) knockout (CgA-KO) mice. CgA is known to be associated with protein aggregates in the brains of neurodegenerative diseases including Alzheimer's disease (AD). Here, we investigated the role of CgA in Tau pathogenesis in AD and corticobasal degeneration (CBD). CgA ablation in Tauopathy mice (PS19) (CgA-KO/PS19) reduced pathological Tau aggregation and spreading, extended lifespan, and improved cognitive function. Transcriptomic and metabolite analysis of mouse cortices revealed elevated alpha-1-adrenergic receptors (Adra1) expression and high Epinephrine (EPI) levels in PS19 mice compared to WT mice, mirroring observations in AD and CBD patients. CgA depletion in PS19 mice lowered cortical EPI levels and the expression of Adra1 back to normal. Treatment of WT hippocampal organotypic slice cultures with EPI or Adra1 agonist promoted, while an Adra1 antagonist inhibited Tau hyperphosphorylation and formation of neurofibrillary tangles, which is unaltered upon CgA depletion. These findings demonstrate the involvement of CgA in Tau pathogenesis and highlight the interplay between the EPI-Adra1 signaling pathway and CgA in Tauopathy.

A complex role of chromogranin A and its peptides in inflammation, autoimmunity, and infections

Chromogranin A (CgA), mostly known as a nonspecific neuroendocrine tumor marker, was the first glycoprotein from the granin family characterized as a prohormone for various bioactive peptides including vasostatin I/II (VS-I, VS-II), catestatin (CST), chromofungin (CHR), pancreastatin (PST), WE-14, and others. CgA and its derivatives present various functions, often antagonistic, in maintaining body homeostasis and influencing the immune system. This review aims to summarize the not fully understood role of CgA and its derivatives in inflammation, autoimmunity, and infections. CgA seems to be involved in the complex pathophysiology of cardiovascular disorders, neurodegenerative diseases, and other conditions where immune system dysfunction plays a role in the onset and development of the disease (e.g. systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), or rheumatoid arthritis (RA)). However, the direct immunomodulatory role of CgA is difficult to assess since many of its activities may be linked with its peptides. CST and VS-I are considered anti-inflammatory molecules, due to M2 macrophage polarization stimulation and downregulation of certain proinflammatory cytokines. Conversely, PST is reported to stimulate proinflammatory M1 macrophage polarization and Th1 lymphocyte response. Thus, the final effects of CgA in inflammation may depend on its cleavage pattern. Additionally, peptides like CST, VS-I, or CHR exert direct antimicrobial/antifungal activities. CgA, WE-14, and other less-known CgA-derived peptides have also been reported to trigger autoimmune responses, highly studied in type 1 diabetes mellitus. Overall, CgA and its derivatives have an interesting but complex role in immunity, however, their specific roles require further research.

Main mechanisms and clinical implications of alterations in energy expenditure state among patients with pheochromocytoma and paraganglioma: A review

Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors with diverse clinical presentations. Alterations in energy expenditure state are commonly observed in patients with PPGL. However, the reported prevalence of hypermetabolism varies significantly and the underlying mechanisms and implications of this presentation have not been well elucidated. This review discusses and analyzes the factors that contribute to energy consumption. Elevated catecholamine levels in patients can significantly affect substance and energy metabolism. Additionally, changes in the activation of brown adipose tissue (BAT), inflammation, and the inherent energy demands of the tumor can contribute to increased resting energy expenditure (REE) and other energy metabolism indicators. The PPGL biomarker, chromogranin A (CgA), and its fragments also influence energy metabolism. Chronic hypermetabolic states may be detrimental to these patients, with surgical tumor removal remaining the primary therapeutic intervention. The high energy expenditure of PPGL has not received the attention it deserves, and an accurate assessment of energy metabolism is the cornerstone for an adequate understanding and treatment of the disease.

The Role of Catestatin in Preeclampsia

Preeclampsia (PE) is a unique pregnancy disorder affecting women across the world. It is characterized by the new onset of hypertension with coexisting end-organ damage. Although the disease has been known for centuries, its exact pathophysiology and, most importantly, its prevention remain elusive. The basis of its associated molecular changes has been attributed to the placenta and the hormones regulating its function. One such hormone is chromogranin A (CgA). In the placenta, CgA is cleaved to form a variety of biologically active peptides, including catestatin (CST), known inter alia for its vasodilatory effects. Recent studies indicate that the CST protein level is diminished both in patients with hypertension and those with PE. Therefore, the aim of the present paper is to review the most recent and most relevant in vitro, in vivo, and clinical studies to provide an overview of the proposed impact of CST on the molecular processes of PE and to consider the possibilities for future experiments in this area.

Plasma catestatin levels are related to metabolic parameters in patients with essential hypertension and type 2 diabetes mellitus

Catestatin (CST) is a pleiotropic peptide with cardioprotective and metabolic effects. CST is involved in the pathogenesis of both arterial hypertension (AH) and type 2 diabetes mellitus (T2DM), which are the risk factors of cardiovascular diseases. In this study, we aimed to investigate the plasma CST levels in hypertensive patients, especially with T2DM, as well as compare those with healthy volunteers, and explore the relationship between CST levels and clinical, anthropometric and laboratory parameters. 106 Hypertensive patients, 55 of which had comorbidity T2DM, and 30 healthy volunteers were enrolled in the study. All subjects underwent clinical examination, including vital signs and anthropometric data assessment, medical history interview, and blood sample collection. Plasma CST levels were measured by an enzyme-linked immunosorbent assay (ELISA), using a commercial diagnostic kit. The plasma CST levels were significantly lower in hypertensive patients (N = 106) compared with healthy subjects (N = 30) (5.02 ± 1.09 vs. 6.64 ± 0.72; p < 0.001). Furthermore, hypertensive patients with T2DM (N = 55) have significantly reduced CST levels in comparison with those without T2DM (N = 51) (4.47 ± 1.16 vs. 5.61 ± 0.61; p < 0.001). CST significantly correlated with anthropometric characteristics, in particular, weight (r =  - 0.344; p < 0.001), BMI (r =  - 0.42; p < 0.001), neck (r =  - 0.358; p < 0.001), waist (r =  - 0.487; p < 0.001), hip (r =  - 0.312; p < 0.001), wrist circumferences (r =  - 0.264; p = 0.002), and waist-to-hip ratio (r =  - 0.395; p < 0.001). Due to its antihypertensive effect, CST has significant associations with systolic BP (r =  - 0.475; p < 0.001) and duration of AH (r =  - 0.26; p = 0.007). CST also has an inverse relationship with insulin (r =  - 0.382; p < 0.001), glucose (r =  - 0.45; p < 0.001), index HOMA-IR (r =  - 0.481; p < 0.001) and HbA1c (r =  - 0.525; p < 0.001), that indicate its involvement in T2DM development. Besides, CST has significant correlations with uric acid levels (r =  - 0.412; p < 0.001) as well as lipid parameters, especially HDL-C (r = 0.480; p < 0.001), VLDL-C (r =  - 0.238; p = 0.005), TG (r =  - 0.4; p < 0.001), non-HDL-C/HDL-C (r =  - 0.499; p < 0.001). Multiple linear regression analysis indicated BMI (β =  - 0.22; p = 0.007), AH duration (β =  - 0.25; p = 0.008), HbA1c (β =  - 0.43; p = 0.019) and HDL-C levels (β = 0.27; p = 0.001) as independent predictors of CST levels. The hypertensive patients have significantly decreased CST levels that are even more reduced in the presence of comorbid T2DM. The established correlations with anthropometric and laboratory parameters indicate not only antihypertensive but also metabolic effects of CST. Our results suggest the probable role of CST in the pathophysiology of cardiometabolic diseases and the development of cardiovascular complications.

