Gentaur Pub

#33353295   2020/12/22 To Up

Photorespiration Regulates Carbon-Nitrogen Metabolism by Magnesium Chelatase D Subunit in Rice.

The growth and development of plants are dependent on the interaction between carbon and nitrogen metabolism. Essential information about the metabolic regulation of carbon-nitrogen metabolism is still lacking, such as possible interactions among nitrogen metabolism, photosynthesis, and photorespiration. This study shows that higher photorespiration consumes more CO fixed by photosynthesis, making the high photosynthetic efficiency mutant fail to increase production. In order to clarify the effects of photosynthesis and photorespiration on carbon and nitrogen metabolism in high photosynthetic efficiency mutant, a yellow-green leaf mutant () was isolated from rice ( L.). Its chlorophyll (Chl) content decreased, but chloroplast development was not affected. Genetic analysis demonstrated that encodes the magnesium chelatase D subunit (ChlD). The mutant showed an increased net assimilation rate (An) and electron transport flux efficiency and catalase (CAT) activity, and it also had a higher photorespiration rate (Pr), lower HO, and reduced nitrogen uptake efficiency (NUpE); however, there was no loss in yield. The higher activities of glutamate synthase (GOGAT) and glutamine synthetase (GS) ensure the α-ketoglutaric acid (2-OG) and ammonia (NH) availabilities, which are produced from photorespiration in the mutant. These have an important function for carbon and nitrogen metabolism homeostasis in . Further analysis indicated that the energy and substances derived from carbon metabolism supplemented nitrogen metabolism in the form of photorespiration to ensure its normal development when the An of photosynthesis was increased in the mutant with reduced NUpE.
Yinpei Liang, Jiayu Wang, Faliang Zeng, Qi Wang, Lin Zhu, Hongyu Li, Naihui Guo, Hongwei Chen

2653 related Products with: Photorespiration Regulates Carbon-Nitrogen Metabolism by Magnesium Chelatase D Subunit in Rice.

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#31794025   // To Up

Characterization of glycerophosphodiesterase 4-interacting molecules Gαq/11 and Gβ, which mediate cellular lysophospholipase D activity.

We previously purified lysophospholipase D (lysoPLD), which hydrolyzes lysophosphatidylcholine (lysoPC) to lysophosphatidic acid (LPA), from rat brain and identified the heterotrimeric G protein subunits Gαq and Gβ1 in the lysoPLD active fractions. Tag-affinity purified Gαq exhibits lysoPLD activity but a mutant that affected cellular localization or interaction with the Gβ subunit reduced lysoPLD activity. Size exclusion chromatography revealed that active lysoPLD is a much higher molecular mass complex than is heterotrimeric G protein, suggesting the presence of other components. Liquid chromatography-tandem mass spectrometry of lysoPLD purified from rat brain identified glycerophosphodiesterase 4 (GDE4), recently reported as lysoPLD, in the same fraction as G proteins. The overexpressed and tag-purified Gαq fractions, which exhibit lysoPLD activity, contained GDE4. Exogenously expressed GDE4 was co-immunoprecipitated with endogenous Gαq and Gβ and exhibited high lysoPLD activity. The results of confocal microscopy and cell fractionation experiments indicated that exogenously expressed GDE4 in cells mainly localized at the endoplasmic reticulum and partially co-localized with Gαq protein at the plasma membrane. Proteinase K protection assay results suggested that the catalytic domain of GDE4 faces the lumen/extracellular space. Mutations at the conserved amino acids in the C-terminus cytoplasmic regions amongst GDE1, 4 and 7, dramatically suppressed GDE4 enzyme activities. When both the Gαq and Gα11 genes in Neuro2A cells were disrupted using the CRISPR-Cas9 system, endogenous lysoPLD activity was partially reduced but rescued by overexpression of Gαq. These results suggest that GDE4 is a new effector of G protein signaling that produces bioactive phospholipid LPA and/or modulates membrane homeostasis.
Chieko Aoyama, Yasuhiro Horibata, Hiromi Ando, Satomi Mitsuhashi, Maki Arai, Hiroyuki Sugimoto

2740 related Products with: Characterization of glycerophosphodiesterase 4-interacting molecules Gαq/11 and Gβ, which mediate cellular lysophospholipase D activity.

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#30530493   2018/12/10 To Up

cAMP-dependent activation of the Rac guanine exchange factor P-REX1 by type I protein kinase A (PKA) regulatory subunits.

