Differences in expression of homeobox transcription factors in proximal and distal human small intestine.
OBJECTIVE
Different digestive enzymes and transporters are present in the duodenum, jejunum, and ileum, but the factors determining region-specific gene expression are not yet understood. Homeobox transcription factors are important in defining gradients of cellular differentiation. The aim of this study was to investigate whether their expression differs between proximal (duodenal) and distal (ileal) regions of human small intestine.


METHODS
Intestinal RNA was prepared from surgical patients, and reverse-transcription polymerase chain reactions (PCRs) performed with mixed sequence oligonucleotide primers based on conserved regions. PCR products were identified by cloning and sequencing. Transcript abundance was determined by Northern blotting.


RESULTS
The human homologues were identified as Cdx-1, Cdx-2 (or Cdx-3), Pdx-1 (previously named Islet/duodenal homeobox [Idx]-1, Ipf-1, or Stf-1), and 13 human homeodomain cluster genes, including HOXB3, HOXB4, and HOXA6. The relative abundance of some of these differed between duodenum and ileum. Pdx-1 transcripts were found only in duodenum, Cdx-2, Cdx-1, and HOXB3 were readily detectable in both regions, with Cdx-1 having a more marked distal expression.


CONCLUSIONS
Many homeobox genes are expressed in human adult small intestinal mucosa, and some are found predominantly in one region.
Walters
J R
JR
Gastroenterology Unit, Royal Postgraduate Medical School, Hammersmith Hospital, London, England. jwalters@rpms.ac.uk
Howard
A
A
Rumble
H E
HE
Prathalingam
S R
SR
Shaw-Smith
C J
CJ
Legon
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D006224:Cricetinae; D004247:DNA / Q000032:analysis / Q000737:chemistry / Q000235:genetics; D004386:Duodenum / Q000737:chemistry* / Q000378:metabolism; D005786:Gene Expression Regulation; D005801:Genes, Homeobox / Q000235:genetics; D018398:Homeodomain Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007082:Ileum / Q000737:chemistry* / Q000378:metabolism; D007413:Intestinal Mucosa / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D016133:Polymerase Chain Reaction / Q000379:methods; D012313:RNA / Q000032:analysis / Q000737:chemistry / Q000235:genetics; D051381:Rats; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000032:analysis* / Q000235:genetics / Q000378:metabolism
D018398:Homeodomain Proteins; D014157:Transcription Factors; D012313:RNA; D004247:DNA