Investigating the Molecular Mechanisms of SNED1 Fiber Assembly in the Extracellular Matrix

The extracellular matrix (ECM) is a complex scaffold of 150+ proteins that modulates all cellular functions and is critical for pathophysiological processes including cancer, and fibrosis. Our laboratory is interested in studying a novel ECM protein called SNED1 that Dr. Naba initially identified as a promoter of breast cancer metastasis. Previous work from our lab has shown that SNED1 is a fibrillar protein participating in the formation of the ECM scaffold, however, the mechanisms leading to SNED1 assembly in the ECM remain unknown. Studies of other fibrillar ECM proteins have shown that they must establish interactions with other ECM proteins and cell-surface receptors called integrins, for their assembly. For my dissertation, I hypothesized that SNED1 requires interactions both with other ECM proteins and with integrins for its fibrillar assembly. First, I established an in-vitro system using mouse embryonic fibroblasts to study the mechanisms of ECM assembly. Using this system, I found that SNED1 requires the presence of two ECM proteins, fibronectin and collagen I, for its fibrillar assembly. In addition, using biolayer interferometry, we demonstrated that SNED1 could directly bind to collagen I, which is the first experimentally validated binding partner of SNED1. I also examined the role of integrins in SNED1 assembly. To do this, I generated constructs of SNED1 with mutations in each of its putative integrin binding sites (RGD or LDV). While I found that interactions with integrins are not required for initial assembly of SNED1 fibers, I demonstrated that the LDV site, a sequence known to bind to 41 integrins among others, plays a significant role in ECM organization and remodeling, and, in turn, drives cell proliferation and spreading. My results have not only increased our knowledge of the mechanisms of SNED1 assembly into the ECM, but also of the SNED1-dependent mechanisms controlling ECM remodeling and cellular phenotypes. Our next goals are to precisely map the domains of SNED1 involved in protein-protein interactions driving SNED1 assembly and ECM remodeling, as a first step to devise intervention strategies to modulate SNED1’s functions and attempt to prevent breast cancer metastasis.

Author dc:creator

• Leanna Leverton (24400604)

• Extracellular matrix biology

Statement dc:rights

• In Copyright
• Open Access after 2031-05-01

DOI dc:identifier

https://doi.org/10.25417/uic.32995688.v1

OAI identifier oai:identifier

oai:figshare.com:article/32995688