Abstract

Osteoarthritis (OA) is the most common degenerative joint disease, affecting more than 350 million people worldwide. Along with inflammation and pain, a hallmark of OA is the degradation of articular cartilage (AC), an avascular and aneural tissue that coats and facilitates the bending of diarthrodial joints. AC withstands millions of cyclic mechanical loads annually, and chondrocytes, the only resident cells in the tissue, sense these loads through mechanically gated ion channels, including Transient Receptor Potential Vanilloid 4 (TRPV4), PIEZO1 and PIEZO2. PIEZO1 is a highly expressed calcium ion channel in chondrocytes that can be activated through mechanical loading or chemically with Yoda1, a PIEZO1-specific agonist. Our lab recently demonstrated that PIEZO1 expression is elevated in osteoarthritic cartilage and that interleukin-1α (IL-1α), a pro-inflammatory cytokine abundant in OA, led to the upregulation of PIEZO1 expression in porcine chondrocytes. The increased expression of PIEZO1 in IL-1α-challenged chondrocytes led to a sustained increased intracellular calcium concentration and the rarefication of the actin cytoskeleton. However, while PIEZO1contributes to the development of osteophytes, bony formations on the edges of bones, during OA, PIEZO1 plays a key role in endochondral ossification, a key anabolic process during long bone formation. Therefore, understanding how PIEZO1 mechanotransduction differs in healthy or pathological conditions is key in developing novel therapeutics for treating OA. Herein, the overall goal of my thesis was to characterize PIEZO1 mechanotransduction in healthy articular chondrocytes. First, I employ Atomic Force Microscopy (AFM) to monitor changes in the nuclear elastic modulus in situ in response to PIEZO1 activation with Yoda1. Then, I use confocal live imaging and develop an image analysis pipeline to characterize calcium and actin dynamics following PIEZO1 activation. Finally, I combine qPCR and immunofluorescence to monitor both transcriptomic and epigenetic changes following PIEZO1 activation with Yoda1. My research integrates biophysics, live-cell imaging, and omics approaches to characterize PIEZO1-mediated mechanotransduction in articular chondrocytes. Overall, this work establishes a foundational, mechanistic understanding of PIEZO1 mechanotransduction and provides a molecular basis for developing PIEZO1-modulating drugs to treat OA or other mechanically driven diseases.

Committee Chair

Farshid Guilak

Committee Members

Celeste Morley; Jessica Wagenseil; Rajan Sah; Ram Dixit

Degree

Doctor of Philosophy (PhD)

Author's Department

Biology & Biomedical Sciences (Biochemistry)

Author's School

Graduate School of Arts and Sciences

Document Type

Dissertation

Date of Award

5-6-2025

Language

English (en)

Author's ORCID

https://orcid.org/0000-0002-1245-1891

Download

Included in

Biology Commons

Share

COinS