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Light enhances the unfolded protein response as measured by BiP2 gene expression and the secretory GFP‐2SC marker in Arabidopsis
Author(s) -
Lu DongPing,
Christopher David A.
Publication year - 2008
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2008.01133.x
Subject(s) - unfolded protein response , tunicamycin , green fluorescent protein , protein disulfide isomerase , endoplasmic reticulum , arabidopsis thaliana , arabidopsis , microbiology and biotechnology , biology , chemistry , biochemistry , gene , mutant
Disruption of the protein‐folding capacity in the ER induces the accumulation of unfolded proteins and ER stress, which activate the unfolded protein response (UPR). Although UPR has been extensively studied in yeast and mammals, much less is known about UPR and its relationship with light in plants. Here, we examined the effects of chemically induced UPR and light on a molecular marker of UPR (binding protein, BiP2 , gene expression) and a secretory green fluorescent protein marker (GFP‐2SC) that is trafficked from the ER to vacuole in Arabidopsis thaliana (L). UPR, which was induced by DTT and tunicamycin (TM), increased Bip2 mRNA levels and decreased the levels of microsomal and vacuolar forms of GFP‐2SC. Treatment with protease inhibitors lessened the effects of DTT and TM on GFP‐2SC, indicating the decrease in GFP levels partially involved protein degradation. Light treatments synergistically enhanced the decrease in GFP levels in both the ER and vacuole and induced the expression of UPR marker genes for BiP2 and protein disulfide isomerase (PDI, EC 5.3.4.1). DTT and TM treatments required light for maximal induction of the UPR. Light‐induced UPR occurred during the daily dark to light cycle and when dark‐adapted plants were exposed to light. We propose that light activates the UPR to increase the protein folding capacity in the ER to accommodate an increase in translation during dark to light transitions.