Ubels J L, Sulahian T H, Viel M D
Biology Department, Calvin College, Grand Rapids, MI 49546, USA.
Curr Eye Res. 1997 May;16(5):511-5. doi: 10.1076/ceyr.16.5.511.7045.
The lacrimal gland expresses nuclear retinoic acid receptors. This suggests that retinoids are involved in control of gene expression in the lacrimal gland. Retinoid X receptors (RXRs) form heterodimers with and are required for activation of retinoic acid receptors. The purpose of this study was to identify retinoid X receptors in the lacrimal gland.
Total RNA was purified from rat, rabbit and human lacrimal glands and from cultured rat lacrimal cells. RNA was analyzed by northern blotting using cDNA probes for RXR alpha, RXR beta and RXR gamma. Nuclear protein extracts from rat and rabbit lacrimal glands were probed for RXR beta by immunoblotting, using a mouse monoclonal antibody.
RXR alpha mRNA transcripts (5 kb) and RXR beta mRNA transcripts (3.3 kb) are present in the lacrimal glands of all species studied and in cultured rat lacrimal cells. RXR gamma mRNA (1.9 kb) was detected only in the rabbit lacrimal gland. RXR beta is expressed as a 50 kDa protein in rat and rabbit lacrimal glands.
This study confirms the presence of RXRs in the lacrimal gland, thereby supporting a role for retinoids and their nuclear receptors in the control of gene transcription in the lacrimal gland.
泪腺表达核视黄酸受体。这表明类视黄醇参与泪腺基因表达的调控。视黄酸X受体（RXRs）与视黄酸受体形成异二聚体并是其激活所必需的。本研究的目的是鉴定泪腺中的视黄酸X受体。
从大鼠、兔和人的泪腺以及培养的大鼠泪腺细胞中纯化总RNA。使用针对RXRα、RXRβ和RXRγ的cDNA探针通过Northern印迹分析RNA。使用小鼠单克隆抗体通过免疫印迹检测大鼠和兔泪腺的核蛋白提取物中的RXRβ。
在所研究的所有物种的泪腺以及培养的大鼠泪腺细胞中均存在RXRα mRNA转录本（5 kb）和RXRβ mRNA转录本（3.3 kb）。仅在兔泪腺中检测到RXRγ mRNA（1.9 kb）。RXRβ在大鼠和兔泪腺中表达为50 kDa的蛋白质。
本研究证实了泪腺中存在RXRs，从而支持类视黄醇及其核受体在泪腺基因转录调控中的作用。
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