Capell, B. | Search bioRxiv

bioRxiv2022

Stress vesicles are induced by acute mechanical force and precede the commitment of epidermal stem cells to terminal differentiation

The skin has a pronounced ability to adapt to physical changes in the environment by exhibiting plasticity at the cellular level. Transient mechanical deformations applied to the skin are accommodated without permanent changes to tissue structure. However, sustained physical stress induces long-lasting alterations in the skin, which are mediated by shifts in the fates of epidermal stem cells. To investigate this phenomenon, we implemented two-photon intravital imaging to capture the responses of epidermal cells when an acute mechanical force is applied to the live skin. We show that mechanical stress induces the formation of intracellular vesicles in epidermal stem cells, which are filled with extracellular fluid and gradually enlarge, causing the deformation of the cell nucleus. By lineage tracing analysis we demonstrate that the degree of nuclear deformation is linked to cell fate. Utilizing a fluorescent in vivo reporter, to capture intracellular calcium dynamics, we show that mechanical force induces a sustained increase in intracellular calcium within basal epidermal stem cells. Conditional deletion of Piezo1, a mechanosensitive ion channel, alters intracellular calcium dynamics and increases the number of stress vesicles in epidermal stem cells. Using a human skin xenograft model, we show that stress vesicles are a conserved phenomenon in mammalian skin. This study uncovers stress vesicles as key manifestations of the mechanism that regulates the fate of epidermal stem cells under conditions of mechanical stress, in which Piezo1 and calcium dynamics are also involved.

cell biology↗

bioRxiv2018

Pharmacologic activation of G protein-coupled estrogen receptor inhibits pancreatic ductal adenocarcinoma

Female sex is associated with lower incidence and improved clinical outcomes for many cancer types, including pancreatic ductal adenocarcinoma (PDAC). Although the mechanisms responsible for this sex difference are unknown, recent data suggests nonclassical estrogen signaling through the G Protein-coupled Estrogen Receptor (GPER) is likely involved. Here we used murine syngeneic tumor models and human xenografts to test whether GPER signaling inhibits pancreatic ductal adenocarcinoma (PDAC). Activation of GPER with the specific, small molecule agonist G-1 inhibited PDAC proliferation, depleted c-Myc and programmed death ligand 1 (PD-L1), and increased tumor cell immunogenicity. Systemically delivered G-1 was well tolerated in PDAC bearing mice, significantly prolonged survival, and markedly increased the efficacy of PD-1 targeted immune therapy. We detected GPER protein in a majority of spontaneous human PDAC tumors. These data, coupled with the wide tissue distribution of GPER, and our previous work showing that G-1 inhibits melanoma, suggest that GPER agonists may be useful against many different cancer types.

cancer biology↗