Development of a Potent Wound Healing Agent Based on the Liver Fluke Granulin Structural Fold

Granulins are a family
of protein growth factors that are involved
in cell proliferation. An orthologue of granulin from the human parasitic
liver fluke Opisthorchis viverrini,
known as Ov-GRN-1, induces angiogenesis and accelerates
wound repair. Recombinant Ov-GRN-1 production is
complex and poses an obstacle for clinical development. To identify
the bioactive region(s) of Ov-GRN-1, four truncated
N-terminal analogues were synthesized and characterized structurally
using NMR spectroscopy. Peptides that contained only two native disulfide
bonds lack the characteristic granulin β-hairpin structure.
Remarkably, the introduction of a non-native disulfide bond was critical
for formation of β-hairpin structure. Despite this structural
difference, both two and three disulfide-bonded peptides drove proliferation
of a human cholangiocyte cell line and demonstrated potent wound healing
in mice. Peptides derived from Ov-GRN-1 are leads
for novel wound healing therapeutics, as they are likely less immunogenic
than the full-length protein and more convenient to produce.