Dynamic Expression of PMCA1 and PMCA3 on Hair Cells in Developing Cochlea in Rats

CHEN Qingguo; CHU Hanqi; CHEN Jin; LIU Yun; DU Zhihui; ZHOU Liangqiang

doi:10.3969/j.issn.1672-2922.2025.02.015

Abstract：Objective To report dynamic expression of plasma membrane calcium pumps 1 and 3(PMCA1 and PMCA3)on hair cells in developing cochleae in rats.Methods Rat cochleae were collected on Days 2,6,13 and 21 after birth.After fixation,the basilar membrane was isolated and prepared.Expression sites and levels of PMCA1 and PMCA3 on outer(OHCs)and inner hair cells(IHCs)in all turns were detected by quantitative immunofluorescence labeling,and photographed with confocal microscopy.The Adobe Photoshop software was used to measure fluorescence intensities and age-related expression curves were plotted.Results No PMCA1 expression was found on OHC or IHC hair bundles.At early postnatal days,PMCA1 expression on OHC and IHC basolateral membrane gradually increased,followed by a gradual decrease on OHC basolateral membrane after day 6 of birth and remained at a weak level until adulthood.PMCA1 expression on IHC basolateral membrane peaked at day 13 and remained at this level into adulthood.While PMCA3 was not expressed on OHC and IHC hair bundles,it was strongly expressed on the basolateral membrane during the first 6 days of life.After P13,PMCA3 expression on OHC basolateral membrane had almost disappeared,while its expression on IHC basolateral membrane and pericuticular necklace remained into adulthood,albeit at a decreased level.PMCA1 and PMCA3 expression on OHC and IHC basolateral membranes were at the highest levels in the basal turn,followed by the middle and apical turn before day 6 after birth,although this difference disappeared after P13.Conclusion PMCA1 and PMCA3 expression demonstrate a dynamic pattern during postnatal development on different parts of cochlear hair cells.PMCA1 and PMCA3 are not expressed on OHC and IHC hair bundles,and only transiently expressed on OHC basolateral membrane in early postnatal days,but continuously expressed in IHC basolateral membrane throughout the whole period.Considering that hair cells rely mainly on PMCA to regulate intracellular Ca2+levels,it is speculated that the differential expression of PMCA1 and PMCA3 in HCs is related to the special function of PMCA pumps in different regions in HCs.