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Biology subjects

Gatti, G.

Publications and source records attributed to Gatti, G..

5 recordsLinked to original sources

Scaling recipes for single-cell RNA sequencing foundation models: when do scaling laws hold?

Deep learning models exhibit empirical scaling laws whereby performance changes predictably with model size, dataset size, and training compute. Although these relationships are well established in domains such as language and image modelling, their applicability to biological data remains unclear. Here, we investigate scaling behaviour in foundation models trained on large collec tions of single-cell transcriptomes. We show that pre-training loss decreases systematically with model capacity and training compute, exhibiting a power law dependence on model size. The strength and regularity of these trends differ between model formulations. We identify and quantify empirical relationships linking the optimal learning rate and depth-to-width ratio to model size and depth or compute. These results demonstrate that scaling principles extend to transcriptomic modelling. More broadly, they provide a quantitative framework for estimating the expected returns from additional resources and selecting suit able hyperparameters and architectures, thereby supporting the development of increasingly capable foundation models for omics data.

bioinformatics↗

iPSC-derived hepatocytes accurately recapitulate population diversity in alpha-1-antitrypsin deficiency and offer a novel in vitro model for large-scale drug efficacy screening studies.

BackgroundAlpha-1 antitrypsin deficiency (A1ATD) is a hereditary recessive disorder caused by mutations in the SERPINA1 gene. It is a clinically under-recognised disease characterised by low circulating A1AT levels and intracellular accumulation of misfolded A1AT in hepatocytes. Deposition of excessive abnormal A1AT in the liver leads to liver failure, yet no specific treatments are available due to the lack of physiologically relevant disease modelling platforms. MethodsWe have hypothesised that human induced pluripotent stem cell (iPSC)-derived hepatocytes can provide an efficient platform to study A1ATD. Using CRISPR/Cas9, we have generated wild-type and A1ATD iPSC-derived hepatocytes (Opti-HEP) from healthy and A1ATD donors and developed a bioassay that mimics the accumulation of misfolded A1AT in the liver. Responses to the reference drug carbamazepine (CBZ), known to reduce intracellular misfolded A1AT levels, and RNA-based therapeutics were subsequently investigated. ResultsAll lines successfully differentiated into hepatocytes as measured by comparable key hepatic and disease markers to those seen in primary human hepatocytes. The diseased lines displayed increased intracellular accumulation of misfolded A1AT compared to isogenic controls. Diseased cell lines showed significant decreases in intracellular accumulation of polymeric A1AT following transfection with RNA-based therapeutics, but a differential response upon treatment with CBZ. ConclusionWe have developed a specific and robust in vitro model of A1ATD that recapitulates disease pathophysiology and responds to small molecule-based treatments and advanced therapeutic strategies. These data demonstrate the suitability of this model for large-scale efficacy screening studies for the treatment of A1ATD and help pave the way towards the development of novel therapies.

cell biology↗

Development of a high-throughput 3D culture microfluidic platform for multi-parameter phenotypic and omics profiling of patient-derived organoids

Patient-derived organoids (PDOs) are poised to become central tools both in clinical practice, to preemptively identify patient optimal treatments, and in drug discovery, overcoming the limitations of cancer cell lines. However, the use of PDOs in these settings has been hampered by several bottlenecks, including sample requirements, assay time, and handling in the context of high-throughput assays. We developed a Microfluidic Platform for Organoids culture (MPO) that miniaturises and simplifies PDOs cultures in a 384-plate format. Both retrospective and prospective clinical studies demonstrate MPO predictive value and the straightforward implementation in the clinical setting. MPO allows subcellular phenotypic screenings, as imaging-based applications like Cell Painting, target engagement analyses, alongside the comprehensive definition of PDOs genomic, transcriptomic, proteomic, lipidomic, and metabolomic landscapes. Harnessing the pleiotropic capabilities of MPO, we uncovered the role of EZH2 inhibitors to prevent the long-term emergence of resistance to RAS inhibitors in metastatic colon cancer. In all, we demonstrate the potential of MPO to impact clinical practice, alongside exploration of the mechanisms underlying compound response and resistance.

cancer biology↗

Development of optimised human iPSC-derived hepatocytes with improved liver function for in vitro metabolic disease modelling and toxicity studies

Background & AimsLiver disease is a rising cause of mortality worldwide. Primary human hepatocytes (PHH) and hepatocellular cancer cells are currently used in drug development, however, they come with limitations, including limited supply, rapid loss of function, and tumorigenic origin. In addition, current iPSC differentiation protocols lead to the generation of hepatocyte-like cells with compromised liver-related features. We hypothesised that optimisation of iPSC differentiation protocols can lead to the generation of hepatocyte-like cells with improved metabolic functionality for disease modelling and toxicity screening studies. MethodsHealthy human iPSCs were differentiated to hepatocyte-like cells (Opti-HEP) using a novel 3-step differentiation protocol. Hepatocyte functionality was assessed, including liver maturity marker expression, urea synthesis, de novo gluconeogenesis, and CYP450 expression, activity, and induction. Suitability of Opti-HEP to predict drug-induced liver injury (DILI) was evaluated by cell viability assays. CRISPR/Cas9 gene editing was employed to generate in vitro inherited metabolic disease models. ResultsOpti-HEP expressed similar liver maturity marker levels to those seen in primary human hepatocytes (PHH), in addition to functional urea and gluconeogenesis pathways. CYP450 expression and activity were comparable between Opti-HEP and PHH, with both cell types showing similar levels of CYP3A4 induction upon 1,25-hydroxy-vitamin D3 treatment. Opti-HEP accurately predicted DILI, following treatment with 7 drugs of known DILI liability. CRISPR-derived Opti-HEP harbouring mutations for inherited metabolic disorders (Ornithine Transcarbamylase Deficiency, Progressive Familial Intrahepatic Cholestasis Type 2, Citrullinemia Type 1) recapitulated key pathophysiological disease features, including reduced protein expression, impaired urea secretion, and bile acid transport. ConclusionsWe demonstrate the generation of optimised iPSC-derived hepatocytes with enhanced liver functionality that is comparable to PHH. These data alongside the expansion capacity and amenability of these cells highlight the opportunities this model can offer in the space of disease modelling and large-scale drug efficacy and hepatotoxicity screening.

cell biology↗

The Drosophila Eukaryotic Initiation Factor eIF6 affects development by regulating apoptosis via the ecdysone pathway

During development, ribosome biogenesis and translation reach peak activities, due to impetuous cell proliferation. Current models predict that protein synthesis elevation is controlled by transcription factors and signalling pathways. Developmental models addressing translation factors overexpression effects are lacking. Eukaryotic Initiation Factor (eIF6) is necessary for ribosome biogenesis and efficient translation. eIF6 is a single gene, conserved from yeasts to mammals, suggesting a tight regulation need. We generated a Drosophila melanogaster in vivo model of eIF6 upregulation, demonstrating a boost in general translation and the shut off of the ecdysone biosynthetic pathway. Translation modulation in S2 cells showed that translational rate and ecdysone biosynthesis are inversely correlated. In vivo, eIF6-driven alterations delayed programmed cell death (PCD), resulting in aberrant phenotypes, partially rescued by ecdysone administration. Our data show that eIF6 triggers a translation program with far-reaching effects on metabolism and development, stressing the driving and central role of translation.

developmental biology↗