Surface-Patterned DNA Origami Rulers Reveal Nanoscale Distance Dependency of the Epidermal Growth Factor Receptor Activation.

The nanoscale arrangement of ligands can have a major effect on the activation of membrane receptor proteins and thus cellular communication mechanisms. Here we report on the technological development and use of tailored DNA origami-based molecular rulers to fabricate "Multiscale Origami Structures As Interface for Cells" (MOSAIC), to enable the systematic investigation of the effect of the nanoscale spacing of epidermal growth factor (EGF) ligands on the activation of the EGF receptor (EGFR). MOSAIC-based analyses revealed that EGF distances of about 30-40 nm led to the highest response in EGFR activation of adherent MCF7 and Hela cells. Our study emphasizes the significance of DNA-based platforms for the detailed investigation of the molecular mechanisms of cellular signaling cascades.

Two NOTCH1 O-fucose sites have opposing functions in mouse retinal angiogenesis.

Previous in vitro studies demonstrated that Fringe glycosylation of the NOTCH1 extracellular domain at O-fucose residues in Epidermal Growth Factor-like Repeats (EGFs) 6 and 8 is a significant contributor to suppression of NOTCH1 activation by JAG1 or enhancement of NOTCH1 activation by DLL1, respectively. In this study, we sought to evaluate the significance of these glycosylation sites in a mammalian model by generating 2 C57BL/6J mouse lines carrying NOTCH1 point mutations, which eliminate O-fucosylation and Fringe activity at EGFs 6 (T232V) or 8 (T311V). We assessed changes to morphology during retinal angiogenesis, a process in which expression of Notch1, Jag1, Dll4, Lfng, Mfng, and Rfng genes coordinate cell-fate decisions to grow vessel networks. In the EGF6 O-fucose mutant (6f/6f) retinas, we observed reduced vessel density and branching, suggesting that this mutant is a Notch1 hypermorph. This finding agrees with prior cell-based studies showing that the 6f mutation increased JAG1 activation of NOTCH1 during co-expression with inhibitory Fringes. Although we predicted that the EGF8 O-fucose mutant (8f/8f) would not complete embryonic development due to the direct involvement of the O-fucose in engaging ligand, the 8f/8f mice were viable and fertile. In the 8f/8f retina, we measured increased vessel density consistent with established Notch1 hypomorphs. Overall, our data support the importance of NOTCH1 O-fucose residues for pathway function and confirms that single O-glycan sites are rich in signaling instructions for mammalian development.

Chemical synthesis of per-selenocysteine human epidermal growth factor.

Human seleno-epidermal growth factor (seleno-EGF), a 53-residue peptide where all six cysteine residues of the parent human EGF sequence were replaced by selenocysteines, was synthesized and the oxidative folding of a polypeptide containing three diselenide bonds was compared to that of the parent cysteine peptide. The crude high performance liquid chromatography (HPLC) profiles clearly showed that both the native EGF and its selenocysteine-analogue fold smoothly, yielding a single sharp peak, proving that even in the case of three disulfide-bonded polypeptides the disulfide-to-diselenide bond substitution is highly isomorphous, as confirmed by conformational circular dichroism measurements and particularly by the biological assays.

Notch Missense Mutations in Drosophila Reveal Functions of Specific EGF-like Repeats in Notch Folding, Trafficking, and Signaling.

Notch signaling plays various roles in cell-fate specification through direct cell-cell interactions. Notch receptors are evolutionarily conserved transmembrane proteins with multiple epidermal growth factor (EGF)-like repeats. Drosophila Notch has 36 EGF-like repeats, and while some play a role in Notch signaling, the specific functions of most remain unclear. To investigate the role of each EGF-like repeat, we used 19 previously identified missense mutations of Notch with unique amino acid substitutions in various EGF-like repeats and a transmembrane domain; 17 of these were identified through a single genetic screen. We assessed these mutants' phenotypes in the nervous system and hindgut during embryogenesis, and found that 10 of the 19 Notch mutants had defects in both lateral inhibition and inductive Notch signaling, showing context dependency. Of these 10 mutants, six accumulated Notch in the endoplasmic reticulum (ER), and these six were located in EGF-like repeats 8-10 or 25. Mutations with cysteine substitutions were not always coupled with ER accumulation. This suggests that certain EGF-like repeats may be particularly susceptible to structural perturbation, resulting in a misfolded and inactive Notch product that accumulates in the ER. Thus, we propose that these EGF-like repeats may be integral to Notch folding.

