title: Different degree in proteasome malfunction has various effects on root growth possibly through preventing cell division and promoting autophagic vacuolization.
abstract: The ubiquitin/proteasome pathway plays a vital role in plant development. But the effects of proteasome malfunction on root growth, and the mechanism underlying this involvement remains unclear. In the present study, the effects of proteasome inhibitors on Arabidopsis root growth were studied through the analysis of the root length, and meristem size and cell length in maturation zone using FM4-64, and cell-division potential using GFP fusion cyclin B, and accumulation of ubiquitinated proteins using immunofluorescence labeling, and autophagy activity using LysoTracker and MDC. The results indicated that lower concentration of proteasome inhibitors promoted root growth, whereas higher concentration of inhibitors had the opposite effects. The accumulation of cyclin B was linked to MG132-induced decline in meristem size, indicating that proteasome malfunction prevented cell division. Besides, MG132-induced accumulation of the ubiquitinated proteins was associated with the increasing fluorescence signal of LysoTracker and MDC in the elongation zone, revealing a link between the activation of autophagy and proteasome malfunction. These results suggest that weak proteasome malfunction activates moderate autophagy and promotes cell elongation, which compensates the inhibitor-induced reduction of cell division, resulting in long roots. Whereas strong proteasome malfunction induces severe autophagy and disturbs cell elongation, resulting in short roots.
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing, China. xianyong.sheng@163.com
authors.forename: Xianyong
authors.initials: X
authors.lastname: Sheng
authors.forename: Qian
authors.initials: Q
authors.lastname: Wei
authors.forename: Liping
authors.initials: L
authors.lastname: Jiang
authors.forename: Xue
authors.initials: X
authors.lastname: Li
authors.forename: Yuan
authors.initials: Y
authors.lastname: Gao
authors.forename: Li
authors.initials: L
authors.lastname: Wang
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000254:growth & development* / Q000276:immunology; D001343:Autophagy; D002455:Cell Division; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics; D007150:Immunohistochemistry; D018517:Plant Roots / Q000201:enzymology / Q000254:growth & development*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D019926:Cyclin B; D049452:Green Fluorescent Proteins; D046988:Proteasome Endopeptidase Complex