4. Morphology/Physiology

[P4-18] Insight linking between nitration and myogenic dysfunction of HGF/NK1 domain

〇Alaa Elgaabari^1,2, Nana Imatomi¹, Hirochika Kido^1,3, Yuji Matsuyoshi¹, Takashi Nakashima¹, Shoko Sawano^1,4, Wataru Mizunoya^1,4, Takahiro Suzuki¹, Mako Nakamura¹, Ryuichi Tatsumi¹ (1.Kyushu University, 2.kafrelsheikh University, Egypt, 3.JT Inc, 4.Azabu University)

Purpose: Recently, HGF nitration was reported with associating dysfunction to activate quiescent myogenic stem satellite cells (127th JSAS meeting abstract). Here we examine in vitro nitration of HGF/NK1 segment (N-terminal and kringle1 domains, critical for receptor c-met binding) and the effect on c-met binding that transduces mitogenic signals. Methods: Recombinant NK1 (a kind gift from TORAY Co.) was incubated with peroxynitrite at pH 7.4 and evaluated for tyrosine residue (Y) nitration by ECL-Western Blotting and for physiological activities including satellite cell activation (BrdU incorporation assay) and c-met binding affinity (sandwich ELISA-like assay). Results: Exposure of NK1 segment to peroxynitrite induced its nitration with a primary target of Y198. NK1 is a potent HGF agonist for satellite cell activation and the activity was abolished upon nitration by diminishing NK1-c-met affinity. Results proved that NK1 is a critical target for HGF nitration and the inhibitory effect on c-met binding may be centered on a mechanism that inhibits activation and proliferation of satellite cells.