Targeted elastin-like polypeptide fusion protein for near-infrared imaging of human and canine urothelial carcinoma.

Cystoscopic visualization of bladder cancer is an essential method for initial bladder cancer detection and diagnosis, transurethral resection, and monitoring for recurrence. We sought to develop a new intravesical imaging agent that is more specific and sensitive using a polypeptide based NIR (near-infrared) probe designed to detect cells bearing epidermal growth factor receptors (EGFR) that are overexpressed in 80% of urothelial carcinoma (UC) cases. The NIR imaging agent consisted of an elastin like polypeptide (ELP) fused with epidermal growth factor (EGF) and conjugated to Cy5.5 to give Cy5.5-N24-EGF as a NIR contrast agent. In addition to evaluation in human cells and tissues, the agent was tested in canine cell lines and tissue samples with naturally occurring invasive UC. Flow cytometry and confocal microscopy were used to test cell-associated fluorescence of the probe in T24 human UC cells, and in K9TCC-SH (high EGFR expression) and K9TCC-Original (low EGF expression) canine cell lines. The probe specifically engages these cells through EGFR within 15 min of incubation and reached saturation within a clinically relevant 1 h timeframe. Furthermore, ex vivo studies with resected canine and human bladder tissues showed minimal signal from normal adjacent tissue and significant NIR fluorescence labeling of tumor tissue, in good agreement with our in vitro findings. Differential expression of EGFR ex vivo was revealed by our probe and confirmed by anti-EGFR immunohistochemical staining. Taken together, our data suggests Cy5.5-ELP-EGF is a NIR probe with improved sensitivity and selectivity towards BC that shows excellent potential for clinical translation.

Secretory expression of mammalian NOTCH tandem epidermal growth factor-like repeats based on increased O-glycosylation.

The Notch pathway represents evolutionarily conserved intercellular signaling essential for cell-to-cell communication during development. Dysregulation of Notch signaling has been implicated in various diseases, and its control represents a potential cancer treatment strategy. Notch signaling is initiated by the interaction of NOTCH receptors with their ligands on neighboring cells. Therefore, the truncated NOTCH ectodomain, composed mainly of tandem repeats of epidermal growth factor-like (EGF) domains, serves as a decoy molecule that competes for ligand binding and thus inhibits ligand-dependent Notch signaling. Although full-length NOTCH EGF repeats exhibited potent Notch inhibitory activity, they were poorly produced in the transfected cells. This study evaluated the effect of EGF domain-modifying glycosyltransferases on the secretion of NOTCH EGF repeats. Our results in HEK293T cells revealed that, unlike the effect on endogenous NOTCH receptors, overexpressed EGF domain-specific O-GlcNAc transferase (EOGT) markedly enhanced the secretion of NOTCH1 EGF repeats in an enzyme activity-dependent manner. The co-expression of protein O-glucosyltransferase 1 further manifested the effect of EOGT. The resultant changes in O-glycosylation of NOTCH3 were evaluated by label-free glycopeptide quantification. This study provides an experimental strategy to efficiently generate NOTCH EGF repeats by manipulating the expression of glycosyltransferases that alter the O-glycosylation of EGF domains.

Optimization of production and characterization of a recombinant soluble human Cripto-1 protein inhibiting self-renewal of cancer stem cells.

Human Cripto-1 is a member of the epidermal growth factor (EGF)-Cripto-FRL-1-Cryptic (CFC) family family and performs critical roles in cancer and various pathological and developmental processes. Recently we demonstrated that a soluble form of Cripto-1 suppresses the self-renewal and enhances the differentiation of cancer stem cells (CSCs). A functional form of soluble Cripto-1 was found to be difficult to obtain because of the 12 cysteine residues in the protein which impairs the folding process. Here, we optimized the protocol for a T7 expression system, purification from inclusion bodies under denatured conditions refolding of a His-tagged Cripto-1 protein. A concentrations of 0.2-0.4 mM isopropyl ß-D-1-thiogalactopyranoside (IPTG) at 37°C was found to be the optimal concentration for Cripto-1 expression while imidazole at 0.5 M was the optimum concentration to elute the Cripto-1 protein from a Ni-column in the smallest volume. Cation exchange column chromatography of the Cripto-1 protein in the presence of 8 M urea exhibited sufficient elution profile at pH 5, which was more efficient at recovery. The recovery of the protein reached to more than 26.6% after refolding with arginine. The purified Cripto-1 exhibited high affinity to the anti-ALK-4 antibody and suppressed sphere forming ability of CSCs at high dose and induced cell differentiation.

