Biology subjects

Poleshko, A.

Publications and source records attributed to Poleshko, A..

3 recordsLinked to original sources

bioRxiv2022

PRR14 organizes H3K9me3-modifed heterochromatin at the nuclear lamina

The eukaryotic genome is organized in three dimensions within the nucleus. Transcriptionally active chromatin is spatially separated from silent heterochromatin, a large fraction of which is located at the nuclear periphery. However, the mechanisms by which chromatin is localized at the nuclear periphery remain poorly understood. Here we demonstrate that Proline Rich 14 (PRR14) protein specifically organizes H3K9me3-modified heterochromatin at the nuclear lamina. We show that PRR14 dynamically associates with both the nuclear lamina and heterochromatin, and is able to reorganize heterochromatin in the nucleus of interphase cells independent of mitosis. We demonstrate that PRR14 can bind all isoforms of heterochromatin protein 1 (HP1). We characterize two functional HP1-binding sites within PRR14 that contribute to its association with heterochromatin. Results of fluorescent recovery after photobleaching (FRAP) and super-resolution imaging indicate that PPR14 forms an anchoring surface for heterochromatin at the nuclear lamina where it interacts dynamically with HP1-associated, H3K9me3-modified chromatin. Our study reveals the mechanism through which PRR14 tethers heterochromatin to the nuclear lamina and we propose a model of dynamic heterochromatin organization at the nuclear periphery.

cell biology↗

bioRxiv2019

The PPR14 heterochromatin tether encodes modular domains that mediate and regulate nuclear lamina targeting

A large fraction of epigenetically silent heterochromatin is anchored to the nuclear periphery via \"tethering proteins\" that function to bridge heterochromatin and the nuclear membrane or nuclear lamina. We identified previously a human tethering protein, PRR14, that binds heterochromatin through an N-terminal domain, but the mechanism and regulation of nuclear lamina association remained to be investigated. Here we identify a centrally located, evolutionarily conserved PRR14 nuclear lamina binding domain (LBD) that is both necessary and sufficient for positioning of PRR14 at the nuclear lamina. We also show that PRR14 associates dynamically with the nuclear lamina, and provide evidence that such dynamics are regulated through phosphorylation of the LBD. We also show that the evolutionary conserved PRR14 C-terminal Tantalus domain encodes a PP2A phosphatase recognition site that regulates PRR14 nuclear lamina association. The overall findings demonstrate a heterochromatin anchoring mechanism whereby the PRR14 tether simultaneously binds heterochromatin and the nuclear lamina through two modular domains. Furthermore, the identification of a modular LBD may provide an engineering strategy for delivery of cargo to the nuclear lamina.

cell biology↗

bioRxiv2019

H3K9me2 orchestrates inheritance of spatial positioning of peripheral heterochromatin through mitosis

Cell-type-specific 3D organization of the genome is unrecognizable during mitosis. It remains unclear how essential positional information is transmitted through cell division such that a daughter cell recapitulates the spatial genome organization of the parent. Lamina-associated domains (LADs) are regions of repressive heterochromatin positioned at the nuclear periphery that vary by cell type and contribute to cell-specific gene expression and identity. Here we show that histone 3 lysine 9 dimethylation (H3K9me2) is an evolutionarily conserved, specific mark of nuclear peripheral heterochromatin and that it is retained through mitosis. During mitosis, phosphorylation of histone 3 serine 10 temporarily shields the H3K9me2 mark allowing for dissociation of chromatin from the nuclear lamina. Using high-resolution 3D immuno-oligoFISH, we demonstrate that H3K9me2-enriched genomic regions, which are positioned at the nuclear lamina in interphase cells prior to mitosis, re-associate with the forming nuclear lamina before mitotic exit. The H3K9me2 modification of peripheral heterochromatin ensures that positional information is safeguarded through cell division such that individual LADs are re-established at the nuclear periphery in daughter nuclei. Thus, H3K9me2 acts as a 3D architectural mitotic guidepost. Our data establish a mechanism for epigenetic memory and inheritance of spatial organization of the genome.

cell biology↗