Biology subjects

Mao, A.

Publications and source records attributed to Mao, A..

12 recordsLinked to original sources

bioRxiv2026

α-Synuclein strain homogeneity in multiple system atrophy clinical subtypes

Conformationally distinct strains of -synuclein aggregates are believed to contribute to the clinical and pathological diversity observed among synucleinopathies such as multiple system atrophy (MSA) and Parkinsons disease. Cases of MSA can be classified into two distinct clinical subtypes: the cerebellar variant, MSA-C, and the parkinsonian variant, MSA-P. To assess whether distinct -synuclein strains may be present in individuals with MSA-C versus MSA-P, we characterized the conformational and seeding properties of -synuclein aggregates in various brain regions from MSA-C and MSA-P patients and performed propagation studies in M83 transgenic mice. Biochemical fingerprinting of -synuclein aggregates using limited proteolysis and a conformational stability assay failed to reveal differences between MSA-C and MSA-P either before or after propagation in mice. Similarly, using brain extracts from either MSA patients or MSA-inoculated mice, MSA-C and MSA-P -synuclein aggregates exhibited indistinguishable seeding attributes in a seed amplification assay. Finally, no differences were observed in either the kinetics of disease progression or the extent of cerebral -synuclein deposition in M83 mice inoculated with either MSA-C or MSA-P, regardless of the brain region from which the injected -synuclein aggregates were derived. These results suggest that MSA clinical subtypes are unlikely to arise due to distinct -synuclein strains. Instead, our findings support a model in which the same -synuclein strain initially forms in different brain regions, leading to differences in disease manifestation.

neuroscience↗

bioRxiv2025

Synthetic pectin-cellulose nanofiber capsule provides minimal model capturing mechanics of a regenerating plant cell wall

Plant primary cell walls are dynamic supramolecular assemblies composed of layered cellulose, hemicellulose and pectin, progressively built through synthesis and secretion. However, the specific architectural features and structural components sufficient to endow the mechanical properties of the wall remain unclear. Here, we construct a minimal synthetic spherical shell and compare its structural and mechanical properties to those of a plant single-cell system. To eliminate complexities from intercellular connectivity and developmental history, we exploit the ability of plant protoplasts to regenerate cell walls de novo. Compression tests of regenerating protoplasts between parallel plates reveal that wall stiffness increases with wall thickening over time. Despite differences in assembly pathways, architecture, and composition, the synthetic shell exhibits a similar thickness-dependent modulus and similar material stiffness. The synthetic shell, composed of pectin and cellulose layers, mirrors the mechanical behavior of regenerating primary cell walls, suggesting that these components are sufficient to confer key viscoelastic properties in the limit of small deformations. Given the complexity of natural plant cell walls, the synthetic analogue offers a controllable platform to dissect the mechanical contributions of individual wall components.

plant biology↗

bioRxiv2025

Stochastic Misfolding Drives the Emergence of Distinct α-Synuclein Strains

The existence of -synuclein conformational strains provides a potential explanation for the clinical and pathological differences among synucleinopathies such as Parkinsons disease and multiple system atrophy. However, how distinct -synuclein strains are formed in vivo remains unknown. Here, we examined whether unique strains of self-propagating -synuclein aggregates can arise within a consistent molecular environment. Unexpectedly, we observed conformational heterogeneity between individual preparations of -synuclein pre-formed fibrils (PFFs) generated by polymerizing recombinant wild-type or A53T-mutant human -synuclein under identical conditions. Moreover, we found that -synuclein aggregates formed spontaneously in the brains of a transgenic synucleinopathy mouse model were conformationally diverse, leading to the identification of three distinct disease subtypes. Propagation of putative PFF- and brain-derived -synuclein strains in mice initiated several distinct synucleinopathies, characterized by differences in disease onset times, cerebral -synuclein deposition patterns, and the conformational attributes of -synuclein aggregates. The conformational diversity of -synuclein aggregates across PFF preparations and between the brains of individual transgenic mice demonstrates that -synuclein can spontaneously form multiple self-propagating strains within an identical environment both in vitro and in vivo. This suggests that stochastic misfolding into distinct aggregate structures drives the emergence of -synuclein strains and implies that the intrinsic variability of common synucleinopathy research tools must be considered when designing and interpreting experiments.

