Endocytic BDNF secretion regulated by Vamp3 in astrocytes

Area of Science:

• Neuroscience
• Cell Biology
• Molecular Biology

Background:

• Brain-derived neurotrophic factor (BDNF) is vital for brain functions, acting through TrkB receptors.
• Astrocytes internalize BDNF via receptor-mediated endocytosis, but the mechanism of its re-secretion is unknown.

Purpose of the Study:

• To investigate the molecular mechanism regulating the secretion of endocytosed BDNF from astrocytes.
• To identify proteins involved in astrocytic BDNF recycling.

Main Methods:

• Utilized quantum dot (QD)-conjugated mature BDNF (QD-BDNF) to track BDNF uptake, transport, and secretion in cultured cortical astrocytes.
• Monitored QD-BDNF particle localization in Vamp3-containing vesicles.
• Assessed the impact of ATP stimulation on QD-BDNF vesicle transport and exocytosis.
• Investigated the effect of Vamp3 downregulation on BDNF secretion, uptake, and transport.

Main Results:

• Endocytosed QD-BDNF accumulated in vesicles expressing Vamp3 within astrocytes.
• ATP stimulation induced anterograde and retrograde transport, leading to exocytosis of QD-BDNF vesicles.
• Reduced Vamp3 expression impaired endocytic BDNF secretion without affecting uptake or transport.
• Vamp3 plays a selective role in controlling the release of endocytosed BDNF.

Conclusions:

• Vesicle-associated membrane protein 3 (Vamp3) selectively regulates the secretion of endocytosed BDNF from astrocytes.
• This study elucidates a key mechanism in astrocytic BDNF recycling, essential for maintaining neuronal function.
• Vamp3 is identified as a critical regulator of BDNF exocytosis in astrocytes.