Intraflagellar Transport Inhomogeneity in Chlamydomonas IMP3 Mutant

Abstract

Genetic disorders that affect the development or function of flagella and their associated signalizing pathways are collectively known as ciliopathies. Intraflagellar transport (IFT) is the process that is responsible for the regulation of flagellar growth and signaling. In this study, we perform a single-molecule fluorescence imaging investigation of IFT in a Chlamydomonas mutant (IMP3) that exhibits unexplained phenotypes of slower flagellar regeneration and anterograde IFT speed. Using TIRF microscopy and two-color imaging, we show that the loading and unloading of flagellar membrane signaling proteins is compromised in the IMP3 mutant. We first use BBS4-GFP to quantify IFT speed changes in Chlamydomonas, we then use two-color imaging of IFT20-mCherry and PKD2-GFP to verify that these speed changes correspond to the loading and unloading of cargo membrane signaling proteins onto and from IFT trains, respectively. Preliminary results suggest that the IMP3 mutant is less efficient at the loading of transmembrane cargo proteins onto IFT trains, thus consequently generating a signaling defect.