Project Abstract
The mammalian genome is organized into various regions at different scales as one mechanism to regulate
gene expression and mediate cellular identity. One type of well-characterized region is the lamina-associated
domain (LAD), which contains areas of chromatin that directly interact with the nuclear lamina (NL) at the nuclear
periphery. Found across all chromosomes, LADs dynamically interact with the NL to release or attach genes and
regulatory elements in accordance with cell-type and differentiation state-specific gene expression programs.
Patients with mutations in LMNA, encoding the A and C type lamins in the NL, develop a heterogenous group of
diseases, known as laminopathies. Laminopathies preferentially affect striated muscle, and patients often
develop dilated cardiomyopathy (DCM), which can be fatal. Evidence from mouse models and human genetic
studies of laminopathies have suggested a potential role for the Linker of Nucleoskeleton and Cytoskeleton
(LINC) complex in mediating the disease phenotype. Abrogation of the LINC complex in a laminopathy mouse
model resulted in a phenotypic rescue. Additionally, characterization of LMNA mutations in various cell types
demonstrated a disruption to chromatin-lamina interactions in a cardiomyocyte-specific manner. This suggests
a mechanism where the nuclear lamina and LINC complex are each playing a role in the pathogenesis of
laminopathy phenotypes, and potentially affecting genome organization. However, while a LINC-LMNA-gene
positioning axis has been previously suggested, the mechanism of how this may occur remains elusive. Using a
combination of population-based genomics analyses, single-cell microscopy, and cellular functional assays, I
will test the hypothesis that cytoskeletal-nuclear interactions in lamin variant cardiomyocytes destabilize LADs
and contribute to abnormal cellular function. I aim to define the role of the LINC complex in mediating chromatin
organization in LMNA mutant cardiomyocytes and will determine if disruption of LINC complex components can
preserve the changes to genome organization observed. In addition, I aim to determine how cardiomyocyte
function is affected by disruption of the LINC complex in the presence and absence of LMNA mutations. These
studies will provide mechanistic insights into how the nuclear lamina and LINC complex are contributing to both
LAD organization and cardiomyocyte function, which will begin to provide novel understanding of the molecular
basis of laminopathy phenotypes.