Regulatory subunits of protein kinase A (PKA) inhibit its kinase subunits. Intriguingly, their potential as cAMP-dependent signal transducers remains uncharacterized. We recently reported that type I PKA regulatory subunits (RIα) interact with phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchange factor 1 (P-REX1), a chemotactic Rac guanine exchange factor (RacGEF). Because P-REX1 is known to be phosphorylated and inhibited by PKA, its interaction with RIα suggests that PKA regulatory and catalytic subunits may fine-tune P-REX1 activity or those of its target pools. Here, we tested whether RIα acts as a cAMP-dependent factor promoting P-REX1-mediated Rac activation and cell migration. We observed that G-coupled EP2 receptors indeed promote endothelial cell migration via RIα-activated P-REX1. Expression of the P-REX1-PDZ1 domain prevented RIα/P-REX1 interaction, P-REX1 activation, and EP2-dependent cell migration, and P-REX1 silencing abrogated RIα-dependent Rac activation. RIα-specific cAMP analogs activated P-REX1, but lost this activity in RIα-knockdown cells, and cAMP pulldown assays revealed that P-REX1 preferentially interacts with free RIα. Moreover, purified RIα directly activated P-REX1 We also found that the RIα CNB-B domain is critical for the interaction with P-REX1, which was increased in RIα mutants, such as the acrodysostosis-associated mutant, that activate P-REX1 at basal cAMP levels. RIα and Cα PKA subunits targeted distinct P-REX1 molecules, indicated by an absence of phosphorylation in the active fraction of P-REX1. This was in contrast to the inactive fraction in which phosphorylated P-REX1 was present, suggesting co-existence of dual stimulatory and inhibitory effects. We conclude that PKA's regulatory subunits are cAMP-dependent signal transducers.
Sendi Rafael Adame-García, Rodolfo Daniel Cervantes-Villagrana, Lennis Beatriz Orduña-Castillo, Jason C Del Rio, J Silvio Gutkind, Guadalupe Reyes-Cruz, Susan S Taylor, José Vázquez-Prado

1375 related Products with: cAMP-dependent activation of the Rac guanine exchange factor P-REX1 by type I protein kinase A (PKA) regulatory subunits.

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#30312418   // To Up

A New Multisystem Disorder Caused by the Gαs Mutation p.F376V.

The α subunit of the stimulatory G protein (Gαs) links numerous receptors to adenylyl cyclase. Gαs, encoded by GNAS, is expressed predominantly from the maternal allele in certain tissues. Thus, maternal heterozygous loss-of-function mutations cause hormonal resistance, as in pseudohypoparathyroidism type Ia, whereas somatic gain-of-function mutations cause hormone-independent endocrine stimulation, as in McCune-Albright syndrome.
Heike Biebermann, Gunnar Kleinau, Dirk Schnabel, Detlef Bockenhauer, Louise C Wilson, Ian Tully, Sarah Kiff, Patrick Scheerer, Monica Reyes, Sarah Paisdzior, John W Gregory, Jeremy Allgrove, Heiko Krude, Michael Mannstadt, Thomas J Gardella, Mehul Dattani, Harald Jüppner, Annette Grüters

2232 related Products with: A New Multisystem Disorder Caused by the Gαs Mutation p.F376V.

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#30060753   2018/07/30 To Up

Identification of a novel GNAS mutation in a case of pseudohypoparathyroidism type 1A with normocalcemia.

Pseudohypoparathyroidism type 1A (PHP1A) is a rare genetic disease primarily characterized by resistance to parathyroid hormone along with hormonal resistance and other features of Albright hereditary osteodystrophy (AHO). It is caused by heterozygous inactivating mutations in the maternal allele of the GNAS gene, which encodes the stimulatory G-protein alpha subunit (Gsα) and regulates production of the second messenger cyclic AMP (cAMP). Herein, we report a case of of PHP1A with atypical clinical manifestations (oligomenorrhea, subclinical hypothyroidism, and normocalcemia) and explore the underlying genetic cause in this patient.
Xiao-Dan Long, Jing Xiong, Zhao-Hui Mo, Chang-Sheng Dong, Ping Jin

1735 related Products with: Identification of a novel GNAS mutation in a case of pseudohypoparathyroidism type 1A with normocalcemia.

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#30026030   2018/07/17 To Up

Oocyte-specific deletion of Gα induces oxidative stress and deteriorates oocyte quality in mice.

The stimulatory heterotrimeric G protein alpha subunit (Gα) is a ubiquitous guanine nucleotide-binding protein that regulates the intracellular cAMP signaling pathway and consequently participates in a wide range of biological events. In the reproductive system, despite Gα being associated with oocyte meiotic arrest in vitro, the exact role of Gα in female fertility in vivo remains largely unknown. Here, we generated oocyte-specific Gα knockout mice by using the Cre/LoxP system. We observed that the deletion of Gα caused complete female infertility. Exclusion of post-implantation abnormalities, oogenesis, fertilization, and early embryo development was subsequently monitored; meiosis in Gα-deficient oocytes precociously resumed in only 43% of antral follicles from mutant mice, indicating that alteration of meiotic pause was not the key factor in infertility. Ovulation process and number were normal, but the rate of morphological abnormal oocytes was apparently increased; spindle organization, fertilization, and early embryo development were impaired. Furthermore, the level of ROS (reactive oxygen species) and the mitochondrial aggregation increased, and antioxidant glutathione (GSH) content, ATP level, mtDNA copy number, and mitochondrial membrane potential decreased in Gα-deficient oocytes. GV oocytes from mutant mice showed early-stage apoptosis. Meanwhile, the Gα knockout-induced decline in oocyte quality and low developmental potential was partially rescued by antioxidant supplementation. To sum up, our results are the first to reveal that the profile of Gα oocyte-specific deletion caused female infertility in vivo, and oxidative stress plays an important role in this event.
Yue Xie, Bin Wu, Yecheng Jin, Aizhen Zhang, Xiaoyang Sun, Xinyan Zhang, Xiaotong Gao, Ran Dong, Huashun Li, Jiangang Gao

