Biology subjects

Maves, L.

Publications and source records attributed to Maves, L..

8 recordsLinked to original sources

bioRxiv2025

Determining preclinical safety of Aclarubicin in pediatric malignancies

BackgroundAnthracyclines are among the most effective chemotherapeutic agents used to treat pediatric malignancies. However, their clinical use is limited by dose-dependent toxicities, particularly cardiotoxicity and secondary malignancies. Aclarubicin (Acla) is an anthracycline derivative that induces chromatin damage while sparing DNA, offering potential therapeutic benefit with reduced longterm toxicity. MethodsWe evaluated the anti-tumor efficacy and safety profile of Acla in multiple in vitro pediatric cancer models and in vivo mouse models designed to mimic anthracycline re-treatment following prior doxorubicin (Doxo) exposure. Tumor growth, genotoxic stress, survival, and organ toxicity were assessed. ResultsAcla demonstrated robust anti-tumor activity comparable to Doxo across diverse pediatric in vitro models. Unlike Doxo, Acla treatment did not induce significant genotoxic stress. In vivo, mice receiving Acla after Doxo exposure showed no evidence of cumulative cardiotoxicity or end-organ damage. In contrast, a second course of Doxo led to significant toxic mortality, but was surprisingly not attributable to classic cardiac injury. ConclusionOur study highlights Acla as a promising anthracycline derivative for pediatric cancers, with potent anti-tumor efficacy and a superior safety profile, even following prior anthracycline exposure. These results support continued investigation of chromatin-damaging anthracyclines that can kill pediatric cancer cells without inducing genotoxic stress. In addition, our studies underscore the need to refine preclinical models to better understand both acute and chronic anthracycline toxicities in pediatric and adolescent populations.

cancer biology↗

bioRxiv2025

Epigenetic small molecule screening identifies a new HDACi compound for ameliorating Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common inherited muscle disease. There are currently few effective therapies to treat the disease, although many approaches are being pursued. Certain histone deacetylase inhibitors (HDACi) have been shown to ameliorate DMD phenotypes in mouse and zebrafish animal models, and the HDACi givinostat has recently gained FDA approval for DMD. Our goal was to identify additional HDACi, or other classes of epigenetic small molecules, that are beneficial for DMD. Using an established animal model for DMD, the zebrafish dmd mutant strain sapje, we screened a library of over 800 epigenetic small molecules of various classes. We used a quantitative muscle birefringence assay to assess and compare the effects of these small molecule treatments on dmd mutant zebrafish skeletal muscle. Our screening identified a new HDACi, SR-4370, that ameliorated dmd mutant zebrafish skeletal muscle degeneration, in addition to HDACi previously shown to improve dmd zebrafish. We find that a single early treatment of HDACi can ameliorate dmd zebrafish. Furthermore, we find that HDACi that improve dmd muscle also cause increased histone acetylation in zebrafish larvae, whereas givinostat does not appear to increase histone acetylation or improve zebrafish dmd muscle. Our results add to the growing evidence that HDACi are promising candidates for treating DMD. Our study also provides further support for the effectiveness of small-molecule screening in dmd zebrafish. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/634796v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@1f9f54aorg.highwire.dtl.DTLVardef@15707bborg.highwire.dtl.DTLVardef@bcafb5org.highwire.dtl.DTLVardef@1b3a8f7_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2025

A systems genetics approach identifies roles for proteasome factors in heart development and congenital heart defects

Congenital heart defects (CHDs) occur in about 1% of live births and are the leading cause of infant death due to birth defects. While there have been remarkable efforts to pursue large-scale whole-exome and genome sequencing studies on CHD patient cohorts, it is estimated that these approaches have thus far accounted for only about 50% of the genetic contribution to CHDs. We sought to take a new approach to identify genetic causes of CHDs. By combining analyses of genes that are under strong selective constraint along with published embryonic heart transcriptomes, we identified over 200 new candidate genes for CHDs. We utilized protein-protein interaction (PPI) network analysis to identify a functionally-related subnetwork consisting of known CHD genes as well as genes encoding proteasome factors, in particular POMP, PSMA6, PSMA7, PSMD3, and PSMD6. We used CRISPR screening in zebrafish embryos to preliminarily identify roles for the PPI subnetwork genes in heart development. We then used CRISPR to create new mutant zebrafish strains for two of the proteasome genes in the subnetwork: pomp and psmd6. Phenotypic analyses confirm critical roles for pomp and psmd6 in heart development. In particular, we find defects in myocardial cell shapes and in outflow tract development in pomp and psmd6 mutant zebrafish embryos, and these phenotypes have been observed in other zebrafish CHD-gene mutants. Our study provides a novel systems genetics approach to further our understanding of the genetic causes of human CHDs. Author SummaryCongenital heart defects (CHDs) are birth defects resulting in the abnormal structure and function of the heart. Genetic mutations are a significant cause of CHDs. Many studies have used genome sequencing of CHD patients and their families to gain knowledge of the mutations that cause CHDs. However, these studies have only found about 50 percent of the genes involved in CHDs. Here, we take a new approach to identifying genes that are required for heart development and that may cause CHDs, generating a list of over 200 candidate genes. Using multiple data systems, including human exome sequences, mouse transcriptomes, and protein-protein interactions, we identify a small group of related potential CHD genes that includes multiple genes encoding proteasome factors. These factors are known to be important for assembling the proteasome, a large molecular machine that eliminates unneeded or damaged proteins from the cell, but which has not been shown to contribute to CHD. We use a CRISPR-based approach in zebrafish to specifically eliminate some of these candidate genes and reveal new roles for proteasome genes in heart development. We show that loss of proteasome gene functions leads to zebrafish heart defects that resemble those seen in other zebrafish CHD-gene mutants. This study shows that a proteasome gene family contributes to heart development, advancing our understanding of the causes of CHDs. By increasing our understanding of the genetic causes of CHDs, our work should lead to better screening, more accurate diagnoses, and, ultimately, better treatments for these disorders.

