Recombinant Human Tumor necrosis factor receptor superfamily member 6 protein (FAS), partial (Active)
Description
Introduction
Recombinant Human FAS (TNFRSF6/CD95) is a truncated, non-glycosylated extracellular domain of the full-length FAS receptor, engineered for research and therapeutic applications. This partial form lacks the transmembrane domain, functioning as a soluble decoy receptor to block FAS ligand (FASL)-mediated apoptosis. It is critical in studying immune regulation, cancer, and autoimmune diseases .
Biological Activity
Mechanism of Action:
Recombinant FAS binds to FASL, forming a competitive decoy that inhibits receptor clustering and DISC (death-inducing signaling complex) formation. This blocks caspase-8 activation and subsequent apoptosis .
Functional Assays:
Immunotherapy and Cancer Research
Inflammatory and Autoimmune Diseases
Challenges and Considerations
Production and Stability:
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Solubilization: NativeMP™ platform stabilizes full-length FAS for structural studies .
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Glycosylation: Baculovirus-expressed FASΔTM retains post-translational modifications, enhancing binding affinity .
Therapeutic Risks:
Product Specs
Target Background
FAS (Tumor necrosis factor receptor superfamily member 6) is a receptor for TNFSF6/FASLG. Upon activation, the adaptor molecule FADD recruits caspase-8, forming a death-inducing signaling complex (DISC). This complex activates caspase-8, initiating a caspase cascade that mediates apoptosis. FAS-mediated apoptosis plays a potential role in the induction of peripheral tolerance and/or antigen-stimulated T-cell death. Secreted isoforms 2-6 (in vitro) exhibit anti-apoptotic activity.
- FAS death domain or TP53 DNA-binding domain mutations, and down-regulation of FAS receptor expression. PMID: 30278467
- CD95-mediated apoptosis induces Pim-1 down-regulation in Burkitt's lymphoma (BL) B-cells; however, this down-regulation is insufficient to fully eradicate BL and leukemia. PMID: 27641442
- Fas single-nucleotide polymorphisms rs2234767 and rs1800682 are implicated in the pathogenesis of Idiopathic Aplastic Anemia. PMID: 29611722
- Lower FAS mRNA expression is observed in patients with TP53 mutations compared to TP53 wild-type. This suggests that TP53 mutation may negatively predict the response of metastatic melanoma to CTLA-4 blockade. PMID: 29793878
- Analysis of the alternative splicing of FAS/CD95 exon 6 reveals extensive epistasis, suggesting that exonic regulatory sequences may diverge between species even when exon inclusion levels are functionally conserved. PMID: 27161764
- Study of serum cytokines and lymphocyte apoptosis in nodular goiter, considering autoimmune thyroiditis, thyroid adenoma, apoptosis preparedness, apoptotic lymphocyte counts, pro-apoptotic TNF-α and interleukins, and polymorphisms in BCL-2, CTLA-4, and APO-1 genes. PMID: 29250672
- ING4 overexpression induces apoptosis in melanoma cells and CD3+ T cells via pathways including the Fas/FasL pathway, suggesting a novel therapeutic approach for melanoma. PMID: 29207034
- Tag7 activates lymphocytes capable of FasL-Fas-dependent killing of virus-infected cells. PMID: 29083508
- cMyc and Fas regulate A549 cell radiosensitivity by modulating caspase8-mediated Bid activation and the mitochondrial apoptosis pathway. PMID: 28849062
- Juvenile systemic lupus erythematosus (SLE) exhibits a distinct profile compared to adult SLE, characterized by increased sFas and sTRAIL, and reduced sFasL, particularly in active disease and nephritis. PMID: 28378099
- Lack of association between FAS-670A/G SNP and idiopathic azoospermia in men with idiopathic infertility. PMID: 28942044
- Btk-dependent PIP5K1gamma lipid kinase activation counteracts FasL-induced cell death. PMID: 28879546
- Identification of genes highly expressed in Kras knockout lung cancer cells, including the Fas receptor gene. Fas receptor activation selectively induces apoptosis in Kras-independent lung cancer cells, suggesting a role in KRAS-related drug resistance. PMID: 28320962
- Differential CD95 (Fas) expression in CD27(+) B-cells from cirrhotic patients, inversely correlated with peripheral CD27(+) B-cell frequency. Increased Fas-induced apoptosis sensitivity in these cells, potentially influenced by endotoxin, is associated with reduced circulating memory B-cells. PMID: 27857173
