ISX9, a small molecule targeting Axin, activates Wnt/β-catenin signaling
and promotes hair regrowth
Abstract
Background and Purpose: ISX9 is a neurogenesis-promoting small molecule
compound which can upregulate the expression of NeuroD1 and induce
differentiation of neuronal, cardiac and islet endocrine progenitors. So
far, the molecular mechanisms underlying the action of ISX9 still remain
elusive. Experimental Approach: To identify a novel agonist of the
Wnt/β‐catenin, a cell-based SuperTOPFlash reporter system was used to
screen known-compound libraries. An activation effect of ISX9 on the
Wnt/β‐catenin pathway was analysed with the SuperTOPFlash or
SuperFOPFlash reporter system. Effects of ISX9 on Axin1/LRP6 interaction
were examined using a mammalian two-hybrid system,
co‐immunoprecipitation, microscale thermophoresis (MST), emission
spectra and mass spectroscopy assays. The expression of Wnt target and
stemmness marker genes were evaluated with real‐time PCR and
immunoblotting. In vivo hair regeneration abilities of ISX9 were
analysed by immunohistochemical staining, real‐time PCR and
immunoblotting in hair regrowth model using C57BL/6J mice. Key Results:
In this study, ISX9 was identified as a novel agonist of the
Wnt/β‐catenin pathway. ISX9 targeted Axin1 by covalently binding to its
N-terminal region and potentiated the LRP6-Axin1 interaction, thereby
resulting in the stabilization of β‐catenin and upregulation of Wnt
target genes and stemmness marker genes. Moreover, the topical
application of ISX9 markedly promoted hair regrowth in C57BL/6J mice and
induced hair follicle transition from telogen to anagen via enhancing
Wnt/β‐catenin pathway. Conclusions and Implications: Taken together, our
study unraveled that ISX9 could activate Wnt/β‐catenin signaling by
potentiating the association between LRP6 and Axin1, and may be a
promising therapeutic agent for alopecia treatment