Nadal, F. | Search bioRxiv

bioRxiv2023

GPRC5A regulates keratinocyte adhesion and migration through nuclear translocation of its C-terminus region

G-Protein Coupled Receptor, Class C, Group 5, Member A (GPRC5A) is well-documented in lung and various epithelial cancers. However, its role in the skin remains unexplored. In this study, we investigated the function of this receptor in skin biology and our research demonstrated that its expression responds to mechanical substrate changes in human primary keratinocytes. Furthermore, we observed GPRC5A reinduction during wound healing at the leading edges in an ex vivo burn model, coinciding with the translocation of its C-terminal region into the nucleus. We identified the cleavage site of GPRC5A by N-TAILS analysis, and cathepsin G was characterized as responsible for proteolysis in cultured cells. To gain a deeper understanding of GPRC5As role in keratinocyte, we performed GPRC5A knockdown in N/TERT-1 cells using short-hairpin RNA. Our findings strongly suggest a close association between GPRC5A and adhesion regulation pathways, but also demonstrate that GPRC5AKD enhanced cell adhesion while reducing cell migration and differentiation. Importantly, these effects were reversed by adding a recombinant polypeptide mimicking the C-terminal region of GPRC5A. Overall, our study reveals an unexpected role of GPRC5A in regulating keratinocyte behavior, implicating its C-terminal region translocation into the nucleus. These results open up interesting strategic pathways for wound healing.

cell biology↗

bioRxiv2020

Direct Measurement of Unsteady Microscale Stokes Flow Using Optically Driven Microspheres

A growing body of work on the dynamics of eukaryotic flagella has noted that their oscillation frequencies are sufficiently high that the viscous penetration depth of unsteady Stokes flow is comparable to the scales over which flagella synchronize. Incorporating these effects into theories of synchronization requires an understanding of the global unsteady flows around oscillating bodies. Yet, there has been no precise experimental test on the microscale of the most basic aspects of such unsteady Stokes flow: the orbits of passive tracers and the position-dependent phase lag between the oscillating response of the fluid at a distant point and that of the driving particle. Here, we report the first such direct Lagrangian measurement of this unsteady flow. The method uses an array of 30 submicron tracer particles positioned by a time-shared optical trap at a range of distances and angular positions with respect to a larger, central particle, which is then driven by an oscillating optical trap at frequencies up to 400 Hz. In this microscale regime, the tracer dynamics is considerably simplified by the smallness of both inertial effects on particle motion and finite-frequency corrections to the Stokes drag law. The tracers are found to display elliptical Lissajous figures whose orientation and geometry are in agreement with a low-frequency expansion of the underlying dynamics, and the experimental phase shift between motion parallel and orthogonal to the oscillation axis exhibits a predicted scaling form in distance and angle. Possible implications of these results for synchronization dynamics are discussed.

biophysics↗