Ubels J L, Dennis M H, Rigatti B W, Vergnes J P, Beatty R, Kinchington P R
Department of Ophthalmology, University of Pittsburgh, PA 15213, USA.
Curr Eye Res. 1995 Nov;14(11):1055-62. doi: 10.3109/02713689508998530.
The lacrimal gland secretes and metabolizes retinoids and responds to retinoic acid in culture. Like other retinoid responsive organs it is expected to express the nuclear retinoid receptors. The goal of this study was to identify the retinoic acid receptors (RAR) in the lacrimal glands of rats, rabbits, and humans. Total RNA was prepared from whole lacrimal glands and rat lacrimal gland acinar cells grown in culture. RNA was subjected to Northern blot analysis and probed for the RAR alpha, RAR beta, and RAR gamma mRNAs. Nuclear extracts of rat and rabbit lacrimal glands were incubated with 3H-all-trans retinoic acid and analyzed by gel filtration chromatography. Western blots of the nuclear extracts were probed using monoclonal antibodies to RAR alpha and RAR beta. Rat lacrimal gland expresses RAR alpha mRNA with two transcripts (3.8 and 3.0 kb), a single RAR beta mRNA transcript (3.3 kb), and a single RAR gamma mRNA transcript (3.3 kb). Cultured rat lacrimal acinar cells also expressed the mRNA for all three RAR subtypes. Rabbit lacrimal glands express mRNAs for RAR alpha (3.7 and 2.9 kb) and RAR beta (3.2 kb) but RAR gamma mRNA is not detectable. Human lacrimal glands also express mRNA for RAR alpha (3.5 and 2.3 kb), RAR beta (3.4 kb) and RAR gamma (3.0 kb). Lacrimal gland nuclear extracts contain proteins in the 50 kDa range that specifically bind retinoic acid with Kd = 1.25 nM in rat lacrimal gland and 0.3 nM in rabbit. The monoclonal antibodies identified RAR alpha and RAR beta in both rat and rabbit lacrimal glands. The results of this study support a role for retinoids in maintaining the structure and function of the lacrimal gland. The presence of RARs suggests potential interactions of these receptors with other members of their superfamily, including androgen and thyroid receptors, which also may be involved in lacrimal function.
泪腺分泌并代谢类视黄醇，且在培养过程中对视黄酸有反应。与其他视黄醇反应性器官一样，预计它会表达核视黄醇受体。本研究的目的是鉴定大鼠、兔子和人类泪腺中的视黄酸受体（RAR）。从整个泪腺和培养的大鼠泪腺腺泡细胞中制备总RNA。对RNA进行Northern印迹分析，并检测RARα、RARβ和RARγ mRNA。将大鼠和兔子泪腺的核提取物与3H-全反式视黄酸孵育，并用凝胶过滤色谱法进行分析。使用针对RARα和RARβ的单克隆抗体探测核提取物的蛋白质免疫印迹。大鼠泪腺表达具有两种转录本（3.8和3.0 kb）的RARα mRNA、单一的RARβ mRNA转录本（3.3 kb）和单一的RARγ mRNA转录本（3.3 kb）。培养的大鼠泪腺腺泡细胞也表达所有三种RAR亚型的mRNA。兔子泪腺表达RARα（3.7和2.9 kb）和RARβ（3.2 kb）的mRNA，但未检测到RARγ mRNA。人类泪腺也表达RARα（3.5和2.3 kb）、RARβ（3.4 kb）和RARγ（3.0 kb）的mRNA。泪腺核提取物含有50 kDa范围内的蛋白质，这些蛋白质在大鼠泪腺中以Kd = 1.25 nM、在兔子中以0.3 nM的亲和力特异性结合视黄酸。单克隆抗体在大鼠和兔子泪腺中均鉴定出RARα和RARβ。本研究结果支持类视黄醇在维持泪腺结构和功能中的作用。RAR的存在表明这些受体与其超家族的其他成员（包括雄激素和甲状腺受体，它们也可能参与泪腺功能）之间存在潜在相互作用。