EGF domain peptide of Developmentally regulated endothelial locus1 facilitates gene expression of extracellularly applied plasmid DNA.

BACKGROUND: The successful development of messenger RNA vaccines for SARS-CoV-2 opened up venues for clinical nucleotide-based vaccinations. For development of DNA vaccines, we tested whether the EGF domain peptide of Developmentally regulated endothelial locus1 (E3 peptide) enhances uptake of extracellularly applied plasmid DNA. METHODS: DNA plasmid encoding lacZ or GFP was applied with a conditioned culture medium containing E3 peptide to cell lines in vitro or mouse soleus muscles in vivo, respectively. After 48 h incubation, gene expression was examined by ß-galactosidase (ß-gal) assay and fluorescent microscope, respectively. RESULTS: Application of E3 peptide-containing medium to cultured cell lines induced intense ß-gal activity in a dose-dependent manner. Intra-gastrocnemius injection of E3 peptide-containing medium to mouse soleus muscle succeeded in the induction of GFP fluorescence in many cells around the injection site. CONCLUSIONS: The administration of E3 peptide facilitates transmembrane uptake of extracellular DNA plasmid which induces sufficient extrinsic gene expression.

Structural basis of cytokine-mediated activation of ALK family receptors.

Anaplastic lymphoma kinase (ALK)1 and the related leukocyte tyrosine kinase (LTK)2 are recently deorphanized receptor tyrosine kinases3. Together with their activating cytokines, ALKAL1 and ALKAL24-6 (also called FAM150A and FAM150B or AUGß and AUGα, respectively), they are involved in neural development7, cancer7-9 and autoimmune diseases10. Furthermore, mammalian ALK recently emerged as a key regulator of energy expenditure and weight gain11, consistent with a metabolic role for Drosophila ALK12. Despite such functional pleiotropy and growing therapeutic relevance13,14, structural insights into ALK and LTK and their complexes with cognate cytokines have remained scarce. Here we show that the cytokine-binding segments of human ALK and LTK comprise a novel architectural chimera of a permuted TNF-like module that braces a glycine-rich subdomain featuring a hexagonal lattice of long polyglycine type II helices. The cognate cytokines ALKAL1 and ALKAL2 are monomeric three-helix bundles, yet their binding to ALK and LTK elicits similar dimeric assemblies with two-fold symmetry, that tent a single cytokine molecule proximal to the cell membrane. We show that the membrane-proximal EGF-like domain dictates the apparent cytokine preference of ALK. Assisted by these diverse structure-function findings, we propose a structural and mechanistic blueprint for complexes of ALK family receptors, and thereby extend the repertoire of ligand-mediated dimerization mechanisms adopted by receptor tyrosine kinases.

The epidermal growth factor ortholog of ectromelia virus activates EGFR/ErbB1 and demonstrates mitogenic function in vitro.

Many poxviruses produce proteins that are related to epidermal growth factor (EGF). Prior genome sequencing of ectromelia virus revealed a gene predicted to produce a protein with homology to EGF, which we refer to as ectromelia growth factor (ECGF). ECGF is truncated relative to vaccinia growth factor (VGF) because the former lacks a transmembrane domain. We show these proteins can experience differential N-linked glycosylation. Despite these differences, both proteins maintain the six conserved cysteine residues important for the function of EGF. Since ECGF has not been characterized, our objective was to determine if it can act as a growth factor. We added ECGF to cultured cells and found that the EGF receptor becomes activated, S-phase was induced, doubling time decreased, and in vitro wound healing occurred faster compared to untreated cells. In summary, we demonstrate that ECGF can act as a mitogen in a similar manner as VGF.

Magnitude of Ubiquitination Determines the Fate of Epidermal Growth Factor Receptor Upon Ligand Stimulation.

