Biology subjects

Sieger, D.

Publications and source records attributed to Sieger, D..

4 recordsLinked to original sources

bioRxiv2025

Adenylyl cyclase 9: fundamental change of regulation in vertebrates and gene sub-functionalization after teleost-specific whole-genome duplication

Adenosine 3:5 monophosphate (cAMP) is a ubiquitous signalling molecule generated by the adenylyl cyclase family of proteins which is encoded by ten genes. The biological significance of this diversity is not well understood. In mammals, transmembrane adenylyl cyclase 9 (AC9) is resistant to regulation by heterotrimeric G proteins. A major facet of this resistance is auto-inhibition -- in the presence of activated Gs, AC9 is inhibited by its C-terminal domain. Here, we examined the natural evolution of this seemingly paradoxical control mechanism. At the primary sequence level, the hallmarks of auto-inhibition are apparent in all vertebrates, none are found in invertebrates. Teleost-specific genome duplication (TGD) resulted in adcy9 ohnologs, one of which lacked the hallmarks of auto-inhibition. This was confirmed in functional assays upon cloning and heterologous expression of the requisite cDNAs. The tissue distributions of the adcy9 ohnologs in teleost species also pointed to their sub-functionalization. Above all, auto-inhibited adcy9 was largely restricted to the brain indicating a fundamental role in brain development or function. Our findings document a quantum leap of the regulation of the enzymatic activity of AC9 in vertebrates and the potency of TGD to meet an adaptational challenge through functionally diversified ohnologs.

evolutionary biology↗

bioRxiv2025

RatDISCO, a tissue clearing and immunolabelling protocol for large rat brains.

RatDISCO is a simple, cost-effective, and reproducible tissue-clearing protocol optimised for immunolabeling in adult rat brains. It enables robust detection of diverse neuronal subtypes, glial populations, and vasculature, overcoming key limitations in antibody penetration and optical transparency. It is compatible with virally labelled-and transgenic mice, as well as human-derived brain organoids, highlighting its versatility across species and models. Functionally, it enables the detection of activity-dependent markers after behaviour, verified in a rat model of neurodevelopmental disorders, the Fragile X syndrome. These findings highlight RatDISCO as a broadly applicable tool for investigating neuroanatomical and functional alterations in rat models of disorders. HighlightsO_LIOptimised for immunolabeling in adult rat brains C_LIO_LIEnables detection of neurons, glial cells, and vasculature C_LIO_LIAchieves high tissue transparency without requiring specialised equipment. C_LIO_LICompatible with virally labelled mice and human brain organoids C_LIO_LIFacilitates mapping of activity-dependent markers in rat models of neurodevelopmental disorders C_LI

neuroscience↗

bioRxiv2025

CalciumNetExploreR: An R Package for Network Analysis of Calcium Imaging Data

1Analyzing calcium imaging data to understand complex functional networks can be challenging, often requiring multiple tools, custom scripts, and some coding expertise. To address these challenges, we present CalciumNetExploreR (CNER), an R package designed to streamline and standardize the analysis of time-series data from neuronal populations. While originally developed with calcium imaging in mind, CNERs modular design also makes it adaptable to other sources of neural time-series data, such as fMRI or electrophysiological recordings. CNER integrates essential steps--normalization, binarization, population activity visualization, network construction, degree distribution analysis, principal component analysis (PCA), power spectral density (PSD) evaluation, and event frequency calculations--into a single, cohesive pipeline. This comprehensive approach enables users to efficiently extract and compare network metrics, including clustering coefficients, global efficiency, community structures, and principal component variances. By offering a flexible and customizable framework, CNER simplifies the examination of functional connectivity and network topology, effectively providing the means to characterize a cellular functional network or analogous structures in other modalities. Designed as a user-friendly package, CNER allows both experimental and computational neuroscientists to incorporate robust statistical and graphical analyses into their workflows without extensive coding knowledge. By unifying key analytical components into one pipeline, CNER reduces barriers associated with large-scale data analyses, ultimately facilitating deeper insights into the functional organization and dynamic properties of neuronal networks across diverse recording techniques.

neuroscience↗

bioRxiv2021

Wasl is crucial to maintain microglial core activities during glioblastoma initiation stages.

Microglia actively promote the growth of high-grade gliomas. Within the glioma microenvironment an activated (amoeboid) microglial morphology has been observed, however the underlying causes and the related impact on microglia functions and their tumour promoting activities is unclear. Using the advantages of the larval zebrafish model, we demonstrate that pre-neoplastic glioma cells have an immediate impact on microglial morphology and functions. Overexpression of human HRasV12 in proliferating domains of the larval brain induces an amoeboid morphology of microglia, increases microglial numbers and decreases their motility and phagocytic activity. RNA sequencing analysis revealed lower expression levels of the actin nucleation promoting factor wasla in microglia. Importantly, a microglia specific rescue of wasla expression restores microglial morphology and functions. This results in increased phagocytosis of pre-neoplastic cells and slows down tumour progression. In conclusion, we identified a mechanism that de-activates core microglial functions within the emerging glioma microenvironment.

cancer biology↗