Enhancer-directed gene delivery for digit regeneration based on conserved epidermal factors

Area of Science:

• Regenerative Medicine
• Developmental Biology
• Molecular Genetics

Background:

• Limb loss presents a significant clinical challenge.
• Regenerative medicine, particularly gene therapy, shows promise for triggering endogenous regeneration.
• Identifying optimal molecular targets and delivery systems for appendicular skeletal repair is crucial.

Purpose of the Study:

• To design an enhancer-directed gene delivery platform for appendicular skeletal repair.
• To investigate the role of SP transcription factors in appendage regeneration.
• To explore the potential of FGF8 as a therapeutic target for limb regeneration.

Main Methods:

• Single-cell RNA sequencing of zebrafish fin regeneration.
• Comparative analysis of gene expression in regenerating salamander limbs and mouse digit tips.
• Conditional knockout of SP6 and SP8 in mouse epidermis and in vivo gene delivery using adeno-associated viral vectors.

Main Results:

• SP transcription factors were identified as conserved mediators of appendage regrowth.
• Sp8 null mutants showed impaired salamander limb regeneration.
• Conditional knockout of Sp6/Sp8 in mice resulted in defective digit tip regeneration, involving an IL-17-mediated osteoclastogenic program.
• FGF8 expression, driven by a zebrafish enhancer, partially rescued digit regeneration in knockout mice and accelerated it in wild-type mice.

Conclusions:

• SP transcription factors are key regulators of appendage regeneration across species.
• A gene therapy approach targeting SP factors and FGF8 shows potential for limb regeneration.
• This study provides a foundation for developing gene therapies for limb loss based on conserved regenerative mechanisms.