Smad7 is required for the development and function of the heart

Area of Science:

• Molecular Biology
• Developmental Biology
• Cardiovascular Research

Background:

• Transforming growth factor-beta (TGF-beta) signaling, mediated by Smad proteins, regulates critical cellular processes.
• Smad7 acts as a negative regulator of TGF-beta family signaling.
• Dysregulation of Smad7 is linked to human diseases, but its in vivo roles remain unclear due to a lack of functional models.

Purpose of the Study:

• To investigate the in vivo physiological roles of Smad7 in mouse development and cardiac function.
• To characterize the phenotype of mice with a targeted deletion of the Smad7 MH2 domain.

Main Methods:

• Generation of Smad7 mutant mice via targeted deletion of the MH2 domain.
• Phenotypic analysis of Smad7 mutant mice, including in utero and adult stages.
• Assessment of cardiovascular development, cardiac function, and apoptosis in mutant hearts.

Main Results:

• Smad7 mutant mice exhibit high in utero lethality due to severe cardiovascular defects (ventricular septal defect, non-compaction, outflow tract malformation).
• Surviving adult Smad7 mutant mice display impaired cardiac function and significant arrhythmia.
• Elevated Smad2/3 phosphorylation and increased apoptosis were observed in the atrioventricular cushion of Smad7 mutant hearts.

Conclusions:

• Smad7 plays a critical role in embryonic cardiovascular development.
• Loss of Smad7 function leads to congenital heart defects and impaired cardiac function in vivo.
• These findings establish Smad7 as a key regulator of heart development and function.