Introduction of Human Acidic Fibroblast Growth Factor (FGF1) Variant with Increased Stability and Bioactivity

Human acidic Fibroblast Growth Factor 1 (FGF-1) involves in a broad spectrum of biological processes, including cell growth, proliferation, differentiation, migration, angiogenesis, wound healing, and embryonic development. hFGF1 non-selectively binds to cell surface hFGF receptor isoforms to elicit these cell-signaling processes. Since hFGF1 plays a significant role in tissue repair activity, that is a prime candidate for novel wound healing therapeutics. However, hFGF1 has been found to unfold near physiological temperature due to a strong electrostatic repulsion created by a dense cluster of positively charged amino acids near the c-terminus. The problem not only leads to proteolytic degradation of the unfolded protein but also limits the bioavailability of hFGF1 and then restricts application of hFGF1 in pharmacology. To overcome this instability, hFGF1 with the positively charged residues near the c-terminus in the region known as the heparin-binding pocket binds to the heavily sulfated glycosaminoglycan, heparin, which decreases the charge-charge repulsion. However, the use of heparin in hFGF1 wound-healing therapeutics imposes a serious challenge. To address these issues, I have designed a charged reversed single mutation in the heparin-binding pocket of hFGF1 to decrease the repulsion between the closely packed positively charged, enhanced stability and cell proliferation activity of the protein. Study of this mutation is performed by biophysical experiments. The results show that site-directed mutagenesis in hFGF1 can enhance the inherent stability of the growth factor and increase mitogenic activity of hFGF1 in absence of heparin