Alternative Splicing of CIPK3 Results in Distinct Target Selection to Propagate ABA Signaling in Arabidopsis

Abstract

Calcium (Ca2+) signaling is pivotal in transmission of information in the cell. Various Ca2+ sensing molecules work to sense and relay the encrypted messages to the intended targets in the cell to maintain this signal transduction. CBL-interacting protein kinases (CIPKs) are crucial components of Ca2+ signal transduction during various abiotic stresses. Although there are intron rich CIPKs in the plant genome but very little has been reported about their alternative splicing. Moreover the physiological significance of this event in the Ca2+ signaling is still elusive. Therefore in this study, we have selected CIPK3, which has highest number of splice variants amongst Arabidopsis CIPKs. Expression profiling of five splice variants of CIPK3 by qRT-PCR in four Arabidopsis thaliana ecotypes revealed preferential transcript accumulation but similar subcellular localization of the variants and interaction with similar CBLs. ABA and drought treatment resulted in the higher accumulation of the alternately spliced transcripts of CIPK3 in Arabidopsis ecotype Wassilewkija. The transcripts of CIPK3.1 and CIPK3.4 are relatively more induced compared to other alternative splice variants. Out of four splice variants studied, we found CIPK3.1 and CIPK3.2 showing preference for ABR1, a previously reported interactor of CIPK3. We conclude that the differential expression and choice of downstream partner by CIPK3-splice variants might be one of the mechanisms of Ca2+ mediated preferential regulation of ABA and other stress signals.

The CBL–CIPK Pathway in Plant Response to Stress Signals

“…Based on its abundance of introns, AtCIPK3 was selected for examination of alternative splicing. Five splice variants of AtCIPK3 have shown different expression patterns and downstream proteins, which provides new insights into mechanisms related to Ca 2+ [68].…”

“…Moreover, the intron-rich members undergo alternative splicing, which can generate a diversity of transcripts and proteins owing to the occurrence of premature stop codons [67]. In Arabidopsis, the splice variants of AtCIPK3 exhibit different expression patterns and downstream partners, which may influence the regulation of Ca 2+ and ABA signaling [68]. Alternative splicing is a crucial mechanism affecting the CBL-CIPK network.…”

Plant Calcium Signaling in Response to Potassium Deficiency

“…Within the otherwise divergent C-terminal regulatory domain, CIPKs have a conserved domain, a NAF motif, and a 24-aminoacid domain with the conserved amino acids N, A, and F that are required for the CBL-CIPK interactions; the NAF motif is also referred to as a FISL motif because of the complete conservation of the six amino acid residues A, F, I, S, L, and F. The NAF/FISL motif of CIPKs is sufficient for mediating protein interactions with all CBL proteins [ 128 , 129 , 136 , 137 ]. The NAF/FISL motif is also necessary and sufficient for keeping CIPKs inactive, and serves as an autoinhibitory domain; removal of the NAF/FISL domain can increase the activity of CIPKs [ 129 , 132 ].…”

Two splice variants of the DsMEK1 mitogen-activated protein kinase kinase (MAPKK) is involved different way in salt stress regulation in Dunaliella salina

“…In an increasing number of species, alternative splicing is an important regulation mode under different stress conditions, allowing organisms to reprogram their regulatory networks [39,40]. MAPK cascade pathway plays a pivotal role in plant development or stress response.…”

“…Alternative splicing could provide selective advantage for choosing upstream and downstream regulators [32,39]. So we investigated the effect of AS on the regulation of the variants by performing Y2H assay.…”