Ahlnas, T. | Search bioRxiv

bioRxiv2024

Morphological single-cell analysis of peripheral blood mononuclear cells from 390 healthy blood donors with Blood Cell Painting

The morphological diversity of blood immune cells of healthy individuals, critical for recognizing disease-related phenotypes, remains largely uncharacterized. To address this gap, we developed Blood Cell Painting (BCP): a high content, high throughput fluorescence imaging assay for peripheral blood mononuclear cells. We generated a BCP Atlas with images of 50 million cells from 390 healthy blood donors, identifying 18 distinct immune cell morphology clusters. A genome-wide association study of BCP-derived imaging-based cellular features revealed 93 significant associations across 30 genetic loci. These loci include genes linked to mast cell function, inflammation, immune signaling, mitochondrial maintenance and circadian immune modulation. We also observed correlations between immune cell morphological features and clinical traits, such as respiratory conditions and healthcare visits related to contraceptive management, potentially reflecting hormonal influences on immune cell phenotypes. As a proof of concept for clinical application, acute myeloid leukemia subtypes were distinguished by BCP. Our study establishes BCP as a versatile method for immune cell profiling to uncover genetic, phenotypic and clinical determinants of immune cell morphology in health and disease.

cell biology↗

bioRxiv2018

Refolding activity of bacterial Hsp90 in vivo reveals ancient chaperoning function

The conserved molecular chaperones Hsp70 and Hsp90 play a key role in protein folding. Mechanistically, Hsp90 acts downstream from Hsp70 solving an Hsp70-inflicted folding block. It is unclear, though, when and to which extend the concerted action of this cascade becomes crucial in living organisms. Here we show that, in E. coli cells, Hsp90 dramatically improves protein refolding after heat stress while it is dispensable for de novo folding. We found that Hsp90 inhibition effectively reduced the refolding yields in vivo, leading to strongly reduced enzymatic activity of the paradigmatic chaperone client luciferase and broadly increased aggregation of the E. coli proteome. Additionally, the presence of Hsp90 during refolding reduces the net ATP consumption presumably by sparing the substrate binding-and-release cycles on Hsp70. This mechanism explains how the cooperation of Hsp90 with the Hsp70 chaperone system creates robust folding machinery in a sustainable manner. Together, we describe a general function for bacterial Hsp90 as a key factor of the folding cascade, which may be the ancient activity of this evolutionary conserved machine.

biochemistry↗