The subfamily II catalytic subunits of protein phosphatase 2A (PP2A) are involved in cortical microtubule organization

Joong Tak Yoon, Hee Kyung Ahn, Hyunsook Pai

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Main conclusion: The subfamily II catalytic subunits of protein phosphatase 2A (PP2A) regulate the cortical microtubule dynamics in Arabidopsis, through interaction with TONNEAU2 (TON2)/FASS and modulation of α-tubulin dephosphorylation. Protein phosphatase 2A is a major protein phosphatase in eukaryotes that dephosphorylates many different substrates to regulate their function. PP2A is assembled into a heterotrimeric complex of scaffolding A subunit, regulatory B subunit, and catalytic C subunit. Plant PP2A catalytic C subunit (PP2AC) isoforms are classified into two subfamilies. In this study, we investigated the cellular functions of the Arabidopsis PP2AC subfamily II genes PP2AC-3 and PP2AC-4, particularly regarding the cortical microtubule (MT) organization. PP2AC-3 and PP2AC-4 strongly interacted with the B′′ regulatory subunit TON2. Simultaneous silencing of PP2AC-3 and PP2AC-4 by virus-induced gene silencing (PP2AC-3,4 VIGS) significantly altered plant morphology in Arabidopsis, increasing cell numbers in leaves and stems. The leaf epidermis of PP2AC-3,4 VIGS plants largely lost its jigsaw-puzzle shape and exhibited reduced trichome branch numbers. VIGS of PP2AC-3,4 in Arabidopsis transgenic plants that expressed GFP-fused β-tubulin 6 isoform (GFP-TUB6) for the visualization of MTs caused a reduction in the cortical MT array density in the pavement cells. VIGS of TON2 also led to similar cellular phenotypes and cortical MT patterns compared with those after VIGS of PP2AC-3,4, suggesting that PP2AC-3,4 and their interaction partner TON2 play a role in cortical MT organization in leaf epidermal cells. Furthermore, silencing of PP2AC-3,4 did not affect salt-induced phosphorylation of α-tubulin but delayed its dephosphorylation after salt removal. The reappearance of cortical MT arrays after salt removal was impaired in PP2AC-3,4 VIGS plants. These results suggest an involvement of PP2AC subfamily II in the regulation of cortical MT dynamics under normal and salt-stress conditions in Arabidopsis.

Original languageEnglish
Pages (from-to)1551-1567
Number of pages17
JournalPlanta
Volume248
Issue number6
DOIs
Publication statusPublished - 2018 Dec 1

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Protein Phosphatase 2
phosphoprotein phosphatase
protein subunits
Microtubules
microtubules
Catalytic Domain
Arabidopsis
tubulin
Tubulin
Salts
dephosphorylation
salts
Plant Epidermis
Protein Isoforms
leaves
Trichomes
plant morphology
Plant Genes
Plant Proteins
gene silencing

All Science Journal Classification (ASJC) codes

  • Genetics
  • Plant Science

Cite this

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title = "The subfamily II catalytic subunits of protein phosphatase 2A (PP2A) are involved in cortical microtubule organization",
abstract = "Main conclusion: The subfamily II catalytic subunits of protein phosphatase 2A (PP2A) regulate the cortical microtubule dynamics in Arabidopsis, through interaction with TONNEAU2 (TON2)/FASS and modulation of α-tubulin dephosphorylation. Protein phosphatase 2A is a major protein phosphatase in eukaryotes that dephosphorylates many different substrates to regulate their function. PP2A is assembled into a heterotrimeric complex of scaffolding A subunit, regulatory B subunit, and catalytic C subunit. Plant PP2A catalytic C subunit (PP2AC) isoforms are classified into two subfamilies. In this study, we investigated the cellular functions of the Arabidopsis PP2AC subfamily II genes PP2AC-3 and PP2AC-4, particularly regarding the cortical microtubule (MT) organization. PP2AC-3 and PP2AC-4 strongly interacted with the B′′ regulatory subunit TON2. Simultaneous silencing of PP2AC-3 and PP2AC-4 by virus-induced gene silencing (PP2AC-3,4 VIGS) significantly altered plant morphology in Arabidopsis, increasing cell numbers in leaves and stems. The leaf epidermis of PP2AC-3,4 VIGS plants largely lost its jigsaw-puzzle shape and exhibited reduced trichome branch numbers. VIGS of PP2AC-3,4 in Arabidopsis transgenic plants that expressed GFP-fused β-tubulin 6 isoform (GFP-TUB6) for the visualization of MTs caused a reduction in the cortical MT array density in the pavement cells. VIGS of TON2 also led to similar cellular phenotypes and cortical MT patterns compared with those after VIGS of PP2AC-3,4, suggesting that PP2AC-3,4 and their interaction partner TON2 play a role in cortical MT organization in leaf epidermal cells. Furthermore, silencing of PP2AC-3,4 did not affect salt-induced phosphorylation of α-tubulin but delayed its dephosphorylation after salt removal. The reappearance of cortical MT arrays after salt removal was impaired in PP2AC-3,4 VIGS plants. These results suggest an involvement of PP2AC subfamily II in the regulation of cortical MT dynamics under normal and salt-stress conditions in Arabidopsis.",
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The subfamily II catalytic subunits of protein phosphatase 2A (PP2A) are involved in cortical microtubule organization. / Yoon, Joong Tak; Ahn, Hee Kyung; Pai, Hyunsook.

In: Planta, Vol. 248, No. 6, 01.12.2018, p. 1551-1567.

Research output: Contribution to journalArticle

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AB - Main conclusion: The subfamily II catalytic subunits of protein phosphatase 2A (PP2A) regulate the cortical microtubule dynamics in Arabidopsis, through interaction with TONNEAU2 (TON2)/FASS and modulation of α-tubulin dephosphorylation. Protein phosphatase 2A is a major protein phosphatase in eukaryotes that dephosphorylates many different substrates to regulate their function. PP2A is assembled into a heterotrimeric complex of scaffolding A subunit, regulatory B subunit, and catalytic C subunit. Plant PP2A catalytic C subunit (PP2AC) isoforms are classified into two subfamilies. In this study, we investigated the cellular functions of the Arabidopsis PP2AC subfamily II genes PP2AC-3 and PP2AC-4, particularly regarding the cortical microtubule (MT) organization. PP2AC-3 and PP2AC-4 strongly interacted with the B′′ regulatory subunit TON2. Simultaneous silencing of PP2AC-3 and PP2AC-4 by virus-induced gene silencing (PP2AC-3,4 VIGS) significantly altered plant morphology in Arabidopsis, increasing cell numbers in leaves and stems. The leaf epidermis of PP2AC-3,4 VIGS plants largely lost its jigsaw-puzzle shape and exhibited reduced trichome branch numbers. VIGS of PP2AC-3,4 in Arabidopsis transgenic plants that expressed GFP-fused β-tubulin 6 isoform (GFP-TUB6) for the visualization of MTs caused a reduction in the cortical MT array density in the pavement cells. VIGS of TON2 also led to similar cellular phenotypes and cortical MT patterns compared with those after VIGS of PP2AC-3,4, suggesting that PP2AC-3,4 and their interaction partner TON2 play a role in cortical MT organization in leaf epidermal cells. Furthermore, silencing of PP2AC-3,4 did not affect salt-induced phosphorylation of α-tubulin but delayed its dephosphorylation after salt removal. The reappearance of cortical MT arrays after salt removal was impaired in PP2AC-3,4 VIGS plants. These results suggest an involvement of PP2AC subfamily II in the regulation of cortical MT dynamics under normal and salt-stress conditions in Arabidopsis.

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