Biology subjects

Francois, L.

Publications and source records attributed to Francois, L..

4 recordsLinked to original sources

bioRxiv2024

Industrialization of three-dimensional hiPSC-cardiac microtissues for high-throughput cardiac safety and drug discovery screening

Current cardiac cell models for drug screening often face a trade-off between cellular maturity and achieving high throughput. While three-dimensional human induced pluripotent stem cell-based heart models typically exhibit more adult-like features, their application is hindered by the need for large cell numbers or complex equipment. Here, we developed cost-effective methods to scale up production of three-dimensional cardiac microtissues (cMTs) containing three cardiac cell types, and assess calcium transients and action potential metrics for high-throughput screening (HTS). Automating the procedure revealed reproducible drug responsiveness and predictive accuracy in a reference compound screen. Furthermore, an arrhythmic phenotype was reliably triggered in cMTs containing cardiomyocytes with a RYR2 mutation. A screen of FDA-approved drugs identified 17 drugs that rescued the arrhythmic phenotype. Our findings underscore the scalability of cMTs and their utility in disease modelling and HTS. The advanced "technology-readiness-level" of cMTs supports their regulatory uptake and acceptance within the pharmaceutical industry.

cell biology↗

bioRxiv2023

Pharmacological modulation of developmental and synaptic phenotypes in human SHANK3 deficient stem cell-derived neuronal models

One sentence summaryThis study describes the use of SHANK3 deficient stem cell-derived neuronal models to screen and characterize small molecules that partially rescued developmental and synaptic defects related to Phelan-McDermid syndrome (PMDS). Phelan-McDermid syndrome (PMDS) arises from mutations in the terminal region of chromosome 22q13, impacting the SHANK3 gene. The resulting deficiency of the postsynaptic density scaffolding protein SHANK3 is associated with autism spectrum disorder (ASD). We examined 12 different PMDS patient and CRISPR-engineered stem cell-derived neuronal models and controls and found that reduced expression of SHANK3 leads to neuronal hyperdifferentiation, increased synapse formation, and decreased neuronal activity. We performed automated imaging-based screening of 7,120 target-annotated small molecules and identified three compounds that rescued SHANK3-dependent neuronal hyperdifferentiation. One compound, Benproperine, rescued the decreased colocalization of Actin Related Protein 2/3 Complex Subunit 2 (ARPC2) with {beta}-actin and rescued increased synapse formation in SHANK3 deficient neurons when administered early during differentiation. Neuronal activity was only mildly affected, highlighting Benproperines effects as a neurodevelopmental modulator. This study demonstrates that small molecular compounds that reverse developmental phenotypes can be identified in human neuronal PMDS models.

neuroscience↗

bioRxiv2023

BCAT1 regulates glioblastoma cell plasticity and contributes to immunosuppression

Glioblastoma is the most common malignant brain tumor in adults. Cellular plasticity and the poorly differentiated features result in a fast relapse of the tumors following treatment. Moreover, the immunosuppressive microenvironment proved to be a major obstacle to immunotherapeutic approaches. Branched-chain amino acid transaminase 1 (BCAT1) is a metabolic enzyme that converts branched-chain amino acids into branched-chain keto acids, depleting cellular -ketoglutarate and producing glutamate. BCAT1 is expressed in and drives the growth of glioblastoma and other cancers. Here we show that low-BCAT1 expression correlates with differentiated glioblastoma subtypes and its knockout (KO) results in a differentiated phenotype in human and mouse glioblastoma cells. Consistent with these observations, Bcat1-KO mouse glioblastoma cells were highly susceptible to serum-induced differentiation in vitro. The transition to a differentiated cell state was linked to the increased activity of TET demethylases and the hypomethylation and activation of neuronal differentiation genes. Orthotopic tumor injection into immunocompetent mice demonstrated that the brain microenvironment is sufficient to induce differentiation of Bcat1-KO tumors in vivo. In addition, the knockout of Bcat1 attenuated immunosuppression, allowing for an extensive infiltration of CD8+ cytotoxic T-cells and complete abrogation of tumor growth. Additional analysis in immunodeficient hosts revealed that both Bcat1-KO-induced differentiation and immunomodulation contribute to the long-term suppression of tumor growth. In summary, our study demonstrates that BCAT1 promotes glioblastoma growth by blocking tumor cell differentiation and sustaining an immunosuppressive microenvironment. These findings suggest novel modes limiting glioblastoma phenotypic plasticity and therapeutic failure through targeting BCAT1. Importance of the studyHigh expression of BCAT1 occurs in many tumor entities and is related to aggressiveness, proliferation and invasion of tumor cells. In this study, we show that its expression is crucial for the continuous growth of glioblastoma cells by preventing their differentiation. Furthermore, we show that the expression of BCAT1 modulates the tumor immune microenvironment, suppressing the CD8 T-cell response. BCAT1 knockout causes glioblastoma cell differentiation and a persistent CD8 T-cell response, which is sufficient to abrogate tumor growth and prolong survival in in vivo immunocompetent and immunodeficient models, respectively. Our findings consolidate BCAT1 as a major player in glioblastoma and highlight its importance as a potential future target of research in this and other tumor entities. Key PointsO_LIBCAT1 expression maintains poorly differentiated features of glioblastoma cells and provides resistance to differentiation. C_LIO_LIExpression of BCAT1 in glioblastoma cells contributes to the immunosuppressive features of the tumor. C_LI

cancer biology↗

bioRxiv2018

A novel system for online fertility monitoring based on milk progesterone

Timely identification of a cows reproduction status is essential to minimize fertilityrelated losses on dairy farms. This includes optimal estrus detection, pregnancy diagnosis and the timely recognition of early embryonic death and ovarian problems. On farm milk progesterone (P4) analysis could indicate all of these fertility events simultaneously. However, milk P4 measurements are subject to a large variability both in terms of measurement errors and absolute values between cycles. In this study, an innovative monitoring system based on milk P4 using the principles of synergistic control is presented. Instead of using filtering techniques and fixed thresholds, the present system employs an individually updated online model to describe the P4 profile, combined with a statistical process control chart to identify the cows fertility status. The inputs for the latter are the residuals of the online model, corrected for the concentration-dependent variability which is typical for milk P4 measurements. The objective of this paper is to present the developed methodology and give an indication of its use on farm. To this end, the system was validated on the P4 profiles of 38 dairy cows. The positive predictive value for luteolysis followed by estrus was 100%, meaning that the monitoring system picked up all estrous periods identified by the experts. Pregnancy or embryonic mortality was characterized by the absence or detection of luteolysis following an insemination, respectively. For thirteen cows, no luteolysis was detected by the system within the 25-32 days after insemination, indicating pregnancy, which was confirmed later by rectal palpation. It was also shown that the system is able to cope with deviating P4 profiles having prolonged follicular or luteal phases, which may suggest the occurrence of cysts. Future research is recommended for optimizing sampling frequency, prediction of the optimal insemination window and the establishment of rules to detect problems based on deviating P4 patterns.\n\nINTERPRETIVE SUMMARY. Progestrone-based online fertility monitoring. Adriaens.Milk progesterone based monitoring systems can be valuable for indicating fertility events in dairy cows, as the evolution of the milk progesterone levels can be related to acyclicity, estrus, pregnancy, and ovarian problems. We developed a system to translate raw progesterone measurements into clear information for the farmer, based on a mathematical model and a statistical control chart. In this way, a detailed image of a cows reproduction status on-farm can be obtained and fertility-related losses minimized.

bioengineering↗