Astrocyte secreted proteins selectively increase hippocampal GABAergic axon length, branching, and synaptogenesis

Hughes, Ethan G.; Elmariah, Sarina B.; Balice-Gordon, Rita J.

doi:10.1016/j.mcn.2009.10.004

Cited by 119 publications

(115 citation statements)

References 43 publications

(60 reference statements)

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“…Conditioned media from wt astrocytes, but not from HD astrocytes, rescued the neuritic defect, suggesting that cholesterol dysfunction in glial cells may contribute to neuritic morphology defects, thereby compromising neuron function. Although several glialderived factors may contribute to neurite outgrowth in cultured neurons, 38 we demonstrated a direct link between glial cholesterol and neurite outgrowth in HD neurons. First, we showed that cholesterol administration rescued neuritic defects in HD neurons during early stages of differentiation.…”

Section: Discussionmentioning

confidence: 53%

Disruption of astrocyte-neuron cholesterol cross talk affects neuronal function in Huntington’s disease

et al. 2014

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In the adult brain, neurons require local cholesterol production, which is supplied by astrocytes through apoE-containing lipoproteins. In Huntington's disease (HD), such cholesterol biosynthesis in the brain is severely reduced. Here we show that this defect, occurring in astrocytes, is detrimental for HD neurons. Astrocytes bearing the huntingtin protein containing increasing CAG repeats secreted less apoE-lipoprotein-bound cholesterol in the medium. Conditioned media from HD astrocytes and lipoprotein-depleted conditioned media from wild-type (wt) astrocytes were equally detrimental in a neurite outgrowth assay and did not support synaptic activity in HD neurons, compared with conditions of cholesterol supplementation or conditioned media from wt astrocytes. Molecular perturbation of cholesterol biosynthesis and efflux in astrocytes caused similarly altered astrocyteneuron cross talk, whereas enhancement of glial SREBP2 and ABCA1 function reversed the aspects of neuronal dysfunction in HD. These findings indicate that astrocyte-mediated cholesterol homeostasis could be a potential therapeutic target to ameliorate neuronal dysfunction in HD. Huntington's disease (HD) is an adult-onset neurodegenerative disorder characterized by cell loss mainly in the striatum and cortex. Its pathophysiology is linked to an expanded CAG repeat in the IT-15 gene, which leads to an elongated polyQ tract in huntingtin (HTT) protein. No disease-modifying treatment is available for HD and novel pathophysiological insights and therapeutic strategies are needed. 1 Lipids are vital to brain health and function. Accordingly, the brain has a local source of cholesterol, 2 and a breakdown of cholesterol synthesis causes brain malformations and impaired cognitive function. 3,4 Cholesterol metabolism is disrupted in HD 5,6 as revealed by transcriptional, biochemical, and mass spectrometry analyses in HD rodent models. 7,8 This dysregulation is linked to a specific action of mutant HTT on sterol-regulatory-element-binding proteins (SREBPs) and on its target genes, whose reduced transcription leads to lower brain cholesterol levels. 7 In HD humans, brain cholesterol homeostasis is affected since pre-symptomatic stages, as determined by measurement of the brain-specific cholesterol catabolite 24-S-hydroxy-cholesterol (24OHC). 9,10 However, it remains unclear how reduced brain cholesterol would become pathological for HD neurons.In adulthood, astrocytes produce cholesterol, which is secreted as a complex with apolipoprotein (apo) E lipoproteins and delivered to neurons. 11,12 Mutant HTT is expressed in glial cells, 13,14 and transgenic mice overexpressing mutant HTT in astrocytes show age-dependent neurological symptoms. 15,16 Additionally, primary astrocytes overexpressing full-length human mutant HTT show reduced mRNA levels of cholesterol biosynthetic genes, along with impaired cellular production and secretion of apoE. 8 Here we employed molecular and cellular tools to test the impact of cholesterol perturbation between astrocytes and neur...

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Section: Discussionmentioning

confidence: 53%

Disruption of astrocyte-neuron cholesterol cross talk affects neuronal function in Huntington’s disease

et al. 2014

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“…TSP-induced synapses in culture are ultrastructurally normal and presynaptically active, but lack postsynaptic activity (Christopherson et al 2005;Eroglu et al 2009). TSPs do not promote inhibitory GABAergic synaptogenesis (Hughes et al 2010). Glutamatergic synapatogenic activity is mediated by interaction of the EGF-like domains of TSPs with the vWF_A domain of a2d-1, a ubiquitously expressed, nonessential subunit of L-type calcium channel that is the target of the drug gabapentin (Eroglu et al 2009).…”

