Mentor
Thallapuranam Krishnaswamy Suresh Kumar
Keywords
Fibroblast Growth Factor, mitogenic, Cell Proliferation, Metabolic, Wound Care, Diabetes
Abstract
Fibroblast growth factors (FGFs) are a family of 22 human cytokines involved in critical cellular processes, such as proliferation, differentiation, metabolism, angiogenesis, tumor metastasis, and wound healing. Among these, fibroblast growth factor 1 (FGF1) possesses a powerful mitogenic potential as it can nonspecifically bind to all four FGF receptors. However, the therapeutic applications of FGF1 are hindered by its inherent thermal and proteolytic instability, especially at physiological temperatures. This is believed to be attributed to the heparin-binding pocket at the C-terminus, which contains numerous positively charged residues that repel each other. To combat this instability, FGF1 binds to a negatively charged glycosaminoglycan, heparin. Heparin is hypothesized to play a crucial role in FGF1 signal transduction and intracellular signaling.
To overcome the thermal instability of FGF1, a hyper-stable variant of FGF1 (hsFGF1) was engineered with five amino acid substitutions (R136E, K126N, Q54P, S61L, and H107S), including two mutations within the heparin-binding region. This variant maintains structural integrity with enhanced thermal and proteolytic stability, yet no longer depends on heparin for its activity. Differential scanning calorimetry revealed a substantial increase in thermal stability (ΔTm = 27°C) for hsFGF1 compared to wild-type FGF1 (wtFGF1). Furthermore, limited trypsin digestion assays showed that hsFGF1 exhibits significantly greater resistance to proteolytic cleavage, indicating a more compact and stable protein conformation. Despite its reduced heparin-binding affinity, hsFGF1 retains its mitogenic and metabolic functions. Remarkably, cells treated with hsFGF1 elicited an enhanced proliferation and increased glycolytic respiration compared to those treated with wtFGF1, suggesting that heparin is not critical for FGF1- mediated signaling. Our findings challenge the existing paradigm regarding heparin's role and provide novel insights into the structural and metabolic properties of FGF1. These findings hold significant promise for the development of FGF-based therapeutics targeting wound healing, diabetes, and obesity.
Recommended Citation
Starr, Emma; Edirisinghe, Oshadi; and Kumar, Thallapuranam Krishnaswamy Suresh
(2024)
"Exploring the Metabolic and Mitogenic Potential of a Hyper-Stable Variant of FGF1,"
Inquiry: The University of Arkansas Undergraduate Research Journal: Vol. 23, Article 5.
https://doi.org/10.54119/inquiry.2024.23201
Available at:
https://scholarworks.uark.edu/inquiry/vol23/iss2/5
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