Cholesterol level regulates endosome motility via Rab proteins.
The role of cholesterol in the regulation of endosome motility was investigated by monitoring the intracellular trafficking of endocytosed folate receptors (FRs) labeled with fluorescent folate conjugates. Real-time fluorescence imaging of HeLa cells transfected with green fluorescent protein-tubulin revealed that FR-containing endosomes migrate along microtubules. Moreover, microinjection with antibodies that inhibit microtubule-associated motor proteins demonstrated that dynein and kinesin I participate in the delivery of FR-containing endosomes to the perinuclear area and plasma membrane, respectively. Further, single-particle tracking analysis revealed bidirectional motions of FR endosomes, mediated by dynein and kinesin motors associated with the same endosome. These experimental tools allowed us to use FR-containing endosomes to evaluate the impact of cholesterol on intracellular membrane trafficking. Lowering plasma membrane cholesterol by metabolic depletion or methyl-beta-cyclodextrin extraction was found to both increase FR-containing endosome motility and change endosome distribution from colocalization with Rab7 to colocalization with Rab4. These data provide evidence that cholesterol regulates intracellular membrane trafficking via modulation of the distribution of low molecular weight G-proteins that are adaptors for microtubule motors.
Chen
Hongtao
H
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
Yang
Jun
J
Low
Philip S
PS
Cheng
Ji-Xin
JX
D002784:Cholesterol / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D020409:Molecular Motor Proteins / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
D020409:Molecular Motor Proteins; D002784:Cholesterol; D020691:rab GTP-Binding Proteins