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Arabidopsis AtPLC2 Is a Primary Phosphoinositide-Specific Phospholipase C in Phosphoinositide Metabolism and the Endoplasmic Reticulum Stress Response.

Kanehara K, Yu CY, Cho Y, Cheong WF, Torta F, Shui G, Wenk MR, Nakamura Y - PLoS Genet. (2015)

Bottom Line: The seedlings of plc2-1 mutant showed growth defect that was complemented by heterologous expression of AtPLC2, suggesting that phosphoinositide-specific phospholipase C activity borne by AtPLC2 is required for seedling growth.Moreover, the plc2-1 mutant showed hypersensitive response to ER stress as evidenced by changes in relevant phenotypes and gene expression profiles.Our results revealed the primary enzyme in phosphoinositide metabolism, its involvement in seedling growth and an emerging link between phosphoinositide and the ER stress response.

View Article: PubMed Central - PubMed

Affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan; Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan; Graduate Institute of Biotechnology and Department of Life Sciences, National Chung-Hsing University, Taichung, Taiwan; Muroran Institute of Technology, Muroran, Japan.

ABSTRACT
Phosphoinositides represent important lipid signals in the plant development and stress response. However, multiple isoforms of the phosphoinositide biosynthetic genes hamper our understanding of the pivotal enzymes in each step of the pathway as well as their roles in plant growth and development. Here, we report that phosphoinositide-specific phospholipase C2 (AtPLC2) is the primary phospholipase in phosphoinositide metabolism and is involved in seedling growth and the endoplasmic reticulum (ER) stress responses in Arabidopsis thaliana. Lipidomic profiling of multiple plc mutants showed that the plc2-1 mutant increased levels of its substrates phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate, suggesting that the major phosphoinositide metabolic pathway is impaired. AtPLC2 displayed a distinct tissue expression pattern and localized at the plasma membrane in different cell types, where phosphoinositide signaling occurs. The seedlings of plc2-1 mutant showed growth defect that was complemented by heterologous expression of AtPLC2, suggesting that phosphoinositide-specific phospholipase C activity borne by AtPLC2 is required for seedling growth. Moreover, the plc2-1 mutant showed hypersensitive response to ER stress as evidenced by changes in relevant phenotypes and gene expression profiles. Our results revealed the primary enzyme in phosphoinositide metabolism, its involvement in seedling growth and an emerging link between phosphoinositide and the ER stress response.

No MeSH data available.


Phosphoinositide-specific phospholipase C (PI-PLC) in phosphoinositide metabolism.(A) Proposed phosphoinositide metabolic pathways in Arabidopsis. PI, phosphatidylinositol; PI3K, PI 3-kinase; PI4K, PI 4-kinase; PIP5K, PI4P 5-kinase; Ptase, phosphoinositide phosphatase; DAG, sn-1,2-diacylglycerol; FAB, formation of aploid and binucleate cells; I(1,4,5)P3, inositol 1,4,5-trisphosphate. (B) Schematic representations of AtPLC1 (At5g58670), AtPLC2 (At3g08510), AtPLC3 (At4g38530), AtPLC4 (At5g58700) and AtPLC6 (At2g40116). Gray boxes and lines represent exons and introns, respectively. The positions of T-DNA insertions of plc1-1, plc2-1, plc3-1, plc4-1, and plc6-1 are indicated by triangles. (C) RT-PCR analysis of gene transcripts for AtPLC1 (1.7 kb), AtPLC2 (1.8 kb), AtPLC3 (1.7 kb), AtPLC4 (1.8 kb), and AtPLC6 (1.9 kb) in the wild-type plants and the mutants. The Ws plants were used as the wild type for AtPLC2. Actin (0.5 kb) was used as a control.
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pgen.1005511.g001: Phosphoinositide-specific phospholipase C (PI-PLC) in phosphoinositide metabolism.(A) Proposed phosphoinositide metabolic pathways in Arabidopsis. PI, phosphatidylinositol; PI3K, PI 3-kinase; PI4K, PI 4-kinase; PIP5K, PI4P 5-kinase; Ptase, phosphoinositide phosphatase; DAG, sn-1,2-diacylglycerol; FAB, formation of aploid and binucleate cells; I(1,4,5)P3, inositol 1,4,5-trisphosphate. (B) Schematic representations of AtPLC1 (At5g58670), AtPLC2 (At3g08510), AtPLC3 (At4g38530), AtPLC4 (At5g58700) and AtPLC6 (At2g40116). Gray boxes and lines represent exons and introns, respectively. The positions of T-DNA insertions of plc1-1, plc2-1, plc3-1, plc4-1, and plc6-1 are indicated by triangles. (C) RT-PCR analysis of gene transcripts for AtPLC1 (1.7 kb), AtPLC2 (1.8 kb), AtPLC3 (1.7 kb), AtPLC4 (1.8 kb), and AtPLC6 (1.9 kb) in the wild-type plants and the mutants. The Ws plants were used as the wild type for AtPLC2. Actin (0.5 kb) was used as a control.

