Nuclear Condensates of WW Domain-Containing Adaptor With Coiled-Coil Regulate Mitophagy via Alternative Splicing

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Biomolecular condensates organize nuclear functions.
• The WW domain containing adaptor with coiled-coil (WAC) protein's role in nuclear organization is explored.
• Alternative splicing is a key regulatory mechanism in gene expression.

Purpose of the Study:

• To investigate the role of WAC in nuclear speckle organization and alternative splicing.
• To elucidate the mechanism by which WAC regulates splicing through biomolecular condensate formation.
• To understand the link between WAC-mediated splicing and mitochondrial function.

Main Methods:

• Immunolocalization of WAC to nuclear speckles via its WW domain.
• Analysis of WAC's C-terminal coiled-coil (CC) domain in condensate formation.
• Knockdown of RBM12 and WAC CC domain deletion to assess splicing outcomes.
• Quantification of BECN1-S splice variant levels.

Main Results:

• WAC localizes to nuclear speckles through its WW domain and forms condensates via its CC domain.
• WAC scaffolds RNA-binding motif 12 (RBM12) into nuclear speckles, potentially interacting with U5 snRNP.
• RBM12 knockdown or WAC CC domain deletion alters splicing, increasing BECN1-S levels.
• Elevated BECN1-S upregulates mitophagy.

Conclusions:

• WAC regulates alternative splicing through liquid-liquid phase separation (LLPS) in nuclear speckles.
• This WAC-driven mechanism links nuclear processes to mitochondrial function.
• Findings provide insights into the pathogenesis of WAC-related disorders.