A Missense Variant Associated with Autosomal Dominant Midfrequency Hearing Loss Alters Subnuclear Localization and Transcriptional Capabilities.

BACKGROUND

The pathogenic variant, POU class 4 transcription factor 3 (), is reported to cause autosomal dominant nonsyndromic hearing loss (ADNSHL). Previously, we have examined a four-generation midfrequency sensorineural hearing loss (MFSNHL) family (no. 6126) and established c.602T>C (p.Leu201Pro) as a potential disease-causing variant.

OBJECTIVES

We explored the structural and functional alterations that the c.602T>C (p.Leu201Pro) variant enforces on the POU4F3 protein.

METHODS

We utilized wild-type (WT) and mutant (MUT) c.602T>C plasmid incorporation into HeLa cells to assess functional changes, by immunofluorescence and luciferase assays. To predict protein structural alterations in the MUT versus WT POU4F3, we also generated 3D structures to compare both types of POU4F3 proteins.

RESULTS

The WT POU4F3 is ubiquitously present in the nucleus, whereas the MUT form of POU4F3 exhibits a more restricted nuclear presence. This finding is different from other publications, which report a cytoplasmic localization of the MUT POU4F3. We also demonstrated that, as opposed to WT POU4F3, the MUT POU4F3 had 40% reduced luciferase activity.

CONCLUSIONS

The reduced nuclear presence, combined with reduced transcriptional activity, suggests that the c.602T>C variant alters cellular activity and may contribute to the pathogenicity of -related hearing loss. It, also, provides more evidence of the pathophysiological characteristics of MFSNHL.