genetics↗

bioRxiv2024

A Machine Learning Classifier to Identify and Prioritise Genes Associated with Cardiac Development

Congenital heart disease (CHD) is a major cause of infant mortality and presents life-long challenges to individuals living with these conditions. Genetic causes are known for only a minority of types of CHD. Discovering further genetic causes is limited by challenges in prioritising candidate CHD genes. We examined a wide range of features of mouse genes, including sequence characteristics, protein localisation and interaction data, developmental expression data and gene ontology annotations. Many features differ between cardiac development and non-cardiac genes, suggesting that these two gene types can be distinguished by their attributes. Therefore, we developed a supervised machine learning (ML) method to identify Mus musculus genes with a high probability of being involved in cardiac development. These genes, when mutated, are candidates for causing human CHD. Our classifier showed a cross-validation accuracy of 81% in detecting cardiac and non-cardiac genes. From our classifier we generated predictions of the cardiac development association status for all protein-coding genes in the mouse genome. We also cross-referenced our predictions with datasets of known human CHD genes, determining which are orthologues of predicted mouse cardiac genes. Our predicted cardiac genes have a high overlap with human CHD genes. Thus, our predictions could inform the prioritisation of genes when evaluating CHD patient sequence data for genetic diagnosis. Knowledge of cardiac developmental genes may speed up reaching a genetic diagnosis for patients born with CHD. Author SummaryCongenital heart disease arises during pregnancy when the heart has formed incorrectly. These malformations affect [~]1% of newborns. Yet, despite their frequency, the underlying causes are still not known in many cases. It is clear that genetic factors contribute to these defects, and increasingly DNA sequencing is used to attempt to determine if an individual has a genetic change causative of their condition. However, analysis of patient sequence data often reveals changes that are difficult to interpret due to a lack of knowledge of the function of the gene harbouring a sequence change. We aimed to facilitate the process of sequence evaluation by predicting which genes of unknown function are likely involved in heart formation. Our predictions agree with novel experimental evidence about genes needed for heart development. We found that when mutated, a high proportion of the predicted cardiac genes do indeed cause heart defects. This result suggests that our predictions may be informative for expanding our understanding of the genetic basis of congenital heart disease.

genomics↗

bioRxiv2022

High-throughput, real-time monitoring of engineered skeletal muscle function using magnetic sensing

Engineered muscle tissues represent powerful tools for examining tissue level contractile properties of skeletal muscle. However, limitations in the throughput associated with standard analysis methods limit their utility for longitudinal study, high throughput drug screens, and disease modeling. Here we present a method for integrating 3D engineered skeletal muscles with a magnetic sensing system to facilitate non-invasive, longitudinal analysis of developing contraction kinetics. Using this platform, we show that engineered skeletal muscle tissues derived from both induced pluripotent stem cell and primary sources undergo improvements in contractile output over time in culture. We demonstrate how magnetic sensing of contractility can be employed for simultaneous assessment of multiple tissues subjected to different doses of known skeletal muscle inotropes as well as the stratification of healthy versus diseased functional profiles in normal and dystrophic muscle cells. Based on these data, this combined culture system and magnet-based contractility platform greatly broadens the potential for 3D engineered skeletal muscle tissues to impact the translation of novel therapies from the lab to the clinic.

bioengineering↗

bioRxiv2020

Evolutionarily conserved regulation of embryonic fast-twitch skeletal muscle differentiation by Pbx factors