1745 related Products with: Oocyte-specific deletion of Gα induces oxidative stress and deteriorates oocyte quality in mice.

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#29844055   2018/05/29 To Up

Dual phosphorylation of Ric-8A enhances its ability to mediate G protein α subunit folding and to stimulate guanine nucleotide exchange.

Resistance to inhibitors of cholinesterase-8A (Ric-8A) and Ric-8B are essential biosynthetic chaperones for heterotrimeric G protein α subunits. We provide evidence for the direct regulation of Ric-8A cellular activity by dual phosphorylation. Using proteomics, Western blotting, and mutational analyses, we determined that Ric-8A was constitutively phosphorylated at five serines and threonines by the protein kinase CK2. Phosphorylation of Ser and Thr in rat Ric-8A (corresponding to Ser and Thr in human Ric-8A) was required for high-affinity binding to Gα subunits, efficient stimulation of Gα subunit guanine nucleotide exchange, and mediation of Gα subunit folding. The CK2 consensus sites that contain Ser and Thr are conserved in Ric-8 homologs from worms to mammals. We found that the homologous residues in mouse Ric-8B, Ser and Ser, were also phosphorylated. Mutation of the genomic copy of in to encode alanine in the homologous sites resulted in characteristic reduction-of-function phenotypes that are associated with defective G and G signaling, including reduced locomotion and defective egg laying. The phosphorylation site mutant phenotypes were partially rescued by chemical stimulation of G signaling. These results indicate that dual phosphorylation represents a critical form of conserved Ric-8 regulation and demonstrate that Ric-8 proteins are needed for effective Gα signaling. The position of the CK2-phosphorylated sites within a structural model of Ric-8A reveals that these sites contribute to a key acidic and negatively charged surface that may be important for its interactions with Gα subunits.
Makaía M Papasergi-Scott, Hannah M Stoveken, Lauren MacConnachie, Pui-Yee Chan, Meital Gabay, Dorothy Wong, Robert S Freeman, Asim A Beg, Gregory G Tall

1150 related Products with: Dual phosphorylation of Ric-8A enhances its ability to mediate G protein α subunit folding and to stimulate guanine nucleotide exchange.

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#29491039   2018/02/28 To Up

The N54- Mutant Has Decreased Affinity for and Suggests a Mechanism for Coupling Heterotrimeric G Protein Nucleotide Exchange with Subunit Dissociation.

Ser54 of G binds guanine nucleotide and Mg as part of a conserved sequence motif in GTP binding proteins. Mutating the homologous residue in small and heterotrimeric G proteins generates dominant-negative proteins, but by protein-specific mechanisms. For , this results from persistent binding of to , whereas for small GTP binding proteins and this results from persistent binding to guanine nucleotide exchange factor or receptor. This work examined the role of interactions in mediating the properties of the Ser54-like mutants of G subunits. Unexpectedly, WT- or N54- coexpressed with -adrenergic receptor in human embryonic kidney 293 cells decreased receptor stimulation of IP3 production by a cAMP-independent mechanism, but WT- was more effective than the mutant. One explanation for this result would be that , like Ser47 , blocks receptor activation by sequestering ; implying that N54- has reduced affinity for since it was less effective at blocking IP3 production. This possibility was more directly supported by the observation that WT- was more effective than the mutant in inhibiting activation of phospholipase C2. Further, in vitro synthesized N54- bound biotinylated- with lower apparent affinity than did WT- The Cys54 mutation also decreased binding but less effectively than N54- Substitution of the conserved Ser in with Cys or Asn increased binding, with the Cys mutant being more effective. This suggests that Ser54 of is involved in coupling changes in nucleotide binding with altered subunit interactions, and has important implications for how receptors activate G proteins.
John H Cleator, Christopher A Wells, Jane Dingus, David T Kurtz, John D Hildebrandt

1676 related Products with: The N54- Mutant Has Decreased Affinity for and Suggests a Mechanism for Coupling Heterotrimeric G Protein Nucleotide Exchange with Subunit Dissociation.

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