title: Expression of apical Na(+)-L-glutamine co-transport activity, B(0)-system neutral amino acid co-transporter (B(0)AT1) and angiotensin-converting enzyme 2 along the jejunal crypt-villus axis in young pigs fed a liquid formula.
abstract: Gut apical amino acid (AA) transport activity is high at birth and during suckling, thus being essential to maintain luminal nutrient-dependent mucosal growth through providing AA as essential metabolic fuel, substrates and nutrient stimuli for cellular growth. Because system-B(0) Na(+)-neutral AA co-transporter (B(0)AT1, encoded by the SLC6A19 gene) plays a dominant role for apical uptake of large neutral AA including L-Gln, we hypothesized that high apical Na(+)-Gln co-transport activity, and B(0)AT1 (SLC6A19) in co-expression with angiotensin-converting enzyme 2 (ACE2) were expressed along the entire small intestinal crypt-villus axis in young animals via unique control mechanisms. Kinetics of Na(+)-Gln co-transport activity in the apical membrane vesicles, prepared from epithelial cells sequentially isolated along the jejunal crypt-villus axis from liquid formula-fed young pigs, were measured with the membrane potential being clamped to zero using thiocyanate. Apical maximal Na(+)-Gln co-transport activity was much higher (p < 0.05) in the upper villus cells than in the middle villus (by 29 %) and the crypt (by 30 %) cells, whereas Na(+)-Gln co-transport affinity was lower (p < 0.05) in the upper villus cells than in the middle villus and the crypt cells. The B(0)AT1 (SLC6A19) mRNA abundance was lower (p < 0.05) in the crypt (by 40-47 %) than in the villus cells. There were no significant differences in B(0)AT1 and ACE2 protein abundances on the apical membrane among the upper villus, the middle villus and the crypt cells. Our study suggests that piglet fast growth is associated with very high intestinal apical Na(+)-neutral AA uptake activities via abundantly co-expressing B(0)AT1 and ACE2 proteins in the apical membrane and by transcribing the B(0)AT1 (SLC6A19) gene in the epithelia along the entire crypt-villus axis.
authors.affiliation: Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada. chengbo.yang@umanitoba.ca.|Department of Animal Science, Faculty of Agricultural and Food Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada. chengbo.yang@umanitoba.ca.
authors.forename: Chengbo
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.|Southern Research and Outreach Center, University of Minnesota, Waseca, MN, 56093, USA.
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
authors.forename: Dale
authors.initials: D
authors.lastname: Lackeyram
authors.affiliation: Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.|Department of Exercise and Nutrition Sciences, the State University of New York at Buffalo, New York, 14214, USA.
authors.forename: Todd C
authors.initials: TC
authors.lastname: Rideout
authors.affiliation: College of Animal Science, Xinjiang Agricultural University, Urumqi, 830052, Xinjiang, China.
authors.forename: Zirong
authors.initials: Z
authors.lastname: Wang
authors.affiliation: US Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Stoll
authors.affiliation: Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha, 410125, Hunan, China.
authors.forename: Yulong
authors.initials: Y
authors.lastname: Yin
authors.affiliation: US Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA.
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Burrin
authors.affiliation: Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada. mfan@uoguelph.ca.
authors.forename: Ming Z
authors.initials: MZ
authors.lastname: Fan
mesh_terms: D026923:Amino Acid Transport Systems, Basic / Q000096:biosynthesis*; D026921:Amino Acid Transport Systems, Neutral / Q000096:biosynthesis*; D000085962:Angiotensin-Converting Enzyme 2; D000821:Animal Feed; D000818:Animals; D005260:Female; D005786:Gene Expression Regulation; D007413:Intestinal Mucosa / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism*; D008297:Male; D007703:Peptidyl-Dipeptidase A / Q000096:biosynthesis*; D013552:Swine
chemical_list: D026923:Amino Acid Transport Systems, Basic; D026921:Amino Acid Transport Systems, Neutral; D007703:Peptidyl-Dipeptidase A; D000085962:Angiotensin-Converting Enzyme 2
keywords: Angiotensin-converting enzyme 2; Gut crypt–villus axis; SLC6A19; Small intestinal apical L-glutamine uptake; System-B0 Na+–neutral amino acid co-transporter