Chromogranin A and its derived peptides: potential regulators of cholesterol homeostasis

Chromogranin A (CHGA), a member of the granin family of proteins, has been an attractive therapeutic target and candidate biomarker for several cardiovascular, neurological, and inflammatory disorders. The prominence of CHGA stems from the pleiotropic roles of several bioactive peptides (e.g., catestatin, pancreastatin, vasostatins) generated by its proteolytic cleavage and by their wide anatomical distribution. These peptides are emerging as novel modulators of cardiometabolic diseases that are often linked to high blood cholesterol levels. However, their impact on cholesterol homeostasis is poorly understood. The dynamic nature of cholesterol and its multitudinous roles in almost every aspect of normal body function makes it an integral component of metabolic physiology. A tightly regulated coordination of cholesterol homeostasis is imperative for proper functioning of cellular and metabolic processes. The deregulation of cholesterol levels can result in several pathophysiological states. Although studies till date suggest regulatory roles for CHGA and its derived peptides on cholesterol levels, the mechanisms by which this is achieved still remain unclear. This review aims to aggregate and consolidate the available evidence linking CHGA with cholesterol homeostasis in health and disease. In addition, we also look at common molecular regulatory factors (viz., transcription factors and microRNAs) which could govern the expression of CHGA and genes involved in cholesterol homeostasis under basal and pathological conditions. In order to gain further insights into the pathways mediating cholesterol regulation by CHGA/its derived peptides, a few prospective signaling pathways are explored, which could act as primers for future studies.

In vitro fermentation of glycosaminoglycans from mackerel fish waste and its role in modulating the antioxidant status and gut microbiota of high fat diet-fed C57BL/6 mice

Bioactive polysaccharides such as glycosaminoglycans (GAGs) exhibit potential health benefits for several health complications including obesity. The gut microbiota plays a key role in regulating host metabolism, nutrition and immunity. The present work assessed the potential of extracted GAGs (e-GAGs) in maintaining the gut microbiota and ameliorating the effects of high fat diet in in vitro and in vivo models. The in vitro fermentability of e-GAGs extracted from mackerel fish waste was analyzed with Lactobacillus plantarum (LP) and Bifidobacterium bifidum (BB); e-GAGs at 0.5 and 1% proved their prebiotic nature up to 48 h. The pH value decreased from 6.23 to 3.32, the cell density increased from 1.70 to 2.32, the viable cell count increased from 8 to 12 log CFU mL^-1, and short chain fatty acid (SCFA) production was ≈33, 31 and 36% for LP and ≈37, 29 and 34% for BB in terms of acetic acid, propionic acid and butyric acid, respectively. In vivo studies on high fat diet (HFD)-fed C57BL/6 mice with e-GAGs (380 and 760 mg kg^-1 diet) showed ameliorated gut microbiome and tissue/plasma antioxidant enzyme activities, and also the e-GAG-fed group showed significantly (P < 0.05) decreased lipid peroxidation. Cecal microbial analysis showed the health-promoting effects of e-GAGs in reducing (P < 0.05) the obesity ratio of Firmicutes to Bacteroidetes (F/B) within the range (5.32 and 5.26) compared with HFD (6.23). Hence, e-GAGs can be a potential molecule for the treatment of obesity by restoring the redox status under oxidative stress and ameliorating the gut microbes that produce SCFAs which are known to have health beneficial effects.

Low catestatin as a risk factor for cardiovascular disease - assessment in patients with adrenal incidentalomas

Background

Catestatin (Cts) is a peptide derived from proteolytic cleavage of chromogranin A, which exhibits cardioprotective and anti-inflammatory properties. Cts has been proposed as a potential biomarker for cardiovascular (CV) disease.

Objectives

examining Cts in patients with incidentally discovered adrenocortical adenomas (AI), and its associations with CV risk factors and blood pressure (BP).

Materials and methods

In this cross-sectional study, 64 AI patients without overt CV disease other than primary hypertension were recruited along with 24 age-, sex-, and body-mass-index (BMI)-matched controls with normal adrenal morphology. Laboratory, 24-h ambulatory BP monitoring, echocardiography, and common carotid artery sonography examinations were performed.

Results

Unadjusted Cts was higher in AI patients (median 6.5, interquartile range: 4.9-37 ng/ml) versus controls (4.5 (3.5 - 28)), p=0.048, however, the difference was insignificant after adjusting for confounding variables. Cts was lower in subjects with metabolic syndrome than in those without it (5.2 (3.9- 6.9) vs. 25.7 (5.8-115) ng/ml, p<0.01), and in men compared to women (4.9 (4-7.4) ng/ml vs. 7 (4.8-100), p=0.015). AI patients in the lower half of Cts levels compared to those in the upper had a higher prevalence of hypertension (OR 0.15, 95% CI: 0.041-0.5, p<0.001) and metabolic syndrome (OR 0.15, 95% CI 0.041-0.5, p<0.001). In AI patients Cts correlated positively with high-density lipoprotein cholesterol (Spearman's r=0.31), negatively with BMI (r=-0.31), and 10-year atherosclerotic CV disease risk (r=-0.42).

Conclusions

Our data indicate associations between CV risk factors and Cts. More clinical research is needed to apply serum Cts as a biomarker.

Prognostic Value of Plasma Catestatin Concentration in Patients with Heart Failure with Reduced Ejection Fraction in Two-Year Follow-Up

The primary objective of the study was to evaluate the prognostic value of measuring plasma catestatin (CST) concentration in patients with heart failure with reduced ejection fraction (HFrEF) as a predictor of unplanned hospitalization and all-cause death independently and as a composite endpoint at 2-year follow-up. The study group includes 122 hospitalized Caucasian patients in NYHA classes II to IV. Patients who died during the 24-month follow-up period (n = 44; 36%) were significantly older on the day of enrollment, were more likely to be in a higher NYHA class, had lower TAPSE, hemoglobin concentration, hematocrit, and platelet count, higher concentrations of CST, NT-proBNP, troponin T, creatinine, and glucose, and higher red cell distribution width value and leukocyte and neutrocyte count than patients who survived the follow-up period. Plasma catestatin concentration increased with NYHA class (R = 0.58; p <0.001) and correlated significantly with blood NT-proBNP concentration (R = 0.44; p <0.001). We showed that higher plasma catestatin concentration increased the risk of all-cause death by more than five times. Plasma CST concentration is a valuable prognostic parameter in predicting death from all causes and unplanned hospitalization in patients with HFrEF.

Chromogranin A-derived peptides pancreastatin and catestatin: emerging therapeutic target for diabetes

Chromogranin A (ChgA) is an acidic pro-protein found in neuroendocrine organs, pheochromocytoma chromaffin granules, and tumor cells. Proteolytic processing of ChgA gives rise to an array of biologically active peptides such as pancreastatin (PST), vasostatin, WE14, catestatin (CST), and serpinin, which have diverse roles in regulating cardiovascular functions and metabolism, as well as inflammation. Intricate tissue-specific role of ChgA-derived peptide activity in preclinical rodent models of metabolic syndrome reveals complex effects on carbohydrate and lipid metabolism. Indeed, ChgA-derived peptides, PST and CST, play a pivotal role in metabolic syndrome such as obesity, insulin resistance, and diabetes mellitus. Additionally, supplementation of specific peptide in ChgA-KO mice have an opposing effect on physiological functions, such as PST supplementation reduces insulin sensitivity and enhances inflammatory response. In contrast, CST supplementation enhances insulin sensitivity and reduces inflammatory response. In this review, we focus on the tissue-specific role of PST and CST as therapeutic targets in regulating carbohydrate and lipid metabolism, along with the associated risk factors.

Selected Serum Markers Associated with Pathogenesis and Clinical Course of Type 1 Diabetes in Pediatric Patients-The Effect of Disease Duration

Biochemical abnormalities in the course of type 1 diabetes (T1D) may cause the production/activation of various proteins and peptides influencing treatment and causing a risk of complications. The aim of this study was to assess concentrations of selected serum substances involved in the pathogenesis and course of T1D and to correlate their concentrations with the duration of T1D. The study included patients with T1D (n = 156) at the age of 3-17, who were divided according to the duration of the disease into those newly diagnosed (n = 30), diagnosed after 3-5 (n = 77), 6-7 (n = 25), and over 7 (n = 24) years from the onset of T1D, and age-matched healthy controls (n = 30). Concentrations of amylin (IAPP), proamylin (proIAPP), catestatin (CST), chromogranin A (ChgA), nerve growth factor (NFG), platelet-activating factor (PAF), uromodulin (UMOD), and intestinal fatty acid binding protein (I-FABP) were measured in sera using immunoenzymatic tests. There were significant differences in concentrations of all the substances except UMOD and NGF between T1D patients and healthy children. The duration of the disease affected concentrations of CST, ChgA, PAF, and NGF, i.e., proteins/peptides which could have an impact on the course of T1D and the development of complications. In long-term patients, a decrease in concentrations of CST and ChgA, and an increase in PAF concentrations were found. In the case of NGF, a decrease was observed after the initial high values, followed by an increase over 7 years after T1D diagnosis. Concluding, the results show that concentrations of selected serum indicators may change in the course of T1D. Further studies are needed to establish whether these indicators could be used in the context of predicting long-term complications.

