Phosphoinositide effector proteins in the mouse organ of Corti

Phosphoinositides (PIs) are phospholipid components of all cell membranes that regulate several different key cellular functions like membrane trafficking, ion channel and transporter activity, cytoskeletal dynamics, and signal transduction. Even though these components are essential for hearing, to date the role of PIs in cells of the organ of Corti is currently understudied. The purpose of this study was to establish possible roles PIs play in cellular functions that underlie hearing. Therefore, we examined several known PI effector proteins: Tubby-like protein 3 (TULP3), a PI- dependent regulator of G-protein coupled receptors; tubby, a putative transcription factor affected by hydrolysis of the phosphoinositide PI(4,5)P₂, and SWAP70, a cytoskeletal regulator, dependent on the production of PI(3,4)P₂. Using immunohistochemistry on whole-mount preparations of the mouse organ of Corti, we were able to detect protein expression and cellular localization of these effectors. Here we report that TULP3 is mainly expressed in the apical parts of the inner and outer pillar cells, as well as in the phalangeal processes of the Deiters cells. Both structures are known to be filled with microtubules, which have also been shown to be regulated by PIs. We further detected TULP3 in the cell bodies of the inner and outer hair cells. While we did not find expression of SWAP70, however tubby immune-reactivity was localized to the distal segments of the stereocilia of outer hair cells, where previously prominent PI(4,5)P₂ labelling was described, and also in the nuclei of the Deiters cells. Together our observations show that these effectors distribute throughout the organ of Corti, suggesting that PIs are involved in controlling a variety of important functions in hearing.

Poster-PDF A-1173.pdf

Publication History

Article published online:
13 May 2021