Genome-wide association study for circulating fibroblast growth factor 21 and 23

Multi-trait Analysis of GWAS for circulating FGF23 Identifies Novel Network Interactions Between HRG-HMGB1 and Cardiac Disease in CKD

Background

Genome-wide association studies (GWAS) have identified numerous genetic loci associated with mineral metabolism (MM) markers but have exclusively focused on single-trait analysis. In this study, we performed a multi-trait analysis of GWAS (MTAG) of MM, exploring overlapping genetic architecture between traits, to identify novel genetic associations for fibroblast growth factor 23 (FGF23).

Methods

We applied MTAG to genetic variants common to GWAS of 5 genetically correlated MM markers (calcium, phosphorus, FGF23, 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH)) in European-ancestry subjects. We integrated information from UKBioBank GWAS for blood levels for phosphate, 25(OH)D and calcium (n=366,484), and CHARGE GWAS for PTH (n=29,155) and FGF23 (n=16,624). We then used functional genomics to model interactive and dynamic networks to identify novel associations between genetic traits and circulating FGF23.

Results

MTAG increased the effective sample size for all MM markers to n=50,325 for FGF23. After clumping, MTAG identified independent genome-wide significant SNPs for all traits, including 62 loci for FGF23. Many of these loci have not been previously reported in single-trait analyses. Through functional genomics we identified Histidine-rich glycoprotein (HRG) and high mobility group box 1(HMGB1) genes as master regulators of downstream canonical pathways associated with FGF23. HRG-HMGB1 network interactions were also highly enriched in left ventricular heart tissue of a cohort of deceased hemodialysis patients.

Conclusion

Our findings highlight the importance of MTAG analysis of MM markers to boost the number of genome-wide significant loci for FGF23 to identify novel genetic traits. Functional genomics revealed novel networks that inform unique cellular functions and identified HRG-HMGB1 as key master regulators of FGF23 and cardiovascular disease in CKD. Future studies will provide a deeper understanding of genetic signatures associated with FGF23 and its role in health and disease.

New insights into the physiology and pathophysiology of the atypical sodium leak channel NALCN

Cell excitability and its modulation by hormones and neurotransmitters involve the concerted action of a large repertoire of membrane proteins, especially ion channels. Unique complements of coexpressed ion channels are exquisitely balanced against each other in different excitable cell types, establishing distinct electrical properties that are tailored for diverse physiological contributions, and dysfunction of any component may induce a disease state. A crucial parameter controlling cell excitability is the resting membrane potential (RMP) set by extra- and intracellular concentrations of ions, mainly Na+, K+, and Cl-, and their passive permeation across the cell membrane through leak ion channels. Indeed, dysregulation of RMP causes significant effects on cellular excitability. This review describes the molecular and physiological properties of the Na+ leak channel NALCN, which associates with its accessory subunits UNC-79, UNC-80, and NLF-1/FAM155 to conduct depolarizing background Na+ currents in various excitable cell types, especially neurons. Studies of animal models clearly demonstrate that NALCN contributes to fundamental physiological processes in the nervous system including the control of respiratory rhythm, circadian rhythm, sleep, and locomotor behavior. Furthermore, dysfunction of NALCN and its subunits is associated with severe pathological states in humans. The critical involvement of NALCN in physiology is now well established, but its study has been hampered by the lack of specific drugs that can block or agonize NALCN currents in vitro and in vivo. Molecular tools and animal models are now available to accelerate our understanding of how NALCN contributes to key physiological functions and the development of novel therapies for NALCN channelopathies.

A Network Pharmacology and Multi-Omics Combination Approach to Reveal the Effect of Strontium on Ca2+ Metabolism in Bovine Rumen Epithelial Cells

Strontium (Sr) belongs to the same group in the periodic table as calcium (Ca). Sr level can serve as an index of rumen Ca absorption capacity; however, the effects of Sr on Ca²⁺ metabolism are unclear. This study aims to investigate the effect of Sr on Ca²⁺ metabolism in bovine rumen epithelial cells. The bovine rumen epithelial cells were isolated from the rumen of newborn Holstein male calves (n = 3, 1 day old, 38.0 ± 2.8 kg, fasting). The half maximal inhibitory concentration (IC50) of Sr-treated bovine rumen epithelial cells and cell cycle were used to establish the Sr treatment model. Transcriptomics, proteomics, and network pharmacology were conducted to investigate the core targets of Sr-mediated regulation of Ca²⁺ metabolism in bovine rumen epithelial cells. The data of transcriptomics and proteomics were analyzed using bioinformatic analysis (Gene Ontology and Kyoto Encyclopedia of genes/protein). Quantitative data were analyzed using one-way ANOVA in GraphPad Prism 8.4.3 and the Shapiro-Wilk test was used for the normality test. Results presented that the IC50 of Sr treatment bovine rumen epithelial cells for 24 h was 43.21 mmol/L, and Sr increased intracellular Ca²⁺ levels. Multi-omics results demonstrated the differential expression of 770 mRNAs and 2436 proteins after Sr treatment; network pharmacology and reverse transcriptase polymerase chain reaction (RT-PCR) revealed Adenosylhomocysteine hydrolase-like protein 2 (AHCYL2), Semaphoring 3A (SEMA3A), Parathyroid hormone-related protein (PTHLH), Transforming growth factor β2 (TGF-β2), and Cholesterol side-chain cleavage enzyme (CYP11A1) as potential targets for Sr-mediated Ca²⁺ metabolism regulation. Together these results will improve the current comprehension of the regulatory effect of Sr on Ca²⁺ metabolism and pave a theoretical basis for Sr application in bovine hypocalcemia.

