Lactase phlorizin hydrolase synthesis is decreased in protein-malnourished pigs.
We have examined the effect of protein malnutrition on brush border (BB) lactase phlorizin hydrolase (LPH) synthesis in young pigs. Two groups of four 3-wk-old pigs were fed diets containing either 19 g soy protein, 63 g carbohydrate and 5 g fat per 100 g diet (a protein-sufficient diet) or 3 g soy protein, 85 g carbohydrate and 5 g fat per 100 g diet (a protein-deficient diet). After 8 wk of consuming the diets, pigs were infused intravenously with 2H3-leucine for 8 h, then killed. The jejunum was collected for measurement of lactase activity, LPH mRNA abundance and the rate of LPH post-translational synthesis. Lactase activities did not differ between groups (mean 8.1 +/- 1.2 micromol x min(-1) x g mucosa(-1)). LPH mRNA abundance relative to elongation factor-1alpha mRNA (the constitutive/reference mRNA) was significantly (P < 0.05) higher in well-nourished pigs (0.36 +/- 0.03%) than in protein-malnourished pigs (0.21 +/- 0.02%). The rate constants of BB LPH post-translational synthesis were also significantly higher in the well-nourished (103 +/- 9% x d(-1)) than in the protein-malnourished pigs (66 +/- 8% x d(-1)). Further, the absolute synthesis rate of BB LPH, a measure of the amount of enzyme synthesized per gram of tissue, was significantly higher in well-nourished than in protein-malnourished pigs (in arbitrary units, 892 +/- 90 vs. 450 +/- 34, respectively). Thus, protein malnutrition affects both LPH mRNA abundance and post-translational processing in young pigs.
Dudley
M A
MA
Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston 77030, USA.
Wykes
L
L
Dudley
A W
AW
Fiorotto
M
M
Burrin
D G
DG
Rosenberger
J
J
Jahoor
F
F
Reeds
P J
PJ
D000818:Animals; D000831:Animals, Newborn; D015152:Blotting, Northern / Q000379:methods; D018753:Diet, Protein-Restricted; D007583:Jejunum / Q000737:chemistry / Q000166:cytology / Q000201:enzymology*; D010694:Lactase-Phlorizin Hydrolase / Q000096:biosynthesis* / Q000235:genetics; D008871:Microvilli / Q000737:chemistry / Q000201:enzymology; D014176:Protein Biosynthesis / Q000502:physiology; D011499:Protein Processing, Post-Translational; D011502:Protein-Energy Malnutrition / Q000201:enzymology*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D012709:Serum Albumin / Q000378:metabolism; D013552:Swine
D012333:RNA, Messenger; D012709:Serum Albumin; D010694:Lactase-Phlorizin Hydrolase