- Increased FasR and/or FasL expression is associated with disease progression. Spherical cancer cell models may be more reliable for certain analyses due to greater resemblance to cancer stem cells (CSCs) from human colorectal cancer (CRC) samples compared to adherent cells. PMID: 28766682
- FAS-FASL promoter SNPs may promote cross-reactive anti-ganglioside antibody production in Guillain-Barré syndrome (GBS). PMID: 29432441
- Hyperplasias in primary hyperparathyroidism show the highest TRAIL and Fas expression; adenomas show increased expression compared to normal tissue, but lower than in hyperplasias. PMID: 27763797
- Fas and TNFR1 are involved in glaucoma mechanisms in the cornea; clonidine's pro-apoptotic effect on corneal epithelial cells triggers Fas/TNFR1-mediated, mitochondria-dependent signaling. (Fas = Fas cell surface death receptor; TNFR1 = TNF receptor superfamily member 1A) PMID: 28115640
- YY1 regulates Fas expression during sepsis, influencing apoptosis and potentially serving as a therapeutic target and prognostic marker. PMID: 28447715
- Fas activation alters phosphatidylcholine (PC) and phosphatidylinositol (PI) interconversion, enhancing endocytosis and propagating death signaling. PMID: 28299505
- Pifithrin α decreases MG132- and APO-1/MG132-induced apoptosis, suggesting p53 restoration contributes to APO-1 sensitivity. Proteasome pathway inhibition might activate cell death, offering new cancer treatment opportunities. PMID: 27766434
- No significant difference in FAS-670A/G genotypes or alleles between controls and transplant recipients, or among recipients with and without acute rejection after pediatric renal transplantation. PMID: 27109035
- miR-374a negatively regulates the Fas death receptor, enhancing cell survival and protecting retinal pigment epithelial cells from oxidative stress. PMID: 28543858
- CD3(+) CD8(+) NKG2D(+) T lymphocytes induce apoptosis and necroptosis in HLA-negative cells via FasL-Fas interaction. PMID: 28294381
- High-grade gliomas (HGG) show significantly lower FAS but higher FAS ligand (FAS-L) expression than low-grade gliomas. PMID: 29187439
- Peripheral CD95 expression above 30% may be an exclusion criterion in a mycosis fungoides diagnostic score. PMID: 28206666
- BclxL, Bcl-2, BAD, and BID cooperate to promote migration of triple-negative breast cancer cells stimulated with cl-CD95L. PMID: 27367565
- Caspase-8, CD95, or FADD knockout/knockdown prevents Plk3 activation upon CD95 stimulation, indicating a requirement for a functional death-inducing signaling complex. PMID: 27325299
- STAT1 regulates the cancer stem cell-inducing activity of CD95. PMID: 28273453
- Two patients with severe recessive autoimmune lymphoproliferative syndrome had rare splicing defects in FAS exon 6. PMID: 28668589
- CD95-induced senescence is caused by chronic DNA damage. PMID: 28300842
- CD95 maintains stem cell-like and non-classical epithelial-mesenchymal transition programs in primary human glioblastoma cells. PMID: 27124583
- IL1B mediates islet amyloid-induced FAS up-regulation and apoptosis in pancreatic beta-cells and down-regulates IAPP precursor processing, potentiating amyloid formation. (IL1B = interleukin-1beta; FAS = FAS cell surface death receptor; IAPP = islet amyloid polypeptide) PMID: 28058779
- MACC1 regulates Fas-mediated apoptosis through STAT1/3-Mcl-1 signaling in solid cancers. PMID: 28649004
- No association between FAS polymorphism (rs1800682) and susceptibility to persistent precancerous lesions and cervical cancer. PMID: 27899077
- FAS c.-671A>G polymorphism is associated with increased proviral load in HTLV-1-associated myelopathy/tropical spastic paraparesis. PMID: 27603042
- FAS c.-671A>G polymorphism shows conflicting associations with cervical cancer risk in different studies. PMID: 28279307
- Fas is an independent prognostic marker for recurrence-free survival in breast cancer, with varying expression across receptor subtypes. PMID: 28121628
- CD154 inhibits Fas-mediated cell death by suppressing caspase-8 cleavage, independent of de novo protein synthesis or surface Fas expression changes. PMID: 27391025
- MBL and CD95 polymorphisms are associated with severe infections after doxorubicin/cyclophosphamide breast cancer therapy. PMID: 27940354
- Allele-specific transcription factor complex assembly and disruption by causal variants contribute to disease and phenotypic diversity, exemplified by FAS rs7901656. PMID: 27616356
