Stress granule formation in HEI-OC1 auditory cells and the organ of Corti

Introduction Stress granules (SG) are membraneless cytoplasmic assemblies that form in cells in response to stress. SGs are composed by untranslated mRNA and RNA-binding proteins, and are thought to form as a self-protective mechanism. Evidence suggests that stress-related RNA metabolism plays an important role in neurodegenerative diseases, which underscores the relevance of studying this field while elucidating the mechanisms underlying ototoxicity and cochlear neurodegeneration.

Materials and methods Postnatal day 5 organs of Corti (OC) of wild-type C57BL6/J mice, House Ear Institute-organ of Corti 1 (HEI-OC1) auditory cells, and two cell lines from non-cochlear origin, Human embryonic kidney 293 (HEK293) and Human neuroglioma H4 (H4) cells, were used for experiments, in order to cover different sets of proteostasis components. OCs and cells were incubated with an established stress-inducing agent, sodium arsenite (SA). For comparison, gentamicin was used. We analyzed for stress granule formation (SGF) using immunocytochemistry, immunohistochemistry and western blot. Results SA induced SGF in the OC after 90 min incubation with SA 500μM. HEI-OC1, HEK293 and H4 cells SGF was able to be triggered after 30 min exposure to SA 500μM for 30 min. Gentamicin activated SGF in the OC and HEI-OC1 cells after a 24h exposision to gentamicin 500μM and 200μM, respectively. HEK293 and H4 cells incubated with gentamicin showed no SGF. Conclusion We characterized the activation of SGF in the OC and HEI-OC1 auditory cells using SA and gentamicin. Cell lines from non-cochlear origin showed SGF only while incubation with SA. Our study provides novel important insights into the molecular underpininngs of ototoxicity and a possilbe association with SG assembly in the inner ear.

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Publication History

Article published online:
13 May 2021