human fgf21 quantikine elisa assay  (R&D Systems)

Journal: Nature Communications

Article Title: Hepatocyte SLCO4C1 is a cAMP uptake transporter for inhibiting lipogenesis and a therapeutic target for MASLD

doi: 10.1038/s41467-026-70729-0

Figure Lengend Snippet: A Cytokines stimulated Slco4c1 mRNA transcription in primary mouse hepatocytes ( B ) FGF21 expression levels in different hepatic cell types. C Hepatic Fgf21 mRNA levels in GAN diet fed mice. D Correlation analysis between hepatic Fgf21 and Slco4c1 mRNA levels ( n = 6). E , F Treatment with FGF21 stimulated Slco4c1 mRNA and protein expression in primary mouse hepatocytes ( G ) Schematic illustration of the predicted transcription factors. H The predicted transcription factor mRNA transcripts in the FGF21-treated primary mouse hepatocytes. I , J Hepatic Egr1/2/3 mRNA transcripts and protein expression in the indicated groups of mice. (* p < 0.05, vs. Chow diet-WT) ( K ) Correlation between hepatic Slco4c1 and Egrs mRNA levels in the GAN diet-fed WT mice ( n = 6). L A diagram illustrating the potential EGRs binding sites in human SLCO4C1 proximal promoter and the reporter constructs. M Luciferase activities in 293 T cells co-transfected with truncated SLCO4C1 promoters with, or without, plasmids for EGRs overexpression. N A schematic diagram displayed the EGR1-binding site in the SLCO4C1 promoter and its mutant. O Luciferase activity in 293 T cells co-transfected with the mutant Slco4c1 promoter and the plasmid for EGR1 overexpression. Relative levels of Egr1 mRNA ( P ) and protein ( Q ) expression in primary mouse hepatocytes treated with, or without, an ERK/MAPK inhibitor, and after stimulated by FGF21 were examined. R ChIP assay revealed that FGF21 increased Egr1 binding to the Slco4c1 -59 promoters in primary mouse hepatocytes. Relative levels Slco4c1 mRNA (S) and protein (T) expression in primary mouse hepatocytes treated with, or without, an ERK/MAPK inhibitor, and after stimulated by FGF21 were examined. A n = 5 and M , O n = 3, Biological replicates; C , I , J Each dot represents one mouse sample; Statistics: unpaired two-tailed Student’s t test. R: n = 3 and E , F , H , P , Q , S , T n = 5, Biological replicates; Statistics: one-way ANOVA test, Multiple comparisons. *p < 0.05, * *p < 0.01, *** p < 0.001, **** p < 0.0001. F: * p < 0.05 vs. FGF21 0 μg/ml; # p < 0.05 vs. FGF21 0.1 μg/ml. Q, T: * p < 0.05 vs. FGF21 0 μg/ml; # p < 0.05 vs. FGF21 1 μg/ml. All data statistics are presented as mean ± SD and 95% confidence interval.

Article Snippet: After fasting for 12 h, HepG2 cells were treated with 375 μM PA (MCE, New Jersey, USA, Cat: HY-N0830) in a complete medium for 12 h or 24 h. The isolated primary mouse hepatocytes were cultured in 5% fetal bovine serum-Williams’ Medium E for 6-8 h, and subsequently treated with 250 μM PA for 12 h or 24 h. In addition, the cells were treated with different concentrations of FGF21 (SinoBiological, Beijing, China, Cat:10911-HNAE) for varying time periods and their viability was examined by CCK-8 assays using the specific kit (Bgbiotech, Chongqing, China, Cat: L2544823X).

Techniques: Expressing, Binding Assay, Construct, Luciferase, Transfection, Over Expression, Mutagenesis, Activity Assay, Plasmid Preparation, Two Tailed Test

Journal: Nature Communications

Article Title: Hepatocyte SLCO4C1 is a cAMP uptake transporter for inhibiting lipogenesis and a therapeutic target for MASLD

doi: 10.1038/s41467-026-70729-0

Figure Lengend Snippet: During the pathogenic process, metabolic disorder stimulates FGF21 expression, which through its receptors, activates the ERK/MAPK signaling to induce EGR1 expression. The transcription factor of EGR1 binds to the SLCO4C1 promoter and up-regulates its expression in hepatocytes. The SLCO4C1 functions as a cAMP uptake transporter through the interaction of its Gln463 with cAMP, increasing intracellular cAMP levels that activate the PKA-CREB signaling to feedback down-regulate SREBP1 and downstream ACC1, FASN and SCD1 expression, inhibiting fatty acid synthesis. Accordingly, induction of SLCO4C1 overexpression by AAV8-mediated hepatic SLCO4C1 expression and/or increasing intracellular cAMP levels by the Forskolin treatment effectively prevent and mitigate the progression of MASLD. Therefore, SLCO4C1 is a therapeutic target for MASLD. Conceivably, our findings may aid in the design of therapeutic strategies for treating MASLD.