neuroscience↗

bioRxiv2025

Specific Pathogen Free Ten Gene-Edited Pig Donor for Xenotransplantation

Xenotransplantation has entered the clinical phase to fulfill the global organ shortage. However, recent clinical studies revealed that the xenograft from current gene-edited (GE) pigs still poses the risk of immune rejection, and biosafety concerns. In this study, we successfully constructed a large batch of 10- (GTKO/CMAHKO/ {beta}4GalNT2KO/hCD46/hCD55/hCD59/hTBM/hEPCR/hCD39/hCD47) GE cloned (GEC) donor pigs by utilizing gene editing and somatic cell cloning technology, and successfully obtained F1 generation. Phenotypic characterization of 10-GEC pigs showed the deletion of three xenoantigens along with expression of seven human transgenes in various tissues. Digital droplet polymerase chain reaction, and whole genome sequencing indicated 2 copies of hCD46/hCD55/hCD59/hTBM/hCD39 and 1 copy of hEPCR/hCD47 in pig genome without significant off-target and damage to the porcine own functional genes. The validation results showed that 10-GEC pigs effectively inhibited the attacks of human antibodies, complement, and macrophages on porcine endothelial cells and alleviated the coagulation abnormalities between pigs and humans. 10-GEC pigs were negative for all zoonotic pathogens (48) including cytomegalovirus, except streptococcal infections. Kidney, heart, and liver xenografts from these 10-GE pigs were transplanted to non-human primates (NHP), which started working normally without hyperacute rejection. Among them, the heart and liver transplant recipient died without resuscitation due to unexpected interruption of oxygen supply, while the 2 kidney transplant recipients survived for 23 and 16 days, respectively. Pathological analysis showed that 10-GE pig kidney xenografts showed mesenchymal congestion, and fibrosis, cellular hyperplasia, with minor antibody and complement deposition, and significantly reduced the infiltration of CD68+ macrophage. In summary, we successfully produced a group of specific pathogen free GEC donor pigs that effectively mitigated immune rejection upon multi-organ transplantation to NHP.

immunology↗

bioRxiv2025

TD2: finding protein coding regions in transcripts

The transcriptome encompasses all RNA transcripts in eukaryotic cells, orchestrating gene expression and regulating cellular function, development, and adaptation. Identifying open reading frames (ORFs) in transcripts is a critical step in transcriptome analysis. We introduce TD2, a new tool for ab initio annotation of protein-coding ORFs in transcripts. We find TD2 to be sensitive and precise when compared to other state-of-the-art tools in reference transcripts and transcriptome assemblies from a diverse array of eukaryotes. TD2 is available at https://github.com/Markusjsommer/TD2. The project is open-source, developed in Python with PyTorch, and is freely available to all academic, government, and commercial users under the MIT license.

genomics↗

bioRxiv2025

OpenSpliceAI: An efficient, modular implementation of SpliceAI enabling easy retraining on non-human species

The SpliceAI deep learning system is currently one of the most accurate methods for identifying splicing signals directly from DNA sequences. However, its utility is limited by its reliance on older software frameworks and human-centric training data. Here we introduce OpenSpliceAI, a trainable, open-source version of SpliceAI implemented in PyTorch to address these challenges. OpenSpliceAI supports both training from scratch and transfer learning, enabling seamless retraining on species-specific datasets and mitigating human-centric biases. Our experiments show that it achieves faster processing speeds and lower memory usage than the original SpliceAI code, allowing large-scale analyses of extensive genomic regions on a single GPU. Additionally, OpenSpliceAIs flexible architecture makes for easier integration with established machine learning ecosystems, simplifying the development of custom splicing models for different species and applications. We demonstrate that OpenSpliceAIs output is highly concordant with SpliceAI. In silico mutagenesis (ISM) analyses confirm that both models rely on similar sequence features, and calibration experiments demonstrate similar score probability estimates.

genomics↗

bioRxiv2024

Combining DNA and protein alignments to improve genome annotation with LiftOn

As the number and variety of assembled genomes continues to grow, the number of annotated genomes is falling behind, particularly for eukaryotes. DNA-based mapping tools help to address this challenge, but they are only able to transfer annotation between closely-related species. Here we introduce LiftOn, a homology-based software tool that integrates DNA and protein alignments to enhance the accuracy of genome-scale annotation and to allow mapping between relatively distant species. LiftOns protein-centric algorithm considers both types of alignments, chooses optimal open reading frames, resolves overlapping gene loci, and finds additional gene copies where they exist. LiftOn can reliably transfer annotation between genomes representing members of the same species, as we demonstrate on human, mouse, honey bee, rice, and Arabidopsis thaliana. It can further map annotation effectively across species pairs as far apart as mouse and rat or Drosophila melanogaster and D. erecta.

bioinformatics↗

bioRxiv2024

Hypergraph Cortical Cytoarchitectonic Parcellation with Multimodal Canine Brain Atlas

Brain atlases are vital tools in exploring the brain structure-function relationship. The burgeoning cross-species atlases have significantly accelerated our understanding of human brain development, evolution, function, and diseases. However, the existing coarse-grained macroscopic canine brain atlases greatly constrain their utility as an animal model for neurocognition research. Finer-grained brain atlas and partitions are crucial for decoding brain spatial heterogeneity and topology at different scales. Therefore, we conduct macroscopic and microscopic brain imaging to construct an interactive online dataset of multimodal canine brain atlas. Additionally, we develop a pioneering method for cortical cytoarchitectonic partitioning based on hypergraph learning. By integrating high-dimensional cytoarchitectonic features and spatial connections between cortical columns, the method leads to fine-grained partitioning patterns. This innovative approach aims to decode the biological heterogeneity of cortical microstructures, contributing to the structural annotation of canine atlas as well as public human brain atlases. The study not only offers valuable resources but also presents a novel zonation approach to investigate the cellular organization pattern and topology of the cortex.

