HERD-1 mediates multiphase condensate immiscibility to regulate small RNA-driven transgenerational epigenetic...

Area of Science:

• Cell Biology
• Developmental Biology
• Genetics

Background:

• Biomolecular condensates, like germ granules, are crucial cellular structures but their formation and function are not fully understood.
• Understanding the protein composition of these condensates is key to deciphering their roles in biological processes.

Purpose of the Study:

• To identify the protein constituents of P, Z, and M condensates within Caenorhabditis elegans germ granules.
• To investigate the functional significance of condensate organization in germline small RNA pathways and epigenetic inheritance.

Main Methods:

• Utilized optimized TurboID-mediated proximity biotin labeling to identify protein components of germ granules.
• Conducted a functional screen to identify proteins involved in regulating condensate interactions.
• Employed nanobody-mediated forced mixing experiments to assess condensate immiscibility effects.

Main Results:

• Identified 462, 41, and 86 proteins in P, Z, and M condensates, respectively, with 522 novel constituents.
• Discovered that HERD-1 protein prevents the mixing of P, Z, and M condensates.
• Observed that mixing of condensates disrupts germline small RNA pathways and prolongs RNA interference-induced gene silencing.

Conclusions:

• The distinct protein compositions suggest divergent functions and assembly mechanisms for P, Z, and M condensates.
• Active maintenance of germ granule immiscibility is critical for organizing and regulating small RNA-mediated transgenerational epigenetic inheritance.
• These findings provide insights into the molecular mechanisms governing germline development and inheritance.