Biology subjects

Kretz, O.

Publications and source records attributed to Kretz, O..

6 recordsLinked to original sources

bioRxiv2025

Distinct and Combined Interferon-α/β-receptor-1 Loss in Neurons and Astrocytes Disrupt Brain Energy Metabolism and Drive Parkinsonian Dementia

Dysregulated interferon-alpha/beta-receptor 1 (IFNAR1) signaling was recently identified to contribute to the development of sporadic Parkinsons Disease (PD) into PD with Dementia (PDD). The molecular, cellular, and phenotypic impacts of brain IFNAR1 loss in aging have not been explored in vivo, which may reveal novel disease mechanisms and therapeutic targets. Here it is shown that baseline IFNAR1 expression varies in the major brain cell types, including neurons and astrocytes, and is differentially affected in PD and Lewy Body Dementia patients compared to unaffected controls. Neuron- and astrocyte-specific transcriptomic and proteomic alterations in Ifnar1-/- mice implicate mitochondrial defects and synergistic dysfunctional neurotransmission upon IFNAR1 loss, leading to glucose hypermetabolism measured by functional metabolic analysis. Consequently, Ifnar1-/- mice exhibited PDD-like pathogenesis, including dopaminergic cell loss in the substantia nigra, cortical neurodegeneration, Lewy-body-like inclusions, neuroinflammation, and progressive PDD-like behavior deficits. Brain cell-specific IFNAR1 loss examined in vivo revealed delayed but distinct development of PDD-like phenotypes, where neuropathology, motor, and cognitive behavior deficits were specifically recapitulated only in mice lacking neuronal IFNAR1, and behavior resembling neuropsychiatric abnormalities recapitulated only in mice lacking astrocytic IFNAR1. This work supports a crucial role of IFNAR1 in brain homeostasis and emphasizes a need for understanding neurodegenerative pathophysiology in cell-specific contexts. HighlightsO_LIIFNAR1 and related type-I IFN genes are differentially expressed among major brain cell types in Parkinsons Disease, Lewy Body Dementia, and unaffected controls C_LIO_LIEarly molecular alterations in Ifnar1-/- mice show lack of immunomodulation contributing to neuroinflammation, mitochondrial defects, and dysregulated energy metabolism C_LIO_LIIfnar1-/- mice develop a progressive Parkinsonian-like disease phenotype, including dopaminergic cell loss in substantia nigra, cortical neurodegeneration, phosphorylated (p)alpha-synuclein+ and pTau+ Lewy-body-like inclusions, neuroinflammation, and progressive motor, cognitive, and neuropsychiatric disturbance-like behavior deficits C_LIO_LINeuropathologies, motor, and cognitive deficits are recapitulated in mice lacking neuronal IFNAR1 (Syn1Cre;Ifnar1fl/fl) whereas neuropsychiatric abnormalities are recapitulated in mice lacking astrocytic IFNAR1 (GFAPCre;Ifnar1fl/fl) C_LI

neuroscience↗

bioRxiv2025

Chlamydial membrane vesicles deliver the chlamydial porin OmpA to mitochondria to inhibit apoptosis

Chlamydiae are obligate intracellular bacteria that inhibit mitochondrial apoptosis to maintain integrity of the host cell. We have previously reported that a chlamydial outer membrane {beta}-barrel protein, the porin OmpA, can during ectopic expression inhibit mitochondrial apoptosis through direct interaction with the BCL-2-family effectors BAX and BAK. We here show that OmpA from Chlamydia trachomatis (Ctr) uses membrane vesicles for its delivery to the outer mitochondrial membrane during Ctr infection. Using a number of imaging and fractionation techniques, we show that OmpA during infection reaches mitochondria and is inserted into mitochondrial membranes. Purified membrane vesicles (MV) from Ctr-infected cells contained OmpA. When added to uninfected cells, MV fused with mitochondrial membranes, causing the interaction of OmpA with BAK and the cytosolic retro-translocation of BAX. MV addition to uninfected cells protected the cells against apoptosis. We propose a structural model of this BAK inhibition by OmpA that reenacts the inhibition of BAK by the mitochondrial porin VDAC2. The results provide evidence that the porin from Chlamydia, as well as the structurally similar porin from the related Simkania, specifically exploits its relationship to mitochondrial porins to protect the infected cell against apoptosis and to enable intracellular growth of the bacteria in human cells.

cell biology↗

bioRxiv2023

Structure of the N-terminal didomain d1_d2 of the Thrombospondin type-1 domain-containing 7A

Thrombospondin type-1 domain-containing 7A (THSD7A) is a large extracellular protein that is found in podocyte foot processes of the kidney glomerulus. It has been established as a causative autoantigen in membranous nephropathy. Amongst the predicted 21 thrombospondin repeat domains of its extracellular segment, the highest frequency of autoimmune response has been associated with the two N-terminal domains. Here, we show that antibodies against this THSD7A segment in mice induce typical clinical and morphological signs of membranous nephropathy. The high-resolution structure of these two domains reveals a non-canonical thrombospondin repeat fold that is distinct from the established type 1 thrombospondin repeat. As it shares a conserved disulfide pattern with the canonical fold, we refer to these domains d1 and d2 as type 1A thrombospondin repeats. Both domains comprise a seven layered CC-W-PP-R-W-QQ-CC pattern, which is only partly shared by other THSD7A thrombospondin repeat domains. The two domains form a well-defined V-shaped tandem arrangement. Our findings provide crucial insight into specific structural features of these two domains that are distinct from other regions of THSD7A and hence could cause the high level of antigenicity found for these two domains.

