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1.
Plant Cell Physiol ; 64(10): 1178-1188, 2023 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-37522618

RESUMO

Lateral root (LR) formation is an important developmental event for the establishment of the root system in most vascular plants. In Arabidopsis thaliana, the fewer roots (fwr) mutation in the GNOM gene, encoding a guanine nucleotide exchange factor of ADP ribosylation factor that regulates vesicle trafficking, severely inhibits LR formation. Local accumulation of auxin response for LR initiation is severely affected in fwr. To better understand how local accumulation of auxin response for LR initiation is regulated, we identified a mutation, fewer roots suppressor1 (fsp1), that partially restores LR formation in fwr. The gene responsible for fsp1 was identified as SUPERROOT2 (SUR2), encoding CYP83B1 that positions at the metabolic branch point in the biosynthesis of auxin/indole-3-acetic acid (IAA) and indole glucosinolate. The fsp1 mutation increases both endogenous IAA levels and the number of the sites where auxin response locally accumulates prior to LR formation in fwr. SUR2 is expressed in the pericycle of the differentiation zone and in the apical meristem in roots. Time-lapse imaging of the auxin response revealed that local accumulation of auxin response is more stable in fsp1. These results suggest that SUR2/CYP83B1 affects LR founder cell formation at the xylem pole pericycle cells where auxin accumulates. Analysis of the genetic interaction between SUR2 and GNOM indicates the importance of stabilization of local auxin accumulation sites for LR initiation.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos/metabolismo , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Raízes de Plantas/metabolismo
2.
J Exp Bot ; 71(20): 6273-6281, 2020 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-32777040

RESUMO

A putative component protein of the nuclear lamina, KAKU4, modulates nuclear morphology in Arabidopsis thaliana seedlings, but its physiological significance is unknown. KAKU4 was highly expressed in mature pollen grains, each of which has a vegetative cell and two sperm cells. KAKU4 protein was highly abundant on the envelopes of vegetative nuclei and less abundant on the envelopes of sperm cell nuclei in pollen grains and elongating pollen tubes. Vegetative nuclei are irregularly shaped in wild-type pollen. However, KAKU4 deficiency caused them to become more spherical. After a pollen grain germinates, the vegetative nuclei and sperm cells enter and move along the pollen tube. In the wild type, the vegetative nucleus preceded the sperm cell nuclei in >90% of the pollen tubes, whereas, in kaku4 mutants, the vegetative nucleus preceded the sperm cell nuclei in only about half of the pollen tubes. kaku4 pollen was less competitive for fertilization than wild-type pollen after pollination. These results led us to hypothesize that the nuclear shape in vegetative cells of pollen grains affects the orderly migration of the vegetative nucleus and sperm cells in pollen tubes.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Núcleo Celular , Masculino , Membrana Nuclear , Tubo Polínico/genética , Espermatozoides
3.
Plant Cell ; 26(5): 2143-2155, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24824484

RESUMO

In animals, the nuclear lamina is a fibrillar meshwork on the inner surface of the nuclear envelope, composed of coiled-coil lamin proteins and lamin binding membrane proteins. Plants also have a meshwork on the inner surface of the nuclear envelope, but little is known about its composition other than the presence of members of the CROWDED NUCLEI (CRWN) protein family, possible plant lamin analogs. Here, we describe a candidate lamina component, based on two Arabidopsis thaliana mutants (kaku2 and kaku4) with aberrant nuclear morphology. The responsible gene in kaku2 encodes CRWN1, and the responsible gene in kaku4 encodes a plant-specific protein of unknown function (KAKU4) that physically interacts with CRWN1 and its homolog CRWN4. Immunogold labeling revealed that KAKU4 localizes at the inner nuclear membrane. KAKU4 deforms the nuclear envelope in a dose-dependent manner, in association with nuclear membrane invagination and stack formation. The KAKU4-dependent nuclear envelope deformation was enhanced by overaccumulation of CRWN1, although KAKU4 can deform the nuclear envelope even in the absence of CRWN1 and/or CRWN4. Together, these results suggest that plants have evolved a unique lamina-like structure to modulate nuclear shape and size.

4.
J Exp Bot ; 66(6): 1641-7, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25711706

RESUMO

The nuclear envelope (NE) is a fundamental structure of the nucleus and plays an important role in nuclear morphology through the strict regulation of NE protein function. Beyond its physical barrier function between nucleoplasm and cytoplasm, recent studies of the plant NE have provided novel insights into basic aspects of nuclear morphology as well as cellular organization. In this review, we focus on plant NE proteins that have emerged from recent studies in nuclear morphology, and we discuss their physiological functions in cellular activities. A better understanding of the NE protein functions should provide key insights into the physiological significance of proper nuclear structure in plants.


