Search bioRxiv⌕ Search

Biology subjects

Roussin, M.

Publications and source records attributed to Roussin, M..

2 recordsLinked to original sources

An Interpretable Framework to Characterize Compound Treatments on Filamentous Fungi using Cell Painting and Deep Metric Learning

The cell painting microscopy imaging protocol has recently gained traction in the biology community as it allows, through the addition of fluorescent dyes, to acquire images that highlight intra-cellular components that are not visible through traditional whole-cell microscopy. While previous works have successfully applied cell painting to mammalian cells, we devise a staining protocol applicable to a filamentous fungus model. Following a principled visual inspection and annotation protocol of phenotypes by domain-experts, we devise an efficient, robust, and conceptually simple image analysis strategy based on the Deep Cosine Metric Learning paradigm that allows to estimate phenotypical similarities across different imaging modalities. We experimentally demonstrate the benefits of our pipeline in the tasks of estimating dose-response curves over a wide range of subtle phenotypical variations. Last, we showcase how our learned metrics can group image samples according to different modes of action and biological targets in an interpretable manner.

bioinformatics↗

The TIR-domain containing effectors BtpA and BtpB from Brucella abortus block energy metabolism

Brucella species are facultative intracellular Gram-negative bacteria relevant to animal and human health. Their ability to establish an intracellular niche and subvert host cell pathways to their advantage depends on the delivery of bacterial effector proteins through a type IV secretion system. Brucella Toll/Interleukin-1 Receptor (TIR)-domain-containing proteins BtpA (also known as TcpB) and BtpB are among such effectors. Although divergent in primary sequence, they interfere with Toll-like receptor (TLR) signaling to inhibit the innate immune responses. However, the molecular mechanisms implicated still remain unclear. To gain insight into the functions of BtpA and BtpB, we expressed them in the budding yeast Saccharomyces cerevisiae as a eukaryotic cell model. We found that both effectors were cytotoxic and that their respective TIR domains were necessary and sufficient for yeast growth inhibition. Growth arrest was concomitant with actin depolymerization, endocytic block and a general decrease in kinase activity in the cell, suggesting a failure in energetic metabolism. Indeed, levels of ATP and NAD+ were low in yeast cells expressing BtpA and BtpB TIR domains, consistent with the recently described enzymatic activity of some TIR domains as NAD+ hydrolases. In human epithelial cells, both BtpA and BtpB expression reduced intracellular total NAD levels. In infected cells, both BtpA and BtpB contributed to reduction of total NAD, indicating that their NAD+ hydrolase functions are active intracellularly during infection. Overall, combining the yeast model together with mammalian cells and infection studies our results show that BtpA and BtpB modulate energy metabolism in host cells through NAD+ hydrolysis, assigning a novel role for these TIR domain-containing effectors in Brucella pathogenesis.

microbiology↗