To investigate the protein and mRNA expression of pancreas/duodenal homeobox-1 (PDX-1), a transcription factor as a marker for pancreatic stem cells, in pancreatic ductal cells of rats after partial (90%) pancreatectomy and evaluated the significance of the PDX-1 expression. Western blot and Reverse transcriptase-polymerase chain reaction (RT-PCR) were used to detect the expression of PDX-1 protein and mRNA respectively. PDX-1 protein was only faintly detected in pancreatic ductal cells on the day 1 after partial pancreatectomy. On the day 2 and 3 after operation in operation group, a 2-3 fold increased PDX-1 protein was observed, corresponding to the characteristic 42-kD protein in Western blot. There was significant difference between operation group and sham-operation group (P<0.05). PDX-1 protein expression on the day 5 and 7 after operation had already been no difference from control group (P>0.05). RT-PCR revealed the PDX-1 mRNA expression showed no significant difference between operation group at various time points and sham-operation group (P> 0.05). These results indicate that there was overexpression of PDX-1 in the cells of pancreatic epithelium during the regeneration of remnant pancreas after partial pancreatectomy in adult rats, suggesting the pancreatic stem cells in pancreatic ductal epithelial cells are involved in the regeneration of remnant pancreas and the expression of PDX-1 in ductal cells was regulated posttranscription.
Epithelial Cells/metabolism ; Homeodomain Proteins/*biosynthesis ; Homeodomain Proteins/genetics ; Pancreatectomy/methods ; Pancreatic Ducts/cytology ; Pancreatic Ducts/*metabolism ; RNA, Messenger/biosynthesis ; RNA, Messenger/genetics ; Rats, Sprague-Dawley ; Trans-Activators/*biosynthesis ; Trans-Activators/genetics

To investigate the protein and mRNA expression of pancreas/duodenal homeobox-1 (PDX-1), a transcription factor as a marker for pancreatic stem cells, in pancreatic ductal cells of rats after partial (90%) pancreatectomy and evaluated the significance of the PDX-1 expression. Western blot and Reverse transcriptase-polymerase chain reaction (RT-PCR) were used to detect the expression of PDX-1 protein and mRNA respectively. PDX-1 protein was only faintly detected in pancreatic ductal cells on the day 1 after partial pancreatectomy. On the day 2 and 3 after operation in operation group, a 2-3 fold increased PDX-1 protein was observed, corresponding to the characteristic 42-kD protein in Western blot. There was significant difference between operation group and sham-operation group (P<0.05). PDX-1 protein expression on the day 5 and 7 after operation had already been no difference from control group (P>0.05). RT-PCR revealed the PDX-1 mRNA expression showed no significant difference between operation group at various time points and sham-operation group (P> 0.05). These results indicate that there was overexpression of PDX-1 in the cells of pancreatic epithelium during the regeneration of remnant pancreas after partial pancreatectomy in adult rats, suggesting the pancreatic stem cells in pancreatic ductal epithelial cells are involved in the regeneration of remnant pancreas and the expression of PDX-1 in ductal cells was regulated posttranscription.
Animals ; Epithelial Cells ; metabolism ; Homeodomain Proteins ; biosynthesis ; genetics ; Pancreatectomy ; methods ; Pancreatic Ducts ; cytology ; metabolism ; RNA, Messenger ; biosynthesis ; genetics ; Rats ; Rats, Sprague-Dawley ; Trans-Activators ; biosynthesis ; genetics

Pancreatic duct cells secrete HCO3(-) ions into a HCO3(-)-rich luminal fluid (~140 mmol/L in human) against at least a 6-fold concentration gradient. Candidate mechanisms for HCO3(-) transport across the apical membrane include Cl(-)-HCO3(-)exchange by an SLC26 anion transporter and diffusion via the HCO3(-) conductance of cystic fibrosis transmembrane conductance regulator (CFTR). Members of the SLC26 family are known to mediate Cl(-)-HCO3(-) exchange across the apical membrane of other epithelia and both SLC26A6 and SLC26A3 have been detected in pancreatic ducts. Co-expression studies have also revealed that murine slc26a6 and slc26a3 physically interact with CFTR through the STAS domain of slc26 and the R domain of CFTR, resulting in mutually enhanced activity. Other studies have indicated that these exchangers are electrogenic: slc26a6 mediating 1Cl(-)-2HCO3(-) exchange and slc26a3 mediating 2Cl(-)-1HCO3(-) exchange. Recent experiments using isolated pancreatic ducts from slc26a6(-)/(-) mice suggest that slc26a6 mediates most of the Cl(-)-dependent secretion of HCO3(-) across the apical membrane in the mouse and the data are consistent with the reported electrogenicity of slc26a6. However, the role of SLC26A6 in human pancreatic HCO3(-) secretion is less clear because human ducts are capable of secreting much higher concentrations of HCO3(-). The role of SLC26A6 must now be evaluated in a species such as the guinea pig which, like the human, is capable of secreting HCO3(-) at a concentration of ~140 mmol/L. From existing guinea pig data we calculate that a 1Cl(-)-2HCO3(-) exchanger such as slc26a6 would be unable to secrete HCO3(-) against such a steep gradient. On the other hand, the HCO3(-) conductance of CFTR could theoretically support secretion of HCO3(-) to a much higher concentrations. CFTR may therefore play a more important role than SLC26A6 in HCO3(-) secretion by the guinea pig and human pancreas.
Animals ; Bicarbonates ; metabolism ; Chloride-Bicarbonate Antiporters ; physiology ; Cystic Fibrosis Transmembrane Conductance Regulator ; physiology ; Guinea Pigs ; Humans ; Membrane Transport Proteins ; physiology ; Mice ; Pancreatic Ducts ; cytology ; secretion

OBJECTIVETo explore the mechanisms of differentiation and development of pancreatic endocrine cells as well as pancreatic regeneration.

METHODSHuman embryonic pancreatic tissue at 7-14 weeks of gestation was collected. Diabetes mellitus rat model was induced with 65 mg/kg of streptozotocin. Insulin, glucagon, somatostatin, nestin, and cytokeratin 19 (CK19) of pancreatic tissues were observed by immunohistochemistry.

RESULTSAt 9 weeks of gestation, pancreatic epithelial cells began to co-express insulin, glucagon, somatostatin, and CK19 before migration. Islet cells gradually congregated along with the increase of aging, and at 14 weeks of gestation histological examination showed islet formation. At 12 weeks of gestation, nestin-positive cells could be seen in the pancreatic mesenchyme. During early embryogenesis, islet cells of pancreatic ducts co-expressed insulin, glucagon, and somatostatin. During pancreatic regeneration after damage, nestin expression of islet cells increased.

CONCLUSIONIn the early stage of embryogenesis, islet cells of primary pancreatic ducts can be differentiated to multipotential endocrine cells before migration. During tissue regeneration, pancreatic stem cells may differentiate and proliferate to form pancreatic islet.

Animals ; Cell Differentiation ; Diabetes Mellitus, Experimental ; chemically induced ; metabolism ; pathology ; Embryonic Development ; physiology ; Epithelial Cells ; cytology ; physiology ; Humans ; Insulin-Secreting Cells ; cytology ; physiology ; Islets of Langerhans ; cytology ; physiology ; Male ; Pancreas ; cytology ; embryology ; physiology ; Pancreatic Ducts ; cytology ; embryology ; physiology ; Rats ; Rats, Sprague-Dawley ; Regeneration ; physiology ; Stem Cells ; cytology ; metabolism ; physiology