Specific expression of apolipoprotein A-IV in the follicle-associated epithelium of the small intestine.
BACKGROUND
Peyer's patches (PPs), which are covered by specialized follicle-associated epithelium (FAE) including M cells, play a central role in immune induction in the gastrointestinal tract. This study is to investigate a new molecule to characterize PPs.


METHODS
We generated a monoclonal antibody (mAb 10-15-3-3) that specifically reacts to the epithelium of PPs and isolated lymphoid follicles. Target antigen was analyzed by immunoprecipitation and mass spectrometry. Localization and expression of target antigen were evaluated by immunofluorescence, in situ hybridization and real-time PCR.


RESULTS
Immunoprecipitation and mass spectrometry revealed that mAb 10-15-3-3 recognized apolipoprotein A-IV (ApoA-IV), a well-known lipid transporter; this finding was confirmed by the specific reactivity of mAb 10-15-3-3 to cells transfected with the murine ApoA-IV gene. Immunofluorescence using mAb 10-15-3-3 showed intestinal localization of ApoA-IV, in which strong expression of the ApoA-IV protein occurred throughout the entire intestinal epithelium during developing period before weaning but was restricted to the FAE in adult mice. In support of these findings, in situ hybridization showed strong expression of the ApoA-IV gene throughout the entire intestinal epithelium during developing period before weaning, but this expression was restricted to the FAE predominantly and the tips of villi to a lesser extent in adult mice. Deficiency of ApoA-IV had no effect on the organogenesis of PP in mice.


CONCLUSIONS
Our current results reveal ApoA-IV as a novel FAE-specific marker especially in the upper small intestine of adult mice.
Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan.
Daisuke
D
Tokuhara
Tomonori
T
Nochi
Akiko
A
Matsumura
Mio
M
Mejima
Yuko
Y
Takahashi
Shiho
S
Kurokawa
Hiroshi
H
Kiyono
Yoshikazu
Y
Yuki
D000818:Animals; D000911:Antibodies, Monoclonal; D001054:Apolipoproteins A / Q000235:genetics / Q000378:metabolism*; D015415:Biomarkers; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D005786:Gene Expression Regulation; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010581:Peyer's Patches; D011247:Pregnancy; D012333:RNA, Messenger; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000911:Antibodies, Monoclonal; D001054:Apolipoproteins A; D015415:Biomarkers; D012333:RNA, Messenger