Up-regulation of Cbfa1 and Pit-1 in calcified artery of uraemic rats with severe hyperphosphataemia and secondary hyperparathyroidism.
BACKGROUND
Cardiovascular disease is the most frequent cause of death in patients with end-stage kidney disease (ESKD). Vascular calcification is a confirmed risk factor for cardiovascular events in the general population and has a high occurrence in patients with ESKD. Despite the high prevalence of vascular calcification in ESKD, the pathogenesis of the disorder is still obscure. The present study examined the expressions of bone-associated factors in calcified arteries in subtotally nephrectomized rats with severe secondary hyperparathyroidism (SHPT).


METHODS
Seven-week-old male Sprague-Dawley rats were divided into five groups as follows: sham-operated rats that received a normal diet [0.8% of phosphorus (P), 1.1% of calcium (Ca)] (Sham), sham-operated rats that received a high-phosphorus and low-calcium (HPLCa) diet (1.2% P, 0.4% Ca) (Sham+HPLCa), 5/6 nephrectomized rats that received a normal diet as the uraemic control group (Nx), and 5/6 nephrectomized rats that received a HPLCa diet to induce the development of SHPT (Nx+HPLCa), and 5/6 nephrectomized and parathyroidectomized rats that received a HPLCa diet (Nx+PTx+HPLCa). The feeding period of each group was 10 weeks. The rats were then sacrificed and their serum was examined. The upper part of the abdominal aorta was used to investigate the expression of mRNAs of core-binding factor alpha-1 (Cbfa1) and sodium-dependent phosphate cotransporter (Pit-1) by real-time reverse transcriptase polymerase chain reaction (real-time PCR) analysis. The lower part was examined for calcification by von Kossa staining.


RESULTS
Serum P level and Ca x P products increased significantly in the Nx+HPLCa group compared with those of any other groups. Severe hyperparathyroidism was also observed in the Nx+HPLCa group. Vascular calcification (medial layer) was observed in the Nx+HPLCa group only. There was a significant increase in Cbfa1 and Pit-1 mRNA expression levels in the aorta of the Nx+HPLCa group compared with that of any other groups.


CONCLUSIONS
These results suggest that medial layer vascular calcification in uraemic rats with severe hyperphosphataemia and SHPT may be caused in part by Cbfa1 and Pit-1.
Mizobuchi
Masahide
M
Center of Blood Purification Therapy, Wakayama Medical University, Japan.
Ogata
Hiroaki
H
Hatamura
Ikuji
I
Koiwa
Fumihiko
F
Saji
Fumie
F
Shiizaki
Kazuhiro
K
Negi
Shigeo
S
Kinugasa
Eriko
E
Ooshima
Akira
A
Koshikawa
Shozo
S
Akizawa
Tadao
T
D000818:Animals; D001012:Aorta, Abdominal; D001018:Aortic Diseases / Q000378:metabolism*; D002114:Calcinosis / Q000378:metabolism*; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006962:Hyperparathyroidism, Secondary / Q000209:etiology / Q000378:metabolism*; D008297:Male; D010760:Phosphorus Metabolism Disorders / Q000209:etiology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050611:Sodium-Phosphate Cotransporter Proteins, Type III / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
D050659:Core Binding Factor Alpha 1 Subunit; D012333:RNA, Messenger; C493588:Slc20a1 protein, rat; D050611:Sodium-Phosphate Cotransporter Proteins, Type III