Role of Catestatin in the Cardiovascular System and Metabolic Disorders

Catestatin is a multifunctional peptide that is involved in the regulation of the cardiovascular and immune systems as well as metabolic homeostatis. It mitigates detrimental, excessive activity of the sympathetic nervous system by inhibiting catecholamine secretion. Based on in vitro and in vivo studies, catestatin was shown to reduce adipose tissue, inhibit inflammatory response, prevent macrophage-driven atherosclerosis, and regulate cytokine production and release. Clinical studies indicate that catestatin may influence the processes leading to hypertension, affect the course of coronary artery diseases and heart failure. This review presents up-to-date research on catestatin with a particular emphasis on cardiovascular diseases based on a literature search.

Catestatin induces glycogenesis by stimulating the phosphoinositide 3-kinase-AKT pathway

AIM

Defects in hepatic glycogen synthesis contribute to post-prandial hyperglycaemia in type 2 diabetic patients. Chromogranin A (CgA) peptide Catestatin (CST: hCgA352-372 ) improves glucose tolerance in insulin-resistant mice. Here, we seek to determine whether CST induces hepatic glycogen synthesis.

METHODS

We determined liver glycogen, glucose-6-phosphate (G6P), uridine diphosphate glucose (UDPG) and glycogen synthase (GYS2) activities; plasma insulin, glucagon, noradrenaline and adrenaline levels in wild-type (WT) as well as in CST knockout (CST-KO) mice; glycogen synthesis and glycogenolysis in primary hepatocytes. We also analysed phosphorylation signals of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), phosphatidylinositol-dependent kinase-1 (PDK-1), GYS2, glycogen synthase kinase-3β (GSK-3β), AKT (a kinase in AKR mouse that produces Thymoma)/PKB (protein kinase B) and mammalian/mechanistic target of rapamycin (mTOR) by immunoblotting.

RESULTS

CST stimulated glycogen accumulation in fed and fasted liver and in primary hepatocytes. CST reduced plasma noradrenaline and adrenaline levels. CST also directly stimulated glycogenesis and inhibited noradrenaline and adrenaline-induced glycogenolysis in hepatocytes. In addition, CST elevated the levels of UDPG and increased GYS2 activity. CST-KO mice had decreased liver glycogen that was restored by treatment with CST, reinforcing the crucial role of CST in hepatic glycogenesis. CST improved insulin signals downstream of IR and IRS-1 by enhancing phospho-AKT signals through the stimulation of PDK-1 and mTORC2 (mTOR Complex 2, rapamycin-insensitive complex) activities.

CONCLUSIONS

CST directly promotes the glycogenic pathway by (a) reducing glucose production, (b) increasing glycogen synthesis from UDPG, (c) reducing glycogenolysis and (d) enhancing downstream insulin signalling.

Putative regulation of macrophage-mediated inflammation by catestatin

Catestatin (CST) is a bioactive cleavage product of the neuroendocrine prohormone chromogranin A (CgA). Recent findings show that CST can exert anti-inflammatory and antiadrenergic effects by suppressing the inflammatory actions of mammalian macrophages. However, recent findings also suggest that macrophages themselves are major CST producers. Here, we hypothesize that macrophages produce CST in an inflammation-dependent manner and thereby might self-regulate inflammation in an autocrine fashion. CST is associated with pathological conditions hallmarked by chronic inflammation, including autoimmune, cardiovascular, and metabolic disorders. Since intraperitoneal injection of CST in mouse models of diabetes and inflammatory bowel disease has been reported to be beneficial for mitigating disease, we posit that CST should be further investigated as a candidate target for treating certain inflammatory diseases.

Gut microbiota transplantation drives the adoptive transfer of colonic genotype-phenotype characteristics between mice lacking catestatin and their wild type counterparts

The gut microbiota is in continuous interaction with the intestinal mucosa via metabolic, neuro-immunological, and neuroendocrine pathways. Disruption in levels of antimicrobial peptides produced by the enteroendocrine cells, such as catestatin, has been associated with changes in the gut microbiota and imbalance in intestinal homeostasis. However, whether the changes in the gut microbiota have a causational role in intestinal dyshomeostasis has remained elusive. To this end, we performed reciprocal fecal microbial transplantation in wild-type mice and mice with a knockout in the catestatin coding region of the chromogranin-A gene (CST-KO mice). Combined microbiota phylogenetic profiling, RNA sequencing, and transmission electron microscopy were employed. Fecal microbiota transplantation from mice deficient in catestatin (CST-KO) to microbiota-depleted wild-type mice induced transcriptional and physiological features characteristic of a distorted colon in the recipient animals, including impairment in tight junctions, as well as an increased collagen area fraction indicating colonic fibrosis. In contrast, fecal microbiota transplantation from wild-type mice to microbiota-depleted CST-KO mice reduced collagen fibrotic area, restored disrupted tight junction morphology, and altered fatty acid metabolism in recipient CST-KO mice. This study provides a comprehensive overview of the murine metabolic- and immune-related cellular pathways and processes that are co-mediated by the fecal microbiota transplantation and supports a prominent role for the gut microbiota in the colonic distortion associated with the lack of catestatin in mice. Overall, the data show that the gut microbiota may play a causal role in the development of features of intestinal inflammation and metabolic disorders, known to be associated with altered levels of catestatin and may, thus, provide a tractable target in the treatment and prevention of these disorders.

Chromogranin A regulates gut permeability via the antagonistic actions of its proteolytic peptides

AIM

A "leaky" gut barrier has been implicated in the initiation and progression of a multitude of diseases, for example, inflammatory bowel disease (IBD), irritable bowel syndrome and celiac disease. Here we show how pro-hormone Chromogranin A (CgA), produced by the enteroendocrine cells, and Catestatin (CST: hCgA_352-372 ), the most abundant CgA-derived proteolytic peptide, affect the gut barrier.

METHODS

Colon tissues from region-specific CST-knockout (CST-KO) mice, CgA-knockout (CgA-KO) and WT mice were analysed by immunohistochemistry, western blot, ultrastructural and flowcytometry studies. FITC-dextran assays were used to measure intestinal barrier function. Mice were supplemented with CST or CgA fragment pancreastatin (PST: CgA_250-301 ). The microbial composition of cecum was determined. CgA and CST levels were measured in blood of IBD patients.

RESULTS

Plasma levels of CST were elevated in IBD patients. CST-KO mice displayed (a) elongated tight, adherens junctions and desmosomes similar to IBD patients, (b) elevated expression of Claudin 2, and (c) gut inflammation. Plasma FITC-dextran measurements showed increased intestinal paracellular permeability in the CST-KO mice. This correlated with a higher ratio of Firmicutes to Bacteroidetes, a dysbiotic pattern commonly encountered in various diseases. Supplementation of CST-KO mice with recombinant CST restored paracellular permeability and reversed inflammation, whereas CgA-KO mice supplementation with CST and/or PST in CgA-KO mice showed that intestinal paracellular permeability is regulated by the antagonistic roles of these two peptides: CST reduces and PST increases permeability.

CONCLUSION

The pro-hormone CgA regulates the intestinal paracellular permeability. CST is both necessary and sufficient to reduce permeability and primarily acts by antagonizing PST.