Assuntos
Membrana Nuclear/metabolismo , Proteínas Nucleares/genética , Proteínas de Plantas/genética , Plantas/genética , Proteínas Nucleares/metabolismo , Proteínas de Plantas/metabolismo , Plantas/metabolismo
5.
Front Plant Sci ; 12: 673905, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34177991

RESUMO

The shape of plant nuclei varies among different species, tissues, and cell types. In Arabidopsis thaliana seedlings, nuclei in meristems and guard cells are nearly spherical, whereas those of epidermal cells in differentiated tissues are elongated spindle-shaped. The vegetative nuclei in pollen grains are irregularly shaped in angiosperms. In the past few decades, it has been revealed that several nuclear envelope (NE) proteins play the main role in the regulation of the nuclear shape in plants. Some plant NE proteins that regulate nuclear shape are also involved in nuclear or cellular functions, such as nuclear migration, maintenance of chromatin structure, gene expression, calcium and reactive oxygen species signaling, plant growth, reproduction, and plant immunity. The shape of the nucleus has been assessed both by labeling internal components (for instance chromatin) and by labeling membranes, including the NE or endoplasmic reticulum in interphase cells and viral-infected cells of plants. Changes in NE are correlated with the formation of invaginations of the NE, collectively called the nucleoplasmic reticulum. In this review, what is known and what is unknown about nuclear shape determination are presented, and the physiological significance of the control of the nuclear shape in plants is discussed.

6.
Nat Commun ; 11(1): 5914, 2020 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-33219233

RESUMO

The nuclear lamina plays an important role in the regulation of chromatin organization and gene positioning in animals. CROWDED NUCLEI (CRWN) is a strong candidate for the plant nuclear lamina protein in Arabidopsis thaliana but its biological function was largely unknown. Here, we show that CRWNs localize at the nuclear lamina and build the meshwork structure. Fluorescence in situ hybridization and RNA-seq analyses revealed that CRWNs regulate chromatin distribution and gene expression. More than 2000 differentially expressed genes were identified in the crwn1crwn4 double mutant. Copper-associated (CA) genes that form a gene cluster on chromosome 5 were among the downregulated genes in the double mutant exhibiting low tolerance to excess copper. Our analyses showed this low tolerance to copper was associated with the suppression of CA gene expression and that CRWN1 interacts with the CA gene locus, enabling the locus to localize at the nuclear lamina under excess copper conditions.


Assuntos
Proteínas de Arabidopsis , Cobre/metabolismo , Lâmina Nuclear , Proteínas Nucleares , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Núcleo Celular/metabolismo , Cromatina/metabolismo , Regulação da Expressão Gênica de Plantas , Hibridização in Situ Fluorescente , Mutação/genética , Lâmina Nuclear/genética , Lâmina Nuclear/metabolismo , Lâmina Nuclear/ultraestrutura , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , RNA-Seq
7.
Nucleus ; 10(1): 81-92, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-30961429

RESUMO

In eukaryotes, the nucleus plays key roles in fundamental cellular processes, including DNA replication, chromatin maintenance, transcription, and translation. To better understand the functional diversity of nuclei, we developed a method for the comprehensive extraction of the nuclear proteome from Arabidopsis. We used a buffer with a high sucrose concentration to purify nuclei and then conducted solubility-based fractionation to increase proteome coverage. We identified 1539 proteins and two novel nuclear envelope (NE) proteins in the nuclear fraction of Arabidopsis cultured cells. The localization of 25 proteins was determined by GFP fusion analyses; 23 of these proteins were localized either in the nucleus or the NE-associated endoplasmic reticulum. This result was indicative of the high quality of the proteome. These findings will be useful for clarifying novel nuclear functions in plants.


Assuntos
Proteínas de Arabidopsis/isolamento & purificação , Arabidopsis/química , Núcleo Celular/química , Proteoma/isolamento & purificação , Arabidopsis/citologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Núcleo Celular/metabolismo , Células Cultivadas , Biologia Computacional , Membrana Nuclear/química , Membrana Nuclear/metabolismo , Proteoma/química , Proteoma/metabolismo , Proteômica , Solubilidade , Sacarose/química
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