The mRNA and protein expression of ruminal MCT1 is increased by feeding a mixed hay/concentrate diet compared with hay <i>ad libitum</i> diet (Short Communication)

Abstract

In this study the protein and mRNA expression of Monocarboxylate transporter 1 (MCT1) was evaluated in rumen epithelial cells (REC) obtained from sheep fed hay ad libitum (control, h diet, n=4) or a mixed hay/concentrate diet (h/c diet, n=4) for two weeks. REC were isolated via fractionated trypsination and three groups consisting of fractions 3 to 5=G1, fractions 6 to 8=G2, and fractions 9 and 10=G3 were formed. Using an anti-basal cytokeratin antibody and flow cytometric analysis, the proportion of REC originating from the stratum basale (SB) was determined for each group. In addition, MCT1 mRNA and protein expression was determined by qRT-PCR and Western blot, respectively. Feeding the h/c diet led to a 299±93 % elevation of the number of SB cells known to express the MCT1 protein. This is accompanied by an increased MCT1 mRNA (1.8 to 2.2-fold) and protein (1.3-fold) expression. Thus, an increased number of MCT1 expressing cells and upregulation of ruminal MCT1 protein seem to be components of rumen epithelium functional adaptation to high energy diet.Keywords: sheep, rumen, epithelial cells, transport protein, high energy diet Zusammenfassung Die mRNA-und Protein-Expression des MCT1 in Pansenepithelzellen wird durch Zufütterung von Konzentrat zu einer ad libitum Heu-Ration erhöhtIn der vorliegenden Studie wurden die mRNA-und Proteinexpression des Monocarboxylattransporters 1 (MCT1) in Pansenepithelzellen (PEZ) von Schafen, die über zwei Wochen entweder Heu ad libitum (h-Diät, n=4) oder eine Heu/Konzentrat-Mischration (h/c-Diät, n=4) erhielten, untersucht. Ovine PEZ wurden mittels fraktionierter Trypsinierung gewonnen und anschließend drei Zellgruppen, bestehend aus den Fraktionen 3-5 (G1), 6-8 (G2) und 9/10 (G3), zugeordnet. Mittels Flowzytometrie und unter Nutzung eines spezifischen Antikörpers gegen basales Cytokeratin wurde der Anteil von PEZ aus dem Stratum basale (SB) für jede Zellgruppe ermittelt. Die Expression von MCT1-mRNA und -Protein wurde mittels qRT-PCR und Western Blot analysiert. Die Anzahl MCT1-exprimierender SB-Zellen, stieg nach Füt-terung der h/c-Diät um 299±93 %. Damit ist eine Erhöhung der MCT1-mRNA-(1,8-2,2-fach) sowie der Proteinexpression (1,3-fach) verbunden. Ein erhöhter Anteil MCT1-expremierender PEZ und die Aufregulation der MCT1 Proteinmenge scheinen somit Komponenten der funktionellen Anpassung des Pansenepithels an energiereiche Fütterung darzustellen.

Dietary modulation of the expression of genes involved in short-chain fatty acid absorption in the rumen epithelium is related to short-chain fatty acid concentration and pH in the rumen of goats

“…One possible explanation for the observed change is that the SCFA transport system of epithelial cells was enhanced by feeding additional concentrate. Kuzinski and Röntgen (2011) reported that the rumen epithelium of sheep fed additional concentrate had increased MCT1 expression. Similarly, a report in calves showed that the gene expression of DRA was upregulated by concentrate feeding (Connor et al, 2010).…”

“…During the last decade, a surge of studies were done to determine dietary effects on the transcription changes in proteins involved in SCFA absorption (Penner et al, 2009;Kuzinski and Röntgen, 2011;Steele et al, 2011); however, most of those studies looked for individual SCFA transporter genes without further investigation into the influencing factors. The results of previous studies showed that luminal factors, especially SCFA and pH, can work as the modulators of gene transcription (DeCastro et al, 2005;Li and Li, 2006;Yang et al, 2012).…”

“…Past research has demonstrated that feeding a high-concentrate diet could lead to enhanced SCFA absorptive capacity of rumen epithelium (Gäbel et al, 1991), even when no change occurred in the absorptive surface area of the rumen papillae (Sehested et al, 2000). Some experiments show that one reason for the changes of SCFA absorptive capacity is that diets could modulate the expression of genes encoding for proteins involved in SCFA absorption (Connor et al, 2010;Kuzinski and Röntgen, 2011).…”

Modulation of vH+-ATPase is part of the functional adaptation of sheep rumen epithelium to high-energy diet

“…The adaptation processes include morphological transformations, such as alterations of the rumen epithelium papillae number and size (44). In addition, changes occur in the metabolic properties of rumen epithelial cells (REC) (3) and the expression and activity of cellular transport proteins (26,43,44).Ruminal transport processes are known to be energized by a highly expressed Na ϩ /K ϩ -ATPase, and modulation of the pump expression and activity by concentrate feeding and by forage types, inducing different rumen fermentation patterns, have been observed (24,25). In addition to the Na ϩ /K ϩ -ATPase, the existence of functional vacuolar-type H ϩ -ATPases (vH ϩ -ATPase) in REC has been shown by our group (1, 9).…”

“…The adaptation processes include morphological transformations, such as alterations of the rumen epithelium papillae number and size (44). In addition, changes occur in the metabolic properties of rumen epithelial cells (REC) (3) and the expression and activity of cellular transport proteins (26,43,44).…”