Catestatin peptide of chromogranin A as a potential new target for several risk factors management in the course of metabolic syndrome

Obesity, lipodystrophy, diabetes, and hypertension collectively constitute the main features of Metabolic Syndrome (MetS), together with insulin resistance (IR), which is considered as a defining element. MetS generally leads to the development of cardiovascular disease (CVD), which is a determinant cause of mortality and morbidity in humans and animals. Therefore, it is essential to implement and put in place adequate management strategies for the treatment of this disease. Catestatin is a bioactive peptide with 21 amino acids, which is derived through cleaving of the prohormone chromogranin A (CHGA/CgA) that is co-released with catecholamines from secretory vesicles and, which is responsible for hepatic/plasma lipids and insulin levels regulation, improves insulin sensitivity, reduces hypertension and attenuates obesity in murine models. In humans, there were few published studies, which showed that low levels of catestatin are significant risk factors for hypertension in adult patients. These accumulating evidence documents clearly that catestatin peptide (CST) is linked to inflammatory and metabolic syndrome diseases and can be a novel regulator of insulin and lipid levels, blood pressure, and cardiac function. The goal of this review is to provide an overview of the CST effects in metabolic syndrome given its role in metabolic regulation and thus, provide new insights into the use of CST as a diagnostic marker and therapeutic target.

Serum Catestatin Levels and Arterial Stiffness Parameters Are Increased in Patients with Inflammatory Bowel Disease

Catestatin (CST) is an important peptide in the pathophysiology of chronic inflammatory disorders. However, clinical studies on inflammatory bowel disease (IBD) patients are lacking. Our goal was to investigate CST concentrations in IBD patients compared to healthy subjects. Additionally, we aimed to determine arterial stiffness parameters in relation to CST. This cross-sectional study compared 80 IBD patients (45 Crohn's disease (CD) and 35 ulcerative colitis (UC) patients) with 75 control subjects. Serum CST levels were significantly higher in the IBD group compared to control subjects (11.29 ± 9.14 vs. 7.13 ± 6.08 ng/mL, p = 0.001) and in the UC group compared to CD patients (13.50 ± 9.58 vs. 9.03 ± 6.92 ng/mL, p = 0.021), irrespective of age and BMI. IBD patients exhibited significantly higher values of heart rate adjusted central augmentation index (cAIx-75) (14.88 ± 10.59 vs. 6.87 ± 9.50 %, p < 0.001) and pulse wave velocity (PWV) (8.06 ± 3.23 vs. 6.42 ± 1.47 m/s, p < 0.001) compared to control group. Furthermore, PWV was the only significant independent correlate of CST (B = 1.20, t = 4.15, p < 0.001), while CST, PWV, cAIx-75, high-sensitivity C-reactive protein and BMI were significant predictors of positive IBD status (1.089 (1.022-1.161), 1.515 (1.166-1.968), 1.060 (1.024-1.097), 1.458 (1.116-1.906), 0.793 (0.683-0.920), respectively). Serum CST levels were significantly higher in IBD patients compared to controls and an independent positive correlation of CST with PWV existed. Therefore, it is possible that CST could have a role in the complex pathophysiology of IBD and its cardiovascular complications.

Catestatin in defense of oxidative-stress-induced apoptosis: A novel mechanism by activating the beta2 adrenergic receptor and PKB/Akt pathway in ischemic-reperfused myocardium

Apoptosis induced by oxidative stress is one of the most important cardiomyocytes losses during ischemia-reperfusion (I/R). Catestatin (CST) has been demonstrated to have the anti-oxidative capacity in vitro. We hypothesized that CST intervention could reduce apoptosis of cardiomyocytes induced by oxidative stress in I/R. In Langendorff-perfused rat heart global I/R model, CST was introduced at the reperfusion stage. In comparison to the control group, CST led to preservation on activities of superoxide dismutase and glutathione peroxidase, improvement of hemodynamics, and reduced infarction area in reperfused myocardium. The protection of CST was also shown by less apoptotic cardiomyocytes in TUNEL staining, less caspase-3 activation, and increased phosphorylation of protein kinase B (PKB/Akt) in Western blot. To further demonstrate the benefits of CST and explore the possible underlying mechanism, H₂O₂-challenged primary-cultured neonatal rat cardiomyocytes were used to simulate the oxidative-stressed scenario. CST incubation with the H₂O₂-challenged cardiomyocytes led to reduction of apoptosis, which was demonstrated by less Hoechst 33342 positive staining of nuclei, less caspase-3 activation, and DNA fragmentation. The effect of CST was abrogated by pretreatment of the cardiomyocytes with the PI3K inhibitor LY294002. Furthermore, Akt activation and the anti-apoptosis effect of CST were abolished by pretreatment of the cardiomyocytes with β2 receptor inhibitor ICI118551. Thus, the salvage of oxidative-stress-induced apoptotic cardiomyocytes in I/R by CST might involve activation β2 receptor and regulation of PI3K/Akt signaling in reperfusion injury salvage kinase (RISK) pathway.

Catestatin reverses the hypertrophic effects of norepinephrine in H9c2 cardiac myoblasts by modulating the adrenergic signaling

Catestatin (CST) is a catecholamine release-inhibitory peptide secreted from the adrenergic neurons and the adrenal glands. It regulates the cardiovascular functions and it is associated with cardiovascular diseases. Though its mechanisms of actions are not known, there are evidences of cross-talk between the adrenergic and CST signaling. We hypothesized that CST moderates the adrenergic overdrive and studied its effects on norepinephrine-mediated hypertrophic responses in H9c2 cardiac myoblasts. CST alone regulated the expression of a number of fetal genes that are induced during hypertrophy. When cells were pre-treated CST, it blunted the modulation of those genes by norepinephrine. Norepinephrine (2 µM) treatment also increased cell size and enhanced the level of Troponin T in the sarcomere. These effects were attenuated by the treatment with CST. CST attenuated the immediate generation of ROS and the increase in glutathione peroxidase activity induced by norepinephrine treatment. Expression of fosB and AP-1 promoter-reporter constructs was used as the endpoint readout for the interaction between the CST and adrenergic signals at the gene level. It showed that CST largely attenuates the stimulatory effects of norepinephrine and other mitogenic signals through the modulation of the gene regulatory modules in a characteristic manner. Depending upon the dose, the signaling by CST appears to be disparate, and at 10-25 nM doses, it primarily moderated the signaling by the β1/2-adrenoceptors. This study, for the first time, provides insights into the modulation of adrenergic signaling in the heart by CST.

Chromogranin A and its fragments in cardiovascular, immunometabolic, and cancer regulation

Chromogranin A (CgA)-the index member of the chromogranin/secretogranin secretory protein family-is ubiquitously distributed in endocrine, neuroendocrine, and immune cells. Elevated levels of CgA-related polypeptides, consisting of full-length molecules and fragments, are detected in the blood of patients suffering from neuroendocrine tumors, heart failure, renal failure, hypertension, rheumatoid arthritis, and inflammatory bowel disease. Full-length CgA and various CgA-derived peptides, including vasostatin-1, pancreastatin, catestatin, and serpinin, are expressed at different relative levels in normal and pathological conditions and exert diverse, and sometime opposite, biological functions. For example, CgA is overexpressed in genetic hypertension, whereas catestatin is diminished. In rodents, the administration of catestatin decreases hypertension, cardiac contractility, obesity, atherosclerosis, and inflammation, and it improves insulin sensitivity. By contrast, pancreastatin is elevated in diabetic patients, and the administration of this peptide to obese mice decreases insulin sensitivity and increases inflammation. CgA and the N-terminal fragment of vasostatin-1 can enhance the endothelial barrier function, exert antiangiogenic effects, and inhibit tumor growth in animal models, whereas CgA fragments lacking the CgA C-terminal region promote angiogenesis and tumor growth. Overall, the CgA system, consisting of full-length CgA and its fragments, is emerging as an important and complex player in cardiovascular, immunometabolic, and cancer regulation.

Peptide/Receptor Co-evolution Explains the Lipolytic Function of the Neuropeptide TLQP-21

Structural and functional diversity of peptides and GPCR result from long evolutionary processes. Even small changes in sequence can alter receptor activation, affecting therapeutic efficacy. We conducted a structure-function relationship study on the neuropeptide TLQP-21, a promising target for obesity, and its complement 3a receptor (C3aR1). After having characterized the TLQP-21/C3aR1 lipolytic mechanism, a homology modeling and molecular dynamics simulation identified the TLQP-21 binding motif and C3aR1 binding site for the human (h) and mouse (m) molecules. mTLQP-21 showed enhanced binding affinity and potency for hC3aR1 compared with hTLQP-21. Consistently, mTLQP-21, but not hTLQP-21, potentiates lipolysis in human adipocytes. These findings led us to uncover five mutations in the C3aR1 binding pocket of the rodent Murinae subfamily that are causal for enhanced calculated affinity and measured potency of TLQP-21. Identifying functionally relevant peptide/receptor co-evolution mechanisms can facilitate the development of innovative pharmacotherapies for obesity and other diseases implicating GPCRs.

