Biology subjects

Marschall, S.

Publications and source records attributed to Marschall, S..

7 recordsLinked to original sources

bioRxiv2025

The functional maturation of mouse spermatozoa is underpinned by global remodeling of the cellular phosphoproteome

The functional maturation of mammalian spermatozoa is driven by modification of their intrinsic proteome as the cells transit the male (epididymal sperm maturation) and female reproductive tracts (capacitation). Here, high-resolution mass spectrometry was used to interrogate the central role that phosphoproteomic changes play in the functional remodeling of mouse spermatozoa. This strategy identified 14,586 site-specific phosphorylation events, including the phosphorylation of 573 proteins and dephosphorylation of 426 during epididymal maturation and additional phosphorylation changes in 211 proteins linked to capacitation. We identified over 300 kinases that putatively govern these events, including three novel kinases (STK33, HIPK4, and PAK1) implicated in acrosomal exocytosis. The functional relevance of these data was confirmed via the use of knockout mouse models, which demonstrated several phosphoproteins as being essential for sperm motility and fertilization capacity. These findings illustrate that large-scale phosphorylation remodeling occurs during sperm maturation with implications extending to novel means of fertility regulation. HIGHLIGHTSO_LISperm phosphoproteome is dramatically remodeled during post-testicular maturation C_LIO_LIIdentification of >14,000 site-specific phosphorylation events providing comprehensive insight into sperm cell signaling events associated with functional maturation C_LIO_LIMajor changes in the sperm phosphoproteome coincide with epididymal maturation whereas capacitation results in more modest changes C_LIO_LIIdentification of 343 novel kinases potentially important for conferring functional maturity to spermatozoa and demonstrated role for STK33, HIPK4 and PAK1 kinases C_LIO_LIKnockout mouse models of 23 genes provided in vivo validation, with loss of these proteins leading to pronounced defects in sperm motility and fertilization capacity C_LIO_LIAll data is available via our interactive ShinySpermPhospho application - https://reproproteomics.shinyapps.io/ShinySpermPhospho/ C_LI

cell biology↗

bioRxiv2025

Rethinking ratio-based normalization: A guide towards model-based approaches in heart weight analysis

Heart weight is a critical parameter in cardiology and mouse research, reflecting structural and functional changes linked to cardiac size or hypertrophy and pathophysiological conditions. Normalizing heart weight (HW) to body weight (BW) or tibia length (TL) is a common practice; however, the validity of these ratios has been questioned due to non-proportional relationships between parameters, and this becomes particularly problematic when comparing distinct populations based on such normalized values. Using data from over 25,000 C57BL/6N wildtype mice provided by the International Mouse Phenotyping Consortium (IMPC), we investigated the limitations of ratio-based normalization when comparing different groups, aiming to propose a robust framework for HW analysis. Our findings reveal negligible to weak correlations between HW, BW, and TL across age and sex groups, undermining the validity of ratio-based methods. A modelling study using simulated data demonstrated that ratios could produce misleading results, including reversed or false group differences, when scaling assumptions are violated. Ratios yield accurate and interpretable results only when a truly proportional relationship exists between the variables--specifically, when the regression line passes through the origin--conditions under which ratio-based normalization aligns with outcomes obtained from more robust modelling approaches. These results underscore the superiority of linear models with covariate adjustment and allometric scaling for organ weight analysis, as they more accurately capture biologically relevant scaling relationships. By leveraging the IMPCs large-scale wildtype dataset, we establish the necessity of reassessing normalization practices in quantitative biology traits and propose that ratios should be avoided when comparing normalized values across distinct populations unless key mathematical assumptions are met. This study advances the analytical rigor in phenotyping research, enabling more accurate interpretations of organ mass and function across biological contexts.

physiology↗

bioRxiv2025

Establishing Comprehensive Transthoracic Echocardiography Reference Ranges for Mouse Models: Insights into the Impact of Anesthesia, Sex, and Age

Mouse models play a critical role in cardiology research, offering valuable insights into the molecular mechanisms, genetics, and potential treatments for cardiovascular diseases. However, the ability to transfer findings in mice between studies is limited by the absence of standardized protocols and valid reference values for the assessment of normal cardiac function in mice. This study aims to establish comprehensive transthoracic echocardiography (TTE) reference ranges for mice, particularly focusing on C57BL/6N wildtype controls. The study, which includes data from over 15,000 mice through the International Mouse Phenotyping Consortium (IMPC), highlights how variables such as sex, age, body weight, and anesthesia affect TTE parameters. The findings showed that anesthesia is the primary predictor of variability in cardiac function. Isoflurane and tribromoethanol anesthetized mice presented with modified cardiac function compared to conscious mice. Additionally, we observed minimal sex differences in cardiac morphology and function, except for small variations influenced by anesthesia. The effects of aging on cardiac function were modest, characterized by a decrease in heart rate and subtle changes in ventricular dimensions without evidence of pathological remodeling, likely attributable to disease-free cardiovascular aging. Validation of the reference ranges across multiple mouse strains showed that these values provide a reliable baseline for experiments involving cardiac function in mice. The data underscore the importance of using anesthesia-specific reference values when interpreting TTE results, ensuring robust comparisons in genetic and pharmacological studies. These reference ranges serve as quality assurance tools for future cardiac studies in mice, offering insights into typical TTE parameter values, supporting the detection of experimental perturbations, and contributing to more effective translation of findings from mouse to human.

