Biology subjects

Boumeester, V.

Publications and source records attributed to Boumeester, V..

3 recordsLinked to original sources

bioRxiv2023

Interactome mapping reveals a role for LRP10 in autophagy and NDFIP1-mediated alpha-synuclein secretion

Variants in the LRP10 gene have been found in a spectrum of neurodegenerative disorders, including Lewy body diseases (LBDs). In brains of LBD patients, LRP10 is found in neuronal -synuclein-containing Lewy bodies, astrocytes, and vasculature, but not in inclusion-free neurons. Furthermore, recent work suggests that LRP10 is involved in -synuclein processing and transmission, which is disrupted by the LBD-associated LRP10:c.1424+5G>A variant (LRP10-Splice). In spite of the cumulating genetic and functional evidence for a role of LRP10 in neurodegenerative disorders, our knowledge about the biological processes in which LRP10 is involved is incomplete. In this work, we provide a list of LRP10 interactors identified via LRP10 co-immunoprecipitation and mass spectrometry in LRP10-overexpressing cells and induced pluripotent stem cells (iPSC)-derived astrocytes. In addition to interactors and biological processes previously associated with LRP10, we identified novel interactors and pathways that may provide new insights into LRP10 function. Based on these findings, we focused on the involvement of LRP10 in the autophagy and unconventional secretion pathways via its interaction with the autophagy receptor SQSTM1/p62 and the ubiquitin-proteasome adaptor protein NDFIP1, respectively. We demonstrate that changes in LRP10 levels, either via knock-out or overexpression, affect p62 levels and autophagy in HuTu-80 cells and iPSC-derived astrocytes. Furthermore, we found that both LRP10 and NDFIP1 stimulate -synuclein secretion and synergistically affect intracellular -synuclein levels. Next, we studied the LRP10 interactome and related biological processes in iPSC-derived astrocytes carrying the LRP10-Splice variant. Although various interactors and biological processes were shared between wild-type LRP10 (LRP10-WT) and LRP10-Splice, others were only found in either LRP10-WT or LRP10-Splice. Interestingly, we found that LRP10-Splice responded differently to autophagy-modulating drugs in comparison to LRP10-WT. Furthermore, we show that LRP10-Splice interferes with the LRP10-WT:NDFIP1 interaction and NDFIP1-mediated -synuclein secretion. Finally, we investigated the interactome of a secreted LRP10 species only found in conditioned media from LRP10-Splice carrier cells, and identify biological processes that might be impacted by the secreted LRP10-Splice specific protein. In summary, this study enhances our understanding of LRP10 biology, describes LRP10 functions in autophagy and NDFIP1-mediated -synuclein secretion, and reveals potentially interesting differences between LRP10-WT and LRP10-Splice carrier cells that might be relevant to better understand the role of LRP10 in LBDs pathogenesis.

neuroscience↗

bioRxiv2023

LRP10 as a novel α-synuclein regulator in Lewy body diseases

Autosomal dominant variants in LRP10 have been identified in patients with Lewy body diseases (LBDs), including Parkinsons disease (PD), Parkinsons disease-dementia (PDD), and dementia with Lewy bodies (DLB). Nevertheless, there is little mechanistic insight into the role of LRP10 in disease pathogenesis. In the brains of non-demented individuals, LRP10 is typically expressed in non-neuronal cells like astrocytes and neurovasculature, but in idiopathic and genetic cases of PD, PDD, and DLB it is also present in -synuclein-positive neuronal Lewy bodies. These observations raise the questions of what leads to the accumulation of LRP10 in Lewy bodies and whether a possible interaction between LRP10 and -synuclein plays a role in disease pathogenesis. Here, we demonstrate that wild-type LRP10 is secreted via extracellular vesicles (EVs) and can be internalised via clathrin-dependent endocytosis. Additionally, we show that LRP10 secretion is highly sensitive to autophagy inhibition, which induces the formation of atypical LRP10 vesicular structures in neurons in human induced pluripotent stem cells (iPSC)-derived midbrain-like organoids (hMLOs). Furthermore, we show that LRP10 overexpression leads to a strong induction of monomeric -synuclein secretion, together with time-dependent, stress-sensitive changes in intracellular -synuclein levels. Interestingly, patient-derived astrocytes carrying the c.1424+5G>A LRP10 variant secrete aberrant high-molecular-weight species of LRP10 in EV-free media fractions. Finally, we show that the truncated LRP10splice protein binds to wild-type LRP10, reduces LRP10 wild-type levels, and antagonises the regulatory effect of LRP10 on -synuclein levels and distribution. Together, this work provides initial evidence for a functional role of LRP10 in LBDs by regulating intra- and extracellular -synuclein levels, and pathogenic mechanisms linked to the disease-associated c.1424+5G>A LRP10 variant, pointing towards potentially important disease mechanisms in LBDs.

neuroscience↗

bioRxiv2022

deCLUTTER2+ pipeline to analyze calcium traces in a novel stem cell model for ventral midbrain patterned astrocytes

Astrocytes are the most populous cell type of the human central nervous system and are essential for physiological brain function. Increasing evidence suggests multiple roles for astrocytes in Parkinsons disease (PD), nudging a shift in the research focus, which historically pivoted around the ventral midbrain dopaminergic neurons (vmDANs). Studying human astrocytes and other cell types in vivo remains technically and ethically challenging. However, in vitro reprogrammed human stem cell-based models provide a promising alternative. Here, we describe a novel protocol for astrocyte differentiation from human stem cell-derived vmDANs-generating progenitors. This protocol simulates the regionalization, gliogenic switch, radial migration, and final differentiation that occur in the developing human brain. We have characterized the morphological, molecular, and functional features of these ventral midbrain astrocytes with a broad palette of techniques. In addition, we have developed a new pipeline for calcium imaging data analysis called deCLUTTER2+ (deconvolution of Ca2+ fluorescent patterns) that can be used to discover spontaneous or cue-dependent patterns of Ca2+ transients. Altogether, our protocol enables the characterization of the functional properties of human ventral midbrain astrocytes under physiological conditions and in PD.

neuroscience↗