Enterophilins, a new family of leucine zipper proteins bearing a b30.2 domain and associated with enterocyte differentiation.
Enterocyte terminal differentiation occurs at the crypt-villus junction through the transcriptional activation of cell-specific genes, many of which code for proteins of the brush border membrane such as intestinal alkaline phosphatase, sucrase-isomaltase, or the microvillar structural protein villin. Several studies have shown that this sharp increase in specific mRNA levels is intimately associated with arrest of cell proliferation. We isolated several clones from a guinea pig intestine cDNA library. They encode new proteins characterized by an original structure associating a carboxyl-terminal B30.2/RFP-like domain and a long leucine zipper at the amino terminus. The first member of this novel gene family codes for a 65-kDa protein termed enterophilin-1, which is specifically expressed in enterocytes before their final differentiation. Enterophilin-1 is the most abundant in the small intestine but is still present in significant amounts in colonic enterocytes. In Caco-2 cells, a similar 65-kDa protein was recognized by a specific anti-enterophilin-1 antibody, and its expression was positively correlated with cell differentiation status. In addition, transfection of HT-29 cells with enterophilin-1 full-length cDNA slightly inhibited cell growth and promoted an increase in alkaline phosphatase activity. Taken together, these data identify enterophilins as a new family of proteins associated with enterocyte differentiation.
Gassama-Diagne
A
A
Institut Fédératif de Recherche Claude de Préval, Université Paul Sabatier and Centre Hospitalo-Universitaire de Toulouse, INSERM Unité 326, France.
Hullin-Matsuda
F
F
Li
R Y
RY
Nauze
M
M
Ragab
A
A
Pons
V
V
Delagebeaudeuf
C
C
Simon
M F
MF
Fauvel
J
J
Chap
H
H
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D020895:Enterocytes / Q000166:cytology / Q000502:physiology*; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment
D002352:Carrier Proteins; D018076:DNA, Complementary; D011506:Proteins; C429554:enterophilin-1