genetics↗

bioRxiv2025

Towards a Kingdom of Reproductive Life - the Core Sperm Proteome

Reproductive biology is often considered in three siloed research areas; humans, agriculture and wildlife. Yet, each demand solutions for treatment of subfertility, fertility biomarkers, development of assisted reproductive technologies and effective contraception. To efficiently develop solutions applicable to all species, we must improve our understanding of the common biology underpinning reproductive processes. Accordingly, we integrate proteomic data from 29 publicly available datasets (>2 TB of data) to characterize mature sperm proteomes spanning 12 vertebrate species, identifying 13,853 proteins. Although human and mouse have relatively well-annotated sperm proteomes, many non-model species rely heavily on predicted or homology-inferred identifications. Despite variation in proteome size, composition and reproductive strategies, comparative analyses revealed that vertebrates share a fundamental molecular framework essential for sperm function. A core set of 45 species-level and 135 order-level conserved proteins mapped to critical processes, including energy generation, acrosome function, as well as novel signalling pathways (BAG2 and FAT10). Knockout mouse models further validate the significance of these conserved proteins, demonstrating that their disruption impairs sperm motility and fertilization capacity. Moreover, we discovered loss-of-function variants of two additional core sperm proteins in clinical samples, linking them to severe sperm defects. Intriguingly, in-silico analysis reveals function-driven, context-dependent diversity surpassing evolutionary patterns. Collectively, these results highlight the value of integrating publicly available datasets and underscore the need for improved genome/proteome annotation in non-model species in mammals. This work provides a foundation for developing cross-species strategies to enhance fertility treatments, assisted reproductive technologies, and conservation efforts. All data is available via ShinySpermKingdom (https://reproproteomics.shinyapps.io/ShinySpermKingdom/). IN BRIEFSperm function is essential for fertility across humans, agriculture, and wildlife, yet comparative studies remain limited. This study integrates multi-species proteomic data to identify a core sperm proteome, uncovering conserved molecular pathways and validating novel sperm proteins critical for motility and fertilization.

cell biology↗

bioRxiv2024

Characterization of liver-pancreas crosstalk following beta-cell loss reveals a role for the molybdenum cofactor in beta-cell regeneration

Regeneration of insulin-producing {beta}-cells is an alternative avenue to manage diabetes, and it is crucial to unravel this process in vivo during physiological responses to the lack of {beta}-cells. Here, we aimed to characterize how hepatocytes can contribute to {beta}-cell regeneration in a zebrafish model of {beta}-cell ablation. Using lineage-tracing, we show that hepatocytes do not directly convert into {beta}-cells even under extreme {beta}-cell ablation conditions. A transcriptomics analysis of isolated hepatocytes following {beta}-cell ablation displayed altered lipid- and glucose-related processes. Based on the transcriptomics, we performed a genetic screen that uncovers a potential role for the molybdenum cofactor (Moco) biosynthetic pathway in {beta}-cell regeneration and glucose metabolism in zebrafish. Consistently, Mocs2 haploinsufficiency in mice indicated dysregulated glucose metabolism and liver function. Together, our study sheds light on the liver-pancreas crosstalk and suggests that the molybdenum cofactor biosynthesis pathway should be further studied in relation to glucose metabolism and diabetes.

developmental biology↗

bioRxiv2021

The production of 4,182 mouse lines identifies experimental and biological variables impacting Cas9-mediated mutant mouse line production

The International Mouse Phenotyping Consortium (IMPC) systematically produces and phenotypes mouse lines with presumptive null mutations to provide insight into gene function. The IMPC now uses the programmable RNA-guided nuclease Cas9 for its increased capacity and flexibility to efficiently generate null alleles in the C57BL/6N strain. In addition to being a valuable novel and accessible research resource, the production of 3,313 knockout mouse lines using comparable protocols provides a rich dataset to analyze experimental and biological variables affecting in vivo gene engineering with Cas9. Mouse line production has two critical steps - generation of founders with the desired allele and germline transmission (GLT) of that allele from founders to offspring. A systematic evaluation of the variables impacting success rates identified gene essentiality as the primary factor influencing successful production of null alleles. Collectively, our findings provide best practice recommendations for using Cas9 to generate alleles in mouse essential genes, many of which are orthologs of genes linked to human disease.

genetics↗

bioRxiv2021

Susceptibility to diet induced obesity at thermoneutral conditions is independent of UCP1

ObjectiveActivation of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) upon cold stimulation leads to substantial increase in energy expenditure to defend body temperature. Increases in energy expenditure after a high caloric food intake, termed diet-induced thermogenesis, are also attributed to BAT. These properties render BAT a potential target to combat diet-induced obesity. However, studies investigating the role of UCP1 to protect against diet-induced obesity are controversial and rely on the phenotyping of a single constitutive UCP1-knockout model. To address this issue, we generated a novel UCP1-knockout model by Cre-mediated deletion of Exon 2 in the UCP1 gene. We studied the effect of constitutive UCP1 knockout on metabolism and the development of diet-induced obesity. MethodsUCP1 knockout and wildtype mice were housed at 30{degrees}C and fed a control diet for 4-weeks followed by 8-weeks of high-fat diet. Body weight and food intake were monitored continuously over the course of the study and indirect calorimetry was used to determine energy expenditure during both feeding periods. ResultsBased on Western blot analysis, thermal imaging and noradrenaline test, we confirmed the lack of functional UCP1 in knockout mice. However, body weight gain, food intake and energy expenditure were not affected by deletion of UCP1 gene function during both feeding periods. ConclusionConclusively, we show that UCP1 does not protect against diet-induced obesity at thermoneutrality. Further we introduce a novel UCP1-KO mouse enabling the generation of conditional UCP1-knockout mice to scrutinize the contribution of UCP1 to energy metabolism in different cell types or life stages.

physiology↗