Clevenger, A. J. | bioRxiv Science

bioRxiv2024

Endothelial cell Piezo1 promotes vascular smooth muscle cell differentiation on large arteries

Vascular stabilization is a mechanosensitive process, in part driven by blood flow. Here, we demonstrate the involvement of the mechanosensitive ion channel, Piezo1, in promoting arterial accumulation of vascular smooth muscle cells (vSMCs) during zebrafish development. Using a series of small molecule antagonists or agonists to temporally regulate Piezo1 activity, we identified a role for the Piezo1 channel in regulating klf2a levels and altered targeting of vSMCs between arteries and veins. Increasing Piezo1 activity suppressed klf2a and increased vSMC association with the cardinal vein, while inhibition of Piezo1 activity increased klf2a levels and decreased vSMC association with arteries. We supported the small molecule data with in vivo genetic suppression of piezo1 and 2 in zebrafish, resulting in loss of transgelin+ vSMCs on the dorsal aorta. Further, endothelial cell (EC)-specific Piezo1 knockout in mice was sufficient to decrease vSMC accumulation along the descending dorsal aorta during development, thus phenocopying our zebrafish data, and supporting functional conservation of Piezo1 in mammals. To determine mechanism, we used in vitro modeling assays to demonstrate that differential sensing of pulsatile versus laminar flow forces across endothelial cells changes the expression of mural cell differentiation genes. Together, our findings suggest a crucial role for EC Piezo1 in sensing force within large arteries to mediate mural cell differentiation and stabilization of the arterial vasculature.

developmental biology↗

bioRxiv2024

Oncogenic KRAS Mutations Confer a Unique Mechanotransduction Response to Peristalsis in Colorectal Cancer Cells

Colorectal cancer (CRC) tumors start as precancerous polyps on the inner lining of the colon or rectum, where they are exposed to the mechanics of colonic peristalsis. Our previous work leveraged a custom-built peristalsis bioreactor to demonstrate that colonic peristalsis led to cancer stem cell enrichment in colorectal cancer cells. However, this malignant mechanotransductive response was confined to select CRC lines that harbored an oncogenic mutation in the KRAS gene. In this work, therefore, we explored the involvement of activating KRAS mutations on peristalsis-associated mechanotransduction in CRC. Peristalsis enriched the cancer stem cell marker LGR5 in KRAS mutant (G13D, etc.) lines, in a Wnt-independent manner. Conversely, LGR5 enrichment in wild type KRAS lines exposed to peristalsis were minimal. LGR5 enrichment downstream of peristalsis translated to increased tumorigenicity in vivo in KRAS mutant vs. wild type lines. Differences in mechanotransduction response was additionally apparent via unbiased gene set enrichment analysis, where many unique pathways were enriched in wild type vs. mutant lines, in response to peristalsis. Interestingly, peristalsis also triggered {beta}-catenin nuclear localization independent of Wnt, particularly in KRAS mutant lines. The central involvement of KRAS in the mechanotransductive responses was validated via gain and loss of function strategies. {beta}-catenin activation and LGR5 enrichment downstream of peristalsis converged to the activation of the MEK/ERK kinase cascade, that remains active in cells that harbor oncogenic KRAS mutations. Taken together, our results demonstrated that oncogenic KRAS mutations conferred a unique peristalsis-associated mechanotransduction response to colorectal cancer cells, resulting in cancer stem cell enrichment and increased tumorigenicity. These mechanosensory connections can be leveraged in improving the sensitivity of emerging therapies that target oncogenic KRAS.

bioengineering↗