Nuclear bodies: news insights into structure and function

- Cajal bodies have a definitive role in regulating the maturation of snRNPs.
- Numerous nuclear bodies contain scaffolding RNAs, including paraspeckles and Sam68 bodies, as well as other uncharacterized bodies.
- Nuclear bodies form through multivalent interactions that drive liquid liquid phase separation.
- Nuclear bodies have distinct molecular organization that can be distinguished with super-resolution microscopy.

The cell nucleus contains a number of different dynamic bodies that are variously composed of proteins and generally, but not always, specific RNA molecules. Recent studies have revealed new understanding about nuclear body formation and function in different aspects of nuclear metabolism. Here, we focus on findings describing the role of nuclear bodies in the biogenesis of specific ribonucleoprotein complexes, processing of key mRNAs, and subnuclear sequestration of protein factors. We highlight how nuclear bodies are involved in stress responses, innate immunity and tumorigenesis. We further review organization of nuclear bodies and principles that govern their assembly, highlighting the pivotal role of scaffolding noncoding RNAs, and liquid-liquid phase separation, which are transforming our picture of nuclear body formation.