FGF 21 Human, His
Description
Molecular Structure and Production
FGF21 Human, His is synthesized as a 209-amino-acid precursor with a 28-residue signal peptide. The mature protein (residues 29–209) features a β-trefoil structure characteristic of FGFs but lacks heparin-binding domains, enabling endocrine signaling . Recombinant production involves mammalian expression systems to ensure proper post-translational modifications, with the His tag facilitating affinity chromatography purification .
Key structural features:
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Species cross-reactivity: Active in mice, primates, and humans
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Receptor binding: Requires β-Klotho co-receptor for FGFR1c/2c/3c activation
Biological Mechanisms and Signaling Pathways
FGF21 exerts metabolic effects through tissue-specific pathways:
In vitro studies demonstrate FGF21 increases oxygen consumption rates by 20–25% in adipocytes and upregulates CPT1a (1.6-fold) and cytochrome C (2.1-fold) .
Preclinical Research Findings
Key experimental data from animal models:
Mechanistically, FGF21:
Clinical Correlations and Therapeutic Potential
Human studies reveal complex associations:
Metabolic benefits (interventional):
Diagnostic/prognostic markers:
Paradoxically, chronically elevated FGF21 correlates with adverse outcomes in aging (HR=2.1 for all-cause mortality) , suggesting context-dependent effects.
Pharmacological Challenges
Despite promising preclinical data, therapeutic development faces hurdles:
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Pharmacokinetics: Short half-life (1–2 hrs) necessitates pegylation or Fc fusion
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Tissue specificity: Requires β-Klotho co-expression, limiting targets to liver/adipose tissue
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Dose-dependent effects: Supraphysiological doses induce bone loss in primates
Current Research Directions
Emerging areas of investigation:
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Mitochondrial uncoupling: FGF21 increases UCP1 expression in brown adipose tissue (3.2-fold)
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Gut-liver axis: Modulates bile acid metabolism via FXR antagonism
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Neuroprotection: Reduces neuroinflammation (30–40% IL-6 suppression)
Ongoing clinical trials focus on FGF21 analogs (e.g., PF-05231023) for NAFLD and type 2 diabetes, with phase III results expected in 2026 .
Product Specs
Q&A
Fibroblast Growth Factor 21 (FGF21) is a critical metabolic regulator with complex biochemical interactions and therapeutic potential. Below are structured FAQs addressing key research considerations for working with recombinant human FGF21 containing a His-tag (FGF21 Human, His), organized by research complexity and methodological requirements.
What expression systems are optimal for producing bioactive recombinant human FGF21 with His-tag?
Recombinant human FGF21 is typically expressed in HEK293 cells due to their ability to perform post-translational modifications critical for bioactivity . Key quality control steps include:
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SDS-PAGE verification: Expected molecular weight ranges from 25-30 kDa due to glycosylation
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Affinity testing: Surface plasmon resonance (SPR) assays (e.g., Biacore T200) confirm binding to β-Klotho co-receptor with affinity constants ≤20 nM
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Endotoxin levels: Ensure <1 EU/μg via LAL assay for in vivo applications
How does His-tag placement affect FGF21 receptor binding and functional assays?
N-terminal His-tags are preferred for human FGF21 to avoid interference with:
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Receptor binding interfaces: The C-terminal domain (residues 132-209) interacts with FGFR1c/β-Klotho complexes
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Proteolytic stability: The cleavage site for fibroblast activation protein (FAP) resides at P171-S172 in humans . His-tags at the N-terminus do not block this site.
What functional assays validate FGF21 bioactivity in adipocyte models?
How do species-specific FGF21 cleavage mechanisms impact translational research?
Human FGF21 is cleaved by fibroblast activation protein (FAP) at P171-S172, reducing half-life in vivo . Mouse FGF21 lacks this cleavage site, complicating preclinical studies:
| Species | Cleavage Site | Protease Sensitivity | Pharmacokinetic Implication |
|---|---|---|---|
| Human | P171-S172 | FAP-dependent | Short plasma half-life (~1-2 hr) |
| Mouse | Absent | Resistant to FAP | Prolonged activity in rodents |
Methodological solution: Use FAP inhibitors (e.g., ARI-3099) in humanized mouse models or engineer cleavage-resistant mutants (e.g., S172A) .
What experimental strategies resolve discrepancies in FGF21’s metabolic effects between in vitro and in vivo systems?
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Central vs. peripheral actions: FGF21 crosses the blood-brain barrier in mice, activating hypothalamic neurons to suppress sweet preference . Use intracerebroventricular (ICV) cannulation to isolate central effects.
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Tissue-specific receptor density: Quantify β-Klotho expression via qPCR (liver > adipose > pancreas) to interpret response variability.
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Nutrient-state dependency: Fast rodents for 16-24 hr to mimic FGF21 induction during starvation , as fed states blunt responses.
How can structural modifications enhance FGF21 stability without compromising receptor activation?
Engineering approaches:
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C-terminal truncation: Remove disordered residues 182-209 (predicted by AlphaFold) to reduce proteolytic susceptibility
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PEGylation: Attach polyethylene glycol at N-terminus to prolong half-life while preserving receptor-binding domains
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Glycosylation site mutagenesis: Modify Asn171/Asn208 to study glycan roles in solubility and activity
Why do human studies show variable FGF21 correlations with obesity/metabolic health?
Confounding factors include:
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Assay variability: Commercial ELISAs differ in epitope recognition (full-length vs. cleaved FGF21)
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Temporal dynamics: Circulating FGF21 increases during prolonged fasting (≥7 days) but not acute starvation
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Tissue-specific release: Hepatic vs. adipose FGF21 pools may have divergent biological roles . Use tissue-specific knockout models (e.g., Alb-Cre for liver).
Product Science Overview
FGF-21 is a protein that consists of 209 amino acids, with a signal peptide of 28 amino acids at the N-terminus, resulting in a mature polypeptide of 181 amino acids . The recombinant human FGF-21 (His Tag) is produced in E. coli and includes a polyhistidine tag at the N-terminus to facilitate purification . This recombinant form is typically lyophilized and can be reconstituted in sterile water or buffer for experimental use .
FGF-21 has been identified as a novel adipokine, which is a type of cytokine secreted by adipose tissue. It plays a significant role in regulating metabolic processes, particularly in the context of obesity-related complications . Interestingly, serum levels of FGF-21 are paradoxically increased in obese individuals, which may indicate a compensatory response or resistance to FGF-21 .
FGF-21 exhibits promising therapeutic characteristics, especially for the treatment of metabolic diseases such as diabetes. It has been shown to improve insulin sensitivity, reduce blood glucose levels, and promote weight loss in animal models . These effects make FGF-21 a potential candidate for developing new treatments for metabolic disorders.
The recombinant human FGF-21 (His Tag) is stable for up to one year when stored at -20°C to -80°C. After reconstitution, it should be stored in working aliquots at -20°C to -80°C to avoid repeated freeze-thaw cycles . Proper storage and handling are crucial to maintain the protein’s biological activity and integrity.
FGF-21 is widely used in research to study its effects on cell proliferation, metabolism, and its potential therapeutic applications. It is often used in cell proliferation assays, where its activity is measured using specific cell lines such as NIH-3T3 mouse embryonic fibroblast cells . The recombinant protein’s high purity and biological activity make it a valuable tool for scientific investigations.
