High impact information on RCN1

• Plants containing mutations in either gene show enhanced ethylene response by stabilizing EIN3, whereas efb1 efb2 double mutants show constitutive ethylene phenotypes [1].
• The RCN1 gene rescues the rcn1 mutant phenotype and also complements the temperature-sensitive phenotype of the Saccharomyces cerevisiae PP2A-A mutation, tpd3-1 [2].
• Analysis of the RCN1 cDNA reveals that the T-DNA insertion disrupts a gene for the regulatory A subunit of protein phosphatase 2A (PP2A-A) [2].
• Mutation of PLS results in an enhanced ethylene-response phenotype, defective auxin transport and homeostasis, and altered microtubule sensitivity to inhibitors [3].
• A guard cell-expressed PP2A gene, RCN1, which had been characterized previously as a molecular component affecting auxin transport and gravity response, was isolated [4].

Biological context of RCN1

• Calcium imaging analyses show a reduced sensitivity of ABA-induced cytosolic calcium increases in rcn1, whereas mechanisms downstream of cytosolic calcium increases show wild-type responses, suggesting that RCN1 functions in ABA signal transduction upstream of cytosolic Ca(2+) increases [4].
• Instead, we found that Arabidopsis PP2A-1C, a PP2A catalytic subunit previously characterized as interacting with RCN1, associates strongly with the kinase domain of CTR1 in vitro [5].
• RCN1-regulated phosphatase activity and EIN2 modulate hypocotyl gravitropism by a mechanism that does not require ethylene signaling [6].
• Furthermore, rcn1 shows ABA insensitivity in ABA inhibition of seed germination and ABA-induced gene expression [4].

Associations of RCN1 with chemical compounds

• A T-DNA disruption mutation in RCN1 confers recessive ABA insensitivity to Arabidopsis [4].
• Disruption of a guard cell-expressed protein phosphatase 2A regulatory subunit, RCN1, confers abscisic acid insensitivity in Arabidopsis [4].
• Our analysis shows that neither RCN1 expression nor PP2A activity is regulated by ethylene [5].
• Using mass spectrometric analysis, several of these proteins, including Hsp90, 14-3-3 proteins, an SnRK2 serine/threonine protein kinase and the PP2A regulatory subunit RCN1 could be identified [7].
• An NPA treatment that reduced basipetal transport in rcn1 and cantharidin-treated wild-type plants also restored a normal gravity response and asymmetric auxin-induced gene expression, indicating that increased basipetal auxin transport impedes gravitropism [8].

Other interactions of RCN1

• We therefore conclude that the RCN1 protein affects overall hypocotyl elongation via negative regulation of ethylene synthesis in etiolated seedlings, and that RCN1 and EIN2 modulate hypocotyl gravitropism and ethylene responses through independent pathways [6].
• Constitutive overexpression of RCN1 or RCN2 in Arabidopsis caused a late-flowering and highly branching phenotype, indicating that they possess conserved biochemical functions as TFL1 [9].
• This work demonstrates that mutational loss of the ethylene receptor ETR1 alters responsiveness to ethylene in Arabidopsis and that enhanced ethylene response in Arabidopsis not only results in increased sensitivity but exaggeration of response [10].

Analytical, diagnostic and therapeutic context of RCN1

• These data show that RCN1 functions as a general positive transducer of early ABA signaling [4].
• Molecular cloning of eer1 reveals that its mutant phenotype results from a loss-of-function mutation in the previously characterized RCN1, one of three PP2A A regulatory subunits in Arabidopsis [5].

References