Insights into the nucleolar dysfunction and associated genetic disorders

The nucleolus, a dynamic and membrane-less nuclear subcompartment, plays a central role in maintaining cellular homeostasis. Traditionally recognized as the site of ribosomal RNA (rRNA) synthesis and ribosome assembly, the nucleolus is now known to participate in diverse cellular processes, including cell-cycle regulation, DNA-damage response, and stress signaling. Structurally organized into three main components—the fibrillar center (FC), dense fibrillar component (DFC), and granular component (GC)—it undergoes rapid remodeling under physiological and pathological conditions. Dysfunction of the nucleolus has been increasingly linked to a group of genetic disorders collectively termed ribosomopathies, characterized by defective ribosome biogenesis and function. Mutations affecting nucleolar proteins or rRNA-processing factors can disrupt ribosomal output, activate the p53 pathway, and result in tissue-specific abnormalities, hematological disorders, and heightened cancer susceptibility. Notable ribosomopathies include Diamond–Blackfan anemia, Treacher Collins syndrome, and Dyskeratosis congenita. This review provides a comprehensive overview of the structural and functional aspects of the nucleolus, explores its role in genetic-disease mechanisms, and highlights current advances in understanding nucleolar stress and its downstream effects. We also discuss how emerging insights into nucleolar biology are revealing novel diagnostic and therapeutic strategies. Given the centrality of the nucleolus in cellular physiology, elucidating its dysfunction may significantly improve our understanding of a wide spectrum of human diseases.