Development of Potent Myostatin Inhibitory Peptides through Hydrophobic Residue-Directed Structural Modification

Abstract

Myostatin, a negative regulator of skeletal muscle growth, is a promising target for treating muscle atrophic disorders. Recently, we discovered a minimal myostatin inhibitor (WRQNTRYSRIEAIKIQILSKLRL-amide) derived from positions 21-43 of the mouse myostatin prodomain. We previously identified key residues (N-terminal Trp, rodent-specific Tyr, and all aliphatic amino acids) required for effective inhibition through structure-activity relationship (SAR) studies based on and characterized a 3-fold more potent inhibitor bearing a 2-naphthyloxyacetyl group at position 21. Herein, we performed -based SAR studies focused on all aliphatic residues and Ala, discovering that the incorporations of Trp and Ile at positions 32 and 38, respectively, enhanced the inhibitory activity. Combining these findings with , a novel peptide displayed an IC value of 0.32 μM, which is 11 times more potent than . The peptide would have the potential to be a promising drug lead to develop better peptidomimetics.

Chain-Shortened Myostatin Inhibitory Peptides Improve Grip Strength in Mice

“…Therefore, we examined the in vivo efficacy of E31R in mdx mice (5-week-old male) through histological analysis based on hematoxylin and eosin staining using a previously reported procedure. 21 As shown in Figure S1, intramuscularly injected E31R, compared to saline, induced an increase of gastrocnemius (GAS) muscle fiber sizes. Additionally, peptides 3 and E31R similarly increased GAS muscle fiber sizes in wild-type C57BL/6 mice compared to saline ( Figure S2).…”

“…These results suggested that the myostatin inhibitory activity of peptide 4a is attributed to the adequate hydrophobic interaction derived from its β-sheet structure, predominantly formed by amino acid substitutions at positions 32 and 38, which is a similar case previously observed in peptide 3. 21 Compared with peptide 4a, other inhibitory peptides 4b, 5, 6, and 8a exhibited even higher content of the β-sheet structure along with their enhanced inhibitory activity ( Figure 5). In particular, the content of the most potent peptide 8a was 76%.…”

“…As shown in Figure 1 and in our previous SAR study, 16 it is known that Ile and Trp are also favored amino acid residues at position 38 for effective inhibition of myostatin. 21 Therefore, we focused on the change to Chg at positions 35 and 41 in E31R and synthesized monosubstituted (7a and 7b) and disubstituted (7c) peptides ( Figure 3A). In addition to these peptides, since substitutions I30F and I37F in peptide 1 showed an inhibitory activity similar to that of 1, 21 we synthesized the corresponding E31R derivatives 7d (I30F) and 7e (I37F) to examine the applicability of these substitutions ( Figure 3A).…”

“…18−21 Peptide 3 increases muscular mass in both the DMD-model mdx and wild-type mice. 21 In an alternative SAR study, we identified residues important for effective myostatin inhibition by Ala-scanning of peptide 1. The important residues were Trp21, Tyr27, Ile30, Ile33, Ile35, Ile37, Leu38, Leu41, and Leu43.…”

Detection of the myostatin‐neutralizing antibody Domagrozumab in serum by means of Western blotting and LC‐HRMS

“…Different strategies are currently in preclinical and clinical investigation. They comprise drug candidates specifically targeting the cytokine such as anti‐myostatin antibodies, peptibodies, adnectin‐ and follistatin‐Fc fusion proteins, and agents derived from the myostatin propeptide, as well as multi‐target approaches such as receptor competitors and anti‐ActRII antibodies . Domagrozumab (PF‐06252616; Pfizer, New York City, NY) is a humanized monoclonal anti‐myostatin antibody developed for the treatment of Duchenne muscular dystrophy, which prevents receptor activation through binding to the circulating cytokine .…”