Roles of ASYMMETRIC LEAVES2 (AS2) and Nucleolar Proteins in the Adaxial–Abaxial Polarity Specification at the Perinucleolar Region in Arabidopsis

Autor: Chiyoko Machida, Hiro Takahashi, Yasunori Machida, Hidekazu Iwakawa
Rok vydání: 2020
Předmět:
0106 biological sciences
0301 basic medicine
ETTIN/AUXIN RESPONSE FACTOR3 (ETT/ARF3)
ASYMMETRIC LEAVES2
Arabidopsis
Review
AS2 body
01 natural sciences
lcsh:Chemistry
adaxial–abaxial polarity
DEAD-box RNA Helicases
Gene Expression Regulation
Plant
AS2/LOB domain
lcsh:QH301-705.5
Spectroscopy
biology
Cell Polarity
Nuclear Proteins
RNA-Binding Proteins
General Medicine
Computer Science Applications
Cell biology
gene body methylation
DNA-Binding Proteins
DNA methylation
Catalysis
Inorganic Chemistry
03 medical and health sciences
Ribosomal protein
Epigenetics
nucleolus
ribosomal DNA (rDNA)
Physical and Theoretical Chemistry
Molecular Biology
Transcription factor
Gene
Indoleacetic Acids
Arabidopsis Proteins
Organic Chemistry
RNA
Phosphoproteins
biology.organism_classification
Plant Leaves
030104 developmental biology
lcsh:Biology (General)
lcsh:QD1-999
Epigenetic Repression
Transcription Factors
010606 plant biology & botany
Zdroj: International Journal of Molecular Sciences
International Journal of Molecular Sciences, Vol 21, Iss 7314, p 7314 (2020)
ISSN: 1422-0067
Popis: Leaves of Arabidopsis develop from a shoot apical meristem grow along three (proximal–distal, adaxial–abaxial, and medial–lateral) axes and form a flat symmetric architecture. ASYMMETRIC LEAVES2 (AS2), a key regulator for leaf adaxial–abaxial partitioning, encodes a plant-specific nuclear protein and directly represses the abaxial-determining gene ETTIN/AUXIN RESPONSE FACTOR3 (ETT/ARF3). How AS2 could act as a critical regulator, however, has yet to be demonstrated, although it might play an epigenetic role. Here, we summarize the current understandings of the genetic, molecular, and cellular functions of AS2. A characteristic genetic feature of AS2 is the presence of a number of (about 60) modifier genes, mutations of which enhance the leaf abnormalities of as2. Although genes for proteins that are involved in diverse cellular processes are known as modifiers, it has recently become clear that many modifier proteins, such as NUCLEOLIN1 (NUC1) and RNA HELICASE10 (RH10), are localized in the nucleolus. Some modifiers including ribosomal proteins are also members of the small subunit processome (SSUP). In addition, AS2 forms perinucleolar bodies partially colocalizing with chromocenters that include the condensed inactive 45S ribosomal RNA genes. AS2 participates in maintaining CpG methylation in specific exons of ETT/ARF3. NUC1 and RH10 genes are also involved in maintaining the CpG methylation levels and repressing ETT/ARF3 transcript levels. AS2 and nucleolus-localizing modifiers might cooperatively repress ETT/ARF3 to develop symmetric flat leaves. These results raise the possibility of a nucleolus-related epigenetic repression system operating for developmental genes unique to plants and predict that AS2 could be a molecule with novel functions that cannot be explained by the conventional concept of transcription factors.
Databáze: OpenAIRE
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