Osada unit aims to discover new bioactive small molecules that will contribute to the development of novel pharmaceuticals and agrochemicals. We test the effects of screening samples against cancer cells and pathogenic microbes, contributing to discover distinctive anticancer drugs and antibiotics. For the antifungal screening, we have constructed phenotypic screening systems based on new technologies, such as artificial intelligence (AI), heterozygous gene deletion mutant collection, and silkworm infection models.
Themes
Phenotypic screening for new antifungal agents
Target identification of novel antibiotics
in vivo Antifungal activity test using silkworms as a model organism
Themes
1. Phenotypic screening for new antifungal agents
We carry out in-house phenotypic evaluation (iHOPE) screening system, where the growth inhibitory activity of test samples against not only fungi, but also mammalian cells, bacteria, and protozoa are systematically evaluated. By profiling characteristic growth inhibition patterns, called “Fingerprints”, highly specific antifungals can be selected. We have also constructed other phenotypic screening system using MorphoBase, a database of cell morphological changes induced by typical antifungal drugs, and use MorphoBase to screen promising first-in-class compounds from initial hits. Currently, we are improving the system by introducing AI that has learned a huge amount of image data to accelerate our drug discovery program.
Phenotypic screening systems; iHOPE (dead/alive) and MorphoBase (morphological change).
2. Target identification of novel antibiotics
The Merck Candida albicans double barcoded strain library (DBC) is a collection of haploid mutants in ca. 5,000 distinct genes. Haploinsufficiency is a phenomenon where the drug sensitivity increases when the amount of the target protein is reduced. The genome-wide haploinsufficiency profiling using this collection enabled to speculate the mode of action of various antifungal agents (PLoS Pathog, 2007). We are analyzing the mode of action of screening hits by this genetic interaction-based approach as well as other physiological interaction-based ones, such as affinity selection by compound-immobilized beads and cell thermal shift assay.
Overview of haploinsufficiency profiling.
3. in vivo Antifungal activity test using silkworms as a model organism
Compared to mice as a model organism, silkworms have many advantages, such as easy to handle, low cost, and few ethical issues. Recently, in vivo models using silkworms infected with various pathogenic microbes were reported and utilized for the evaluation of therapeutic potential of antibiotics (Microbe Pathog, 2002). We applied this system and are evaluating in vivo antifungal activity of the antifungal candidates.
Development of in vivo pathogen infection model using silkworm.