Serum catestatin concentrations are decreased in obese children and adolescents

BACKGROUND

Catestatin is a chromogranin A-derived peptide with a wide spectrum of biological activities, such as inhibiting catecholamine release, decreasing blood pressure, stimulating histamine release, reducing beta-adrenergic stimulation, and regulating oxidative stress.

OBJECTIVES

The aims of our study were to determine serum catestatin concentrations in obese children and adolescents in regard to presence or absence of metabolic syndrome (MS) and to evaluate the possible relations between catestatin levels and other cardiovascular risk factors.

SUBJECTS

Ninety-two obese subjects with a body mass index z score > 2, aged 10 to 18 years, and 39 healthy, normal weight controls were enrolled in the study.

METHODS

Serum catestatin concentrations were measured using an enzyme-linked immunosorbent assay.

RESULTS

Significantly lower serum catestatin concentrations were recorded in the group of obese subjects compared with a control group (10.03 ± 5.05 vs 13.13 ± 6.25 ng/mL, P = 0.004). Further analyses revealed significantly lower catestatin concentrations in the subgroup of obese patients with MS (9.02 ± 4.3 vs 10.54 ± 5.36 vs 13.13 ± 6.25, P = 0.008). Serum catestatin concentrations were significantly negatively correlated with diastolic blood pressure (r = -0.253, P = 0.014), homeostatic model assessment of insulin resistance (r = -0.215, P = 0.037) and high sensitivity C-reactive protein (r = -0.208, P = 0.044).

CONCLUSIONS

To the best of our knowledge, this study is the first to report catestatin concentrations in obese children and adolescents and their possible relations with MS and cardiovascular risk factors in a pediatric population. Obese subjects with MS have lower serum catestatin concentrations than obese subjects without MS and controls.

Catestatin in Acutely Decompensated Heart Failure Patients: Insights from the CATSTAT-HF Study

The role of catestatin (CST) in acutely decompensated heart failure (ADHF) and myocardial infarction (MI) is poorly elucidated. Due to the implicated role of CST in the regulation of neurohumoral activity, the goals of the study were to determine CST serum levels among ninety consecutively enrolled ADHF patients, with respect to the MI history and left ventricular ejection fraction (LVEF) and to examine its association with clinical, echocardiographic, and laboratory parameters. CST levels were higher among ADHF patients with MI history, compared to those without (8.94 ± 6.39 vs. 4.90 ± 2.74 ng/mL, p = 0.001). CST serum levels did not differ among patients with reduced, midrange, and preserved LVEF (7.74 ± 5.64 vs. 5.75 ± 4.19 vs. 5.35 ± 2.77 ng/mL, p = 0.143, respectively). In the multivariable linear regression analysis, CST independently correlated with the NYHA class (β = 0.491, p < 0.001), waist-to-hip ratio (WHR) (β = −0.237, p = 0.026), HbA1c (β = −0.235, p = 0.027), LDL (β = −0.231, p = 0.029), non-HDL cholesterol (β = −0.237, p = 0.026), hs-cTnI (β = −0.221, p = 0.030), and the admission and resting heart rate (β = −0.201, p = 0.036 and β = −0.242, p = 0.030), and was in positive association with most echocardiographic parameters. In conclusion, CST levels were increased in ADHF patients with MI and were overall associated with a favorable cardiometabolic profile but at the same time reflected advanced symptomatic burden (CATSTAT-HF ClinicalTrials.gov number, NCT03389386).

Five genomic regions have a major impact on fat composition in Iberian pigs

The adipogenic nature of the Iberian pig defines many quality attributes of its fresh meat and dry-cured products. The distinct varieties of Iberian pig exhibit great variability in the genetic parameters for fat deposition and composition in muscle. The aim of this work is to identify common and distinct genomic regions related to fatty acid composition in Retinto, Torbiscal, and Entrepelado Iberian varieties and their reciprocal crosses through a diallelic experiment. In this study, we performed GWAS using a high density SNP array on 382 pigs with the multimarker regression Bayes B method implemented in GenSel. A number of genomic regions showed strong associations with the percentage of saturated and unsaturated fatty acid in intramuscular fat. In particular, five regions with Bayes Factor >100 (SSC2 and SSC7) or >50 (SSC2 and SSC12) explained an important fraction of the genetic variance for miristic, palmitoleic, monounsaturated (>14%), oleic (>10%) and polyunsaturated (>5%) fatty acids. Six genes (RXRB, PSMB8, CHGA, ACACA, PLIN4, PLIN5) located in these regions have been investigated in relation to intramuscular composition variability in Iberian pigs, with two SNPs at the RXRB gene giving the most consistent results on oleic and monounsaturated fatty acid content.

Decreased circulating catestatin levels are associated with coronary artery disease: The emerging anti-inflammatory role

BACKGROUND AND AIMS

The neuropeptide catestatin (CST) is an endogenous nicotinic cholinergic antagonist that acts as pleiotropic cardiac protective hormone. This study investigated the association between CST and coronary artery disease (CAD) and the underlying mechanisms.

METHODS AND RESULTS

The serum concentration of CST among 224 CAD patients and 204 healthy controls was compared, and its association with atherosclerosis severity in 921 CAD patients was further analyzed. Compared to healthy subjects, serum CST concentration was lower in patients with CAD [1.14 (1.05-1.24) ng/mL vs. 2.15 (1.92-2.39) ng/mL, p < 0.001] and was inversely correlated with disease severity (r = -0.208, p < 0.001). In cultured endothelial cells, CST suppressed TNF-α-elicited expression of inflammatory cytokines and adhesion molecules by activating angiotensin-converting enzyme-2 (ACE2). Administration of CST reduced leukocyte-endothelium interactions in vitro and in vivo, and attenuated the development of atherosclerotic in ApoE^-/- mice fed a high-fat diet. These protective effects by CST were blocked by an ACE2 inhibitor.

CONCLUSIONS

Serum CST concentration is lower in CAD patients and is inversely associated with the severity of atherosclerosis. CST acts as a novel anti-atherogenic peptide that inhibits inflammatory response and EC-leukocyte interactions via an ACE2-dependent mechanism.

Catestatin as a Target for Treatment of Inflammatory Diseases

It is increasingly clear that inflammatory diseases and cancers are influenced by cleavage products of the pro-hormone chromogranin A (CgA), such as the 21-amino acids long catestatin (CST). The goal of this review is to provide an overview of the anti-inflammatory effects of CST and its mechanism of action. We discuss evidence proving that CST and its precursor CgA are crucial for maintaining metabolic and immune homeostasis. CST could reduce inflammation in various mouse models for diabetes, colitis and atherosclerosis. In these mouse models, CST treatment resulted in less infiltration of immune cells in affected tissues, although in vitro monocyte migration was increased by CST. Both in vivo and in vitro, CST can shift macrophage differentiation from a pro- to an anti-inflammatory phenotype. Thus, the concept is emerging that CST plays a role in tissue homeostasis by regulating immune cell infiltration and macrophage differentiation. These findings warrant studying the effects of CST in humans and make it an interesting therapeutic target for treatment and/or diagnosis of various metabolic and immune diseases.

Catestatin serum levels are increased in male patients with obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is a complex sleep disorder associated with autonomic and sympathetic dysregulation. To the contrary, catestatin, an endogenous pleiotropic peptide cleaved from chromogranin A, is known for its inhibitory effects on catecholamine release and sympathetic activity. The aims of the study were to determine catestatin serum levels among male OSA patients compared to healthy control subjects and to explore associations of catestatin with anthropometric, polysomnographic, and lipid profile parameters.

METHODS

Seventy-eight male OSA patients aged 50.3 ± 8.8 years and 51 age/sex/BMI-matched control subjects aged 50.4 ± 7.8 years were enrolled in the study. Catestatin serum levels were determined by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Catestatin serum levels were significantly higher among OSA patients compared to control subjects (2.9 ± 1.2 vs. 1.5 ± 1.1 ng/mL, p < 0.001). Serum catestatin levels significantly correlated with apnea-hypopnea index (AHI) among non-obese OSA subjects (r = 0.466, p = 0.016; β = 0.448, p = 0.026), while in whole OSA population, catestatin levels significantly correlated with neck circumference (r = 0.318, p < 0.001; β = 0.384, p < 0.001) and high-density lipoprotein (HDL) cholesterol (r = - 0.320, p < 0.001; β = - 0.344, p < 0.001). In multivariate-adjusted regression model, serum catestatin was significant and independent predictor of OSA status (OR 4.98, 95% CI 2.17-11.47, p < 0.001).

