Nucleolar RNA in action: Ultrastructure revealed during protein translation through a terpyridyl manganese(II) complex

Abstract

Nucleolar RNA stored within the interphase nucleus offers a targetable site for processing ribosomal RNAs that can significantly impact the synthesis of cytosolic protein. Nevertheless, information regarding nucleolus ultrastructure is still largely limited to observations from electron microscopy, while its interior information including the correlation between nucleolar RNA and ribosomes remains to be elucidated. In this work, we designed a highly charged terpyridyl manganese(II) complex which could rapidly penetrate into live cell nucleus and selectively ‘light up’ nucleolar RNA. Its superior optical properties allow the observation nucleolar ultrastructures under super-resolution nanoscopy including RNA rich dense fibrillar components and fibrillar centers. Moreover, this complex allowed us to explain the nucleolar RNA dynamics and its relationship with ribosomes under the translation of protein synthesis.