Renal transcription of high-affinity type-2 cationic amino acid transporter is up-regulated in LPS-stimulated rodents.
OBJECTIVE
Sepsis stimulates renal nitric oxide (NO) biosynthesis through up-regulation of inducible NO synthase (iNOS) expression. Type-2 cationic amino acid transporter (CAT-2) mediation of trans-membrane L-arginine (L-Arg) transportation has been identified as one of the crucial regulatory mechanisms involved in the formation of NO by iNOS. We had previously shown that CAT-2B, a high-affinity alternative-spliced transcript of the CAT-2, is involved in induced NO biosynthesis by iNOS (Nitric Oxide, 2002). In this present study, we sought to assess the effects of sepsis on the expression of CAT-2B in lipopolysaccharide (LPS)-stimulated rat kidney.


METHODS
Forty rats were randomized to either a normal saline (N/S)-treated group or a LPS-treated group. Renal NO production was determined using chemiluminescence. Semi-quantitative RT-PCR was used to determine the mRNA concentrations of iNOS and L-Arg transporters (CAT-1, CAT-2 and CAT-2B) in kidney.


RESULTS
Lipopolysaccharide-coinduced iNOS, CAT-2 and CAT-2B mRNA expression in kidney and caused renal NO overproduction. A significant linear regression relationship was defined between renal NO concentrations and iNOS, CAT-2 and CAT-2B, respectively. On the contrary, CAT-1 expression was not affected by LPS-stimulation.


CONCLUSIONS
We provide the first evidence to illustrate that sepsis/septic shock induces the transcription of high-affinity CAT-2B in renal tissues. Transcription of iNOS, CAT-2 and CAT-2B correlates well with renal NO biosynthesis. Regulation of L-Arg uptake by modulating the expression regulation of induced CAT-2 and CAT-2B might be a potential target for therapies against renal pathologic conditions related to NO overproduction.
Department of Urology, Mackay Memorial Hospital, Taipei, Taiwan.
S
S
Yang
C-J
CJ
Huang
P-S
PS
Tsai
C-R
CR
Cheng
B R
BR
Stevens
J W
JW
Skimming
D000818:Animals; D001806:Blood Urea Nitrogen; D027201:Cationic Amino Acid Transporter 1 / Q000032:analysis / Q000235:genetics; D027202:Cationic Amino Acid Transporter 2 / Q000032:analysis* / Q000235:genetics; D003404:Creatinine / Q000097:blood; D019446:Endotoxemia / Q000201:enzymology / Q000378:metabolism; D004926:Escherichia coli; D007668:Kidney / Q000201:enzymology / Q000378:metabolism*; D016014:Linear Models; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D009569:Nitric Oxide / Q000032:analysis / Q000235:genetics; D019001:Nitric Oxide Synthase / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D018805:Sepsis / Q000201:enzymology / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
D027201:Cationic Amino Acid Transporter 1; D027202:Cationic Amino Acid Transporter 2; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D009569:Nitric Oxide; D003404:Creatinine; D019001:Nitric Oxide Synthase