Receptor tyrosine kinases (RTK) bind growth factors and are critical for cell proliferation and differentiation. Their dysregulation leads to a loss of growth control, often resulting in cancer. Epidermal growth factor receptor (EGFR) is the prototypic RTK and can bind several ligands exhibiting distinct mitogenic potentials. Whereas the phosphorylation on individual EGFR sites and their roles for downstream signaling have been extensively studied, less is known about ligand-specific ubiquitination events on EGFR, which are crucial for signal attenuation and termination. We used a proteomics-based workflow for absolute quantitation combined with mathematical modeling to unveil potentially decisive ubiquitination events on EGFR from the first 30 seconds to 15 minutes of stimulation. Four ligands were used for stimulation: epidermal growth factor (EGF), heparin-binding-EGF like growth factor, transforming growth factor-α and epiregulin. Whereas only little differences in the order of individual ubiquitination sites were observed, the overall amount of modified receptor differed depending on the used ligand, indicating that absolute magnitude of EGFR ubiquitination, and not distinctly regulated ubiquitination sites, is a major determinant for signal attenuation and the subsequent cellular outcomes.

GB Tags: Small Covalent Peptide Tags Based on Protein Fragment Reconstitution.

Developing peptide tags that can bind target proteins covalently under mild conditions is of great importance for a myriad of applications, ranging from chemical biology to biotechnology. Here we report the development of a small covalent peptide tag system, termed as GB tags, that can covalently label the target protein with high specificity and high yield under oxidizing conditions. The GB tags consist of a pair of short peptides, GN and GC (GN contains 45 residues and GC contains 19 residues). GN and GC, which are split from a parent protein GB1, can undergo protein fragment reconstitution to reconstitute the folded structure of the parent protein spontaneously. The engineered cysteines in GN and GC can readily form a disulfide bond oxidized by air oxygen after protein reconstitution. Using thermally stable variants of GB1, we identified two pairs of GB tags that display improved thermodynamic stability and binding affinity. They can serve as efficient covalent peptide tags for various applications, including specific labeling of mammalian cell surface receptors. We anticipate that these new GB tags will find applications in biochemical labeling as well as biomaterials, such as protein hydrogels.

Epidermal Growth Factor Based Targeted Toxin for the Treatment of Bladder Cancer.

BACKGROUND/AIM: Reports on over-expression of the epidermal growth factor receptor (EGFR) in bladder cancer and its function in tumorigenesis have suggested to target this antigen. MATERIALS AND METHODS: We generated the targeted toxin EGF-PE40 consisting of the human epidermal growth factor (EGF) as the binding domain and PE40, a truncated version of Pseudomonas Exotoxin A, as the toxin domain. EGF-PE40 was tested on EGFR-expressing bladder cancer cells in view of binding via flow cytometry, and cytotoxicity via WST viability assay. Induction of apoptosis was examined by western blot. RESULTS: The targeted toxin specifically triggered cytotoxicity in the bladder cancer cells with 50% inhibitory concentration (IC50) values in the low nanomolar or picomolar range, and was about 1,250- to 1,500-fold more cytotoxic than the EGFR inhibitor erlotinib. Cytotoxicity of EGF-PE40 was based on the induction of apoptosis. CONCLUSION: EGF-PE40 represents a promising candidate for the future treatment of bladder cancer.

FRET detects lateral interaction between transmembrane domain of EGF receptor and ganglioside GM3 in lipid bilayers.

Ganglioside GM3 in the plasma membranes suppresses cell growth by preventing the autophosphorylation of the epidermal growth factor receptor (EGFR). Biological studies have suggested that GM3 interacts with the transmembrane segment of EGFR. Further biophysical experiments are particularly important for quantitative evaluation of the peptide-glycolipid interplay in bilayer membranes using a simple reconstituted system. To examine these interactions in this way, we synthesized the transmembrane segment of EGFR bearing a nitrobenzoxadiazole fluorophore (NBD-TM) at the N-terminus. The affinity between EGFR and GM3 was evaluated based on Förster resonance energy transfer (FRET) between NBD-TM and ATTO594-labeled GM3 in bilayers where their non-specific interaction due to lateral proximity was subtracted by using NBD-labeled phospholipid. This method for selectively detecting the specific lipid-peptide interactions in model lipid bilayers disclosed that the lateral interaction between GM3 and the transmembrane segment of EGFR plays a certain role in disturbing the formation of active EGFR dimers.