Vertebrate skeletal muscles are composed of both slow-twitch and fast-twitch fiber types. How the differentiation of distinct fiber types is activated during embryogenesis is not well characterized. Skeletal muscle differentiation is initiated by the activity of the myogenic basic helix-loop-helix (bHLH) transcription factors Myf5, Myod1, Myf6, and Myog. Myod1 functions as a muscle master regulatory factor and directly activates muscle differentiation genes, including those specific to both slow and fast muscle fibers. Our previous studies showed that Pbx TALE-class homeodomain proteins bind with Myod1 on the promoter of the zebrafish fast muscle gene mylpfa and are required for proper activation of mylpfa expression and the fast-twitch muscle-specific differentiation program in zebrafish embryos. Pbx proteins have also been shown to bind regulatory regions of muscle differentiation genes in mammalian muscle cells in culture. Here, we use new zebrafish mutant strains to confirm the essential roles of zebrafish Pbx factors in embryonic fast muscle differentiation. Furthermore, we examine the requirements for Pbx genes in mouse embryonic skeletal muscle differentiation, an area that has not been investigated in the mammalian embryo. Removing Pbx1 function from skeletal muscle in Myf5Cre/+;Pbx1fl/fl mouse embryos has minor effects on embryonic muscle development. However, concomitantly deleting Pbx2 function in Myf5Cre/+;Pbx1fl/fl;Pbx2-/- mouse embryos causes delayed activation and reduced expression of fast muscle differentiation genes. In the mouse, Pbx1/Pbx2-dependent fast muscle genes closely match those that have been previously shown to be dependent on murine Six1 and Six4. This work establishes evolutionarily conserved requirements for Pbx factors in embryonic fast muscle differentiation. Our studies are revealing how Pbx homeodomain proteins help direct specific cellular differentiation pathways.

developmental biology↗

bioRxiv2020

A novel drug-combination screen in zebrafish identifies epigenetic small molecule candidates for Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a severe neuromuscular disorder and is one of the most common muscular dystrophies. There are currently few effective therapies to treat the disease, although many small-molecule approaches are being pursued. Specific histone deacetylase inhibitors (HDACi) can ameliorate DMD phenotypes in mouse and zebrafish animal models and have also shown promise for DMD in clinical trials. However, beyond these HDACi, other classes of epigenetic small molecules have not been broadly and systematically studied for their benefits for DMD. Here, we performed a novel chemical screen of a library of epigenetic compounds using the zebrafish dmd model. We identified candidate pools of epigenetic compounds that improve skeletal muscle structure in dmd zebrafish. We then identified a specific combination of two drugs, oxamflatin and salermide, that significantly rescued dmd zebrafish skeletal muscle degeneration. Furthermore, we validated the effects of oxamflatin and salermide in an independent laboratory. Our results provide novel, effective methods for performing a combination small-molecule screen in zebrafish. Our results also add to the growing evidence that epigenetic small molecules may be promising candidates for treating DMD.

pharmacology and toxicology↗

bioRxiv2018

Functional testing of a human PBX3 variant in zebrafish reveals a potential modifier role in congenital heart defects

Whole-genome and whole-exome sequencing efforts are increasingly identifying candidate genetic variants associated with human disease. However, predicting and testing the pathogenicity of a genetic variant remains challenging. Genome editing allows for the rigorous functional testing of human genetic variants in animal models. Congenital heart defects (CHDs) are a prominent example of a human disorder with complex genetics. An inherited sequence variant in the human PBX3 gene (PBX3 p.A136V) has previously been shown to be enriched in a CHD patient cohort, indicating that the PBX3 p.A136V variant could be a modifier allele for CHDs. PBX genes encode TALE (Three Amino acid Loop Extension)-class homeodomain-containing DNA-binding proteins with diverse roles in development and disease and are required for heart development in mouse and zebrafish. Here we use CRISPR-Cas9 genome editing to directly test whether this PBX gene variant acts as a genetic modifier in zebrafish heart development. We used a single-stranded oligodeoxynucleotide to precisely introduce the human PBX3 p.A136V variant in the homologous zebrafish pbx4 gene (pbx4 p.A131V). We find that zebrafish that are homozygous for pbx4 p.A131V are viable as adults. However, we show that the pbx4 p.A131V variant enhances the embryonic cardiac morphogenesis phenotype caused by loss of the known cardiac specification factor, Hand2. Our study is the first example of using precision genome editing in zebrafish to demonstrate a function for a human disease-associated single nucleotide variant of unknown significance. Our work underscores the importance of testing the roles of inherited variants, not just de novo variants, as genetic modifiers of CHDs. Our study provides a novel approach toward advancing our understanding of the complex genetics of CHDs.\n\nSummary statementOur study provides a novel example of using genome editing in zebrafish to demonstrate how a human DNA sequence variant of unknown significance may contribute to the complex genetics of congenital heart defects.

genetics↗