Article Snippet: After fasting for 12 h, HepG2 cells were treated with 375 μM PA (MCE, New Jersey, USA, Cat: HY-N0830) in a complete medium for 12 h or 24 h. The isolated primary mouse hepatocytes were cultured in 5% fetal bovine serum-Williams’ Medium E for 6-8 h, and subsequently treated with 250 μM PA for 12 h or 24 h. In addition, the cells were treated with different concentrations of FGF21 (SinoBiological, Beijing, China, Cat:10911-HNAE) for varying time periods and their viability was examined by CCK-8 assays using the specific kit (Bgbiotech, Chongqing, China, Cat: L2544823X).

Techniques: Expressing, Over Expression

Journal: Frontiers in Endocrinology

Article Title: Metformin increases glycolysis and the stress-induced cytokine GDF15 but not FGF21 in humans

doi: 10.3389/fendo.2026.1797525

Figure Lengend Snippet: Effect of metformin on circulating GDF15 and FGF21. (a) Serum GDF15 (b) and serum FGF21 in healthy individuals fasted for 42 h without (white) and with (black) prior metformin (MET) treatment for seven days. Data is given in mean +/- SEM. #p<0.0001.

Article Snippet: FGF21 was measured on fasting serum samples by the human FGF21 Quantikine ® ELISA assay essentially as described (R&D Systems, Abingdon, UK).

Techniques:

Journal: Frontiers in Endocrinology

Article Title: Metformin increases glycolysis and the stress-induced cytokine GDF15 but not FGF21 in humans

doi: 10.3389/fendo.2026.1797525

Figure Lengend Snippet: Metformin increases mRNA levels of GDF15 in human intestinal Caco-2 cells with no related increase in FGF21. Relative mRNA expression of GDF15, FGF21, SLC2A1 , and the ISR genes ATF4 and DDIT3 in differentiated Caco-2 cells after (a) 6 h or (b) 22 h without treatment (0 mM) or 0.3 mM, 1 mM, or 3 mM metformin treatment at media glucose concentrations of 5.5 mM (c) Raw ct values of GDF15 and FGF21 at 5.5 mM glucose. n = 6-8, 2 wells from 4 independent experiments evaluated in parallel. The data is presented as mean +/- SEM. **p<0.01, ***p<0.001, and ****p<0.0001 as indicated.

Article Snippet: FGF21 was measured on fasting serum samples by the human FGF21 Quantikine ® ELISA assay essentially as described (R&D Systems, Abingdon, UK).

Techniques: Expressing

Journal: Frontiers in Endocrinology

Article Title: Metformin increases glycolysis and the stress-induced cytokine GDF15 but not FGF21 in humans

doi: 10.3389/fendo.2026.1797525

Figure Lengend Snippet: GDF15 secretion is increased in Caco-2 cells upon chronic metformin treatment. (a) GDF15 concentration in media collected from non-treated (0 mM) Caco-2 cells kept in media with glucose concentrations of 5.5 mM, 11 mM, or 25 mM or from cells treated with 0.3 mM, 1 mM, or 3 mM metformin at similar glucose concentrations. (b) A schematic representation of metformin-stimulated GDF15 secretion from Caco-2 cells, where FGF21 protein levels were undetectable. n = 8, 2 wells from 4 independent experiments evaluated in parallel. The data is presented as mean +/- SEM. **p<0.01, determined by two-way ANOVA analysis with Dunnett correction. Figure 3b is created in BioRender. Møller, P. (2025) https://BioRender.com/o87c709 .

Article Snippet: FGF21 was measured on fasting serum samples by the human FGF21 Quantikine ® ELISA assay essentially as described (R&D Systems, Abingdon, UK).

Techniques: Concentration Assay

Journal: Frontiers in Nutrition

Article Title: Serum fibroblast growth factor 21 is a novel biomarker of cachexia in chronic liver disease

doi: 10.3389/fnut.2026.1730695

Figure Lengend Snippet: (a) Comparison of serum FGF21, TNF- α , and IL-6 levels between patients with and without cachexia. (b) Comparison of the proportion of cachexia between patients with high and low serum FGF21 levels in the discovery cohort. (c) Comparison of serum FGF21 levels between patients with and without cachexia in the validation cohort. (d) Comparison of the proportion of cachexia cases between patients with high and low FGF21 levels in the validation cohort. FGF, Fibroblast Growth Factor; TNF, Tumor Necrosis Factor; IL, Interleukin.