Proof-of-Concept Study of Multifunctional Hybrid Nanoparticle System Combined with NIR Laser Irradiation for the Treatment of Melanoma.

The global impact of cancer emphasizes the importance of developing innovative, effective and minimally invasive therapies. In the context of superficial cancers, the development of a multifunctional nanoparticle-based system and its in vitro and in vivo safety and efficacy characterization are, herein, proposed as a proof-of-concept. This multifunctional system consists of gold nanoparticles coated with hyaluronic and oleic acids, and functionalized with epidermal growth factor for greater specificity towards cutaneous melanoma cells. This nanoparticle system is activated by a near-infrared laser. The characterization of this nanoparticle system included several phases, with in vitro assays being firstly performed to assess the safety of gold nanoparticles without laser irradiation. Then, hairless immunocompromised mice were selected for a xenograft model upon inoculation of A375 human melanoma cells. Treatment with near-infrared laser irradiation for five minutes combined with in situ administration of the nanoparticles showed a tumor volume reduction of approximately 80% and, in some cases, led to the formation of several necrotic foci, observed histologically. No significant skin erythema at the irradiation zone was verified, nor other harmful effects on the excised organs. In conclusion, these assays suggest that this system is safe and shows promising results for the treatment of superficial melanoma.

Bi-Functional Radiotheranostics of 188Re-Liposome-Fcy-hEGF for Radio- and Chemo-Therapy of EGFR-Overexpressing Cancer Cells.

Epidermal growth factor receptor (EGFR) specific therapeutics is of great importance in cancer treatment. Fcy-hEGF fusion protein, composed of yeast cytosine deaminase (Fcy) and human EGF (hEGF), is capable of binding to EGFR and enzymatically convert 5-fluorocytosine (5-FC) to 1000-fold toxic 5-fluorocuracil (5-FU), thereby inhibiting the growth of EGFR-expressing tumor cells. To develop EGFR-specific therapy, 188Re-liposome-Fcy-hEGF was constructed by insertion of Fcy-hEGF fusion protein onto the surface of liposomes encapsulating of 188Re. Western blotting, MALDI-TOF, column size exclusion and flow cytometry were used to confirm the conjugation and bio-activity of 188Re-liposome-Fcy-hEGF. Cell lines with EGFR expression were subjected to treat with 188Re-liposome-Fcy-hEGF/5-FC in the presence of 5-FC. The 188Re-liposome-Fcy-hEGF/5-FC revealed a better cytotoxic effect for cancer cells than the treatment of liposome-Fcy-hEGF/5-FC or 188Re-liposome-Fcy-hEGF alone. The therapeutics has radio- and chemo-toxicity simultaneously and specifically target to EGFR-expression tumor cells, thereby achieving synergistic anticancer activity.

Piptides: New, Easily Accessible Chemotypes For Interactions With Biomolecules.

Small molecule probe development is pivotal in biomolecular science. Research described here was undertaken to develop a non-peptidic chemotype, piptides, that is amenable to convenient, iterative solid-phase syntheses, and useful in biomolecular probe discovery. Piptides can be made from readily accessible pip acid building blocks and have good proteolytic and pH stabilities. An illustrative application of piptides against a protein-protein interaction (PPI) target was explored. The Exploring Key Orientations (EKO) strategy was used to evaluate piptide candidates for this. A library of only 14 piptides contained five members that disrupted epidermal growth factor (EGF) and its receptor, EGFR, at low micromolar concentrations. These piptides also caused apoptotic cell death, and antagonized EGF-induced phosphorylation of intracellular tyrosine residues in EGFR.

Bladder Regeneration Using a Polycaprolactone Scaffold with a Gradient Structure and Growth Factors in a Partially Cystectomized Rat Model.