Serum Fibroblast Growth Factor 23 and FGF23 Gene Variants in Patients with Type 2 Diabetes and Essential Hypertension. Association with Chronic Kidney Disease

INTRODUCTION

Fibroblast growth factor 23 (FGF23) gene variants could influence the production of FGF23 in subjects at risk for chronic kidney disease (CKD). Our purpose was to analyze the association of serum levels of FGF23 and two FGF23 gene variants with metabolic and renal function parameters in Mexican patients with Type 2 Diabetes (T2D) and/or essential hypertension (HTN).

MATERIALS/METHODS

The study included 632 individuals diagnosed with T2D and/or HTN, of which 269 (43%) were diagnosed with CKD. FGF23 serum levels were determined and FGF23 gene variants rs11063112 and rs7955866 were genotyped. Genetic association analysis included binary and multivariate logistic regressions adjusted for age and sex.

RESULTS

Patients with CKD were older, had higher systolic blood pressure, uric acid, and glucose levels than those without CKD. Also, patients with CKD had higher FGF23 levels (106 vs. 73 pg/mL p = 0.003). No correlation of any gene variants with FGF23 levels was found, but minor allele for rs11063112 and haplotype rs11063112A-rs7955866A were associated with low probability of CKD (Odds Ratio [OR] = 0.62 and 0.58, respectively). Conversely, the haplotype rs11063112T-rs7955866A was associated with increased FGF23 levels and risk for CKD (OR = 6.90).

CONCLUSIONS

In addition to the traditional risk factors, levels of FGF23 are higher in Mexican patients with diabetes and/or essential hypertension and CKD, compared to those without renal damage. In contrast, the two minor alleles of two variants of the FGF23 gene, rs11063112 and rs7955866, as well as the haplotype carrying these two alleles, were found to be protective against renal disease in this Mexican patients' sample.

Genome-wide association and Mendelian randomization study of fibroblast growth factor 21 reveals causal associations with hyperlipidemia and possibly NASH

BACKGROUND

Fibroblast growth factor 21 (FGF21) is a hepatokine that produces metabolic benefits, such as improvements of lipid profile. We performed a genome-wide association study (GWAS) to identify genetic variants associated with circulating FGF21 and investigated the causal effects of FGF21 on pertinent outcomes using Mendelian randomization (MR).

METHODS

We conducted a GWAS testing ∼7.8 million DNA sequence variants with circulating FGF21 in a discovery cohort of 6259 Swedish adults with replication in 4483 Swedish women. We then performed two-sample MR analyses of genetically predicted circulating FGF21 in relation to alcohol and nutrient intake, cardiovascular and metabolic biomarkers and diseases, and liver function biomarkers using publicly available GWAS summary statistics data.

RESULTS

Our GWAS identified multiple single-nucleotide polymorphisms with genome-wide significant associations (P < 5 × 10^-8) with circulating FGF21 on chromosomes 2 and 19 in or near the GCKR and FGF21 genes, respectively. The strongest signal at the FGF21 locus (rs2548957, β = 0.181, P < 2.18 × 10^-42) displayed in two-sample MR analyses robust associations with lower alcohol intake, lower circulating low-density lipoprotein cholesterol, apolipoprotein B, C-reactive protein, gamma-glutamyl transferase, and galectin-3 concentrations, and higher circulating insulin-like growth factor-I and alkaline phosphatase concentrations after correcting for multiple testing (P < 0.0018) whereas associations with fat mass, type 2 diabetes, and cardiovascular disease were largely null.

CONCLUSIONS

We identified robust associations of certain genetic variants in or near the GCKR and FGF21 genes with circulating FGF21 concentrations. Furthermore, our results support a strong causal effect of FGF21 on improved lipid profile, reduced alcohol consumption and C-reactive protein concentrations, and liver function biomarkers including fibrosis. We found largely null or weak positive associations with fat mass, diabetes, and cardiovascular disease as well as higher insulin-like growth factor-I concentrations, which could indicate a compensatory increase to regulate the above FGF21 resistant states in humans.