Article Snippet: The baseline levels of the candidate serum biomarkers, including FGF21, TNF- α , and IL-6, were evaluated using commercial enzyme-linked immunosorbent assays according to the manufacturer’s protocols (FGF21 [Catalog #DF2100], TNF-α, and IL-6: R&D Systems, Minneapolis, MN, United States).

Techniques: Comparison, Biomarker Discovery

Journal: Journal of Inflammation Research

Article Title: FGF21 Exacerbates Obesity-Induced Airway Hyperresponsiveness and FGFR1-Dependent Mast Cell Activation in Mice

doi: 10.2147/JIR.S570000

Figure Lengend Snippet: FGF21 is upregulated in serum and BALF of obese mice, and positively correlated with airway resistance. Mice were fed either a standard chow diet (lean) or a high-fat diet (obese) for 16 weeks prior to analysis. ( A ) Measurements of body weight from the lean and obese group mice. ( B ) Representative pictures of lean and obese mice. ( C ) Levels of serum FGF21 in lean and obese mice were measured by ELISA (n=10). ( D ) Levels of BALF FGF21 in lean and obese mice were measured by ELISA (n=10). ( E ) DIO mice exhibit pronounced AHR. Results showed the changes in specific airway resistance (sRaw) as a measure of AHR. ( F ) Pearson’s correlation tests results represent FGF21 level in serum of obese mice was positively correlated with sRaw (C methacholine :50.0 mg/mL). ( G ) Pearson’s correlation tests results represent FGF21 level in BALF of obese mice was positively correlated with sRaw (C methacholine :50.0 mg/mL). Data are mean ± SEM, ** p < 0.01, *** p < 0.001.

Article Snippet: FGF21 concentration in serum collected from patients was measured by ELISA kits (Human FGF21 ELISA Kit, Sangon Biotech) with a detection range of 31.25–2000 pg/mL.

Techniques: Enzyme-linked Immunosorbent Assay

Journal: Journal of Inflammation Research

Article Title: FGF21 Exacerbates Obesity-Induced Airway Hyperresponsiveness and FGFR1-Dependent Mast Cell Activation in Mice

doi: 10.2147/JIR.S570000

Figure Lengend Snippet: FGF21 level is increased in serum from obese patients with asthma and positively correlated with reduced pulmonary function. ( A ) Serum FGF21 levels in lean patients with asthma and obese patients with asthma were measured by ELISA (n=20-23). Data are mean ± SEM, * p < 0.05, *** p < 0.001 ( B ) Multivariable linear regression results represent serum FGF21 level was negatively correlated with FEV1%. ( C ) Multivariable linear regression results represent serum FGF21 level was negatively correlated with FEV1/FVC%, n=43.

Article Snippet: FGF21 concentration in serum collected from patients was measured by ELISA kits (Human FGF21 ELISA Kit, Sangon Biotech) with a detection range of 31.25–2000 pg/mL.

Techniques: Enzyme-linked Immunosorbent Assay

Journal: Journal of Inflammation Research

Article Title: FGF21 Exacerbates Obesity-Induced Airway Hyperresponsiveness and FGFR1-Dependent Mast Cell Activation in Mice

doi: 10.2147/JIR.S570000

Figure Lengend Snippet: Recombinant FGF21 aggravates AHR in obese mice, while Anti-FGF21 ameliorates obesity-induced AHR and inhibits mast cell infiltration. ( A ) The schematic diagram for recombinant FGF21 treatment in DIO mice. ( B ) Changes of airway resistance in DIO mice treated with recombinant FGF21. ( C ) Representative immunohistochemical images (× 400) for lung tissue sections staining of chymase. ( D ) Quantitative analysis of chymase staining. ( E ) The schematic diagram for Anti-FGF21 treatment in lean mice or DIO mice. ( F ) Changes of lung resistance (R L ) in DIO mice treated with the Anti-FGF21. ( G ) Representative immunohistochemical images (× 400) for lung tissue sections staining of chymase. ( H ) Quantitative analysis of chymase staining. n=5. Data are mean ± SEM, * p < 0.05, ** p < 0.01, *** p < 0.001. IgG: the normal IgG control antibody.

Article Snippet: FGF21 concentration in serum collected from patients was measured by ELISA kits (Human FGF21 ELISA Kit, Sangon Biotech) with a detection range of 31.25–2000 pg/mL.

