Audra M. Rogers, Martin J. Egan et al. @UArkansas demonstrate that heat stress triggers nucleolar remodeling in filamentous fungi, enabling segregation of damaged material and selective inheritance of a new nucleolar compartment. This reveals a chaperone-mediated quality control mechanism that preserves nuclear function in highly polarized, multinucleate cells.
Model for nucleolar remodeling, partitioning, and quality control following heat shock. Schematic illustration of nucleolar remodeling in M. oryzae during recovery from heat stress. Heat shock damages the existing nucleolus. (2–3) A new nucleolar bud emerges from the old (preexisting) nucleolus and expands through de novo synthesis. Partial nuclear envelope breakdown permits entry of the molecular chaperones such as Hsp104 and Hsp70. The old nucleolar compartment accumulates SUMO-modified material and selectively recruits Hsp70 and Hsp104, mediating the partitioning of old and new nucleolar material. The newly formed nucleolus disassembles at mitotic onset and is preferentially inherited by daughter nuclei, while the old nucleolus is extruded and diminishes.
Figure 5.









