Lactase synthesis is pretranslationally regulated in protein-deficient pigs fed a protein-sufficient diet.

Abstract

The in vivo effects of protein malnutrition and protein rehabilitation on lactase phlorizin hydrolase (LPH) synthesis were examined. Five-day-old pigs were fed isocaloric diets containing 10% (deficient, n = 12) or 24% (sufficient, n = 12) protein. After 4 wk, one-half of the animals in each dietary group were infused intravenously with [(13)C(1)]leucine for 6 h, and the jejunum was analyzed for enzyme activity, mRNA abundance, and LPH polypeptide isotopic enrichment. The remaining animals were fed the protein-sufficient diet for 1 wk, and the jejunum was analyzed. Jejunal mass and lactase enzyme activity per jejunum were significantly lower in protein-deficient vs. control animals but returned to normal with rehabilitation. Protein malnutrition did not affect LPH mRNA abundance relative to elongation factor-1alpha, but rehabilitation resulted in a significant increase in LPH mRNA relative abundance. Protein malnutrition significantly lowered the LPH fractional synthesis rate (FSR; %/day), whereas the FSR of LPH in rehabilitated and control animals was similar. These results suggest that protein malnutrition decreases LPH synthesis by altering posttranslational events, whereas the jejunum responds to rehabilitation by increasing LPH mRNA relative abundance, suggesting pretranslational regulation.

• Authors: M A Dudley, P A Schoknecht, A W Dudley Jr, L Jiang, R P Ferraris, J N Rosenberger, J F Henry, P J Reeds
• Journal: American journal of physiology. Gastrointestinal and liver physiology (Am J Physiol Gastrointest Liver Physiol) Vol. 280 Issue 4 Pg. G621-8 (Apr 2001) ISSN: 0193-1857 [Print] United States
• PMID: 11254488 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Amino Acids
• Dietary Proteins
• RNA, Messenger
• Lactase-Phlorizin Hydrolase
• Leucine

Topics

• Amino Acids (metabolism)
• Animals
• Body Weight (drug effects)
• Diet
• Dietary Proteins (pharmacology)
• Gene Expression Regulation, Enzymologic (physiology)
• Intestinal Mucosa (metabolism)
• Jejunum (enzymology, pathology)
• Lactase-Phlorizin Hydrolase (biosynthesis, genetics)
• Leucine (metabolism)
• Protein Biosynthesis (genetics, physiology)
• Protein-Energy Malnutrition (diet therapy, enzymology, pathology)
• RNA, Messenger (analysis, biosynthesis)
• Swine