Biology subjects

Moser, S.

Publications and source records attributed to Moser, S..

6 recordsLinked to original sources

bioRxiv2025

A Screening Approach Unveils an Unknown Mn2+ - dependent Endopolyphosphatase Activity in Yeast

Inorganic polyphosphate (polyP) is a ubiquitous biopolymer composed of multiple orthophosphates connected by energy-rich phosphoanhydride bonds. In organisms, polyP is digested by two types of enzymes: exopolyphosphatases, which shorten the chain from the ends by cleaving off monophosphate units, and endopolyphosphatases, which cut the chain internally. While several continuous methods are available to monitor exopolyphosphatase activity, endopolyphosphatase activity assays are less common and typically involve multiple tedious steps. Here, we introduce FRET-polyP8, a novel probe for real-time detection of endopolyphosphatase activity. The FRET assay enabled rapid, highly sensitive, single-step detection of specific endopolyphosphatase activity both from isolated proteins and cell extracts. The simple read-out additionally enabled enzyme inhibitor screening. Furthermore, a novel Mn2+-dependent endopolyphosphatase activity in bakers yeast was detected in a quadruple mutant, highlighting the ability to screen for metal-dependence of new endopolyphosphatase activity. This approach thus represents a significant addition to existing methodologies, facilitating the discovery and classification of new endopoly-phosphatases and their inhibitors to advance our understanding of polyP metabolism and regulation.

biochemistry↗

bioRxiv2025

Tissular glucocorticoid reactivating enzyme 11beta-HSD1 drives pathogenic myofibroblast differentiation in chronic kidney disease

Chronic kidney disease (CKD) is a growing public health crisis, affecting over 10% of the global population and significantly increasing mortality and morbidity. Irrespective of its underlying cause, tubulointerstitial fibrosis (TIF) is a hallmark of CKD progression, with myofibroblasts being the primary effectors of renal fibrosis. Here, we show that 11beta-hydroxysteroid dehydrogenase type 1 (11{beta}-HSD1) is a critical driver of pathogenic myofibroblast differentiation and fibrosis in CKD. Using genetic deletion and pharmacological inhibition of 11{beta}-HSD1 in mouse models, we demonstrate a marked reduction in TIF severity and improved renal function, linked to the suppression of a regulatory myofibroblast (Reg-MF) subpopulation. Single-cell and spatial transcriptomics data reveal that 11{beta}-HSD1 is essential for the activation and expansion of Reg-MFs, which is conserved across species and predicts worse outcomes in CKD patients and kidney allograft recipients. These findings establish a direct link between 11{beta}-HSD1 activity and renal fibrogenesis, highlighting its role during the transition from pericytes to pathogenic Reg-MFs. Our results support 11{beta}-HSD1 inhibition as a promising therapeutic strategy to mitigate CKD progression, offering both mechanistic insights and translational potential for improving patient outcomes.

physiology↗

bioRxiv2024

Optical tomography reconstructing 3D motion and structure of multiple-scattering samples under rotational actuation

Optical Diffraction Tomography (ODT) has emerged as a powerful tool for imaging biological cells in a non-invasive and label-free manner. However, conventional approaches using ODT by varying the illumination are plagued by the missing cone problem, which introduces ambiguity and deteriorates the axial resolution in the reconstruction. Although utilizing object rotation has the potential to yield isotropic resolution, experimental control or prior retrieval of the rotational parameters is challenging. In this work, we demonstrate ODT of multiple-scattering samples undergoing variable rotational motion, unlocking the potential for isotropic resolution in non-contact systems. We introduce a comprehensive reconstruction method to jointly retrieve both sample and rotational motion in 3D. An interferometric setup enables the recording of amplitude and phase data while the object is rotated in a non-contact manner around one or more chosen axes in an acoustofluidic device. We evaluate the tomographic reconstruction performance of the method for clusters of micro-beads and highlight its suitability for biomedical application beyond single cells, demonstrating high-resolution reconstruction of dense cancer spheroids containing more than 100 cells.

bioengineering↗

bioRxiv2024

Expanding the cultivable human archaeome: Methanobrevibacter intestini sp. nov. and strain Methanobrevibacter smithii GRAZ-2 from human feces

