Copper-induced activation of TRPs and VDCCs triggers a calcium signature response regulating gene expression inEctocarpus siliculosus

Abstract

In certain multicellular photoautotrophs, such as plants and green macroalgae, it has been demonstrated that calcium signaling importantly mediates tolerance to copper excess. However, there is no information in brown macroalgae, which are phylogenetically distant from green algae and plants. We have previously shown that chronic copper levels (2.5 μM) activate transient receptor potential (TRP) channels in the model brown macroalga Ectocarpus siliculosus, allowing extracellular calcium entry at 13, 29, 39 and 51 min. Here, we showed that intracellular calcium increases also occurred at 3 and 5 h of exposure; these increases were inhibited by antagonists of voltage-dependent calcium channels (VDCCs); a chelating agent of extracellular calcium; an antagonist of endoplasmic reticulum (ER) ATPase; and antagonists of cADPR-, NAADP- and IP3-dependent calcium channels. Thus, copper activates VDCCs allowing extracellular calcium entry and intracellular calcium release from the ER via cADPR-, IP3- and NAADP-dependent channels. Furthermore, the level of transcripts encoding a phytochelatin synthase (PS) and a metallothionein (MT) were analyzed in the alga exposed to 2.5 μM copper from 3 to 24 h. The level of ps and mt transcripts increased until 24 h and these increases were inhibited by antagonists of calmodulins (CaMs), calcineurin B-like proteins (CBLs) and calcium-dependent protein kinases (CDPKs). Finally, activation of VDCC was inhibited by a mixture of TRP antagonists and by inhibitors of protein kinases. Thus, copper-mediated activation of TRPs triggers VDCCs via protein kinases, allowing extracellular calcium entry and intracellular calcium release from ER that, in turn, activate CaMs, CBLs and CDPKs increasing expression of PS and MT encoding genes in E. siliculosus.

The Hydrophobin HYTLO1 Secreted by the Biocontrol Fungus Trichoderma longibrachiatum Triggers a NAADP-Mediated Calcium Signalling Pathway in Lotus japonicus

“…Although NAADP has been shown to trigger Ca 2+ release also in higher plants [ 29 ], its involvement in plant physiological events had yet to emerge. By using Ned-19, a newly-developed chemical probe for NAADP [ 27 ], a NAADP-gated Ca 2+ release was shown to occur in response to copper excess in the marine alga Ulva compressa [ 30 ], as well as in the brown alga Ectocarpus siliculosus [ 31 ]. These data suggest that the spectrum of photosynthetic organisms responsive to NAADP might be broader than previously envisaged.…”

“…By using the model legume Lotus japonicus [ 25 , 26 ] stably expressing the genetically encoded Ca 2+ indicator aequorin, we demonstrated that HYTLO1 triggers in plant cells a signal transduction pathway leading to the activation of defence genes in a Ca 2+ -dependent manner. Experiments performed by using the chemical probe Ned-19 [ 27 ] showed that the Ca 2+ signalling pathway activated by HYTLO1 is mediated by nicotinic acid adenine dinucleotide phosphate (NAADP), a metabolite of nicotinamide adenine dinucleotide phosphate (NADP) which has been demonstrated to act as a potent Ca 2+ mobilizing messenger in a wide variety of eukaryotes (see [ 28 ] for a review), including plants [ 29 ], as well as green and brown macroalgae [ 30 , 31 ]. The obtained data provide the first evidence for the involvement of this pyridine nucleotide-based Ca 2+ agonist in a physiological event in higher plants and offer new insights into the mechanism of action of fungal hydrophobins.…”

The Genome of the Marine Alga Ulva compressa (Chlorophyta) Reveals Protein-Coding Genes with Similarity to Plants and Green Microalgae, but Also to Animal, Bacterial, and Fungal Genes

“…The genome of E. Siliculosus encodes 18 TRP channels [2], which are functional TRPs that allow extracellular calcium entry [42]. The genome of C. reinhardtii encodes 10 TRP channels and they are functional mosaic TRPs, as in U. compressa, since they are a combination of human TRPA, TRPC, TRPM, and TRPV [43].…”

RNA sequencing-based exploration of the effects of far-red light on lncRNAs involved in the shade-avoidance response ofD. officinale

“…Due to the rapid development of sequencing technology, low-abundance transcripts at the genome-wide transcription level have been detected. lncRNAs, which are noncoding RNAs longer than 200 nucleotides, have extremely complex and important biological functions; they not only regulate gene expression at the epigenetic, transcription, and posttranscriptional levels but also participate in the regulation of many various biological processes, such as genomic imprinting, chromosome remodelling, and transcriptional activation (Garima et al, 2017;Wang et al, 2017). Recent studies have shown that lncRNAs play an important role in the plant response to external factors.…”