- Increased TIM3+CD8+ T cells with lower perforin/granzyme B and higher CD95 expression in myelodysplastic syndrome (MDS) patients. PMID: 27846431
- FAS c.-671AG genotype is not a risk factor in familial Mediterranean fever. PMID: 28442396
- miR-29c functional inhibition causes resistance to Fas-mediated apoptosis in lung fibroblasts. PMID: 27765762
- Fas deficiency in most plasma cells of a patient with a heterozygous germline FAS mutation suggests a role for Fas signaling in germinal center B cell selection into long-lived plasma cells. PMID: 26907631
- Defective Fas function, particularly decreased Fas expression in activated T cells, is observed in a subset of immune thrombocytopenic purpura (ITP) patients. PMID: 27391055
- Fas gene polymorphism is associated with Hashimoto's thyroiditis. PMID: 27572459
- Positive correlation between serum sFasL (Fas/FasL axis) and parotid gland uptake index; decreased sFasL in liver injury involvement in Sjögren's syndrome (SS); positive correlation between IL-10 expression and sFasL expression. PMID: 28326325
- Fas-1377G > A polymorphism is associated with increased pre-eclampsia risk. PMID: 27277758
- Fas rs2234767 G/A SNPs might be associated with increased rheumatoid arthritis risk. PMID: 26905515
Q&A
Basic Research Questions
What structural and functional domains are preserved in recombinant partial FAS protein?
The partial FAS protein (aa 26-173 or 17-173 across sources) retains critical extracellular domains required for Fas ligand (FasL) binding and oligomerization . Key features include:
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Cysteine-rich domains (CRDs): Essential for ligand interaction and receptor activation .
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Trimerization interface: Facilitates FAS self-assembly upon ligand binding .
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Proteolytic stability: Lacks the transmembrane/intracellular domains, enhancing solubility for in vitro studies .
How does recombinant FAS protein modulate apoptosis in experimental systems?
Recombinant FAS acts as a decoy receptor to inhibit FasL-mediated apoptosis by:
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Preventing DISC (Death-Inducing Signaling Complex) formation, as shown by reduced caspase-8 activation .
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Effective concentrations: 0.01–0.04 µg/mL in functional assays with cross-linking enhancers .
What quality control parameters are critical for functional studies?
Advanced Research Questions
How can researchers reconcile discrepancies between preclinical FAS agonist efficacy and clinical trial outcomes?
Preclinical models (e.g., tumor-bearing mice) showed apoptosis induction with recombinant FasL/TRAIL, but clinical trials failed due to:
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Tumor microenvironment factors: Proinflammatory cytokines (e.g., IL-6, TGF-β) upregulate anti-apoptotic proteins like FLIP and Bcl-2 .
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Receptor heterogeneity: Tumors expressing FAS variants lacking death domains resist apoptosis .
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Methodological mitigation: Use patient-derived organoids to pre-screen responders .
What strategies optimize recombinant FAS activity in vitro?
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Cross-linking enhancers: Anti-polyhistidine antibodies increase inhibitory potency 20–50 fold .
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Co-culture systems: Mimic physiological ligand presentation using FasL-expressing effector cells .
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Protease inhibitors: Prevent FAS degradation in serum-containing media (e.g., 10 µM E-64) .
How does glycosylation impact recombinant FAS functionality across expression systems?
What methods validate FAS-mediated signaling inhibition in complex models?
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Flow cytometry: Measure caspase-3/7 activation in Jurkat cells treated with FasL ± recombinant FAS .
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Transcriptomics: Identify NF-κB/MAPK pathway suppression using RNA-seq .
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In vivo imaging: Track tumor apoptosis in xenografts with FAS-Fc fusion proteins .
