Yang, Y.* ; Sadri, H.* ; Prehn, C. ; Adamski, J. ; Rehage, J.* ; Dänicke, S.* ; von Soosten, D.* ; Metges, C.C.* ; Ghaffari, M.H.* ; Sauerwein, H.*
     
 
    
        
Proteasome activity and expression of mammalian target of rapamycin signaling factors in skeletal muscle of dairy cows supplemented with conjugated linoleic acids during early lactation.
    
    
        
    
    
        
        J. Dairy Sci. 103, 2829-2846 (2020)
    
    
    
		
		
			
				The mammalian target of rapamycin (mTOR) is a major regulator of protein synthesis via its main down-stream effectors, ribosomal protein S6 kinase (S6K1) and eukaryotic initiation factor 4E binding protein (4EBP1). The ubiquitin-proteasome system (UPS) is the main proteolytic pathway in muscle, and the muscle-specific ligases tripartite motif containing 63 (TRIM63; also called muscle-specific ring-finger protein 1, MuRF-1) and F-box only protein 32 (FBXO32; also called atrogin-1) are important components of the UPS. We investigated 20S proteasome activity and mRNA expression of key components of mTOR signaling and UPS in skeletal muscle of dairy cows during late gesta-tion and early lactation and tested the effects of dietary supplementation (from d 1 in milk) with conjugated linoleic acids (sCLA; 100 g/d; n = 11) compared with control fat-supplemented cows (CTR; n = 10). Blood and muscle tissue (semitendinosus) samples were col- lected on d 1, 21, and 70 relative to parturition. Dry matter intake increased with time of lactation in both groups. It was lower in sCLA than in CTR on d 21, which resulted in a reduced calculated metaboliz-able protein balance. Most serum and muscle concen-trations of AA followed time-related changes but were unaffected by CLA supplementation. In both groups, serum and muscle 3-methylhistidine (3-MH) concentrar tions and the ratio of 3-MH:creatinine increased from d -21 to d 1, followed by a decline on d 21. The mRNA abundance of MTOR on d 21 and 70 was greater in sCLA than in CTR. The abundance of 4EBP1 mRNA did not differ between groups but was upregulated in both on d 1. The mRNA abundance of SOK1 on d 70 was greater in CTR than in sCLA, but remained unchanged over time in both groups. The mRNA abundance of FBXOS2 (encoding atrogin-1) on d 21 was greater in sCLA than in CTR. The mRNA abundance of TRIM63 (also known as MuRF1) showed a similar pattern as FBXO32 in both groups: an increase from d -21 to d 1, followed by a decline. The mRNA for the alpha (BCKDHA) and beta (BCKDHB) polypeptide of branched-chain a-keto acid dehydrogenase was elevated in sCLA and CTR cows on d 21, respectively, suggesting a role of CLA in determining the metabolic fate of branched-chain AA. For the mTOR protein, no group differences were observed. The abundance of 56K1 protein was greater across all time points in sCLA versus CTR. The antepartum 20S proteasome activity in muscle was elevated in both groups compared with postpartum, probably reflecting the start of protein mobilization before parturition. Plasma insulin concentrations decreased in both groups postpartum but to a greater extent in CTR than in sCLA, resulting in greater insulin concentrations in sCLA than in CTR. Thus, the greater abundance of MTOR mRNA and S6K1 protein in sCLA compared with CTR might be mediated by the greater plasma insulin postpartum. The upregulation of MTOR mRNA in sCLA cows on d 21, despite greater PBxon mRNA abundance, may reflect a simultaneous activation of both anabolic and catabolic signaling pathways, likely resulting in greater protein turnover.
			
			
				
			
		 
		
			
				
					
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        Publikationstyp
        Artikel: Journalartikel
    
 
    
        Dokumenttyp
        Wissenschaftlicher Artikel
    
 
    
        Typ der Hochschulschrift
        
    
 
    
        Herausgeber
        
    
    
        Schlagwörter
        Conjugated Linoleic Acid ; Mammalian Target Of Rapamycin ; Ubiquitin-proteasome System ; Muscle ; Dairy Cow; Protein-synthesis; Gene-expression; Transition Period; Body-composition; Dietary-fat; Food-intake; Ubiquitin; Metabolism; Milk; Serum
    
 
    
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        Sprache
        englisch
    
 
    
        Veröffentlichungsjahr
        2020
    
 
    
        Prepublished im Jahr 
        
    
 
    
        HGF-Berichtsjahr
        2020
    
 
    
    
        ISSN (print) / ISBN
        0022-0302
    
 
    
        e-ISSN
        1525-3198
    
 
    
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	    Band: 103,  
	    Heft: 3,  
	    Seiten: 2829-2846 
	    Artikelnummer: ,  
	    Supplement: ,  
	
    
 
  
        
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            Verlag
            Elsevier
        
 
        
            Verlagsort
            Ste 800, 230 Park Ave, New York, Ny 10169 Usa
        
 
	
        
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        Begutachtungsstatus
        Peer reviewed
    
 
    
        Institut(e)
        Molekulare Endokrinologie und Metabolismus (MEM)
    
 
    
        POF Topic(s)
        30201 - Metabolic Health
    
 
    
        Forschungsfeld(er)
        Genetics and Epidemiology
    
 
    
        PSP-Element(e)
        G-505600-003
    
 
    
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        Erfassungsdatum
        2020-03-31