Furmanik Malgorzata, Shanahan Catherine M
Cardiovascular Division, James Black Centre, King's College London, 125 Coldharbour Lane, London, SE5 9NU, UK.
Department of Biochemistry, CARIM-Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
BMC Res Notes. 2018 Jul 16;11(1):483. doi: 10.1186/s13104-018-3582-4.
Vascular calcification is the deposition of hydroxyapatite crystals in the blood vessel wall. Osteogenic differentiation of vascular smooth muscle cells (VSMCs) plays a key role in this process. Increased expression of alkaline phosphatase (ALP) occurs in some in vitro models of VSMC calcification and is thought to be crucial for mineralization, however, little is known about the transcriptional regulation of ALP in VSMCs. Recently, ALP upregulation was shown to coincide with endoplasmic reticulum (ER) stress-mediated vascular calcification, specifically with expression of the transcription factor ATF4. As no direct links between ALP expression and ER stress have previously been demonstrated in VSMCs, the aim of this study was to investigate whether ATF4 interacts directly with the ALP promoter.
The present study shows that ALP mRNA and activity were significantly increased by ER stress treatment of human primary VSMCs in vitro and that this was ATF4-dependent. Bioinformatics analysis predicted two ATF4 binding sites in ER-stress responsive regions of the ALP promoter (- 3631 to - 2048 bp from the first intron). However, we found that ATF4 does not bind within this fragment of the ALP promoter region.
血管钙化是羟基磷灰石晶体在血管壁中的沉积。血管平滑肌细胞（VSMC）的成骨分化在这一过程中起关键作用。碱性磷酸酶（ALP）表达增加出现在一些VSMC钙化的体外模型中，并且被认为对矿化至关重要，然而，关于VSMC中ALP的转录调控知之甚少。最近，ALP上调被证明与内质网（ER）应激介导的血管钙化同时发生，特别是与转录因子ATF4的表达有关。由于此前在VSMC中尚未证明ALP表达与ER应激之间存在直接联系，本研究的目的是调查ATF4是否直接与ALP启动子相互作用。
本研究表明，体外对人原代VSMC进行ER应激处理可显著增加ALP mRNA和活性，且这是ATF4依赖性的。生物信息学分析预测在ALP启动子的ER应激反应区域（从第一个内含子起-3631至-2048 bp）有两个ATF4结合位点。然而，我们发现ATF4不在ALP启动子区域这个片段内结合。
