Fatherazi Sahba, Belton Carol M, Cai Shiwei, Zarif Shukriya, Goodwin Paul C, Lamont Richard J, Izutsu Kenneth T
Department of Oral Biology, School of Dentistry, University of Washington, Seattle, WA 98195, USA.
Pflugers Arch. 2004 Apr;448(1):93-104. doi: 10.1007/s00424-003-1223-8. Epub 2004 Feb 10.
Calcium-sensing receptor (CaSR) expression and function were studied in proliferating and differentiating cultured human gingival keratinocytes (HGKs). CaSR mRNA and protein were present in proliferating HGKs cultured in 0.03 mM [Ca(2+)] and decreased in cells induced to differentiate by culturing in 1.2 mM [Ca(2+)] for 2 days. CaSR protein was also detected in gingival tissue. Exposure to 10 mM extracellular [Ca(2+)] activated two sequential whole-cell currents. The first was a small, transient calcium release activated calcium current I(CRAC)-like current with an inwardly rectifying I-V curve. The second current was larger with a linear I-V curve. Both currents were significantly decreased in differentiating cells. Neither neomycin nor gadolinium induced changes in whole cell currents nor in intracellular [Ca(2+)], but neomycin inhibited the late large current. Extracellular Ca(2+) increased intracellular [Ca(2+)] of proliferating HGKs in a dose-dependent fashion. Comparison of the time-courses of the whole-cell currents and the intracellular [Ca(2+)] responses indicated both induced currents supported a Ca(2+) influx. Extracellular [Mg(2+)] changes did not affect intracellular [Ca(2+)]. La(3+) and 2-APB inhibited the whole cell current and intracellular [Ca(2+)] changes. The results indicate that the CaSR signaling response likely plays a major role in initiating Ca(2+) induced differentiation responses in HGKs.
在体外培养的人牙龈角质形成细胞（HGK）增殖和分化过程中，对钙敏感受体（CaSR）的表达和功能进行了研究。在0.03 mM [Ca(2+)] 条件下培养的增殖HGK中存在CaSR mRNA和蛋白，而在1.2 mM [Ca(2+)] 条件下培养2天诱导分化的细胞中其表达下降。在牙龈组织中也检测到了CaSR蛋白。暴露于10 mM细胞外[Ca(2+)] 可激活两个连续的全细胞电流。第一个是小的、瞬时的钙释放激活钙电流I(CRAC)样电流，其I-V曲线呈内向整流。第二个电流较大，I-V曲线呈线性。在分化细胞中，这两种电流均显著降低。新霉素和钆均未引起全细胞电流和细胞内[Ca(2+)] 的变化，但新霉素抑制了后期的大电流。细胞外Ca(2+) 以剂量依赖的方式增加增殖HGK的细胞内[Ca(2+)]。全细胞电流和细胞内[Ca(2+)] 反应的时间进程比较表明，两种诱导电流均支持Ca(2+) 内流。细胞外[Mg(2+)] 的变化不影响细胞内[Ca(2+)]。La(3+) 和2-APB抑制全细胞电流和细胞内[Ca(2+)] 的变化。结果表明，CaSR信号反应可能在启动HGK中Ca(2+) 诱导的分化反应中起主要作用。