BACKGROUND: Tissue engineering can be used for bladder augmentation. However, conventional scaffolds result in fibrosis and graft shrinkage. This study applied an alternative polycaprolactone (PCL)-based scaffold (diameter = 5 mm) with a noble gradient structure and growth factors (GFs) (epidermal growth factor, vascular endothelial growth factor, and basic fibroblast growth factor) to enhance bladder tissue regeneration in a rat model. METHODS: Partially excised urinary bladders of 5-week-old male Slc:SD rats were reconstructed with the scaffold (scaffold group) or the scaffold combined with GFs (GF group) and compared with sham-operated (control group) and untreated rats (partial cystectomy group). Evaluations of bladder volume, histology, immunohistochemistry (IHC), and molecular markers were performed at 4, 8, and 12 weeks after operation. RESULTS: The bladder volumes of the scaffold and GF group recovered to the normal range, and those of the GF group showed more enhanced augmentation. Histological evaluations revealed that the GF group showed more organized urothelial lining, dense extracellular matrix, frequent angiogenesis, and enhanced smooth muscle bundle regeneration than the scaffold group. IHC for α-smooth muscle actin, pan-cytokeratin, α-bungarotoxin, and CD8 revealed that the GF group showed high formation of smooth muscle, blood vessel, urothelium, neuromuscular junction and low immunogenicity. Concordantly, real-time polymerase chain reaction experiments revealed that the GF group showed a higher expression of transcripts associated with smooth muscle and urothelial differentiation. In a 6-month in vivo safety analysis, the GF group showed normal histology. CONCLUSION: This study showed that a PCL scaffold with a gradient structure incorporating GFs improved bladder regeneration functionally and histologically.

EGF Conjugation Improves Safety and Uptake Efficacy of Titanium Dioxide Nanoparticles.

Titanium dioxide nanoparticles (TiO2 NPs) have a strong potential for cancer therapeutic and bioimaging applications such as photodynamic therapy (PDT) and photodynamic diagnosis (PDD). Our previous results have shown that TiO2 NPs have a low cellular uptake and can induce cell proliferation. This suggests that TiO2 NPs could increase the risk of tumor overgrowth while being used for PDD and PDT. To solve this problem, we constructed epidermal growth factor-ligated polyethylene glycol-coated TiO2 NPs (EGF-TiO2 PEG NPs). In this work, we studied the effect of EGF conjugation on the cellular uptake of TiO2 PEG NPs. Then, we investigated the effect of both non-conjugated and EGF-TiO2 PEG NPs on the A431 epidermal cancer cell line, proliferation and growth via the investigation of EGFR localization and expression. Our results indicated that TiO2 PEG NPs induced EGFRs aggregation on the A431 cells surface and induced cell proliferation. In addition, EGF-TiO2 PEG NPs induced the internalization of EGFRs inside of cells with increased cellular NPs uptake and decreased cellular proliferation compared to TiO2 PEG NPs-treated cells. These findings suggest that EGF conjugation can increase the efficacy of TiO2 PEG NPs for biomedical applications such as PDD and PDT with decreased risk of tumor overgrowth.

Molecular Pharming of the Recombinant Protein hEGF-hEGF Concatenated with Oleosin Using Transgenic Arabidopsis.

We set out to assess the NIH/3T3 cell proliferation activity of Arabidopsis oil body-expressed recombinant oleosin-hEGF-hEGF protein. Normally, human epidermal growth factor (hEGF) is purified through complex process, however, oleosin fusion technology provides an inexpensive and scalable platform for its purification. Under a phaseolin promoter, we concatenated oleosin gene to double hEGF (hEGF-hEGF) with plant-preferred codons in the expression vectors and the construct was transformed into Arabidopsis thaliana (Arabidopsis). The transgenic Arabidopsis was validated by RT-PCR and the content of recombinant protein oleosin-hEGF-hEGF was quantified by western blot. Subsequently, the proliferation assay and transdermal absorption were determined by MTT method and immunohistochemical staining, respectively. First, the expression level of hEGF was recorded to be 14.83-ng/µL oil body and due to smaller size transgenic oil bodies expressing the recombinant oleosin-hEGF-hEGF, they were more skin permeable than those of control. Second, via the staining intensity of transgenic oil bodies was greater than EGF at all time points via immunohistochemical staining in transdermal absorption process. Lastly, activity assays of oil bodies expressed oleosin-hEGF-hEGF indicated that they stimulated the NIH/3T3 cell proliferation activity. Our results revealed oil-body-expressed oleosin-hEGF-hEGF was potential new material having implications in the field of medicine.