NR2F1 and IRE1beta suppress microsomal triglyceride transfer protein expression and lipoprotein assembly in undifferentiated intestinal epithelial cells.
OBJECTIVE
Our aim was to elucidate mechanisms involved in the acquisition of lipid transport properties during enterocyte differentiation.


RESULTS
We show that lipid mobilization via apolipoprotein B lipoproteins is dependent on the expression of microsomal triglyceride transfer protein (MTP) during differentiation of Caco-2 cells into enterocyte-like cells. Mechanistic studies showed that binding of the nuclear receptor family 2 group F member 1 (NR2F1) to the DR1 element in the MTTP promoter suppresses MTTP expression in undifferentiated cells. During cellular differentiation, NR2F1 expression and its binding to MTTP promoter decline and MTP induction ensues. Moreover, undifferentiated cells express inositol-requiring enzyme 1beta (IRE1beta), a protein that posttranscriptionally degrades MTP mRNA, and its expression substantially decreases during differentiation, contributing to MTP induction. Immunohistochemical studies revealed a significant negative relationship between the expressions of MTP and NR2F1/IRE1beta in undifferentiated and differentiated Caco-2 cells, as well as in crypt-villus and jejunum-colon axes of mouse intestine.


CONCLUSIONS
We propose that transcriptional and posttranscriptional mechanisms involving NR2F1 and IRE1beta ensure low MTP expression in undifferentiated intestinal cells and avoid apolipoprotein B lipoprotein biosynthesis.
Dai
Kezhi
K
Department of Anatomy and Cell Biology, SUNY Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11230, USA. , USA
Khatun
Irani
I
Hussain
M Mahmood
MM
D000818:Animals; D001055:Apolipoproteins B / Q000378:metabolism; D001483:Base Sequence; D051838:COUP Transcription Factor I / Q000378:metabolism*; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D003106:Colon / Q000166:cytology / Q000378:metabolism; D004722:Endoribonucleases / Q000378:metabolism*; D020895:Enterocytes / Q000166:cytology / Q000378:metabolism; D051537:Hepatocyte Nuclear Factor 1 / Q000235:genetics / Q000378:metabolism; D051557:Hepatocyte Nuclear Factor 4 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D007583:Jejunum / Q000166:cytology / Q000378:metabolism; D008074:Lipoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*
D001055:Apolipoproteins B; D051838:COUP Transcription Factor I; D002352:Carrier Proteins; D051557:Hepatocyte Nuclear Factor 4; D008074:Lipoproteins; D008565:Membrane Proteins; C497589:NR2F1 protein, human; C106092:microsomal triglyceride transfer protein; D051537:Hepatocyte Nuclear Factor 1; C403982:ERN2 protein, human; D017346:Protein Serine-Threonine Kinases; D004722:Endoribonucleases