iPAR: a new reporter for eukaryotic cytoplasmic protein aggregation.

Background: Cells employ myriad regulatory mechanisms to maintain protein homeostasis, termed proteostasis, to ensure correct cellular function. Dysregulation of proteostasis, which is often induced by physiological stress and ageing, often results in protein aggregation in cells. These aggregated structures can perturb normal physiological function, compromising cell integrity and viability, a prime example being early onset of several neurodegenerative diseases. Understanding aggregate dynamics Methods: Here, we report an improved methodology for production of fluorescent aggregates in model budding yeast which can be detected, tracked and quantified using fluorescence microscopy in live cells. This new openly-available technology, iPAR (inducible Protein Aggregation Reporter), involves monomeric fluorescent protein reporters fused to a ∆ssCPY* aggregation biomarker, with expression controlled under the copper-regulated Results: Monomeric tags overcome challenges associated with non-physiological reporter aggregation, whilst Discussion: Time lapse imaging shows that although larger iPAR aggregates associate with nuclear and vacuolar compartments, we show directly, for the first time, that these proteotoxic accumulations are not inherited by daughter cells, unlike nuclei and vacuoles. If suitably adapted, iPAR offers new potential for studying diseases relating to protein oligomerization processes in other model cellular systems. Supplementary Information: The online version contains supplementary material available at 10.1186/s44330-025-00023-w.