Mentions: The phosphoinositides are phosphorylated derivatives of phosphatidylinositol, which represent a minor portion of phospholipids but a major role in lipid signaling from bacteria to seed plants or mammals [1]. The final step of phosphoinositide metabolism is the hydrolysis of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] into inositol 1,4,5-trisphosphate (IP3) and sn-1,2-diacylglycerol (DAG) that is catalyzed by phospholipase C (PLC) (Fig 1A). This reaction is a crucial step in achieving signal transduction: IP3 triggers Ca2+ influx and DAG kinase readily converts DAG to phosphatidic acid (PA), which serves as a lipid second messenger to fulfill distinct roles of signal transduction in plants [2]. Therefore, investigating function of PLC has utmost importance in understanding the entire phosphoinositide signaling.


Arabidopsis AtPLC2 Is a Primary Phosphoinositide-Specific Phospholipase C in Phosphoinositide Metabolism and the Endoplasmic Reticulum Stress Response.

Kanehara K, Yu CY, Cho Y, Cheong WF, Torta F, Shui G, Wenk MR, Nakamura Y - PLoS Genet. (2015)

Phosphoinositide-specific phospholipase C (PI-PLC) in phosphoinositide metabolism.(A) Proposed phosphoinositide metabolic pathways in Arabidopsis. PI, phosphatidylinositol; PI3K, PI 3-kinase; PI4K, PI 4-kinase; PIP5K, PI4P 5-kinase; Ptase, phosphoinositide phosphatase; DAG, sn-1,2-diacylglycerol; FAB, formation of aploid and binucleate cells; I(1,4,5)P3, inositol 1,4,5-trisphosphate. (B) Schematic representations of AtPLC1 (At5g58670), AtPLC2 (At3g08510), AtPLC3 (At4g38530), AtPLC4 (At5g58700) and AtPLC6 (At2g40116). Gray boxes and lines represent exons and introns, respectively. The positions of T-DNA insertions of plc1-1, plc2-1, plc3-1, plc4-1, and plc6-1 are indicated by triangles. (C) RT-PCR analysis of gene transcripts for AtPLC1 (1.7 kb), AtPLC2 (1.8 kb), AtPLC3 (1.7 kb), AtPLC4 (1.8 kb), and AtPLC6 (1.9 kb) in the wild-type plants and the mutants. The Ws plants were used as the wild type for AtPLC2. Actin (0.5 kb) was used as a control.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4581737&req=5