CONCLUSIONS

Catestatin serum levels are significantly increased in male OSA population and positively correlate with disease severity in non-obese patients. OSA status is independently predicted by catestatin levels; however, this finding is restricted to patients with moderate-to-severe disease. Further studies are necessary to elucidate the mechanistic role of catestatin in the complex pathophysiology of OSA.

Role of the neuroendocrine antimicrobial peptide catestatin in innate immunity and pain

Catestatin (CST) is a neuroendocrine peptide which is derived from the chromogranin A. It has been demonstrated that CST can affect a wide range of processes, such as innate immunity, inflammatory and autoimmune reactions, and several homeostatic regulations. Furthermore, CST is positive against several kinds of bacterial strains at micromolecular range, which shows its antimicrobial activity. Recently, the role of CST in acute and chronic pain has attracted much attention. In this review, we discussed the latest research findings of CST and its role in innate immunity and pain.

Identification of novel loci affecting circulating chromogranins and related peptides

Chromogranins are pro-hormone secretory proteins released from neuroendocrine cells, with effects on control of blood pressure. We conducted a genome-wide association study for plasma catestatin, the catecholamine release inhibitory peptide derived from chromogranin A (CHGA), and other CHGA- or chromogranin B (CHGB)-related peptides, in 545 US and 1252 Australian subjects. This identified loci on chromosomes 4q35 and 5q34 affecting catestatin concentration (P = 3.40 × 10-30 for rs4253311 and 1.85 × 10-19 for rs2731672, respectively). Genes in these regions include the proteolytic enzymes kallikrein (KLKB1) and Factor XII (F12). In chromaffin cells, CHGA and KLKB1 proteins co-localized in catecholamine storage granules. In vitro, kallikrein cleaved recombinant human CHGA to catestatin, verified by mass spectrometry. The peptide identified from this digestion (CHGA360-373) selectively inhibited nicotinic cholinergic stimulated catecholamine release from chromaffin cells. A proteolytic cascade involving kallikrein and Factor XII cleaves chromogranins to active compounds both in vivo and in vitro.

Reactivation of Intestinal Inflammation Is Suppressed by Catestatin in a Murine Model of Colitis via M1 Macrophages and Not the Gut Microbiota

While there is growing awareness of a relationship between chromogranin-A (CHGA) and susceptibility to inflammatory conditions, the role of human catestatin [(hCTS); CHGA_352–67] in the natural history of established inflammatory bowel disease is not known. Recently, using two different experimental models, we demonstrated that hCTS-treated mice develop less severe acute colitis. We have also shown the implication of the macrophages in this effect. The aims of this study were to determine (1) whether hCTS treatment could attenuate the reactivation of inflammation in adult mice with previously established chronic colitis; (2) whether this effect is mediated through macrophages or the gut microbiota. Quiescent colitis was induced in 7–8-week-old C57BL6 mice using four cycles (2–4%) of dextran sulfate sodium. hCTS (1.5 mg/kg/day) treatment or vehicle started 2 days before the last induction of colitis and continuing for 7 days. At sacrifice, macro- and microscopic scores were determined. Colonic pro-inflammatory cytokines [interleukin (IL)-6, IL-1β, and TNF- α], anti-inflammatory cytokines (IL-10, TGF- β), classically activated (M1) (iNOS, Mcp1), and alternatively activated (M2) (Ym1, Arg1) macrophages markers were studied using ELISA and/or RT-qPCR. In vitro, peritoneal macrophages isolated from naïve mice and treated with hCTS (10⁻⁵ M, 12 h) were exposed to either lipopolysaccharide (100 ng/ml, 12 h) to polarize M1 macrophages or to IL-4/IL-13 (20 ng/ml) to polarize M2 macrophages. M1/M2 macrophage markers along with cytokine gene expression were determined using RT-qPCR. Feces and mucosa-associated microbiota (MAM) samples were collected, and the V4 region of 16 s rRNA was sequenced. Micro- and macroscopic scores, colonic IL-6, IL-1β, TNF- α, and M1 macrophages markers were significantly decreased in the hCTS-treated group. Treatment did not have any effect on colonic IL-10, TGF-β, and M2 markers nor modified the bacterial richness, diversity, or the major phyla in colitic fecal and MAM samples. In vitro, pro-inflammatory cytokines levels, as well as their gene expression, were significantly reduced in hCTS-treated M1 macrophages. hCTS treatment did not affect M2 macrophage markers. These findings suggest that hCTS treatment attenuates the severity of inflammatory relapse through the modulation of the M1 macrophages and the release of pro-inflammatory cytokines.

Granin-derived peptides

The granin family comprises altogether 7 different proteins originating from the diffuse neuroendocrine system and elements of the central and peripheral nervous systems. The family is dominated by three uniquely acidic members, namely chromogranin A (CgA), chromogranin B (CgB) and secretogranin II (SgII). Since the late 1980s it has become evident that these proteins are proteolytically processed, intragranularly and/or extracellularly into a range of biologically active peptides; a number of them with regulatory properties of physiological and/or pathophysiological significance. The aim of this comprehensive overview is to provide an up-to-date insight into the distribution and properties of the well established granin-derived peptides and their putative roles in homeostatic regulations. Hence, focus is directed to peptides derived from the three main granins, e.g. to the chromogranin A derived vasostatins, betagranins, pancreastatin and catestatins, the chromogranin B-derived secretolytin and the secretogranin II-derived secretoneurin (SN). In addition, the distribution and properties of the chromogranin A-derived peptides prochromacin, chromofungin, WE14, parastatin, GE-25 and serpinins, the CgB-peptide PE-11 and the SgII-peptides EM66 and manserin will also be commented on. Finally, the opposing effects of the CgA-derived vasostatin-I and catestatin and the SgII-derived peptide SN on the integrity of the vasculature, myocardial contractility, angiogenesis in wound healing, inflammatory conditions and tumors will be discussed.

Chromogranin A Regulation of Obesity and Peripheral Insulin Sensitivity

Chromogranin A (CgA) is a prohormone and granulogenic factor in endocrine and neuroendocrine tissues, as well as in neurons, and has a regulated secretory pathway. The intracellular functions of CgA include the initiation and regulation of dense-core granule biogenesis and sequestration of hormones in neuroendocrine cells. This protein is co-stored and co-released with secreted hormones. The extracellular functions of CgA include the generation of bioactive peptides, such as pancreastatin (PST), vasostatin, WE14, catestatin (CST), and serpinin. CgA knockout mice (Chga-KO) display: (i) hypertension with increased plasma catecholamines, (ii) obesity, (iii) improved hepatic insulin sensitivity, and (iv) muscle insulin resistance. These findings suggest that individual CgA-derived peptides may regulate different physiological functions. Indeed, additional studies have revealed that the pro-inflammatory PST influences insulin sensitivity and glucose tolerance, whereas CST alleviates adiposity and hypertension. This review will focus on the different metabolic roles of PST and CST peptides in insulin-sensitive and insulin-resistant models, and their potential use as therapeutic targets.

Chromogranin A as biomarker in diabetes

Chromogranin A (CgA) is an established plasma marker of neuroendocrine tumors and has been suggested to also have a role as biomarker in other diseases. Whether CgA has any role as biomarker in diabetes is, however, unresolved, but its widespread distribution in the secretory granules in endocrine tissues including β cells and α cells in pancreas, and the metabolic effects of its peptide fragments suggest that CgA may play a pathophysiological role in diabetes, and thus also be a potential diabetes biomarker. In this review, we summarize the available information on CgA and some of its functional post-translational cleavage products in diabetes, followed by a discussion of its potential as a plasma marker in diabetes and the methodological concerns involved.

