Biology subjects

Mueller-Deile, J.

Publications and source records attributed to Mueller-Deile, J..

4 recordsLinked to original sources

bioRxiv2026

miR-378a and NPNT coordinate autophagy regulation in podocytes through mTOR and MAPK signaling

Autophagy is a critical homeostatic mechanism in podocytes, maintaining cellular integrity under stress and proteostatic challenges. Dysregulation of autophagy has been implicated in different glomerular diseases such as diabetes and membranous glomerulonephropathy (MGN), yet the underlying molecular drivers remain incompletely understood. We identified microRNA-378a (miR-378a), previously found upregulated in MGN, as a functional enhancer of autophagic flux in human podocytes and tubular epithelial cells. While miR-378a did not directly alter transcription of canonical autophagy genes (ATG2A, ATG5, ATG7, ATG12), it increased autophagic flux through suppression of mTOR phosphorylation at Ser2448. Given that NPNT is a miR-378a target and a key glomerular basement membrane component, we investigated its role in autophagy regulation. NPNT knockdown reduced ATG2A, ATG7, and BCN1 expression, but paradoxically increased autophagic flux, independent of mTOR, accompanied by enhanced ERK1/2 phosphorylation. These findings reveal a dual-layered regulatory network in which miR-378a promotes autophagy via mTOR inhibition, whereas NPNT modulates autophagy probably through MAPK-dependent signaling. Our results highlight the complex interplay between miRs, extracellular matrix components, and intracellular signaling pathways in podocyte autophagy. Dysregulation of these pathways in kidney disease may reflect both adaptive and maladaptive responses, providing mechanistic insights and potential therapeutic targets to preserve glomerular filtration barrier integrity in immune-mediated kidney disease.

cell biology↗

bioRxiv2026

Glomerular Endothelial Cell-Derived Extracellular Vesicles Cross the Basement Membrane to Regulate Podocyte Function

BackgroundSmall extracellular vesicles (EVs) are nanosized, endosome-derived particles which transfer RNA, proteins, and bioactive molecules to mediate intercellular communication. While EV signaling has been observed in many organ systems, it remains unclear whether glomerular endothelial cell (GEC)-derived small EVs directly interact with podocytes in vivo or how they traverse the glomerular basement membrane (GBM). MethodsGEC-derived small EVs were characterized by nanoparticle tracking analysis, electron microscopy, RAMAN spectroscopy and flow cytometry. Cargo composition was analyzed by proteomics, and microRNA (miR) profiling. Functional and structural features were examined using protease, collagenase, adhesion, and multimodal imaging assays. GEC-derived small EV uptake and downstream transcriptional effects were studied in cultured podocytes, while in vivo trafficking was assessed by injection of labeled small EVs into transgenic zebrafish larvae under baseline conditions, puromycin-induced damage, and cd2ap-knockdown. ResultsGECs released bona fide exosome-like small EVs carrying a highly cell type-specific miR cargo. Small EV transfer to podocytes induced a defined transcriptional response consistent with miR-mediated repression of target genes involved in extracellular matrix organization, cell cycle regulation, and cellular stress responses. Proteomic analyses revealed enrichment of surface proteases and integrin-associated proteins that conferred sustained proteolytic activity and enabled GEC-derived small EV migration through extracellular matrix surrogates. In vivo, circulating small EVs traversed the GBM and localized selectively to podocytes in healthy glomeruli, whereas glomerular injury permitted small EV entry into the tubular compartment. ConclusionThese findings provide first in vivo evidence that GEC-derived small EVs can cross the GBM and impact on podocytes. By identifying integrin- and protease-dependent mechanisms which facilitate vesicle passage, this study redefines the GBM as a dynamic interface of heterocellular, vesicle-mediated communication.

physiology↗

bioRxiv2026

Gut and Glomerular Barriers Determine Nanoplastic Fate and Systemic Impact

Nanoplastics (NPs) are increasingly recognized as pervasive environmental toxicants, however, their interactions with gut and renal barriers, and the resulting systemic consequences remain poorly understood. Here, we studied the uptake of 50 nm polystyrene (PS) nanoparticles using a multi-scale approach integrating zebrafish models, isolated perfused mouse kidneys, and in vitro assays to delineate uptake and barrier-dependent organ distribution. In zebrafish larvae, PS-NPs were efficiently absorbed via the intestinal tract, as visualized by confocal and label-free stimulated Raman scattering (SRS) microscopy, leading to gut microbiota dysbiosis and systemic inflammatory responses. Despite widespread systemic dissemination, renal accumulation was minimal under physiological conditions, whereas both zebrafish and isolated perfused mouse kidneys exhibited substantial PS-NPs retention only when the glomerular filtration barrier was disrupted. In vitro glomerular endothelial cells and podocytes readily internalized PS-NPs without altering key glomerular identity markers, highlighting their intrinsic uptake capacity that is normally restricted in vivo by barrier integrity. Our findings establish the glomerular filtration barrier as a crucial gatekeeper that prevents renal nanoplastic deposition. Furthermore, we revealed a microbiota-mediated axis that may prime the kidney for the environmentally induced stressing in long term.

systems biology↗

bioRxiv2024

Biofabrication of a filtration barrier by integrating electrospun membranes and flow in a glomerular co-culture

The glomerulus is the functional unit of the kidney, where urine is filtered from blood. This process happens through the glomerular filtration barrier (GFB) which is composed of glomerular endothelial cells, podocytes, and glomerular basement membrane (GBM). Damage to any component of GFB results in failure of the barriers function, causing proteinuria that can lead to end-stage kidney failure. There is a high need for reliable in vitro models of the GFB to study pathological conditions and to test potential novel therapeutic options. We established an artificial GBM generated by electrospinning of poly-L-lactic acid fibers that were coated with polydopamine and gelatin and seeded with human glomerular endothelial cells and podocytes onto different sides. The orientation of fibers in the artificial GBM, their surface chemistry and effects on glomerular cells were characterized in depth. Glomerular endothelial cells and podocytes, including hiPSC-derived podocytes formed monolayers on the artificial GBM and revealed cell type-specific marker expression and morphology. Cell-cell communication was possible between podocytes and glomerular endothelial cells in both directions though the artificial membrane. Different molecular dextrans showed size selective permeability of the ex vivo GFB model. Introduction of shear stress by applying flow with a 3D printed micro-bioreactor improved cellular ultrastructure with formation of glomerular endothelial cell fenestrae-like structures and long podocyte foot process-like protrusions that both are usually absent in other in vitro models. Personalized hiPSC-derived podocytes within our model will allow to study the role of patient-specific podocyte mutations or individual treatment response ex vivo in the future.

bioengineering↗