Plant nuclear envelope as a hub connecting genome organization with regulation of gene expression

Abstract

Eukaryotic cells organize their genome within the nucleus with a double-layered membrane structure termed the nuclear envelope (NE) as the physical barrier. The NE not only shields the nuclear genome but also spatially separates transcription from translation. Proteins of the NE including nucleoskeleton proteins, inner nuclear membrane proteins, and nuclear pore complexes have been implicated in interacting with underlying genome and chromatin regulators to establish a higher-order chromatin architecture. Here, I summarize recent advances in the knowledge of NE proteins that are involved in chromatin organization, gene regulation, and coordination of transcription and mRNA export. These studies support an emerging view of plant NE as a central hub that contributes to chromatin organization and gene expression in response to various cellular and environmental cues.

Keywords: Nuclear envelope; gene expression; genome organization; nuclear lamina; nuclear membrane; nuclear pore complex; plants.

Figure 1.

Summary of plant key regulators at the nuclear envelope involved in genome organization and regulation of gene expression. (a) The plant nuclear periphery mostly features a high concentration of heterochromatin regions with repressive epigenetic marks, termed plant lamina-associated domains (PLADs). Plant nucleoskeleton four CRWN proteins are responsible for chromatin tethering as well as association with chromatin regulators (e.g. H3K27me3, PRC2, SWI/SNF, NTL9, and ABI5). KAKU4 is another plant potential nucleoskeleton component. Plant INM resides some conserved proteins (e.g. MAN1, PNET2s, and SAD/UNC homology (SUNs)), as well as plant-specific components (e.g. NEAPs, GIPs, and OPENER), and is involved in multiple aspects of genome activity regulation. The nuclear basket (b), the core scaffold (c), and the membrane ring (d) of the NPC encompass distinct nucleoporins that are associated with underlying chromatin and/or chromatin-associated complexes. The speculative connections at the NE are highlighted in red dashed lines (b, d), including nucleoporins with the underlying nucleoskeleton, chromatin, and RNA; nuclear membrane constituents with the NPC.