The ubiquitin ligase Nedd4-1 is required for heart development and is a suppressor of thrombospondin-1

Area of Science:

• Molecular Biology
• Developmental Biology
• Biochemistry

Background:

• Nedd4 (Nedd4-1) is a Hect domain E3 ubiquitin ligase with known in vitro functions but poorly understood in vivo roles.
• Understanding the in vivo biological function of Nedd4-1 is crucial for elucidating its role in development.

Purpose of the Study:

• To investigate the in vivo function of Nedd4-1 using a mouse knockout model.
• To identify Nedd4-1 targets and understand the molecular mechanisms underlying developmental defects.

Main Methods:

• Generation of Nedd4-1 knockout mice.
• Analysis of embryonic lethality, heart, and vasculature development.
• Quantitative mass spectrometry and immunoblotting to identify Nedd4-1 targets.
• Assessment of thrombospondin-1 (Tsp-1) levels and transcription.
• In vivo rescue experiments using aspirin.

Main Results:

• Nedd4-1 knockout mice exhibited embryonic lethality at mid-gestation with severe heart and vasculature abnormalities.
• Thrombospondin-1 (Tsp-1), an angiogenesis inhibitor, was significantly upregulated in Nedd4-1 deficient cells and embryos.
• Elevated Tsp-1 levels were primarily due to enhanced transcription.
• Aspirin administration, an inhibitor of Tsp-1, partially rescued the embryonic lethality.

Conclusions:

• Nedd4-1 acts as a suppressor of Tsp-1.
• Upregulation of Tsp-1 contributes to the developmental defects observed in Nedd4-1 knockout embryos.
• Nedd4-1 plays a critical role in embryonic development, particularly in cardiovascular and vascular formation.