Two mesophilic, hydrogenotrophic methanogens, WWM1085 and M. smithii GRAZ-2 were isolated from human fecal samples. WWM1085 was isolated from an individual in the USA, and represents a novel species with in the genus Methanobrevibacter. M. smithii GRAZ-2 (= DSM 116045) was retrieved from fecal samples of a European, healthy female and represents a novel strain within this genus. Both Methanobrevibacter representatives form non-flagellated, short rods with variable morphologies and the capacity to form filaments. Both isolates showed the typical fluorescence of F420 and methane production. Compared to M. smithii GRAZ-2, WWM1085 did not accumulate formate when grown on H2 and CO2. The optimal growth conditions were at 37{degrees}C, and pH 7. Full genome sequencing revealed a genomic difference of WWM1085 to the type strain of M. smithii PS (type strain; DSM 861), with 93.55% ANI and major differences in the sequence of its mcrA gene (3.3% difference in nucleotide sequence). Differences in the 16S rRNA gene were very minor and thus distinction based on this sequence might not be possible. M. smithii GRAZ-2 was identified as a novel strain within the Methanobrevibacter genus (ANI 99.04 % to M. smithii PS). Due to the major differences of WWM1085 and M. smithii type strain PS in phenotypic, genomic and metabolic features, we propose M. intestini sp. nov. as a novel species with WWM1085 as the type strain (DSM 116060T = CECT 30992).

microbiology↗

bioRxiv2023

Ultrasound-Induced Reorientation for Multi-Angle Optical Coherence Tomography

Organoid and spheroid technology have recently provided great insights into oncology, developmental biology as well as personalized medicine. Among the methods to optically monitor the structural and functional organization of such samples, optical coherence tomography (OCT) has emerged as an excellent, label-free approach. Mature organoids, however, are often too opaque for OCT due to regions of strong attenuation. This leads to severe artifacts and reduced morphological tissue information in the reconstruction, since the far-side of the specimen is not reachable. Access to multi-angle views of OCT is therefore highly desirable. This aligns with another problem affecting certain goals of organoid research: The sample needs to be embedded in a growth scaffold such as Matrigel, whereas freely floating objects would not suffer from confinement and be more easily accessible for mechanical or chemical probing. Here we present ULTrasound-Induced reorientation for Multi-Angle-OCT (ULTIMA-OCT), a solution overcoming these limitations. By inserting a small 3D-printed acoustic trap to a spectral-domain OCT system, acoustic actuation enables contact-free levitation and finely tunable stepwise reorientation of samples such as zebrafish larvae and tumor spheroids, in a controlled and reproducible manner. This enables tomographic reconstruction of (sub-)mm samples with enhanced penetration depth and reduced attenuation artifacts, by means of a model-based algorithm we developed. We show that this approach is able to fuse the diverse multi-angle OCT volumes for a joint recovery of 3D-reconstruction of reflectivity, attenuation, refractive index and position registration for zebrafish larvae. We believe that our approach represents a powerful enabling tool for developmental biology and organoid research.

bioengineering↗

bioRxiv2023

Extracellular vesicle-mediated trafficking of developmental cues is altered during human brain disease

Cellular crosstalk is an essential process influenced by numerous factors including secreted vesicles that transfer nucleic acids, lipids, and proteins between cells. Extracellular vesicles (EVs) have been the center of many studies focusing on neuron-to-neuron communication, but the role of EVs in progenitor-to-neuron and -astrocyte communication and whether EVs display cell-type-specific features for cellular crosstalk during neurogenesis is unknown. Here, using human-derived cerebral organoids, neural progenitors, neurons, and astrocytes, we found that many proteins coded by genes associated with neurodevelopmental disorders are transported via EVs. Thus, we characterized the protein content of EVs and showed their cell type-specific dynamics and function during brain development. Changes in the physiological crosstalk between cells can lead to neurodevelopmental disorders. EVs from patients with epilepsy were found altered in composition and function. Alterations in the intracellular and extracellular compartments highlighted a clear dysregulation of protein trafficking. This study sheds new light on the biology of EVs during brain development and neurodevelopmental disorders. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=185 SRC="FIGDIR/small/546646v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1dad15aorg.highwire.dtl.DTLVardef@e699ccorg.highwire.dtl.DTLVardef@17b371borg.highwire.dtl.DTLVardef@5efa7b_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical abstract(left) EV uptake mechanism varies depending on the receiving cell type; NPCs transport neuron EVs (nEVs) and astrocyte EVs (aEVs) to the nucleus, astrocytes localize progenitor EVs (pEVs) to the cytoplasm, and neurons retain pEVs and aEVs along the plasma membrane. (right) Cerebral organoids (COs) from progressive Myoclonus Epilepsy Type I (EPM1) patients release EVs lacking key proteins in neurodevelopment and proteins necessary for EV biogenesis and release. Illustration created using BioRender.

developmental biology↗