Regulation of microsomal triglyceride transfer protein by apolipoprotein A-IV in newborn swine intestinal epithelial cells

Ying Yao, Song Lu, Yue Huang, Casey C. Beeman-Black, Rena Lu, Xiaoyue Pan, M. Mahmood Hussain, Dennis Black

Research output: Contribution to journalArticle

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Abstract

Apolipoprotein (apo) A-IV overexpression enhances chylomicron (CM) assembly and secretion in newborn swine intestinal epithelial cells by producing larger particles (Lu S, Yao Y, Cheng X, Mitchell S, Leng S, Meng S, Gallagher JW, Shelness GS, Morris GS, Mahan J, Frase S, Mansbach CM, Weinberg RB, Black DD. J Biol Chem 281: 3473-3483, 2006). To determine the impact of apo A-IV on microsomal triglyceride transfer protein (MTTP), IPEC-1 cell lines containing a tetracycline-regulatable expression system were used to overexpress native swine apo A-IV and "piglike" human apo A-IV, a mutant human apo A-IV with deletion of the EQQQ-rich COOH-terminus, previously shown to upregulate basolateral triglyceride (TG) secretion 5-fold and 25-fold, respectively. Cells were incubated 24 h with and without doxycycline and oleic acid (OA, 0.8 mM). Overexpression of the native swine apo A-IV and piglike human apo A-IV increased MTTP lipid transfer activity by 39.7% (P = 0.006) and 53.6% (P = 0.0001), respectively, compared with controls. Changes in mRNA and protein levels generally paralleled changes in activity. Interestingly, native swine apo A-IV overexpression also increased MTTP large subunit mRNA, protein levels, and lipid transfer activity in the absence of OA, suggesting a mechanism not mediated by lipid absorption. Overexpression of piglike human apo A-IV significantly increased partitioning of radiolabeled OA from endoplasmic reticulum (ER) membrane to lumen, suggesting increased net transfer of membrane TG to luminal particles. These results suggest that the increased packaging of TG into nascent CMs in the ER lumen, induced by apo A-IV, is associated with upregulation of MTTP activity at the pretranslational level. Thus MTTP is regulated by apo A-IV in a manner to promote increased packaging of TG into the CM core, which may be important in neonatal fat absorption.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume300
Issue number2
DOIs
StatePublished - Feb 1 2011

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Swine
Epithelial Cells
Chylomicrons
Triglycerides
Product Packaging
Endoplasmic Reticulum
microsomal triglyceride transfer protein
apolipoprotein A-IV
Up-Regulation
Lipids
Messenger RNA
Membranes
Doxycycline
Protein Subunits
Oleic Acid
Tetracycline
Fats
Cell Line

All Science Journal Classification (ASJC) codes

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

Cite this

Regulation of microsomal triglyceride transfer protein by apolipoprotein A-IV in newborn swine intestinal epithelial cells. / Yao, Ying; Lu, Song; Huang, Yue; Beeman-Black, Casey C.; Lu, Rena; Pan, Xiaoyue; Hussain, M. Mahmood; Black, Dennis.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 300, No. 2, 01.02.2011.

Research output: Contribution to journalArticle

Yao, Ying ; Lu, Song ; Huang, Yue ; Beeman-Black, Casey C. ; Lu, Rena ; Pan, Xiaoyue ; Hussain, M. Mahmood ; Black, Dennis. / Regulation of microsomal triglyceride transfer protein by apolipoprotein A-IV in newborn swine intestinal epithelial cells. In: American Journal of Physiology - Gastrointestinal and Liver Physiology. 2011 ; Vol. 300, No. 2.
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AU - Pan, Xiaoyue

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