biophysics↗

bioRxiv2021

Synuclein alpha accumulation mediates podocyte injury in Fabry nephropathy

Current therapies for Fabry disease are based on reversing intra-cellular accumulation of globotriaosylceramide (Gb3) by enzyme replacement therapy (ERT) or chaperone-mediated stabilization of the defective enzyme, thereby alleviating lysosome dysfunction. However, their effect in the reversal of endorgan damage, like kidney injury and chronic kidney disease remains unclear. First, ultrastructural analysis of serial human kidney biopsies showed that longterm use of ERT reduced Gb3 accumulation in podocytes but did not reverse podocyte injury. Then, a CRISPR/CAS9-mediated -Galactosidase knockout podocyte cell line confirmed ERT-mediated reversal of Gb3 accumulation without resolution of lysosomal dysfunction. Transcriptome-based connectivity mapping and SILAC-based quantitative proteomics identified alpha-synuclein (SNCA) accumulation as a key event mediating podocyte injury. Genetic and pharmacological inhibition of SNCA improved lysosomal structure and function in Fabry podocytes, exceeding the benefits of ERT. Together, this work reconceptualizes Fabry-associated cell injury beyond Gb3 accumulation, and introduces SNCA modulation as a potential intervention, especially for patients with Fabry nephropathy.

molecular biology↗

bioRxiv2021

Multiplexed mRNA analysis of brain-derived extracellular vesicles upon experimental stroke in mice reveals increased mRNA content related to inflammation and recovery processes

Extracellular vesicles (EVs) are lipid bilayer enclosed structures that not only represent a newly discovered means for cell-to-cell communication but may also serve as promising disease biomarkers and therapeutic tools. Apart from proteins, lipids, and metabolites, EVs can deliver genetic information such as mRNA eliciting a response in the recipient cells. In the present study, we have analyzed the mRNA content of brain-derived EVs (BDEVs) isolated 72 hours after experimental stroke in mice and compared them to controls (shams) using the nCounter(R) Nanostring panels, with or without prior RNA isolation from BDEVs. We found that both panels show similar results when comparing upregulated mRNA in stroke. Notably, the higher upregulated mRNAs were related to processes of stress and immune system responses, but also to anatomical structure development, cell differentiation, and extracellular matrix organization, indicating that regenerative mechanisms are already taking place at this time-point. The five top overexpressed mRNAs in stroke mice compared to shams were confirmed by RT-qPCR and, interestingly, were found to be present as full-length open-reading frame in BDEVs. We could reveal that the majority of the mRNA cargo in BDEVs was of microglial origin and probably predominantly present in small BDEVs ([≤] 200 nm in diameter). However, the EV population with the highest increase in the total BDEVs pool at 72 h after stroke was of oligodendrocytic origin. Our study shows that nCounter(R) panels are a good tool to study mRNA content in tissue-derived EVs as they can be carried out even without previous mRNA isolation and that the mRNA cargo of BDEVs indicates their participation in inflammatory but also recovery processes after stroke.

neuroscience↗

bioRxiv2019

The proteome of small urinary extracellular vesicles after kidney transplantation as an indicator of renal cellular biology and a source for markers predicting outcome

Kidney transplantation is the preferred renal replacement therapy available. Yet, the biological processes during and after kidney transplantation and how they translate into the overall functional graft outcome are insufficiently understood. Recent developments in the field of extracellular vesicle research allow the deeper exploitation of this non-invasive source. We separated small urinary extracellular vesicles (suEVs) throughout the course of living donor kidney transplantation. SuEVs were collected longitudinally from both the donor and the recipient in 22 living donor kidney transplantations. Unbiased proteomic analysis revealed specific temporal patterns of suEV proteins indicative of the cellular processes involved in the allografts response after transplantation with proteins playing a role in complement activation being among the most dynamically regulated components. Using a leave-one-out cross validation model, we identified potential prognostic markers of kidney function at 1 year after transplantation. One of the proteins identified - phosphoenol pyruvate carboxykinase (PCK2) - could be confirmed in an independent validation cohort of another 22 donor-recipient pairs using targeted mass spectrometry. This study sheds the light on early molecular processes during the course of kidney transplantation and shows the future potential of suEVs as a source of biomarkers in this setting. The data set is provided as a unique resource directly accessible through an online tool that allows dynamic interrogation of this first comprising suEV proteome atlas after kidney transplantation. One Sentence SummaryThis study represents the first atlas of the proteomic changes in small urinary extracellular vesicles throughout living donor kidney transplantation identifying PCK2 abundance as a biomarker for renal function 12 months after transplantation

molecular biology↗