The role of FGF21 and its analogs on liver associated diseases

Fibroblast growth factor 21 (FGF21), a member of fibroblast growth factor family, is a hormone-like growth factor that is synthesized mainly in the liver and adipose tissue. FGF21 regulates lipid and glucose metabolism and has substantial roles in decreasing lipogenesis and increasing hepatic insulin sensitivity which causing lipid profile improvement. FGF21 genetic variations also affect nutritional and addictive behaviors such as smoking and alcohol consumption and eating sweets. The role of FGF21 in metabolic associated diseases like diabetes mellitus had been confirmed previously. Recently, several studies have demonstrated a correlation between FGF21 and liver diseases. Non-alcoholic fatty liver disease (NAFLD) is the most prevalent type of chronic liver disease worldwide. NAFLD has a wide range from simple steatosis to steatohepatitis with or without fibrosis and cirrhosis. Elevated serum levels of FGF21 associated with NAFLD and its pathogenesis. Alcoholic fatty liver disease (AFLD), another condition that cause liver injury, significantly increased FGF21 levels as a protective factor; FGF21 can reverse the progression of AFLD and can be a potential therapeutic agent for it. Also, NAFLD and AFLD are the most important risk factors for hepatocellular carcinoma (HCC) which is the fourth deadliest cancer in the world. Several studies showed that lack of FGF21 induced oncogenic condition and worsened HCC. In this review article, we intend to discuss different aspects of FGF21 in NAFLD, AFLD and HCC; including the role of FGF21 in pathophysiology of these conditions, the effects of FGF21 mutations, the possible use of the FGF21 as a biomarker in different stages of these diseases, as well as the usage of FGF21 and its analog molecules in the treatment of these diseases.

Relationship between the development of hyperlipidemia in hypothyroidism patients

As shown in the previous studies, hypothyroidism (HT) is identified to be closely associated with the elevated plasma levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and with the decreased plasma levels of high density lipoprotein cholesterol (HDL-C). On the other hand, the thyroid hormone (TH), which has been considered as a vital hormone produced and released by the thyroid gland, are well-established to regulate the metabolism of plasma TC; whereas other evidence proposed that the thyroid-stimulating hormone (TSH) also regulated the plasma cholesterol metabolism independently of the TH, which further promotes the progression of hyperlipidemia. Nevertheless, the potential mechanism is still not illustrated. It is worth noting that several studies has found that the progression of HT-induced hyperlipidemia might be associated with the down-regulated plasma levels of TH and the up-regulated plasma levels of TSH, revealing that HT could promote hyperlipidemia and its related cardio-metabolic disorders. Otherwise, multiple novel identified plasma proteins, such as proprotein convertase subtilisin/kexin type 9 (PCSK9), angiopoietin-like protein (ANGPTLs), and fibroblast growth factors (FGFs), have also been demonstrated to embrace a vital function in modulating the progression of hyperlipidemia induced by HT. In the present comprehensive review, the recent findings which elucidated the association of HT and the progression of hyperlipidemia were summarized. Furthermore, other results which illustrated the underlying mechanisms by which HT facilitates the progression of hyperlipidemia and its cardio-metabolic disorders are also listed in the current review.

Investigation of the Characteristics of Crimean Congo Hemorrhagic Fever Cases Reported in Afyonkarahisar Province

OBJECTIVE

Crimean Congo Hemorrhagic Fever (CCHF); fever, widespread pain in the body, deterioration in liver function tests; it is a tick-borne viral infectious disease that can cause bleeding and death in the skin, mucous membranes, and sometimes internal organs. In this study, we retrospectively evaluated the clinical, laboratory, and epidemiological characteristics of CCHF cases diagnosed in Afyonkarahisar.

METHODS

Demographic and clinical characteristics, laboratory findings, treatments, and prognoses of patients diagnosed with CCHF in Afyonkarahisar were retrospectively analyzed.

RESULTS

In Afyonkarahisar, it was determined that 35 case reports were made between 2002 and November 2019, the date when the CCHF was first seen in Turkey. A history of tick attachment was detected in 31 subjects. Tick arrest cases were most common in June (12 cases; 34.3%) and July (9 cases; 2.9%). There was a history of living in rural areas in twenty-seven (77.1%) patients, close contact with animals in 12 patients, and a history of contact with animal blood in 4 patients. All the 35 cases that followed resulted in healing and no mortality was observed.

CONCLUSION

CCHF is an endemic disease that still maintains its importance in our country. The most important factor in the control with the disease is to prevent virus contact to prevent transmission. People living in endemic areas should be informed about the precautions to be taken against tick bites, and awareness should be raised by providing education about the disease.