During cell division, accurate segregation of genetic material into daughter cells is critical to maintain genome integrity. However, this process can be challenged by various cellular stresses, including ultraviolet (UV) irradiation, which can induce DNA damage and impair chromosome segregation. To cope with such stress conditions, cells have evolved protective mechanisms, such as the formation of stress granules. Stress granules are cytoplasmic foci that contain stalled translation complexes and various RNA-binding proteins, and they are thought to play a role in mRNA storage, RNA decay, and translational control under stress conditions.

Recent studies have shed light on the role of stress granules in protecting daughter cells from UV-induced RNA damage. Here's an overview of the mechanisms involved:

Sequestration of damaged RNA: Upon UV irradiation, cells experience the formation of RNA lesions, which can disrupt translation and compromise mRNA integrity. Stress granules act as storage compartments that sequester damaged RNA molecules, preventing their translation into potentially harmful proteins. By sequestering damaged RNA, stress granules help to maintain the quality of the cellular transcriptome and minimize the production of aberrant proteins that could interfere with cellular functions.

Recruitment of RNA repair factors: Stress granules serve as platforms for the recruitment of RNA repair factors, which are essential for repairing damaged RNA molecules. The sequestration of damaged RNA into stress granules facilitates their interaction with RNA repair machinery, promoting efficient repair processes. Various RNA repair factors, such as RNA helicases, RNA exonucleases, and RNA ligases, are known to localize to stress granules, where they can access and repair RNA lesions.

Translational repression: Stress granules also contribute to the repression of translation under stress conditions. This is achieved by sequestering translation initiation factors and ribosomal proteins into stress granules, thereby inhibiting the assembly of active translation complexes. By reducing global translation, cells can conserve energy and resources, while also preventing the synthesis of proteins that could exacerbate cellular damage. Moreover, the sequestration of translation factors into stress granules helps to prevent the translation of damaged RNA molecules, further minimizing the production of harmful proteins.

Interaction with mRNA decay pathways: Stress granules are interconnected with mRNA decay pathways, which are responsible for the degradation of damaged or unnecessary RNA molecules. Damaged RNA molecules sequestered into stress granules can be targeted for degradation through the exosome-mediated RNA decay pathway. The exosome is a multi-subunit complex that degrades RNA molecules and is often found in close association with stress granules. By facilitating the degradation of damaged RNA, stress granules contribute to the maintenance of cellular RNA homeostasis and prevent the accumulation of potentially harmful RNA species.

Overall, the formation of stress granules in response to UV irradiation serves as a protective mechanism to safeguard daughter cells from RNA damage. By sequestering damaged RNA, recruiting RNA repair factors, repressing translation, and interacting with mRNA decay pathways, stress granules help to maintain the integrity of the cellular transcriptome and prevent the propagation of RNA damage to daughter cells, ensuring their viability and proper development.