Peroxisomes contribute to intracellular calcium dynamics

Peroxisomes communicate with other cellular compartments by transfer of various metabolites. However, whether peroxisomes are sites for calcium handling and exchange has remained contentious. Here we generated sensors for assessment of peroxisomal calcium and applied them for single cell-based calcium imaging in HeLa cells and cardiomyocytes. We found that peroxisomes in HeLa cells take up calcium upon depletion of intracellular calcium stores and upon calcium influx across the plasma membrane. Further, we show that peroxisomes of neonatal rat cardiomyocytes and human induced pluripotent stem cell-derived cardiomyocytes can take up calcium in a controlled manner. Our results indicate that peroxisomal and cytosolic calcium signals are tightly interconnected. Hence, peroxisomes may play an important role in shaping cellular calcium dynamics by serving as buffers or sources of intracellular calcium.