Renal expression of two rat kallikrein genes under diabetic conditions.
OBJECTIVE
We have reported that bradykinin (BK) excretion is increased in severely diabetic rats, independent of the activity of the main renal kinin-forming enzyme, true kallikrein (KLK). To further investigate the relationship between renal BK excretion and renal KLK in diabetes we studied the regulation of the renal kallikrein-like gene, rat kallikrein 7 (rKLK7), as well as of the KLK encoding gene, rKLK1, in streptozotocin-induced (STZ) diabetic rats.


METHODS
Experiments were performed in STZ-induced diabetic male Wistar rats and their non-diabetic controls (n = 7 each group). Twelve weeks after STZ injection, urinary KLK activity, glomerular filtration rate and total protein excretion were determined. After extraction of total renal cortical RNA, specific oligonucleotides were used to generate a reverse transcription-polymerase chain reaction (RT-PCR) products of renal cortical rKLK1 and rKLK7 messenger (m)RNA. Southern blot analysis of these RT-PCR products were hybridized with appropriate gene-specific oligonucleotide probes.


RESULTS
After 12 weeks, the rats showed hyperglycemia, proteinuria and a reduced glomerular filtration rate. Renal kininogenase was reduced, as indicated by a reduction in the expression of rKLK1, as well as of the KLK-related gene, rKLK7.


CONCLUSIONS
Our data show that the expression of the two principal renal KLK genes is downregulated in the renal cortex of STZ-diabetic rats. We suggest that under severe diabetic conditions the rise in urinary BK excretion is not related to activation of the renal kinin-forming enzyme system.
Tschöpe
C
C
Department of Cardiology and Pneumology, University Hospital Benjamin Franklin, Free University of Berlin, Germany.
Yu
M
M
Reinecke
A
A
Csikos
T
T
Hilgenfeldt
U
U
Pesquero
J B
JB
Ritz
E
E
Unger
T
T
D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015139:Blotting, Southern; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D005919:Glomerular Filtration Rate; D007610:Kallikreins / Q000235:genetics / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000378:metabolism; D008297:Male; D015345:Oligonucleotide Probes / Q000737:chemistry; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D000199:Actins; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D007610:Kallikreins