Section: Neuronal Cellsmentioning

confidence: 99%

The Thrombospondins

Adams¹,

Lawler²

2011

Cold Spring Harbor Perspectives in Biology

403

416

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Thrombospondins are evolutionarily conserved, calcium-binding glycoproteins that undergo transient or longer-term interactions with other extracellular matrix components. They share properties with other matrix molecules, cytokines, adaptor proteins, and chaperones, modulate the organization of collagen fibrils, and bind and localize an array of growth factors or proteases. At cell surfaces, interactions with an array of receptors activate celldependent signaling and phenotypic outcomes. Through these dynamic, pleiotropic, and context-dependent pathways, mammalian thrombospondins contribute to wound healing and angiogenesis, vessel wall biology, connective tissue organization, and synaptogenesis. We overview the domain organization and structure of thrombospondins, key features of their evolution, and their cell biology. We discuss their roles in vivo, associations with human disease, and ongoing translational applications. In many respects, we are only beginning to appreciate the important roles of these proteins in physiology and pathology.T hrombospondins (TSPs) comprise a conserved family of extracellular, oligomeric, multidomain, calcium-binding glycoproteins. In general, basal metazoa and protostomes encode a single TSP in their genomes and deuterostomes have multiple TSP genes. The TSPs of mammals have many complex tissue-specific roles, including activities in wound healing and angiogenesis, vessel wall biology, connective tissue organization, and synaptogenesis. These activities derive mechanistically from interactions with cell surfaces, growth factors, cytokines, or components of the extracellular matrix (ECM) that collectively regulate many aspects of cell phenotype. Emerging evidence on the functions of TSPs in invertebrates suggests that ancient functions include bridging activities in cell-cell and cell-ECM interactions. Knowledge of TSP domain structures provides a rational basis for understanding their roles in vivo and associations with human disease and is assisting ongoing translational applications. DOMAIN ARCHITECTURE AND DOMAIN STRUCTURESThe domain architectures of representative TSP polypeptides are shown in Figure 1A. The invariant carboxy-terminal regions comprise a series of EGF-like domains, thirteen calcium-binding type 3 repeats, and a carboxy-terminal domain structurally homologous to the L-type lectin

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“…Above all, we describe a serum -free culturing method for long -term neuronal cultures with preserved functionality and connectivity, reminiscent of that seen in the intact tissue. The three culturing protocols that we compared were: I-FBS based medium (traditionally used in our lab 26 and by other research groups 17,27,28 ; II-Neurobasal/B27 medium as described in Beaudoin 7 ; III-our serum -free ACM medium. The exact composition for all the three growing media is reported in the Methods section and the conditions are referred to as FBS, B27 and ACM, respectively.…”

Section: Introduction *Manuscript (With Page Numbers) Click Here To Dmentioning

confidence: 99%

An improved method for growing neurons: Comparison with standard protocols

Pozzi

Ban

Iseppon

et al. 2017

Journal of Neuroscience Methods

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Highlights An improved protocol for primary hippocampal cell cultures is proposed.  The method relies on serum-free astrocytes conditioned medium (ACM).  The ACM method is extensively compared with other two commonly used protocols.  ACM improved morphology and function of both short-and long-term cultures. AbstractBackground: Since different culturing parameters -such as media composition or cell density -lead to different experimental results, it is important to define the protocol used for neuronal cultures. The vital role of astrocytes in maintaining homeostasis of neurons -both in vivo and in vitro -is well established: the majority of improved culturing conditions for primary dissociated neuronal cultures rely on astrocytes.New Method: Our culturing protocol is based on a novel serum-free preparation of astrocyteconditioned medium (ACM). We compared the proposed ACM culturing method with other two commonly used methods: Neurobasal/B27-and FBS-based media. We performed morphometric characterization by immunocytochemistry and functional analysis by calcium imaging for all three culture methods at 1,7,14 and 60 days in vitro (DIV).Results: ACM-based cultures gave the best results for all tested criteria, i.e. growth cone's size and shape, neuronal outgrowth and branching, network activity and synchronization, maturation and long-term survival. The differences were more pronounced when compared with FBS-based medium. Neurobasal/B27 cultures were comparable to ACM for young cultures (DIV1), but not for culturing times longer than DIV7. Comparison with Existing Method(s):ACM-based cultures showed more robust neuronal outgrowth at DIV1. At DIV7 and 60, the activity of neuronal network grown in ACM had a more vigorous spontaneous electrical activity and a higher degree of synchronization. Conclusions:We propose our ACM-based culture protocol as an improved and more suitable method for both short-and long-term neuronal cultures.

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Astrocyte secreted proteins selectively increase hippocampal GABAergic axon length, branching, and synaptogenesis

Cited by 119 publications

References 43 publications

Disruption of astrocyte-neuron cholesterol cross talk affects neuronal function in Huntington’s disease

Disruption of astrocyte-neuron cholesterol cross talk affects neuronal function in Huntington’s disease

The Thrombospondins

An improved method for growing neurons: Comparison with standard protocols

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