Functional Coordination of the Chromatin-Remodeling Factor AtINO80 and the Histone Chaperones NRP1/2 in Inflorescence Meristem and Root Apical Meristem

Abstract

Chromatin structure requires proper modulation in face of transcriptional reprogramming in the context of organism growth and development. Chromatin-remodeling factors and histone chaperones are considered to intrinsically possess abilities to remodel chromatin structure in single or in combination. Our previous study revealed the functional synergy between the Arabidopsis chromatin-remodeling factor INOSITOL AUXOTROPHY 80 (AtINO80) and the histone chaperone NAP1-RELATED PROTEIN 1 (NRP1) and NRP2 in somatic homologous recombination, one crucial pathway involved in repairing DNA double strand breaks. Here, we report genetic interplay between AtINO80 and NRP1/2 in regulating inflorescence meristem (IM) and root apical meristem (RAM) activities. The triple mutant atino80-5 m56-1 depleting of both AtINO80 (atino80-5) and NRP1/2 (m56-1) showed abnormal positioning pattern of floral primordia and enlargement of IM size. Higher mRNA levels of several genes involved in auxin pathway (e.g., PIN1, FIL) were found in the inflorescences of the triple mutant but barely in those of the single mutant atino80-5 or the double mutant m56-1. In particular, the depletion of AtINO80 and NRP1/2 decreased histone H3 levels within the chromatin regions of PIN1, which encodes an important auxin efflux carrier. Moreover, the triple mutant displayed a severe short-root phenotype with higher sensitivity to auxin transport inhibitor NPA. Unusual high level of cell death was also found in triple mutant root tips, accompanied by double-strand break damages revealed by γ-H2A.X loci and cortex cell enlargement. Collectively, our study provides novel insight into the functional coordination of the two epigenetic factors AtINO80 and NRP1/2 in apical meristems during plant growth and development.

New moonlighting functions of mitochondrial cytochrome c in the cytoplasm and nucleus

“…The plant protein NRP1 also belongs to the NAP‐1 family and, in fact, shares a high degree of homology with SET/TAF‐Iβ, both at the structural and functional levels . NRP1 is considered a H2A/H2B histone chaperone and, as its animal counterpart, can form homodimers or heterodimers with NRP2 , another NAP‐1 member with which it shares some functional redundancy . The importance of NRP1 in maintaining genomic integrity and functionality to prevent DNA damage and the activation of PCD is established .…”

“…NRP1 is considered a H2A/H2B histone chaperone and, as its animal counterpart, can form homodimers or heterodimers with NRP2 , another NAP‐1 member with which it shares some functional redundancy . The importance of NRP1 in maintaining genomic integrity and functionality to prevent DNA damage and the activation of PCD is established . NRP1 fulfills these functions by virtue of its ability to assemble/disassemble nucleosomes and its participation in histone eviction, which allows it to regulate DNA replication, transcription, and repair .…”

“…For example, NRP1 interacts with the transcription factor WEREWOLF (WER) and the complex is recruited to the promoter region of GL2, a gene coding for the transcription factor GLABRA2 that suppresses the formation of root hairs, where NRP1 would induce chromatin remodeling to promote the expression of GLABRA2 . It has also been shown that the PIN1 gene, whose expression is involved in the transport and distribution of the growth phytohormone auxin, is regulated by NRP1 . Furthermore, the crucial role of NRP1 in the regulation of homologous recombination has extensively been documented both under normal conditions and after the generation of DSBs .…”

Activities of Chromatin Remodeling Factors and Histone Chaperones and Their Effects in Root Apical Meristem Development

“…These two chromatin factors are recruited to the chromatin regions of the auxin efflux carrier gene PIN1, and mediate the local histone occupancy, thereby modulating the transcription level. Their combined functions are also implicated in chromatin replication and the maintenance of genomic integrity to ensure the viability of root meristem cells [98]. However, the functional interplay between plant INO80 and CAF-1 has not been analyzed yet.…”

The role of cyadox and recombinant growth hormone (rGH) on the promotion of growth through epigenetics

“…DNA methylation and histone modi cation in the nucleus can also affect the three-dimensional structure of chromatin, thus in uencing on gene expression related to growth and development [29,30]. Chromatin remodeling can lead to changes in the position and structure of nucleosomes, leading to changes in chromatin [31].…”