Kenichi Tsujii

Dominant expression of ATP-binding cassette transporter-1 on basolateral surface of Caco-2 cells stimulated by LXR/RXR ligands

ATP-binding cassette transporter-1 (ABCA1) is a cause of Tangier disease, which is a familial deficiency of plasma high density lipoproteins (HDL). This molecule is known to be expressed in the multiple tissues and organs including small intestines, liver, and macrophages in the blood vessels. Recent in vivo studies suggested that ABCA1 plays some roles in the flux of cholesterol in the intestines. One of the major questions to understand the roles of ABCA1 in the intestines is the expression pattern in the intestinal epithelial cells. To address this issue, we have investigated the expression and regulation of ABCA1 in Caco-2 cells cultured on Transwell as a model, especially focusing on possible polarized expression of ABCA1. The expression of ABCA1 was up-regulated during the differentiation and under the stimulation of LXR/RXR by the addition of 9-cis-retinoic acid (9-cis-RA) and 22-R-hydroxycholesterol (22-OH). Apolipoprotein-AI-mediated cholesterol efflux was dominant toward the basolateral side of polarized cells when stimulated by 9-cis-RA and 22-OH. The cell surface biotinylation experiment followed by Western blot analyses demonstrated a markedly dominant expression of ABCA1 on the basolateral surface, which was clearly confirmed by the confocal laser scanning microscopy. In conclusion, the present study demonstrates that ABCA1 is dominantly expressed on the basolateral surface of Caco-2 cells tested, suggesting that this molecule may play a role in the basolateral movement of cholesterol at least when stimulated by LXR/RXR ligands.

Correlation of fasting serum apolipoprotein B-48 with coronary artery disease prevalence

Eur J Clin Invest 2012; 42 (9): 992–999

Carotid intima-media thickness, but not visceral fat area or adiponectin, correlates with intracoronary stenosis detected by multislice computed tomography in people with type 2 diabetes and hypertension

We investigated the relationship between intracoronary stenosis detected by multislice computed tomography and various clinical parameters in type 2 diabetic patients with hypertension treated with candesartan (n=42). The results showed that carotid intima-media thickness, but not visceral fat area or adiponectin, correlated significantly with intracoronary stenosis (p<0.05).