neuroscience↗

bioRxiv2023

Splam: a deep-learning-based splice site predictor that improves spliced alignments

The process of splicing messenger RNA to remove introns plays a central role in creating genes and gene variants. Here we describe Splam, a novel method for predicting splice junctions in DNA based on deep residual convolutional neural networks. Unlike some previous models, Splam looks at a relatively limited window of 400 base pairs flanking each splice site, motivated by the observation that the biological process of splicing relies primarily on signals within this window. Additionally, Splam introduces the idea of training the network on donor and acceptor pairs together, based on the principal that the splicing machinery recognizes both ends of each intron at once. We compare Splams accuracy to recent state-of-the-art splice site prediction methods, particularly SpliceAI, another method that uses deep neural networks. Our results show that Splam is consistently more accurate than SpliceAI, with an overall accuracy of 96% at predicting human splice junctions. Splam generalizes even to non- human species, including distant ones like the flowering plant Arabidopsis thaliana. Finally, we demonstrate the use of Splam on a novel application: processing the spliced alignments of RNA-seq data in order to identify and eliminate errors. We show that when used in this manner, Splam yields substantial improvements in the accuracy of downstream transcriptome analysis on both poly(A) and ribo-depleted RNA-seq libraries. Overall, Splam offers a faster and more accurate approach to detecting splice junctions, while also providing a reliable and efficient solution for cleaning up erroneous spliced alignments.

genomics↗

bioRxiv2022

USP10 strikes down Wnt/β-catenin signaling by dual-wielding deubiquitinase activity and phase transition potential

Wnt/{beta}-catenin signaling is a conserved pathway crucially governing development, homeostasis and oncogenesis. Discovery of novel regulators holds great values in both basic and translational research. Through screening, we identified a deubiquitinase (DUB) USP10 as a novel and critical modulator of {beta}-catenin. Mechanistically, USP10 binds to key scaffold Axin1 via conserved motifs and stabilizes Axin1 through K48-linked deubiquitination, and surprisingly, tethers Axin1 and {beta}-catenin physically while promoting phase separation for {beta}-catenin suppression regardless of its enzymatic activity. Functionally, USP10 prominently regulates embryonic development and intestinal homeostasis by antagonizing {beta}-catenin via DUB activity. In colorectal cancer, USP10 substantially represses cancer growth mainly through physical binding compensation and phase separation promotion and correlates with Wnt/{beta}-catenin magnitude clinically. Collectively, we discovered USP10 functioning in multiple biological processes against {beta}-catenin and unearthed a novel enzyme-dependent and -independent "dual-regulating" mechanism by which USP10 utilizes parallelly and context-dependently. USP10 inhibitor was suggested in treating certain Wnt-related diseases.

cell biology↗

bioRxiv2022

Synthesis of cell-laden alginate microgels with tunable compositions based on microfluidic pico-injection technique

We report a microfluidic pico-injection-based approach for reliably generating monodisperse cell-laden alginate microgels whose composition can be tuned in situ through modulation of the cross-linker concentration. Separating the gelation from emulsification allows for a better control over the microgel size with a microfluidic drop-maker, and an instant adjustment of the microgel composition with a pico-injector.

bioengineering↗

bioRxiv2020

Pharyngeal pouches provide a niche microenvironment for arch artery progenitor specification

The paired pharyngeal arch arteries (PAAs) are transient blood vessels connecting the heart with the dorsal aorta during embryogenesis. Although PAA malformations often occur along with pharyngeal pouch defects, the functional interaction between these adjacent tissues remains largely unclear. Here we report that the ablation of pouches in zebrafish embryos impairs PAA progenitor specification and leads to the absence of PAA structures. Through time-lapse imaging studies, we reveal that the segmentation of pharyngeal pouches coincides spatiotemporally with the emergence of PAA progenitor clusters. These pouches physically associate with pharyngeal mesoderm in discrete regions and provide a niche microenvironment for PAA progenitor commitment by expressing BMP proteins. Specifically, tissue specific knockdown experiments demonstrate that pouch-derived BMP2a and BMP5 are the primary niche cues responsible for activating the BMP/Smad pathway in pharyngeal mesoderm, thereby promoting progenitor specification. In addition, BMP2a and BMP5 play a primary inductive function in the expression of the cloche gene npas4l in PAA progenitors. Mutation of the cloche locus represses the specification of PAA progenitors and generates ectopic muscle precursors in the pharyngeal mesoderm. Therefore, our results support a critical role of pharyngeal pouches in establishing a progenitor niche for PAA morphogenesis via BMP2a/5 expression.

developmental biology↗