Liu X, Wang W, Singh B B, Lockwich T, Jadlowiec J, O'Connell B, Wellner R, Zhu M X, Ambudkar I S
Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Biol Chem. 2000 Feb 4;275(5):3403-11. doi: 10.1074/jbc.275.5.3403.
The trp gene family has been proposed to encode the store-operated Ca(2+) influx (SOC) channel(s). This study examines the role of Trp1 in the SOC mechanism of salivary gland cells. htrp1, htrp3, and Trp1 were detected in the human submandibular gland cell line (HSG). HSG cells stably transfected with htrp1alpha cDNA displayed (i) a higher level of Trp1, (ii) a 3-5-fold increase in SOC (thapsigargin-stimulated Ca(2+) influx), determined by Ca(2+) and Ca(2+)-activated K(+) channel current measurements, and (iii) similar basal Ca(2+) permeability, and inhibition of SOC by Gd(3+) but not by Zn(2+), as compared with control cells. Importantly, (i) transfection of HSG cells with antisense trp1alpha cDNA decreased endogenous Trp1 level and significantly attenuated SOC, and (ii) transfection of HSG cells with htrp3 cDNA did not increase SOC. These data demonstrate an association between Trp1 and SOC and strongly suggest that Trp1 is involved in this mechanism in HSG cells. Consistent with this suggestion, Trp1 was detected in the plasma membrane region, the proposed site of SOC, of acinar and ductal cells in intact rat submandibular glands. Based on these aggregate data, we propose Trp1 as a candidate protein for the SOC mechanism in salivary gland cells.
已有人提出，色氨酸（trp）基因家族编码储存式钙离子内流（SOC）通道。本研究检测了Trp1在唾液腺细胞SOC机制中的作用。在人下颌下腺细胞系（HSG）中检测到了htrp1、htrp3和Trp1。稳定转染htrp1α cDNA的HSG细胞表现出：（i）Trp1水平较高；（ii）通过[Ca²⁺]i和钙离子激活的钾离子通道电流测量确定，SOC（毒胡萝卜素刺激的钙离子内流）增加了3至5倍；（iii）与对照细胞相比，基础钙离子通透性相似，且SOC受钆离子（Gd³⁺）抑制但不受锌离子（Zn²⁺）抑制。重要的是，（i）用反义trp1α cDNA转染HSG细胞可降低内源性Trp1水平并显著减弱SOC；（ii）用htrp3 cDNA转染HSG细胞不会增加SOC。这些数据证明了Trp1与SOC之间的关联，并强烈表明Trp1参与了HSG细胞的这一机制。与此观点一致的是，在完整大鼠下颌下腺腺泡细胞和导管细胞的质膜区域（推测为SOC的位点）检测到了Trp1。基于这些汇总数据我们提出，Trp1是唾液腺细胞SOC机制的候选蛋白。
