Biology subjects

Klaus-Armin, N.

Publications and source records attributed to Klaus-Armin, N..

4 recordsLinked to original sources

bioRxiv2025

Transcriptional dynamics of the oligodendrocyte lineageand its regulation by the brain erythropoietin system

Oligodendrocytes differentiate from oligodendrocyte progenitor cells (OPC) in early postnatal development, but some oligodendrogenesis is maintained throughout adulthood, where oligodendrocyte lineage dynamics may contribute to neuroplasticity, adaptive myelination, and myelin repair. Here, we studied the effect of erythropoietin (EPO) and its receptor (EPOR) on oligodendrocyte lineage dynamics employing murine hippocampus and its myelinated fibers as model region. Using multiple stage-specific markers and single-nuclei-RNA-seq data, we find that EPO stimulates all oligodendroglial lineage cells directly, driving differentiation/maturation. Differential gene expression analysis reveals multiple EPO-regulated mRNAs, including downregulated transcripts for GABA-A receptors, fitting the known inhibition of oligodendrocyte maturation by GABA. Importantly, analogous oligodendrocyte responses are seen when endogenous EPO expression in brain is stimulated by hypoxia. Mice lacking EPOR from mature oligodendrocytes show subtle deficiencies of adult myelination in hippocampal fimbria and mild working memory deficits. These gain- and loss-of-function experiments may further suggest EPO as clinically safe treatment for remyelination therapies.

neuroscience↗

bioRxiv2025

Erythropoietin alleviates intellectual disability and autism-like behavior of mice caused by Zbtb20 haploinsufficiency, a construct-valid model of Primrose syndrome

Among the known genetic causes of syndromic autism spectrum disorders (ASD) are transcription factor deficiencies. In this regard, haploinsufficiency of the zinc finger and broad complex, tramtrack, bric and brac domain-containing protein 20 (ZBTB20) leads to a prototypical clinical picture, referred to as Primrose syndrome, comprising severe ASD symptoms together with intellectual disability. Here, we present a comprehensive behavioral and phenotypical characterization of Zbtb20+/- mice, a construct valid model of this thus far untreatable human condition. Zbtb20+/- mice exhibit diminished sociability, reduced vocalization, distinct repetitive behaviors, impaired cognitive flexibility, hyperactivity and hypoalgesia. Magnetic resonance imaging reveals increased volumes of hippocampus, cerebellum, brain matter, and whole brain, confirmed by postmortem brain weight measurements. Due to our previous observation of enhanced ZBTB20 expression in CA1 pyramidal neurons upon recombinant human erythropoietin (rhEPO) injections, we anticipated a mitigating effect through rhEPO treatment of Zbtb20 deficiency/Primrose syndrome. Indeed, after three weeks of alternate-day rhEPO injections, a remarkable improvement in the behavioral phenotype was observed. Our results highlight rhEPO as a first promising treatment for Primrose syndrome.

neuroscience↗

bioRxiv2025

Forebrain-specific loss of erythropoietin provokes compensatory upregulation of different EPO receptors

The procognitive growth factor erythropoietin (EPO) and its canonical receptor, EPOR, have long been recognized to be expressed by most cell types in the brain. Cognitive domains, improved by injections of exogenous EPO or by endogenous, hypoxia-stimulated EPO, include important forebrain functions, namely attention, working memory, drive, and executive performance. To gain mechanistic insight into the involvement of forebrain-expressed EPO, we deleted EPO in mice using as specific cre-driver Emx1. Here, we report that these mutant mice act comparably to their wildtype littermates in a comprehensive behavioral test battery. Importantly, we find that the transcripts of both EPOR and a novel, brain-expressed EPO receptor, EphB4, respond to EPO deletion with compensatory upregulation. EphB4 expression in brain and its increase upon forebrain erasure of EPOR are confirmed by in situ hybridization and immunohistochemistry. The augmented expression of both EPOR and EphB4 and their regulatory intercorrelation may explain why EmxEPO mutants show an even superior performance in the most challenging working memory task. Using the previously published single-nuclei-RNA-seq dataset, we further confirm the suggested compensatory mechanism, wherein EPO loss or reduction drives elevated EPOR expression, adding another layer to the intricate regulation of EPO signaling in hippocampal pyramidal neurons. Collectively, these data may explain the lack of behavioral and negative cognitive consequences upon forebrain-wide EPO elimination.

neuroscience↗

bioRxiv2025

High affinity cross-context cellular assays reveal novel protein-protein interactions of peripheral myelin protein of 22 kDa

Peripheral Myelin Protein 22 (PMP22) is a tetraspan membrane protein whose altered dosage causes the most common hereditary neuropathy, Charcot-Marie-Tooth disease type 1A (CMT1A). Despite its clinical significance, the physiological functions of PMP22 and the mechanism behind its tightly controlled gene dosage sensitivity remain unknown since over 30 years, in part due to limited knowledge of its protein-protein interactions (PPIs). In fact, integral membrane proteins such as PMP22 are significantly underrepresented in known cellular interactomes, likely due to limited suitability or technical challenges specific to these hydrophobic molecules in the major PPI discovery approaches. Here, we applied a rigorously optimized co-immunoprecipitation and mass spectrometry workflow using the mild detergent DDM and the high affinity ALFA-tag/anti-ALFA nanobody interaction to identify cellular PMP22-associated proteins. In a cross-context approach, we ran our standardized pipeline across multiple cell types including HEK293T, MDCKII epithelial cells, the Schwann cell line MSC80, and primary rat Schwann cells. We confirm known interactors, and uncover distinct, cell type-specific enrichment patterns following functional annotation analysis. Adhesion-related PPIs dominated in MDCKII cells (e.g., CD47, CLDN1, ATP1B1), while in Schwann cells myelin-associated PPIs were enriched. Importantly, we identified novel PPI candidates that may be highly relevant for PMP22 function including enzymes of the de novo sphingolipid biosynthesis pathway.

neuroscience↗