Potential applications of catestatin in cardiovascular diseases

Catestatin (CST) was first named in 1997 for its catecholamine-inhibitory activity. It was discovered as a potent inhibitor of catecholamine secretion and as a regulator of histamine release. Accumulating evidence shows that CST is involved with cardiovascular diseases; however, whether CST is a protective factor for these conditions and the mechanisms by which such actions may be mediated are not well understood. In this article, we review recent basic research and clinical trials in the study of CST and summarize the association of CST with cardiovascular diseases. We review data obtained from MedLine via PubMed and from our own investigations.

Analysis and validation of traits associated with a single nucleotide polymorphism Gly364Ser in catestatin using humanized chromogranin A mouse models

OBJECTIVE

The human prohormone chromogranin A (CHGA), an index member of the granin family is processed to generate catestatin, a peptide that is hypotensive in action and modulates catecholamine release within the sympathoadrenal system. Hypertensive patients with excess sympathetic activity have diminished catestatin. Often the study of physiological consequences of human genetic variation is confounded by elements such as other variations in obligatory linkage disequilibrium with the variant being studied. Also the phenotype of the variant may be influenced by genetic background that varies amongst individuals. This study addresses the effects of a human catestatin polymorphism (rs9658667) using humanized CHGA mouse models.

METHODS

We created pertinent humanized mouse models wherein the mouse Chga gene locus was replaced by the human ortholog wild-type and the variant versions. This allowed for probing of the effects of catestatin variation in vivo with controls for other variations and global genetic background.

RESULTS

Both the wild-type and variant human catestatin expressing mouse models were normotensive. The variant catestatin mouse model recapitulated physiological influence of the polymorphism on autonomic traits. These mice had diminished catecholamine, attenuated stress response and increased baroreceptor slopes that would suggest reduced risk of developing hypertension. Elevated plasma glucose, a trait observed in humans was not observed in mice expressing the variant catestatin.

CONCLUSION

This functional genomics approach of creating humanized mouse models to study rs9658667 polymorphism recapitulated and validated many of the human trait associations. This approach can also be applied in the study of other human gene polymorphisms.

Catestatin and GABA(A)R related feeding habits rely on dopamine, ghrelin plus leptin neuroreceptor expression variations

Catestatin (CST), an endogenously small sympathoinhibitory peptide is capable of interfering with the major cerebral neuroreceptor-blocking site, i.e. γ-aminobutyric acidA receptor (GABAAR) system especially in limbic brain areas that are involved with feeding behaviors. The GABAARergic-related effects seem to derive from its interaction with other molecular neuroreceptors such as dopaminergic, ghrelin and leptinergic. In this context, the present study aimed to investigate probable feeding responses (eating and drinking) induced by treatment with CST and the GABAAR antagonist bicucullin (BIC) alone or simultaneously (CST+BIC) in the Syrian hibernating hamster (Mesocricetus auratus) model. Hamsters that received these compounds via intracerebroventricular infusions displayed notable variations of feeding and drinking bouts. In particular, an anorexigenic response was evident following treatment with CST while BIC evoked a significant increase of eating and drinking behaviors. Surprisingly when both agents were given simultaneously, a predominating anorexigenic response was detected as shown by evident CST-dependent reduction of feeding bouts. Contextually such behaviors, especially those following the combined treatment were tightly correlated with the significantly increased cerebral dopamine receptor 1 (D1) plus reduced ghrelin receptor (GhsR) and leptin receptor (LepR) transcript levels. Overall, the anorexigenic effect of CST deriving from its tight interaction with GABAARs activity plus D1 and GhsR transcripts tends to propose these neuronal elements as pivotal factors responsible for feeding disorders.

Regulation of intestinal SGLT1 by catestatin in hyperleptinemic type 2 diabetic mice

The small intestine is the major site for nutrient absorption that is critical in maintenance of euglycemia. Leptin, a key hormone involved in energy homeostasis, directly affects nutrient transport across the intestinal epithelium. Catestatin (CST), a 21-amino acid peptide derived from proprotein chromogranin A, has been shown to modulate leptin signaling. Therefore, we reasoned that leptin and CST could modulate intestinal Na(+)-glucose transporter 1 (SGLT1) expression in the context of obesity and diabetes. We found that hyperleptinemic db/db mice exhibit increased mucosal mass, associated with an enhanced proliferative response and decreased apoptosis in intestinal crypts, a finding absent in leptin-deficient ob/ob mice. Intestinal SGLT1 abundance was significantly decreased in hyperleptinemic but not leptin-deficient mice, indicating leptin regulation of SGLT1 expression. Phlorizin, a SGLT1/2 inhibitor, was without effect in an oral glucose tolerance test in db/db mice. The alterations in architecture and SGLT1 abundance were not accompanied by changes in the localization of intestinal alkaline phosphatase, indicating intact differentiation. Treatment of db/db mice with CST restored intestinal SGLT1 abundance and intestinal turnover, suggesting a cross-talk between leptin and CST, without affecting plasma leptin levels. Consistent with this hypothesis, we identified structural homology between CST and the AB-loop of leptin and protein-protein docking revealed binding of CST and leptin with the Ig-like binding site-III of the leptin receptor. In summary, downregulation of SGLT1 in an obese type 2 diabetic mouse model with hyperleptinemia is presumably mediated via the short form of the leptin receptor and reduces overt hyperglycemia.

Impact of Chromogranin A deficiency on catecholamine storage, catecholamine granule morphology and chromaffin cell energy metabolism in vivo

Chromogranin A (CgA) is a prohormone and granulogenic factor in neuroendocrine tissues with a regulated secretory pathway. The impact of CgA depletion on secretory granule formation has been previously demonstrated in cell culture. However, studies linking the structural effects of CgA deficiency with secretory performance and cell metabolism in the adrenomedullary chromaffin cells in vivo have not previously been reported. Adrenomedullary content of the secreted adrenal catecholamines norepinephrine (NE) and epinephrine (EPI) was decreased 30-40 % in Chga-KO mice. Quantification of NE and EPI-storing dense core (DC) vesicles (DCV) revealed decreased DCV numbers in chromaffin cells in Chga-KO mice. For both cell types, the DCV diameter in Chga-KO mice was less (100-200 nm) than in WT mice (200-350 nm). The volume density of the vesicle and vesicle number was also lower in Chga-KO mice. Chga-KO mice showed an ~47 % increase in DCV/DC ratio, implying vesicle swelling due to increased osmotically active free catecholamines. Upon challenge with 2 U/kg insulin, there was a diminution in adrenomedullary EPI, no change in NE and a very large increase in the EPI and NE precursor dopamine (DA), consistent with increased catecholamine biosynthesis during prolonged secretion. We found dilated mitochondrial cristae, endoplasmic reticulum and Golgi complex, as well as increased synaptic mitochondria, synaptic vesicles and glycogen granules in Chga-KO mice compared to WT mice, suggesting that decreased granulogenesis and catecholamine storage in CgA-deficient mouse adrenal medulla is compensated by increased VMAT-dependent catecholamine update into storage vesicles, at the expense of enhanced energy expenditure by the chromaffin cell.

A common genetic variant of the chromogranin A-derived peptide catestatin is associated with atherogenesis and hypertension in a Japanese population

Chromogranin A (CHGA) is a major protein in the secretory granules of chromaffin cells. CHGA also gives rise to cardiovascular/metabolism regulatory peptides, such as catestatin (CST) and pancreastatin (PST). While CST is a potent inhibitor of catecholamine secretion, PST is a potent physiological inhibitor of glucose-induced insulin secretion. Recently, several SNPs were identified in the CST and PST domains of CHGA locus in different populations. Among the discovered SNPs, CST variant allele Ser-364 was associated with blood pressure alteration and PST variant allele Ser-297 was associated with significantly higher plasma glucose level. In this study, we examined whether these CST and PST variant alleles exist and influence cardiovascular and metabolic phenotypes in Japanese population. Our study comprised of 343 Japanese subjects aged 45-85 years (143 men and 200 women, mean age 66 ± 8 years). We determined the genotypes of CST and PST by PCR-direct sequencing method and carried out genotype-phenotype association analysis. In 343 participants, the minor allele frequency of CST variant Ser-364 was 6.10%. On the other hand, we did not detect the PST variant Ser-297 in this entire study population. The presence of Ser-364 allele was associated with increased in baPWV (an index of systemic arterial stiffness) that suggests an initiation and/or progression atherogenesis and hypertension. The Ser-364 allele was also associated with elevated systolic blood pressure and pulse pressure, consistent with increased baPWV. In conclusion, the CST Ser-364 allele may increase the risk for cardiovascular diseases in Japanese population.

