Biology subjects

Willnow, T. E.

Publications and source records attributed to Willnow, T. E..

7 recordsLinked to original sources

bioRxiv2025

Familial Alzheimer disease mutation identifies novel role of SORLA in release of neurotrophic exosomes

Sortilin-related receptor with A-type repeats (SORLA) is an intracellular sorting receptor that directs target proteins between endocytic and secretory compartments of cells. Mutations in SORL1, encoding SORLA, are common in individuals suffering from Alzheimer disease (AD) of unknown etiology. Conceptually, characterization of inheritable SORL1 variants associated with AD can provide important new information about functions of this receptor relevant for aging brain health. Here, we focused on elucidation of the AD-associated variant SORLA N1358S, carrying a mutation in the main ligand binding domain of the receptor. Using unbiased quantitative proteome screens, we identified major alterations in the mutant receptor interactome linked to biogenesis and secretion of exosomes. Using advanced biophysical, cell biological, as well as functional studies in stem cell-derived human cell models we corroborated impaired release and loss of neurotrophic action of exosomes from neurons and microglia expressing SORLAN1358S. An impaired neurotrophic potential was attributed to an altered exosomal content of RNA binding proteins and associated microRNAs, known to control neuronal growth and maturation. Our studies identified a so far unknown function for SORLA in controlling the quantity and trophic quality of extracellular vesicles secreted by cells, and they argue for impaired cellular cross talk through exosomes as a pathological trail contributing to the risk of AD seen with carriers of SORL1 variants.

neuroscience↗

bioRxiv2023

Spatially and temporally distinct patterns of expression for VPS10P domain receptors in human cerebral organoids

Vacuolar protein sorting 10 protein (VPS10P) domain receptors are a unique class of intracellular sorting receptors that emerge as major risk factors associated with psychiatric and neurodegenerative diseases, including bipolar disorders, autism, schizophrenia, as well as Alzheimers disease and frontotemporal dementia. Yet, the lack of suitable experimental models to study receptor functions in the human brain has hampered elucidation of receptor actions in brain disease. Here, we have adapted protocols in human cerebral organoids to the detailed characterization of VPS10P domain receptor expression during development and in mature brain tissue, including single-cell RNA sequencing. Our studies uncovered spatial and temporal patterns of expression unique to individual receptor species in the human brain. While SORL1 expression is abundant in stem cells and SORCS1 peaks at onset of neurogenesis, SORT1 and SORCS2 show increasing expression with maturation of neuronal and non-neuronal cell types, arguing for distinct functions in development versus the adult brain. In neurons, subcellular localization also distinguishes between two types of receptors, either mainly localized to the cell soma (SORL1 and SORT1) or also to neuronal projections (SORCS1 and SORCS2), suggesting divergent functions in protein sorting between Golgi and the endo-lysosomal system or along axonal and dendritic tracks. Taken together, our findings provide an important resource concerning temporal, spatial, and subcellular patterns of VPS10P domain receptor expression in cerebral organoids for further elucidation of receptor (dys)functions causative of behavioral and cognitive defects of the human brain.

developmental biology↗

bioRxiv2023

Sorting receptor SORCS2 facilitates a protective stress response in pancreatic islets

ObjectiveSORCS2 is an intracellular sorting receptor genetically associated with body mass index (BMI) in humans, yet its mode of action remains unknown. Elucidating the receptor function that defines its role in metabolic health is the objective of this work. MethodsCombining in vivo metabolic studies in SORCS2-deficient mouse models with ex vivo structural and functional analyses as well as single-cell transcriptomics of murine pancreatic tissues, we studied the pathophysiological consequences of receptor dysfunction for metabolism. ResultsOur studies identified an important role for SORCS2 in islet stress response essential to sustain glucose-stimulated insulin release. In detail, we show that SORCS2 is predominantly expressed in islet alpha cells. Loss of receptor expression coincides with the inability of these cells to produce osteopontin, a secreted factor that facilitates insulin release from beta cells under stress. In line with diminished osteopontin levels, beta cells in SORCS2- deficient islets show changes in gene expression patterns related to aggravated ER stress, protein misfolding, as well as mitochondrial dysfunction; and they exhibit defects in insulin granule maturation and a blunted response to glucose stimulation in vivo and ex vivo. Impaired glucose tolerance in receptor mutant mice coincides with alterations in body weight and composition. ConclusionOur data identified a novel concept in protective islet stress response involving the alpha cell receptor SORCS2 and provide experimental support for association of SORCS2 with metabolic control in humans.

molecular biology↗

bioRxiv2023

SorLA restricts TNFalpha release from microglia to shape glioma-supportive brain microenvironment

