Forced expression of PDX-1 induces insulin production in intestinal epithelia.
BACKGROUND
In the developmental stage, pancreas derives from the endodermal cells where the transcription factor, pancreatic duodenal homeobox gene-1 (pdx-1) is expressed. In adulthood, pdx-1 expression is localized to pancreatic beta cells, which is necessary for maintenance of beta cell function. Recently, ectopic expression of pdx-1 in the liver successfully induced insulin production and ameliorated hyperglycemia. Our study was designed to investigate the effects of forced expression of pdx-1 in ileal epithelia by adenovirus-mediated gene transfer.


METHODS
The recombinant, replication-deficient adenovirus carrying the pdx-1 gene was constructed using the COS-TPC method. ICR mice were treated with intraperitoneal injection of 220 mg/kg streptozotocin (STZ). After determining the hyperglycemia, a loop of ileum was constructed and the adenovirus solutions (Ad-pdx-1 and Ad-lacZ 1 x 10(8) PFU/body) were injected into the lumen of the ileal loop. In this model, immunohistochemical or fluorescent analyses of PDX-1 and insulin in the adenovirus-infected ileal epithelia were carried out. Reverse transcription polymerase chain reaction of pdx-1 and other pancreatic markers were investigated. Blood glucose concentrations were measured by drawing blood from ocular veins. Immunoreactive insulin extracted from the adenovirus-infected ileum was measured.


RESULTS
Ad-pdx-1 induced ectopic PDX-1 expression in the ileum. The PDX-1 positive cells in the ileal epithelia were positive for insulin; mRNA of insulin-1, insulin-2 and pdx-1 were expressed in mice infected with Ad-pdx-1. Hyperglycemia was improved in STZ-treated mice infected with Ad-pdx-1. Immunoreactive insulin in the ileum extract was increased significantly in mice with Ad-pdx-1.


CONCLUSIONS
Gene transfer of PDX-1 in intestinal epithelia could be a promising strategy for diabetes mellitus by inducing ectopic insulin producing cells.
Koizumi
Masayuki
M
Department of Surgery, Kyoto University, Kyoto, Japan.
Nagai
Kazuyuki
K
Kida
Atsushi
A
Kami
Kazuhiro
K
Ito
Daisuke
D
Fujimoto
Koji
K
Kawaguchi
Yoshiya
Y
Doi
Ryuichiro
R
D000256:Adenoviridae; D000818:Animals; D005822:Genetic Vectors; D018398:Homeodomain Proteins / Q000502:physiology*; D006943:Hyperglycemia / Q000139:chemically induced / Q000378:metabolism*; D007082:Ileum / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D012333:RNA, Messenger / Q000378:metabolism; D013311:Streptozocin; D015534:Trans-Activators / Q000502:physiology*; D014162:Transfection
D018398:Homeodomain Proteins; D007328:Insulin; D012333:RNA, Messenger; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D013311:Streptozocin