Connective tissue growth factor-mediated angiotensin II-induced hypertrophy of proximal tubular cells.
BACKGROUND
Cellular hypertrophy is an early, important pathological feature of renal diseases such as diabetic nephropathy and remnant kidney. Recent studies have demonstrated that angiotensin II (AngII) plays a key role in mediating cell hypertrophy. The aim of our work was to explore the role of connective tissue growth factor (CTGF) in mediating AngII-induced tubular cell hypertrophy in vivoandin vitro.


METHODS
In an in vivo study, male Sprague-Dawley rats were randomly divided into three groups: control rats, diabetic rats and diabetic rats treated with irbesartan (IRB). The index of kidney hypertrophy (kidney weight/body weight, KW/BW), glomerular tuft area (AG), glomerular tuft volume (VG) and proximal tubular area (AT) were determined. Renal expression for CTGF was detected by immunohistochemical staining. In an in vitro study, the influence of CTGF antisense oligonucleotide (CTGF AS) on AngII-induced CTGF expression and cell hypertrophy was also investigated.


RESULTS
In an in vivo study, diabetic rats showed a significant increase of KW/BW, AG, VG, and AT from week 1 onwards compared to normal control, which could be significantly inhibited by using IRB. Furthermore, there was a significantly increasing expression of CTGF in both glomeruli and tubuli in diabetic rats compared to control, and the extent of CTGF expression closely correlated with the severity of renal hypertrophy. Treatment with IRB could markedly inhibit the renal expression of CTGF. In an in vitro study, AngII stimulated the expression of CTGF mRNA and CTGF protein. AngII significantly increased the total protein content in HK2 cells, which was markedly inhibited by co-treatment with CTGF AS. The average cellular diameter determined by scanning electronic microscope showed that the increase of cell size induced by AngII could be significantly inhibited by CTGF AS. Furthermore, flow cytometer study showed that AngII arrested the cell cycle in the G0-G1 phase, which was significantly reversed by treatment with CTGF AS.


CONCLUSIONS
Our data provide both in vivo and in vitroevidence that CTGF is involved in mediating AngII-induced renal hypertrophy.
Liu
Bi-Cheng
BC
Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, China. liubc64@yahoo.com.cn
Chen
Long
L
Sun
Jing
J
Huang
Hai-Quan
HQ
Ma
Kun-Ling
KL
Liu
Hong
H
Liu
Dian-Ge
DG
Zhang
Xiao-Liang
XL
D000804:Angiotensin II; D047228:Angiotensin II Type 1 Receptor Blockers / Q000627:therapeutic use; D000818:Animals; D001713:Biphenyl Compounds / Q000627:therapeutic use*; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor; D003921:Diabetes Mellitus, Experimental / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D006984:Hypertrophy; D017874:Immediate-Early Proteins / Q000235:genetics / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D000077405:Irbesartan; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000473:pathology; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects / Q000473:pathology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013777:Tetrazoles / Q000627:therapeutic use*
D047228:Angiotensin II Type 1 Receptor Blockers; D001713:Biphenyl Compounds; C526317:CCN2 protein, human; C526316:CCN2 protein, rat; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D013777:Tetrazoles; D000804:Angiotensin II; D055513:Connective Tissue Growth Factor; D000077405:Irbesartan