Stress granule sequestration of OXPHOS gene transcripts exacerbates glycolytic restriction

Abstract

Stress granules (SGs) are dynamic organelles formed under cellular stress and they are generally regarded as protective entities. Meanwhile, their role in pathogenesis is becoming increasingly recognized, but the underlying mechanisms remain elusive due to the diverse nature of both stress types and biological contexts. Here we investigate SG dynamics and temporal changes in bulk and SG-associated transcriptomes under different regimens that inhibit glycolysis. We subject cells to either single assaults of glucose depletion (GD) or 2-deoxy-D-glucose addition (2DG) or a combined treatment (GD+2DG). We find that SGs formed under these conditions exhibit distinct properties, including eIF2 phosphorylation dependency, mRNA composition, and capacity to disassembly. Our results show that SGs induced by GD+2DG uniquely trap oxidative phosphorylation (OXPHOS) gene transcripts, leading to mitochondrial dysfunction. We provide evidence suggesting that the persistency of SGs formed under GD+2DG treatment is interwoven with mitochondrial dysfunction resulting in heightened apoptosis, effects that can also be recreated under single assaults when combined with mitochondrial inhibition. Our findings suggest that SG formation induced by inhibiting a single metabolic pathway can widen its impact in intensifying cellular metabolic stress under specific conditions, providing mechanistic insights into the paradoxical dual nature of SGs in stress response and pathology.