Centralspindlin proteins Pavarotti and Tumbleweed along with WASH regulate nuclear envelope budding

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Nuclear envelope (NE) budding is a nuclear pore-independent export pathway crucial for protein quality control, synapse development, and mitochondrial integrity.
• The formation of NE buds relies on the Wiskott-Aldrich Syndrome protein (Wash), its regulatory complex (SHRC), and Arp2/3, specifically Wash's actin nucleation activity.
• The molecular machinery responsible for cargo recruitment and organization within NE buds is currently unknown.

Purpose of the Study:

• To identify novel molecular components involved in nuclear envelope budding.
• To elucidate the roles of these new components in the physical formation and cargo organization of NE buds.
• To understand the mechanisms governing this alternative nuclear export pathway.

Main Methods:

• Co-immunoprecipitation assays to identify protein interactions.
• Genetic analysis to assess the function of identified proteins in NE budding.
• Actin binding and bundling assays to characterize protein activities.

Main Results:

• Pavarotti (Pav) and Tumbleweed (Tum) were identified as new molecular components of NE budding.
• Pav and Tum directly interact with Wash, forming a second nuclear Wash-containing complex essential for NE budding.
• The actin-bundling activity of Pav is critical, suggesting a structural role in NE bud organization.

Conclusions:

• Pavarotti and Tumbleweed are key players in nuclear envelope budding, expanding our understanding of this export pathway.
• These findings provide new insights into the physical machinery and cargo organization mechanisms of NE budding.
• The study highlights Pav and Tum as important entry points for studying large cargo export during cellular differentiation and development.