The genome is housed within the nucleus, where transcription is regulated by architectural features that direct DNA packaging and epigenetic modifications. How genome organization and modification are controlled to allow proper gene expression and normal organismal development is an ongoing area of inquiry. Recent discoveries highlight the important role of the nuclear pore complex (NPC), which regulates transport of biomolecules between the cytosol and nucleus, in transcription control. The NPC protein Nup98 has the ability to move on and off the NPC structure to associate with specific sites in the genome inside the nucleus. Research has shown that this interaction promotes gene activation in developing tissues and that its disruption causes leukemia, hinting at the functional importance of Nup98-directed gene activation for normal development. A recently identified variant of another nucleoporin protein termed sPom121 (?short Pom121), which has completely lost the ability to associate with the NPC but interacts with Nup98 and other nucleoporins within the nucleus to regulate genes. sPom121 recruits additional nucleoporin proteins, and likely other unknown proteins, to structures within the nucleoplasm that we refer to as chromatin-associated nucleoporin complexes, or CNCs. Building on recent findings on the overlapping functions of Nup98 and sPom121 to dissect the roles of CNCs in gene regulation in mammals. Specifically, it will be determined what chromatin modifying enzymes Nup98 associates with to mediate gene activation, and determine how those interactions and gene targets are de-regulated in leukemia. sPom121 specifically marks intranuclear sites of genome regulation (CNCs) but does not associate with the NPC to identify nucleoporin-associated proteins that function in gene regulation. Studies will provide new information about Nup98 as a transcription regulator in hematopoietic cells and have the potential to establish CNCs as a novel feature of gene regulation and genome organization.

Public Health Relevance

Nuclear pores are prominent architectural features of cell nuclei and have been shown to participate in chromatin organization and transcription control in species from yeast to man. Based on the discovery of soluble version of the transmembrane nucleoporin (sPom121) this proposal will investigate structures within the nucleoplasm that are referred to as chromatin-associated nucleoporin complexes, or CNCs. Together with the nuclear pore protein Nup98, CNCs regulate chromatin modification and transcription in hematopoietic cells and since their function is perturbed in leukemia these studies will provide new insights into nucleoporin- mediated gene regulation in disease.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Special Emphasis Panel (ZRG1)
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Flicker, Paula F
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Salk Institute for Biological Studies
La Jolla
United States
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McCloskey, Asako; Ibarra, Arkaitz; Hetzer, Martin W (2018) Tpr regulates the total number of nuclear pore complexes per cell nucleus. Genes Dev 32:1321-1331