Translational regulation of Arabidopsis XIPOTL1 is modulated by phosphocholine levels via the phylogenetically conserved upstream open reading frame 30

Abstract

In mammals, cadmium is widely considered as a non-genotoxic carcinogen acting through a methylation-dependent epigenetic mechanism. Here, the effects of Cd treatment on the DNA methylation patten are examined together with its effect on chromatin reconfiguration in Posidonia oceanica. DNA methylation level and pattern were analysed in actively growing organs, under short-(6 h) and long-(2 d or 4 d) term and low (10 mM) and high (50 mM) doses of Cd, through a Methylation-Sensitive Amplification Polymorphism technique and an immunocytological approach, respectively. The expression of one member of the CHROMOMETHYLASE (CMT) family, a DNA methyltransferase, was also assessed by qRT-PCR. Nuclear chromatin ultrastructure was investigated by transmission electron microscopy. Cd treatment induced a DNA hypermethylation, as well as an up-regulation of CMT, indicating that de novo methylation did indeed occur. Moreover, a high dose of Cd led to a progressive heterochromatinization of interphase nuclei and apoptotic figures were also observed after long-term treatment. The data demonstrate that Cd perturbs the DNA methylation status through the involvement of a specific methyltransferase. Such changes are linked to nuclear chromatin reconfiguration likely to establish a new balance of expressed/repressed chromatin. Overall, the data show an epigenetic basis to the mechanism underlying Cd toxicity in plants.

CHOLINE TRANSPORTER-LIKE1 is required for sieve plate development to mediate long-distance cell-to-cell communication

“…2d), indicating that CHER1 may be involved in the regulation and/or maintenance of choline metabolite levels in plants. Furthermore, we analysed the expression of pAPL::GFPer and the distribution of the freely moving GFP driven by the phloem CC-specific pSUC2 promoter during phloem development in the biosynthetic xipotl mutant, which also shows reduced levels of choline and phosphocholine 16,37 . Similar to cher1-1, we observed a reduced movement and unloading defects of pSUC2::GFP ( Supplementary Fig.…”

PHOSPHATIDIC ACID PHOSPHOHYDROLASE Regulates Phosphatidylcholine Biosynthesis in Arabidopsis by Phosphatidic Acid-Mediated Activation of CTP:PHOSPHOCHOLINE CYTIDYLYLTRANSFERASE Activity

“…A comparison of GUS activity between genotypes harboring each of the two ProPEAMT1:GUS constructs also suggests that uORF-dependent repression of PEAMT1 translation occurs in both pah1 pah2 roots and leaves (Figure 6). On the basis of these data, the stimulation of PC production observed in root tissues of pah1 pah2 cannot be explained by changes in PEAMT1 gene expression but could rely on derepression of translation in response to increased utilization of P-Cho (Tabuchi et al, 2006;Eastmond et al, 2010;Alatorre-Cobos et al, 2012). The total fatty acid content (A) and PC content (B) was measured in roots of 4-week-old plants.…”

“…PEAMT1 catalyzes the first committed step in choline biosynthesis in plants and is subject to transcriptional, translational, and biochemical regulation (Tabuchi et al, 2006;BeGora et al, 2010;Eastmond et al, 2010;Alatorre-Cobos et al, 2012). Of particular interest is the 59 untranslated region (59UTR) of PEAMT1, which contains an upstream open reading frame (uORF).…”

“…Bar = 10 mm. transcript abundance (Tabuchi et al, 2006;Alatorre-Cobos et al, 2012). We previously investigated PEAMT1 regulation in leaves using transient expression from two ProPEAMT1:bglucuronidase (GUS) constructs: one containing an intact 59UTR and the other a 59UTR carrying a mutation in the initiation codon of the uORF that prevents repression of GUS translation by P-Cho.…”

Translational Landscape of Photomorphogenic Arabidopsis

“…In a few Arabidopsis genes studied, uORFs could trigger a translational repression of their downstream mORFs in response to various environmental stimuli (Hanfrey et al, 2002;Wiese et al, 2004;Nishimura et al, 2005;Imai et al, 2006;Alatorre-Cobos et al, 2012;Rosado et al, 2012). We wondered whether this function was widespread in Arabidopsis.…”