Techniques: Recombinant, Immunohistochemical staining, Staining, Control

Journal: Journal of Inflammation Research

Article Title: FGF21 Exacerbates Obesity-Induced Airway Hyperresponsiveness and FGFR1-Dependent Mast Cell Activation in Mice

doi: 10.2147/JIR.S570000

Figure Lengend Snippet: FGF21 facilitates mast cell activation through up-regulating cholesterol biosynthesis. ( A ) Release of β-hexosaminidase from LAD2 and P815 cells pre-activated with compound 48/80 following 24 h treatment with recombinant FGF21 (100–400 ng/mL). ( B ) Release of histamine from LAD2 and P815 cells pre-activated with compound 48/80 following 24 h treatment with recombinant FGF21 (100–400 ng/mL). ( C ) Measurement of cellular calcium concentration in mast cells pre-activated with compound 48/80 using fluorescent probe Fluo-4 AM following 24 h treatment with recombinant FGF21 (200 ng/mL). ( D ) Quantitative analysis of fluorescence intensity of Fluo-4. ( E ) Filipin III staining of cholesterol in mast cells pre-activated with compound 48/80 following 24 h treatment with recombinant FGF21 (200 ng/mL). ( F ) Quantitative analysis of fluorescence intensity of Filipin III. ( G ) Expression levels of cholesterol biosynthesis genes in LAD2 cells. ( H ) Expression level of SREBF1 . ( I ) Quantitative analysis of fluorescence intensity of Filipin III in siRNA pretreated cells. ( J ) Representative images of Filipin III staining in siRNA-NC or siRNA- SREBF1 pretreated cells. ( K ) Release rate of β-hexosaminidase from LAD2 cells treated with siRNA and FGF21. ( L ) Measurement of cellular calcium concentration in LAD2 cells using fluorescent probe Fluo-4 AM. ( M ) Quantitative analysis of fluorescence intensity of Fluo-4 in LAD2 cells treated with siRNA and FGF21. n=3. Data are mean ± SEM, * p < 0.05, ** p < 0.01, *** p < 0.001, ns, not significant.

Article Snippet: FGF21 concentration in serum collected from patients was measured by ELISA kits (Human FGF21 ELISA Kit, Sangon Biotech) with a detection range of 31.25–2000 pg/mL.

Techniques: Activation Assay, Recombinant, Concentration Assay, Fluorescence, Staining, Expressing

Journal: Journal of Inflammation Research

Article Title: FGF21 Exacerbates Obesity-Induced Airway Hyperresponsiveness and FGFR1-Dependent Mast Cell Activation in Mice

doi: 10.2147/JIR.S570000

Figure Lengend Snippet: FGF21 promoted cholesterol synthesis and mast cell activation in a FGFR1-dependent manner. ( A ) Expression of FGFR1, FGFR2 and FGFR3 in lung tissues. (Data from Human Protein Atlas, http://www.proteinatlas.org/ ). ( B ) The mRNA expression of FGFR1, FGFR2 , and FGFR3 in LAD2 cells. Relative expression levels were normalized to GAPDH . ( C ) Release rate of β-hexosaminidase from LAD2 cells treated with FGFR1 inhibitor PD173074 . ( D ) Measurement of cellular calcium concentration in PD173074 treated LAD2 cells using fluorescent probe Fluo-4 AM. ( E ) Quantitative analysis of fluorescence intensity of Fluo-4 in LAD2 cells. ( F ) Expression levels of cholesterol biosynthesis genes in PD173074 treated LAD2 cells. ( G ) Representative images of Filipin III staining in PD173074 treated LAD2 cells. ( H ) Quantitative analysis of fluorescence intensity of Filipin III in PD173074 treated cells. n=3. Data are mean ± SEM, * p < 0.05, ** p < 0.01, *** p < 0.001.

Article Snippet: FGF21 concentration in serum collected from patients was measured by ELISA kits (Human FGF21 ELISA Kit, Sangon Biotech) with a detection range of 31.25–2000 pg/mL.

Techniques: Activation Assay, Expressing, Concentration Assay, Fluorescence, Staining

Journal: Journal of Inflammation Research

Article Title: FGF21 Exacerbates Obesity-Induced Airway Hyperresponsiveness and FGFR1-Dependent Mast Cell Activation in Mice

doi: 10.2147/JIR.S570000

Figure Lengend Snippet: Schematic of the role of FGF21 in obesity induced AHR. FGF21 promotes AHR in obese mice through increasing cholesterol synthesis and facilitating mast cell activation in a FGFR1-dependent manner.