Pancreastatin-dependent inflammatory signaling mediates obesity-induced insulin resistance

Chromogranin A knockout (Chga-KO) mice exhibit enhanced insulin sensitivity despite obesity. Here, we probed the role of the chromogranin A-derived peptide pancreastatin (PST: CHGA(273-301)) by investigating the effect of diet-induced obesity (DIO) on insulin sensitivity of these mice. We found that on a high-fat diet (HFD), Chga-KO mice (KO-DIO) remain more insulin sensitive than wild-type DIO (WT-DIO) mice. Concomitant with this phenotype is enhanced Akt and AMPK signaling in muscle and white adipose tissue (WAT) as well as increased FoxO1 phosphorylation and expression of mature Srebp-1c in liver and downregulation of the hepatic gluconeogenic genes, Pepck and G6pase. KO-DIO mice also exhibited downregulation of cytokines and proinflammatory genes and upregulation of anti-inflammatory genes in WAT, and peritoneal macrophages from KO mice displayed similarly reduced proinflammatory gene expression. The insulin-sensitive, anti-inflammatory phenotype of KO-DIO mice is masked by supplementing PST. Conversely, a PST variant peptide PSTv1 (PST-NΔ3: CHGA(276-301)), lacking PST activity, simulated the KO phenotype by sensitizing WT-DIO mice to insulin. In summary, the reduced inflammation due to PST deficiency prevented the development of insulin resistance in KO-DIO mice. Thus, obesity manifests insulin resistance only in the presence of PST, and in its absence obesity is dissociated from insulin resistance.

The important role of catestatin in cardiac remodeling

Catestatin (CST) was first discovered as a potent non-competitive and reversible inhibitor of catecholamine secretion. Recent reports on plasma CST level in heart diseases suggested a cardioprotective role for this peptide. Given that cardiac remodeling is the dominant pathologic process in cardiac dysfunction, we propose that CST participates in the regulation of concern pathways and contributes to the inhibition of cardiac remodeling. In this minireview, the potential mechanism of cardiac remodeling involving CST will be discussed from three aspects: hypertrophy, fibrosis, and apoptosis.

Obligatory role for endothelial heparan sulphate proteoglycans and caveolae internalization in catestatin-dependent eNOS activation

The chromogranin-A peptide catestatin modulates a wide range of processes, such as cardiovascular functions, innate immunity, inflammation, and metabolism. We recently found that the cardiac antiadrenergic action of catestatin requires a PI3K-dependent NO release from endothelial cells, although the receptor involved is yet to be identified. In the present work, based on the cationic properties of catestatin, we tested the hypothesis of its interaction with membrane heparan sulphate proteoglycans, resulting in the activation of a caveolae-dependent endocytosis. Experiments were performed on bovine aortic endothelial cells. Endocytotic vesicles trafficking was quantified by confocal microscopy using a water-soluble membrane dye; catestatin colocalization with heparan sulphate proteoglycans and caveolin 1 internalization were studied by fluorimetric measurements in live cells. Modulation of the catestatin-dependent eNOS activation was assessed by immunofluorescence and immunoblot analysis. Our results demonstrate that catestatin (5 nM) colocalizes with heparan sulphate proteoglycans and induces a remarkable increase in the caveolae-dependent endocytosis and caveolin 1 internalization, which were significantly reduced by both heparinase and wortmannin. Moreover, catestatin was unable to induce Ser¹¹⁷⁹ eNOS phosphorylation after pretreatments with heparinase and methyl-β-cyclodextrin. Taken together, these results highlight the obligatory role for proteoglycans and caveolae internalization in the catestatin-dependent eNOS activation in endothelial cells.

The relationship of plasma catestatin concentrations with metabolic and vascular parameters in untreated hypertensive patients: Influence on high-density lipoprotein cholesterol

OBJECTIVE

Catestatin has several cardiovascular actions, in addition to diminished sympatho-adrenal flow. Decreased plasma catestatin levels may reflect a predisposition for the development of hypertension and metabolic disorders. We planned to investigate the possible roles of catestatin in untreated hypertensive patients. As a secondary objective, we compared catestatin concentrations of healthy subjects with those of hypertensive patients in order to understand whether catestatin is increased reactively or diminished at onset.

METHODS

Our study was cross-sectional and observational. The patient group, comprising 109 consecutive untreated hypertensive patients without additional systemic or coronary heart disease, underwent evaluations of plasma catestatin, waist circumference, lipid parameters, left ventricular mass, carotid intima-media thickness, and flow-mediated dilation of the brachial artery. Additionally, we measured catestatin concentrations of 38 apparently healthy subjects without any disease using a commercial enzyme-linked immunosorbent assay kit.

RESULTS

We documented increased catestatin concentrations in previously untreated hypertensive patients compared to healthy controls (2.27±0.83 vs. 1.92±0.49 ng/mL, p=0.004). However, this association became insignificant after adjustments for age, gender, height, and weight. Within the patient group, catestatin levels were significantly higher in females. Among all study parameters, age, high-density lipoprotein cholesterol (HDL-C) correlated positively to plasma catestatin, whereas triglycerides, hemoglobin, and left ventricular mass correlated negatively to plasma catestatin. We could not detect an association between vascular parameters and catestatin. Catestatin levels were significantly elevated with increasing HDL-C (1.91±0.37, 2.26±0.79, and 3.1±1.23 ng/mL in patients with HDL-C <40, 40-60, and >60 mg/dL, respectively). Multiple linear regression analysis revealed age (beta: 0.201, p=0.041) and HDL-C (beta: 0.390, p<0.001) as independent correlates of plasma catestatin concentration. Additionally, male gender (beta:-0.330, p=0.001) and plasma catestatin (beta: 0.299, p=0.002) were significantly associated with HDL-C concentrations.

CONCLUSION

We documented that plasma catestatin is an independent predictor of high-density lipoprotein cholesterol. In addition to antihypertensive effects, catestatin appears to be related to improved lipid and metabolic profiles. Coexistence of low catestatin levels with low HDL-C may provide a probable mechanism for the predictive value of low HDL-C for increased hypertension and cardiovascular events.

Catestatin and orexin-A influence hamster thermic states during hibernation

Decreased body temperature during hibernation evokes a neuroprotective effect against the frequent neurodegenerative events of ischemic/reperfusion injuries. This neuroprotection appears to stem from a direct involvement of orexin-A plus the sympathoinhibitory neuroactive peptide catestatin on orexin 2 receptor-dependent feeding and motor behaviors of the facultative hibernating hamster.

Catestatin decreases macrophage function in two mouse models of experimental colitis

Mucosal inflammation in patients with inflammatory bowel disease (IBD) is characterized by an alteration of prohormone chromogranin A (CgA) production. The recent demonstration of an implication of CgA in collagenous colitis and immune regulation provides a potential link between CgA-derived peptides (catestatin, CTS) and gut inflammation. Colitis was induced by administration of dextran sulfate sodium or 2, 4 dinitrobenzenesulfonic acid to C57BL/6 mice. Treatment with human (h)CTS or its proximal or distal part was started one day before colitis induction and colonic inflammatory markers were determined. Pro-inflammatory cytokines were evaluated in peritoneal isolated and bone marrow derived macrophages (BMDMs); p-STAT3 level was studied. Serum levels of CgA and CTS were assessed in experimental colitis and in a separate study in IBD patients and healthy controls. We show that sera from IBD patients and that in experimental colitis conditions the colonic level of mouse (m)CgA and mCTS are significantly increased. Moreover, in vivo treatment with human (h)CTS reduces the disease onset and suppresses exacerbated inflammatory responses in preclinical settings of colitis associated with an increase of p-STAT3. In vitro, hCTS treatment decreases proinflammatory cytokine release by peritoneal macrophages and BMDMs and increases p-STAT3 levels. These results support the hypothesis that CTS is increased during colitis and that hCTS modulates intestinal inflammation via the macrophage population and through a STAT-3 dependent pathway in a murine model of colitis. Identification of the molecular mechanism underlying the protective role of this peptide may lead to a novel therapeutic option in IBD.