A mutation in VAPB that causes amyotrophic lateral sclerosis also causes a nuclear envelope defect

Area of Science:

• Cell Biology
• Neuroscience
• Molecular Biology

Background:

• Vesicle-associated membrane protein-associated protein B and C (VAPB) mutations cause a dominant form of amyotrophic lateral sclerosis (ALS).
• Nuclear envelope integrity is crucial for cellular function and neuronal health.

Purpose of the Study:

• To investigate the cellular mechanisms underlying VAPB-linked ALS.
• To elucidate the role of VAPB in nuclear envelope protein transport.

Main Methods:

• Studied a proline to serine mutation (P56S) in VAPB.
• Analyzed the transport of nucleoporins (Nups) and emerin (EMD).
• Utilized overexpression of the FFAT motif and knockdown of endogenous VAPB.

Main Results:

• The P56S mutation in VAPB causes nuclear envelope defects.
• Transport of Nups and EMD to the nuclear envelope is blocked, leading to sequestration in the endoplasmic reticulum-Golgi intermediate compartment (ERGIC).
• Overexpression of the FFAT motif rescues the transport defect, while VAPB knockdown recapitulates the phenotype.

Conclusions:

• VAPB is essential for the retrograde transport of nuclear envelope proteins from the ERGIC.
• Defective VAPB transport function contributes to the pathogenesis of ALS.
• Targeting VAPB-mediated transport pathways may offer therapeutic strategies for ALS.