NoxO1 promotes endosome formation and reduces intracellular vesicle processing

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• NADPH oxidase organizer 1 (NoxO1) is a cytoplasmic subunit of the ROS-forming Nox1 complex.
• NoxO1 interacts with Erbin, a scaffold protein associated with EGFR, but its ROS-independent functions are unclear.

Purpose of the Study:

• To investigate the ROS-independent roles of NoxO1 in cellular trafficking and lysosomal function.
• To elucidate the mechanism by which NoxO1 influences endolysosomal system dynamics and EGFR trafficking.

Main Methods:

• Utilized an ordinary differential equation model to predict EGFR trafficking dynamics.
• Employed fluorescent cargo (EGF, BSA) to track endocytosis and lysosomal retention.
• Investigated the activation of transcription factor EB (TFEB) and protein complex formation using proximity ligation assays.
• Performed genetic ablation of Erbin to assess its role in NoxO1-mediated effects.

Main Results:

• NoxO1 overexpression expanded early endosomes and lysosomes, slowing EGFR trafficking.
• NoxO1 increased cargo internalization by 14% and reduced degradative sorting by 48%.
• NoxO1 activated TFEB in an Erbin-dependent, ROS-independent manner, promoting lysosome formation and prolonging lysosomal cargo retention.

Conclusions:

• NoxO1, through its interaction with Erbin, activates TFEB, contributing to lysosome biogenesis.
• NoxO1 delays cargo degradation by enhancing lysosomal retention, impacting cellular trafficking pathways.
• Erbin is essential for NoxO1-induced alterations in endolysosomal markers and TFEB activation.