Biology subjects

Gerondopoulos, A.

Publications and source records attributed to Gerondopoulos, A..

2 recordsLinked to original sources

bioRxiv2023

Deep super-resolution imaging of thick tissue using structured illumination with adaptive optics

Three-dimensional structured illumination microscopy (3D-SIM) doubles the resolution of fluorescence imaging in all directions and increases the image contrast. However, 3D-SIM has not been widely applied to imaging deep in thick tissues due to its sensitivity to sample-induced aberrations, making the method difficult to apply beyond 10 {micro}m in depth. Furthermore, 3D-SIM has not been available in an upright configuration, limiting its use for live imaging while manipulating the specimen, for example with electrophysiology. Here, we have overcome these barriers by developing a novel upright 3D-SIM system (termed Deep3DSIM) that incorporates adaptive optics for aberration correction and remote focusing, reducing artefacts, improving contrast, restoring resolution, and removing the need to move the specimen or the objective lens in volume imaging. These advantages are equally applicable to inverted 3D-SIM systems. We demonstrate high-quality 3D-SIM imaging in various samples, including an example of imaging 130 {micro}m into Drosophila brain.

cell biology↗

bioRxiv2021

A baton-relay mechanism for ER retrieval signal capture and proofreading by the KDEL receptor

The KDEL-retrieval pathway captures escaped ER proteins with a KDEL or variant C-terminal signal at acidic pH in the Golgi and releases them at neutral pH in the ER. To address the mechanism of signal binding and the molecular basis for differences in signal affinity, we determined the HDEL and RDEL bound structures of the KDEL-receptor. Affinity differences are explained by interactions between the variable -4 position of the signal and W120, whereas initial capture of retrieval signals by their carboxyl-terminus is mediated by a baton-relay mechanism involving a series of conserved arginine residues in the receptor. This explains how the signal is first captured and then pulled into the binding cavity. During capture, retrieval signals undergo a selective proofreading step involving two gatekeeper residues D50 and E117 in the receptor. These mechanisms operate upstream of the pH-dependent closure of the receptor and explain the selectivity of the KDEL-retrieval pathway.

cell biology↗