Annexin 1 Is a Component of eATP-Induced Cytosolic Calcium Elevation in Arabidopsis thaliana Roots

Abstract

Extracellular ATP (eATP) has long been established in animals as an important signalling molecule but this is less understood in plants. The identification of Arabidopsis thaliana DORN1 (Does Not Respond to Nucleotides) as the first plant eATP receptor has shown that it is fundamental to the elevation of cytosolic free Ca2+ ([Ca2+]cyt) as a possible second messenger. eATP causes other downstream responses such as increase in reactive oxygen species (ROS) and nitric oxide, plus changes in gene expression. The plasma membrane Ca2+ influx channels involved in eATP-induced [Ca2+]cyt increase remain unknown at the genetic level. Arabidopsis thaliana Annexin 1 has been found to mediate ROS-activated Ca2+ influx in root epidermis, consistent with its operating as a transport pathway. In this study, the loss of function Annexin 1 mutant was found to have impaired [Ca2+]cyt elevation in roots in response to eATP or eADP. Additionally, this annexin was implicated in modulating eATP-induced intracellular ROS accumulation in roots as well as expression of eATP-responsive genes.

AtCRY2 Negatively Regulates the Functions of AtANN2 and AtANN3 in Drought Tolerance by Affecting Their Subcellular Localization and Transmembrane Ca2+ Flow

“…As AtANN1 mediates Ca 2+ transport across the plasma membrane ( Mohammad-Sidik et al, 2021 ), we examined the transmembrane Ca 2+ flow in AtANN2 - and AtANN3- related mutants and transgenic plants using an NMT system ( Figure 5A ). The main root meristematic zone (within approximately 80 μm from the root tip) of Arabidopsis seedlings was used as the test area ( Figure 5B ).…”

“…In response to mannitol treatment, the AtANN2 and AtANN3 proteins could be targeted to the plasma membrane, and the altered subcellular localization was closely related to their protein functions. Certain annexins localized in the plasma membrane are currently known to be closely related to transmembrane ion transport, such as AtANN1, which constructs the root epidermal cell plasma membrane Ca 2+ channel (Laohavisit et al, 2012;Richards et al, 2014;Zhao et al, 2019;Mohammad-Sidik et al, 2021). On the other hand, the ability of annexins to regulate ion transport may be related to their regulated resistance responses, for example, AtANN1 acted as a root plasma membrane calcium channel during salt, hyperosmotic, oxidative, and cold stress exposure by regulating the Ca 2+ concentration in response to external changes (Laohavisit et al, 2012(Laohavisit et al, , 2013Richards et al, 2014;Liu et al, 2021).…”

“…Recent studies investigating the Arabidopsis annexin family focused on the most abundantly expressed annexin, i.e., AtANN1. AtANN1 constructs plasma membrane Ca 2+ channels and is involved in salt and drought stress processes (Laohavisit et al, 2012;Richards et al, 2014;Zhao et al, 2019;Mohammad-Sidik et al, 2021). Whether AtANN1-regulated stress responses are related to ion transport requires further investigation.…”

Damage Signaling by Extracellular Nucleotides: A Role for Cyclic Nucleotides in Elevating Cytosolic Free Calcium?

“…To date, the plasma membrane NADPH oxidase RBOHC (respiratory burst oxidase homologue C; Demidchik et al, 2009 ) and the heterotrimeric G protein alpha subunit (GPA1; Zhu et al, 2017 ) are implicated in regulating Arabidopsis root eATP-activated channels. Annexin1 (which supports a hydroxyl radical-activated Ca 2+ channel activity; Laohavisit et al, 2012 ) is implicated in eATP-induced [Ca 2+ ] cyt increase of Arabidopsis roots and transcriptional regulation of wound- and defense-response genes, but its mode of action has not been determined ( Mohammad-Sidik et al, 2021 ). It also underpins wounding- and herbivory-induced [Ca 2+ ] cyt increases ( Malabarba et al, 2021 ).…”

Cell Signaling in Model Plants 2.0

“…According to the results, the authors confirmed that GCaMP3 cell lines could be a reliable system for studying the connections between an environmental stimulus and root development that communicate through calcium signaling. Mohammad-Sidik et al studied the response and underlying mechanisms of [Ca 2+ ] cyt that are elevated by extracellular ATP (eATP) and ADP (eADP) in the root of A. thaliana [ 3 ]. The authors identified AtANN1 (annexin 1) that mediates the increase of [Ca 2+ ] cyt in root cells in response to both eATP and eADP, which might be a reactive oxygen species (ROS)-activated Ca 2+ channel in the plasma membrane.…”