pgen.1005511.g001: Phosphoinositide-specific phospholipase C (PI-PLC) in phosphoinositide metabolism.(A) Proposed phosphoinositide metabolic pathways in Arabidopsis. PI, phosphatidylinositol; PI3K, PI 3-kinase; PI4K, PI 4-kinase; PIP5K, PI4P 5-kinase; Ptase, phosphoinositide phosphatase; DAG, sn-1,2-diacylglycerol; FAB, formation of aploid and binucleate cells; I(1,4,5)P3, inositol 1,4,5-trisphosphate. (B) Schematic representations of AtPLC1 (At5g58670), AtPLC2 (At3g08510), AtPLC3 (At4g38530), AtPLC4 (At5g58700) and AtPLC6 (At2g40116). Gray boxes and lines represent exons and introns, respectively. The positions of T-DNA insertions of plc1-1, plc2-1, plc3-1, plc4-1, and plc6-1 are indicated by triangles. (C) RT-PCR analysis of gene transcripts for AtPLC1 (1.7 kb), AtPLC2 (1.8 kb), AtPLC3 (1.7 kb), AtPLC4 (1.8 kb), and AtPLC6 (1.9 kb) in the wild-type plants and the mutants. The Ws plants were used as the wild type for AtPLC2. Actin (0.5 kb) was used as a control.
Mentions: The phosphoinositides are phosphorylated derivatives of phosphatidylinositol, which represent a minor portion of phospholipids but a major role in lipid signaling from bacteria to seed plants or mammals [1]. The final step of phosphoinositide metabolism is the hydrolysis of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] into inositol 1,4,5-trisphosphate (IP3) and sn-1,2-diacylglycerol (DAG) that is catalyzed by phospholipase C (PLC) (Fig 1A). This reaction is a crucial step in achieving signal transduction: IP3 triggers Ca2+ influx and DAG kinase readily converts DAG to phosphatidic acid (PA), which serves as a lipid second messenger to fulfill distinct roles of signal transduction in plants [2]. Therefore, investigating function of PLC has utmost importance in understanding the entire phosphoinositide signaling.

Bottom Line: The seedlings of plc2-1 mutant showed growth defect that was complemented by heterologous expression of AtPLC2, suggesting that phosphoinositide-specific phospholipase C activity borne by AtPLC2 is required for seedling growth.Moreover, the plc2-1 mutant showed hypersensitive response to ER stress as evidenced by changes in relevant phenotypes and gene expression profiles.Our results revealed the primary enzyme in phosphoinositide metabolism, its involvement in seedling growth and an emerging link between phosphoinositide and the ER stress response.

View Article: PubMed Central - PubMed

Affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan; Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan; Graduate Institute of Biotechnology and Department of Life Sciences, National Chung-Hsing University, Taichung, Taiwan; Muroran Institute of Technology, Muroran, Japan.

ABSTRACT
Phosphoinositides represent important lipid signals in the plant development and stress response. However, multiple isoforms of the phosphoinositide biosynthetic genes hamper our understanding of the pivotal enzymes in each step of the pathway as well as their roles in plant growth and development. Here, we report that phosphoinositide-specific phospholipase C2 (AtPLC2) is the primary phospholipase in phosphoinositide metabolism and is involved in seedling growth and the endoplasmic reticulum (ER) stress responses in Arabidopsis thaliana. Lipidomic profiling of multiple plc mutants showed that the plc2-1 mutant increased levels of its substrates phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate, suggesting that the major phosphoinositide metabolic pathway is impaired. AtPLC2 displayed a distinct tissue expression pattern and localized at the plasma membrane in different cell types, where phosphoinositide signaling occurs. The seedlings of plc2-1 mutant showed growth defect that was complemented by heterologous expression of AtPLC2, suggesting that phosphoinositide-specific phospholipase C activity borne by AtPLC2 is required for seedling growth. Moreover, the plc2-1 mutant showed hypersensitive response to ER stress as evidenced by changes in relevant phenotypes and gene expression profiles. Our results revealed the primary enzyme in phosphoinositide metabolism, its involvement in seedling growth and an emerging link between phosphoinositide and the ER stress response.

No MeSH data available.