Heni, M. ; Eckstein, S.S. ; Schittenhelm, J.* ; Böhm, A. ; Hogrefe, N.* ; Irmler, M. ; Beckers, J. ; Hrabě de Angelis, M. ; Häring, H.-U. ; Fritsche, A. ; Staiger, H.
     
    
        
Ectopic fat accumulation in human astrocytes impairs insulin action.
    
    
        
    
    
        
        R. Soc. Open Sci. 7:200701 (2020)
    
    
    
      
      
	
	    Astrocytes provide neurons with structural support and energy in form of lactate, modulate synaptic transmission, are insulin sensitive and act as gatekeeper for water, ions, glutamate and second messengers. Furthermore, astrocytes are important for glucose sensing, possess neuroendocrine functions and also play an important role in cerebral lipid metabolism. To answer the question, if there is a connection between lipid metabolism and insulin action in human astrocytes, we investigated if storage of ectopic lipids in human astrocytes has an impact on insulin signalling in those cells. Human astrocytes were cultured in the presence of a lipid emulsion, consisting of fatty acids and triglycerides, to induce ectopic lipid storage. After several days, cells were stimulated with insulin and gene expression profiling was performed. In addition, phosphorylation of Akt as well as glycogen synthesis and cell proliferation was assessed. Ectopic lipid storage was detected in human astrocytes after lipid exposure and lipid storage was persistent even when the fat emulsion was removed from the cell culture medium. Chronic exposure to lipids induced profound changes in the gene expression profile, whereby some genes showed a reversible gene expression profile upon removal of fat, and some did not. This included FOXO-dependent expression patterns. Furthermore, insulin-induced phosphorylation of Akt was diminished and also insulin-induced glycogen synthesis and proliferation was impaired in lipid-laden astrocytes. Chronic lipid exposure induces lipid storage in human astrocytes accompanied by insulin resistance. Analyses of the gene expression pattern indicated the potential of a partially reversible gene expression profile. Targeting astrocytic insulin resistance by reducing ectopic lipid load might represent a promising treatment target for insulin resistance of the brain in obesity, diabetes and neurodegeneration.
	
	
	    
	
       
      
	
	    
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        Publication type
        Article: Journal article
    
 
    
        Document type
        Scientific Article
    
 
    
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        Keywords
        Astrocyte ; Human ; Insulin ; Lipid Storage; Central-nervous-system; Cerebrospinal-fluid; Glucose-uptake; Human Brain; Food-intake; Resistance; Receptors; Sensitivity; Overweight; Obesity
    
 
    
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        Language
        english
    
 
    
        Publication Year
        2020
    
 
    
        Prepublished in Year
        
    
 
    
        HGF-reported in Year
        2020
    
 
    
    
        ISSN (print) / ISBN
        2054-5703
    
 
    
        e-ISSN
        2054-5703
    
 
    
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	    Volume: 7,  
	    Issue: 9,  
	    Pages: ,  
	    Article Number: 200701 
	    Supplement: ,  
	
    
 
    
        
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            Royal Society of London
        
 
        
            Publishing Place
            6-9 Carlton House Terrace, London Sw1y 5ag, England
        
 
	
        
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        Reviewing status
        Peer reviewed
    
 
     
    
        POF-Topic(s)
        90000 - German Center for Diabetes Research
30201 - Metabolic Health
    
 
    
        Research field(s)
        Helmholtz Diabetes Center
Genetics and Epidemiology
    
 
    
        PSP Element(s)
        G-502400-001
G-500600-004
G-500600-001
    
 
    
        Grants
        Helmholtz Alliance `Aging and Metabolic Programming, AMPro'
German Federal Ministry of Education and Research (BMBF)
    
 
    
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        Erfassungsdatum
        2020-10-14