Systematic elucidation of neuron-astrocyte interaction in models of amyotrophic lateral sclerosis using multi-modal integrated bioinformatics workflow

Abstract

Cell-to-cell communications are critical determinants of pathophysiological phenotypes, but methodologies for their systematic elucidation are lacking. Herein, we propose an approach for the Systematic Elucidation and Assessment of Regulatory Cell-to-cell Interaction Networks (SEARCHIN) to identify ligand-mediated interactions between distinct cellular compartments. To test this approach, we selected a model of amyotrophic lateral sclerosis (ALS), in which astrocytes expressing mutant superoxide dismutase-1 (mutSOD1) kill wild-type motor neurons (MNs) by an unknown mechanism. Our integrative analysis that combines proteomics and regulatory network analysis infers the interaction between astrocyte-released amyloid precursor protein (APP) and death receptor-6 (DR6) on MNs as the top predicted ligand-receptor pair. The inferred deleterious role of APP and DR6 is confirmed in vitro in models of ALS. Moreover, the DR6 knockdown in MNs of transgenic mutSOD1 mice attenuates the ALS-like phenotype. Our results support the usefulness of integrative, systems biology approach to gain insights into complex neurobiological disease processes as in ALS and posit that the proposed methodology is not restricted to this biological context and could be used in a variety of other non-cell-autonomous communication mechanisms.

Taking Cellular Heterogeneity Into Consideration When Modeling Astrocyte Involvement in Amyotrophic Lateral Sclerosis Using Human Induced Pluripotent Stem Cells

“…The biological heterogeneity of astrocytes in the healthy nervous system is, perhaps not surprisingly, correlated with the demonstration that not all astrocytes are equally susceptible to dysfunction in ALS, as well as other neurological conditions (Goursaud et al, 2009;Li et al, 2016;Bugiani et al, 2018;Köhler et al, 2021;Nguyen et al, 2021). Moreover, different types of astrocytes interact selectively with different motor neurons under both physiological and pathological conditions (Kelley et al, 2018a;Gomes et al, 2020;Mishra et al, 2020;Barbosa et al, 2021). More specifically, studies by Kelley and colleagues showed that loss of the inward-rectifying K + channel Kir4.1 in astrocytes located in the ventral horn of the murine spinal cord selectively alters large fast alpha-motor neuron size and function, leading to reduced peak strength (Kelley et al, 2018b).…”

“…As discussed above, the regional and functional diversity of astrocytes in both the brain and spinal cord underlies specialized interactions of specific astrocyte populations with particular neuronal neighbors (Hochstim et al, 2008;Tsai et al, 2012;Bayraktar et al, 2014;Molofsky et al, 2014;Kelley et al, 2018a;Mishra et al, 2020), underscoring the importance of accounting for astrocyte heterogeneity when studying the involvement of astrocytes in neurodegenerative diseases such as ALS. Up to date, hiPSC-derived astrocyte cultures used to model ALS pathophysiology have usually included a mix of multiple types of astrocytes (e.g., Hall et al, 2017;Madill et al, 2017;Qian et al, 2017;Tyzack et al, 2017;Kelley et al, 2018a;Birger et al, 2019;Varcianna et al, 2019;Rajpurohit et al, 2020;Smethurst et al, 2020;Zhao et al, 2020).…”

Storage of Mutant Human SOD1 in Non-Neural Cells from the Type-1 Amyotrophic Lateral Sclerosis ratG93A Model Correlated with the Lysosomes’ Dysfunction

“…Compared to the published studies mainly conducted in ALS1 neural cells (e.g., motor neurons, astrocytes [ 47 , 48 , 49 , 50 , 51 , 52 , 53 ]) we chose primary fibroblasts (rFFFs) and bone marrow- mesenchymal stem cells (rBM-MSCs) from the ALS1 rat G93A as cell models. We demonstrated that the presence of the hallmarks of the disease broad in non-neural cells, and the signs increase with the progression of the disease.…”

Mast Cell and Astrocyte Hemichannels and Their Role in Alzheimer’s Disease, ALS, and Harmful Stress Conditions

“…Non-cell autonomous toxicity to motoneurons has also been shown using conditioned media from human and mouse astrocytes expressing ALS-linked mutations ( SOD1 , TARDBP, C9ORF72 ) or that lack identified causes of ALS (sALS) [ 134 , 135 , 136 , 137 , 138 , 139 , 140 , 141 , 142 ]. Despite considerable efforts, so far, the toxic factor released by ALS astrocytes has not been identified, although a recent study by the Przedborski laboratory indicates that mutant SOD1 astrocytes release a soluble protein(s) or fragment(s) between 5 and 30 kDa [ 143 ]. These and other studies rule out several usual suspect molecules, such as glutamate, ATP, oxygen and nitrogen reactive species, TNFα, and SOD1 [ 134 , 137 , 143 ].…”

“…Despite considerable efforts, so far, the toxic factor released by ALS astrocytes has not been identified, although a recent study by the Przedborski laboratory indicates that mutant SOD1 astrocytes release a soluble protein(s) or fragment(s) between 5 and 30 kDa [ 143 ]. These and other studies rule out several usual suspect molecules, such as glutamate, ATP, oxygen and nitrogen reactive species, TNFα, and SOD1 [ 134 , 137 , 143 ]. Nonetheless, astrocytes release numerous additional small pro-inflammatory molecules or bioactive substances, which can have pathological effects on motoneurons (see Figure 2 ; [ 144 , 145 ]).…”