Gene expression of VEGF and its receptors Flk-1/KDR and Flt-1 in cultured and transplanted rat islets.
BACKGROUND
Vascular endothelial growth factor (VEGF) and its two receptor tyrosine kinases, Flk-1/KDR and Flt-1, may play an important role in mediating the revascularization of transplanted pancreatic islets.


METHODS
Using semiquantitative multiplex reverse-transcribed polymerase chain reaction we determined the gene expression of VEGF and its receptors in cultured and transplanted rat islets.


RESULTS
After exposure of islet cells to hypoxia in vitro, increases were found in the gene expression of the VEGF120 and VEGF164 isoforms, with simultaneous increases in VE-cadherin, Flk-1/KDR, and Flt-1. In vivo studies consisted of analysis of islet grafts transplanted into both normal and diabetic recipients. Expression of both VEGF120 and VEGF164 in grafts was up-regulated for the first 2-3 days after transplantation, with the response being more prolonged in the diabetic rats. These increases were followed by reduced expression of VEGF on days 5, 7, and 9. Increases in the expression of VE-cadherin in islet grafts in normal and diabetic recipients tended to parallel VEGF expression, with the increases in both probably being caused by hypoxia. The early increases of VEGF expression were followed by a rise in the expression of VEGF receptors, which probably represents the early stages of angiogenesis. Graft expression of Flk-1/KDR and Flt-1 was enhanced at 3 and 5 days in the normoglycemic recipients, while in the diabetic recipients increases were found later on days 5, 7, and 14.


CONCLUSIONS
The delayed expression of VEGF receptors in the diabetic recipients could reflect impaired angiogenesis caused by the diabetic milieu; this delay could contribute to the less outcomes of grafts transplanted into a hyperglycemic environment.
Vasir
B
B
Joslin Diabetes Center and Dept. of Medicine, Harvard Medical School, Boston, MA 02215, USA.
Jonas
J C
JC
Steil
G M
GM
Hollister-Lock
J
J
Hasenkamp
W
W
Sharma
A
A
Bonner-Weir
S
S
Weir
G C
GC
D000818:Animals; D015703:Antigens, CD; D001786:Blood Glucose / Q000032:analysis; D015820:Cadherins / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D003921:Diabetes Mellitus, Experimental / Q000235:genetics; D016228:Endothelial Growth Factors / Q000235:genetics*; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D015870:Gene Expression; D006728:Hormones / Q000235:genetics; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016381:Islets of Langerhans Transplantation; D008222:Lymphokines / Q000235:genetics*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000378:metabolism; D018995:Myosin Heavy Chains; D024501:Nonmuscle Myosin Type IIB; D009687:Nuclear Proteins / Q000235:genetics; D009924:Organ Culture Techniques; D011184:Postoperative Period; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D017207:Rats, Sprague-Dawley; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D017978:Receptors, Growth Factor / Q000235:genetics*; D040262:Receptors, Vascular Endothelial Growth Factor; D012016:Reference Values; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D042442:Vascular Endothelial Growth Factors; D000099152:Cadherin 5
D015703:Antigens, CD; D001786:Blood Glucose; D015820:Cadherins; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors; D016326:Extracellular Matrix Proteins; D006728:Hormones; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008222:Lymphokines; D018995:Myosin Heavy Chains; D024501:Nonmuscle Myosin Type IIB; D009687:Nuclear Proteins; D012333:RNA, Messenger; D020794:Receptor Protein-Tyrosine Kinases; D017978:Receptors, Growth Factor; D040262:Receptors, Vascular Endothelial Growth Factor; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D042442:Vascular Endothelial Growth Factors; D000099152:Cadherin 5; C497443:Hif1a protein, mouse; C497444:Hif1a protein, rat; C501163:Flt1 protein, mouse; C501164:Flt1 protein, rat; C103815:nonmuscle myosin type IIB heavy chain