SorLA, encoded by the gene SORL1, is an intracellular sorting receptor of the VPS10P domain receptor gene family. Although SorLA is best recognized for its ability to shuttle target proteins between intracellular compartments in neurons, recent data suggest that also its microglial expression can be of high relevance for the pathogenesis of brain diseases, including glioblastoma (GBM). Here we interrogated the impact of SorLA on the functional properties of glioma-associated microglia and macrophages (GAMs). In the GBM microenvironment, GAMs are re-programmed and in turn lose the ability to elicit anti-tumor responses. Instead, they acquire glioma-supporting phenotype, which is a key mechanism promoting glioma progression. Our analysis of scRNA-seq data from GBM patients revealed that the pro-tumorigenic and pro-inflammatory properties of GAMs are linked to high and low SORL1 expression, respectively. Using cell models, we confirm that SorLA levels are differentially regulated by the presence of glioma cells and by inflammatory cues. We further show that SorLA acts as a sorting receptor for the pro-inflammatory cytokine TNF to restrain its secretion from microglia. As a consequence, loss of SorLA enhanced the pro-inflammatory potential of microglia, having a remarkable impact on glioma progression. In a murine model of glioma, SorLA-deficient mice develop smaller tumors and show hallmarks of anti-tumor response including altered microglia morphology, enhanced necroptosis, and massive neutrophil influx into the tumor parenchyma. Our findings indicate that SorLA is a key player in shaping the phenotype of GAMs, and its depletion can unlock an anti-tumor response. Significance statementOur study provides insight into the mechanisms shaping the tumor microenvironment in glioblastoma (GBM), the most prevalent and aggressive brain malignancy in adults. Poor prognosis in GBM largely results from the properties of the glioma milieu that blocks the anti-tumor response. We show that SorLA restricts release of the pro-inflammatory cytokine TNF from microglia, thereby hampering their anti-glioma response. SorLA depletion reinforces the pro-inflammatory properties of tumor microenvironment and inhibits glioma growth. These findings have significant implications for our understanding of glioma biology, indicating SorLA-TNF interaction as a potential target in GBM therapies. They also offer a new perspective on SorLA activities in microglia which emerge as highly relevant not only for the pathogenesis GBM, but also of other brain diseases such as Alzheimers disease.

neuroscience↗

bioRxiv2019

LRP2 controls sonic hedgehog-dependent differentiation of cardiac progenitor cells during outflow tract formation

Conotruncal malformations are a major cause of congenital heart defects in newborn infants. Recently, genetic screens in humans and mouse models have identified mutations in LRP2 as a novel cause of a common arterial trunk, a severe form of outflow tract (OFT) defect. Yet, the underlying mechanism why the morphogen receptor LRP2 is essential for OFT development remained unexplained. Studying LRP2-deficient mouse models, we now show that LRP2 is expressed in the cardiac progenitor niche of the anterior second heart field (SHF) that contributes to elongation of the OFT during separation into aorta and pulmonary trunk. Loss of LRP2 in mutant mice results in depletion of a pool of sonic hedgehog-dependent progenitor cells in the SHF due to premature differentiation into cardiomyocytes as they migrate into the OFT myocardium. Depletion of this cardiac progenitor cell pool results in aberrant shortening of the OFT, the cause of CAT formation in affected mice. Our findings identified the molecular mechanism whereby LRP2 controls maintenance of progenitor cell fate in the anterior SHF essential for OFT separation, and why receptor dysfunction is a novel cause of conotruncal malformation.

developmental biology↗

bioRxiv2018

SorCS2 controls functional expression of amino acid transporter EAAT3 to protect neurons from oxidative stress and epilepsy-induced pathology

The family of VPS10P domain receptors emerges as central regulator of intracellular protein sorting in neurons with relevance for various brain pathologies. Here, we identified a unique role for the family member SorCS2 in protection of neurons from oxidative stress and from epilepsy-induced cell death. We show that SorCS2 acts as sorting receptor that targets the neuronal amino acid transporter EAAT3 to the plasma membrane to facilitate import of cysteine, required for synthesis of the reactive oxygen species scavenger glutathione. Absence of SorCS2 activity causes aberrant transport of EAAT3 to lysosome for catabolism and impairs cysteine uptake. As a consequence, SorCS2-deficient mice exhibit oxidative brain damage that coincides with enhanced neuronal cell death and increased mortality during epilepsy. Our findings highlight a protective role for SorCS2 in neuronal stress response and provide an explanation for upregulation of the receptor seen in surviving neurons of the human epileptic brain.

neuroscience↗

bioRxiv2018

Single-cell transcriptomics characterizes cell types in the subventricular zone and uncovers molecular defects underlying impaired adult neurogenesis

Neural stem cells (NSCs) contribute to plasticity and repair of the adult brain. Niches harboring NSCs are crucial for regulating stem cell self-renewal and differentiation. We used single-cell RNA profiling to generate an unbiased molecular atlas of all cell types in the largest neurogenic niche of the adult mouse brain, the subventricular zone (SVZ). We characterized > 20 neural and non-neural cell types and gained insights into the dynamics of neurogenesis by predicting future cell states based on computational analysis of RNA kinetics. Furthermore, we apply our single-cell approach to mice lacking LRP2, an endocytic receptor required for SVZ maintenance. The number of NSCs and proliferating progenitors was significantly reduced. Moreover, Wnt and BMP4 signaling was perturbed. We provide a valuable resource for adult neurogenesis, insights into SVZ neurogenesis regulation by LRP2, and a proof-of-principle demonstrating the power of single-cell RNA-seq in pinpointing neural cell type-specific functions in loss-of-function models.\n\nHIGHLIGHTSO_LIunbiased single-cell transcriptomics characterizes adult NSCs and their niche\nC_LIO_LIcell type-specific signatures and marker genes for 22 SVZ cell types\nC_LIO_LIFree online tool to assess gene expression across 9,804 single cells\nC_LIO_LIcell type-specific dysfunctions underlying impaired adult neurogenesis\nC_LI

systems biology↗