Article Snippet: FGF21 concentration in serum collected from patients was measured by ELISA kits (Human FGF21 ELISA Kit, Sangon Biotech) with a detection range of 31.25–2000 pg/mL.

Techniques: Activation Assay

Journal: medRxiv

Article Title: Physiological and molecular characterization of individuals carrying a diabetogenic mtDNA mutation establishes a mitochondrial basis for insulin resistance in humans

doi: 10.64898/2025.12.17.25342274

Figure Lengend Snippet: (A-D) Time course of venous and arterial plasma GDF15 levels during the hyperinsulinemic-euglycemic (HE) clamp. (B) GDF15 levels in venous plasma samples obtained before (Basal) and during the steady-state period of HE clamp (Insulin). (C) Time course of the venous-arterial difference in plasma GDF15 levels during the HE clamp. (D) Venous-arterial difference in plasma GDF15 before (Basal) and during the steady-state period of the HE clamp (Insulin). (E) Time course of venous and arterial plasma FGF21 levels during the HE clamp. n = 29 (15 in m.3243A>G, 14 in Controls). (F) FGF21 levels in venous plasma samples obtained before (Basal) and during the steady-state period of the HE clamp (Insulin). n = 29 (15 in m.3243A>G, 14 in Controls). (G) Time course of the venous-arterial difference in plasma FGF21 levels during the HE clamp. n = 29 (15 in m.3243A>G, 14 in Controls). (H) Venous-arterial difference in plasma FGF21 before (Basal) and during the steady-state period of the HE clamp (Insulin). n = 29 (15 in m.3243A>G, 14 in Controls). Linear mixed models were used to estimate within– and between-group differences [(B), (D), (F), and (H)]. Data are presented as observed individual values (with lines connecting individually matched participants) and estimated means ± 95% confidence limits, unless otherwise stated. For m.3243A>G carriers, individual datapoints are color-shaded to indicate muscle mtDNA heteroplasmy (light red = low, dark red = high). *Different from Basal ( P < 0.05). † Different from zero ( P < 0.05). n = 30 unless otherwise stated.

Article Snippet: Arterial and venous plasma samples were also analyzed for GDF15 and FGF21 using the automated immunoassay platform Ella (ProteinSimple, San Jose, California, USA) with Simple Plex assays for human GDF15 and FGF21 detection, according to the manufacturer’s instructions.

Techniques: Clinical Proteomics

Journal: medRxiv

Article Title: Elevated FGF21 and triglycerides in SLC25A13 carriers support the G3P-ChREBP Citrin Deficiency disease hypothesis

doi: 10.64898/2025.12.10.25342016

Figure Lengend Snippet: Age and ex-matched SLC25A13 mutation carriers from the TWB were assayed for FGF21 circulation and urinary sodium. The data show that male (A) and female (B) mutation carriers have higher levels of FGF21 than control participants and that male and female mutation carriers have higher levels of urinary sodium (C) than control participants. Further, female CD patients have much higher levels of circulating FGF21 than control female age-matched participants (D). (A) Plasma FGF21 levels (N = 25 per group); (B) Plasma FGF21 levels (N = 27 controls, N = 25 carriers); (C) urinary sodium (N = 48 controls, N = 49 carriers); (D) plasma FGF21 (N = 10 controls, N = 2 CD). Symbols: □ male controls; ■ male carriers; ○ female controls; ● female carriers; ● female CD patients. P values are from Student’s t-test.

Article Snippet: Plasma FGF21 levels were quantified in duplicate using the Quantikine® Human FGF-21 ELISA kit (R&D Systems, DF2100) according to the manufacturer’s protocol.

Techniques: Mutagenesis, Control, Clinical Proteomics

Journal: medRxiv

Article Title: Elevated FGF21 and triglycerides in SLC25A13 carriers support the G3P-ChREBP Citrin Deficiency disease hypothesis

doi: 10.64898/2025.12.10.25342016

Figure Lengend Snippet: (A) TGs were compared between the N = 7 control participants and the N =45 SLC25A13 mutation carriers for whom TG values were available in the TWB. These data show a nonsignificant TG increase in mutation carriers. (B) A plot of TGs as a function of FGF21 in mutation carriers shows a strong positive correlation (Pearson’s correlation R = 0.58) that is counter to the depression of TGs by genetically proxied FGF21 in the general population and consistent with elevation of FGF21 and lipogenic transcription by a potentiated ChREBP system in SLC25A13 carriers.

Article Snippet: Plasma FGF21 levels were quantified in duplicate using the Quantikine® Human FGF-21 ELISA kit (R&D Systems, DF2100) according to the manufacturer’s protocol.

Techniques: Control, Mutagenesis