Cell Reports (Aug 2023)

rRNA intermediates coordinate the formation of nucleolar vacuoles in C. elegans

  • Demin Xu,
  • Xiangyang Chen,
  • Yan Kuang,
  • Minjie Hong,
  • Ting Xu,
  • Ke Wang,
  • Xinya Huang,
  • Chuanhai Fu,
  • Ke Ruan,
  • Chengming Zhu,
  • Xuezhu Feng,
  • Shouhong Guang

Journal volume & issue
Vol. 42, no. 8
p. 112915

Abstract

Read online

Summary: The nucleolus is the most prominent membraneless organelle within the nucleus. How the nucleolar structure is regulated is poorly understood. Here, we identified two types of nucleoli in C. elegans. Type I nucleoli are spherical and do not have visible nucleolar vacuoles (NoVs), and rRNA transcription and processing factors are evenly distributed throughout the nucleolus. Type II nucleoli contain vacuoles, and rRNA transcription and processing factors exclusively accumulate in the periphery rim. The NoV contains nucleoplasmic proteins and is capable of exchanging contents with the nucleoplasm. The high-order structure of the nucleolus is dynamically regulated in C. elegans. Faithful rRNA processing is important to prohibit NoVs. The depletion of 27SA2 rRNA processing factors resulted in NoV formation. The inhibition of RNA polymerase I (RNAPI) transcription and depletion of two conserved nucleolar factors, nucleolin and fibrillarin, prohibits the formation of NoVs. This finding provides a mechanism to coordinate structure maintenance and gene expression.

Keywords