Apoptosis during embryonic tissue remodeling is accompanied by cell senescence

Area of Science:

• Developmental Biology
• Cell Biology
• Molecular Biology

Background:

• Limb development involves programmed cell death in interdigital tissues to form free digits.
• The molecular mechanisms driving this tissue regression are not fully understood.

Purpose of the Study:

• To investigate the role of cell senescence and apoptosis in interdigital tissue regression during embryonic limb development.
• To identify key molecular regulators involved in this process.

Main Methods:

• Analysis of β-galactosidase activity, cell cycle progression, and gene expression.
• Investigating the Btg/Tob gene family, specifically Btg2.
• Utilizing in vivo and in vitro overexpression and silencing techniques.
• Examining the role of oxidative stress and survival signals (FGF2, IGF1).

Main Results:

• Interdigital tissue regression is linked to cell senescence, characterized by p21 up-regulation and senescence-associated secretory phenotype.
• Btg2 expression is elevated in species with free digits but not in webbed feet.
• Oxidative stress enhances Btg2 expression, while FGF2 and IGF1 inhibit it.
• Btg2 overexpression recapitulates interdigital regression phenotypes, including senescence and apoptosis, with p21 playing a central role.

Conclusions:

• Cell senescence and apoptosis are complementary processes in embryonic tissue regression.
• Btg2 is a critical regulator of interdigital tissue remodeling, linking senescence and apoptosis.
• Shared regulatory signals control these distinct but coordinated cell death pathways.