Discovery of Hyperstable Noncanonical Plant-Derived Epidermal Growth Factor Receptor Agonist and Analogs

Abstract

Here, we report the discovery of the first plant-derived and noncanonical epidermal growth factor receptor (EGFR) agonist, the 36-residue bleogen pB1 from Pereskia bleo of the Cactaceae family. We show that bleogen pB1 is a low-affinity EGFR agonist using a suite of chemical, biochemical, cellular, and animal experiments which include incisor eruption and wound-healing mouse models. A focused positional scanning pB1 library of Ala- and d-amino acid scans yielded a high-affinity pB1 analog, [K29k]­pB1, with a 60-fold-improved EGFR affinity and mitogenicity. We show that the potency of [K29k]­pB1 and the epidermal growth factor (EGF) is comparable in a diabetic mouse wound-healing model. We also show that both bleogen pB1 and [K29k]­pB1 are hyperstable, being >100-fold more stable than EGF against proteolytic degradation. Overall, our discovery of a noncanonical proteolytic-resistant EGFR agonist scaffold could open new avenues for developing wound healing and skin regeneration therapeutics and biomaterials.

Hololectin Interdomain Linker Determines Asparaginyl Endopeptidase-Mediated Maturation of Antifungal Hevein-Like Peptides in Oats

“…We used a mass spectrometry (MS)-driven approach to profile hev-like peptides in the aqueous extract of oats, and selected cereals and legumes, including B. maxima , C. cajan , C. lacryma , E. canadensis , G. max , P. vulgaris , H. jubatum , H. vulgare , S. cereale , S. bicolor , T. aestivum , V. umbellate , V. radiata , V. unguiculata , and V. angularis ( Loo et al, 2016 , 2017 , 2021a , b ; Tam et al, 2018 ; Kam et al, 2019a , b ; Supplementary Figures 1 – 19 ). Since hev-peptides contain 38–42 amino acids and eight cysteine residues, we focused on peaks around 4 kDa in their MS profiles.…”

“…Cysteine-rich peptides cross-linked by multiple disulfides are known for their stability against heat, acid, and proteolytic degradation ( Kini et al, 2015 , 2017 ; Loo et al, 2016 , 2017 , 2021a , b ; Wong et al, 2016 ; Tam et al, 2018 ; Kam et al, 2019a , b ). To investigate the involvement of the disulfide scaffold on the stability of avenatides, we performed peptide degradation assays on folded avenatide aV1 and compared with its linearized S -alkylated form.…”

Hyperstable EGF-like bleogen derived from cactus accelerates corneal healing in rats

“…Depending on the type and extent of the injury, a prolonged influx of inflammatory cells, an imbalance in the myofibroblast turnover, and/or a disorganized extracellular matrix organization may occur, thereby resulting into corneal scarring and opacity (Bukowiecki et al, 2017). Previously, we showed that both EGF and bleogen pB1 are mitogens that can accelerate incisor eruption in newborn mice and skin wound healing in streptozotocin-induced diabetic rats (Loo et al, 2021a). Similar to EGF, bleogen pB1 activates the EGFR/MEK/ERK signaling pathway in keratinocytes to trigger cell proliferation in healing skin wounds.…”

“…Recently, our laboratory discovered and identified the first plant-derived EGFR agonist known as bleogen pB1 ( Loo et al, 2021a ). Bleogen pB1 is a 36-residue miniprotein and the smallest known EGFR agonist.…”

“…As such, bleogen pB1 is a non-canonical and “first-in-class” EGFR agonist. Although both the sequence and the structure of bleogen pB1 are different from those of EGF ( Figure 1C ), bleogen pB1 binds to and activates EGFR, and also displays functions that are similar to those of EGF in vitro ( Loo et al, 2021a ). Moreover, like EGF, bleogen pB1 promotes skin wound healing in vivo ( Loo et al, 2021a ).…”