CHARACTERIZATION OF GONADAL RECEPTORS AND GONADOTROPIN BIOLOGICAL ACTIVITY

大鼠促黄体生成素受体基因的转录活性区域 被定位在5‘侧翼173个碱基区域内，毗邻 表达细胞和非表达细胞的起始密码子。镇压 这两种细胞类型的启动子活性都是由上游诱导的 元素位于至少两个域中。AM附加上行抑制 只存在于非表达细胞中的元件可能参与 黄体生成素受体的结构性抑制。173个碱基的结构域分析 揭示了两个独立的启动子区域。-1之间的第一个域 和-137个碱基对由典型的塔塔或CAAT盒携带，但确实包含SP1 元素和抑制物部位。第二个启动子结构域位于 核苷酸-120和-173在非表达细胞中占优势。 仅在表达细胞中观察到的组织特异性DNA结合蛋白， 存在于每个启动子结构域中，并且可能在 特定于组织的调控事件。这两种蛋白都有共同的表达 而不表达的细胞类型(C-box蛋白)可能在 基本转录。促黄体生成素受体基因的复杂调控模式 转录水平可以反映这两个启动子的交替激活 结构域，并可能参与激素诱导的基因波动 在性腺成熟过程中的表达。乳素受体的异质性 性腺已经在分子水平上被定义为 编码不同受体的卵巢c DNA克隆的鉴定 异构体(克隆R1，编码80 kDa跨膜形式，短 细胞质结构域；L1，用于40 kDa的跨膜，具有长的细胞质 以及R2，一种可溶的受体形式)。基因的差异杂交 卵巢mRNA分析表明，长形DNA来源于9.7和 4.6mRNA族。两种不同的信使核糖核酸(1.8和2.1 kb) 与短跨膜形式相对应，但不同于非跨膜形式 编码区。2.6kb的信使核糖核酸(尚未克隆或分离蛋白) 是长跨膜形式的变体，带有截断或改变的 胞外区，并可能是一个结构性的活性基因产物。 9.7kb的物种是在早期发育中观察到的唯一物种， 另一种是由FSH或LH诱导的。所有五种mRNA物种 以发育阶段特有的方式表达和调控 在促性腺激素诱导的卵巢成熟、黄体化和 脱敏。协调受体结合的上调和下调 促性腺激素的活性和mRNA水平表明，常见的 其作用机制与这两种受体基因的表达调控有关。

The region of transcriptional activity in the rat LH receptor gene has been localized within the 5' flanking 173 bp domain adjacent to the initiation codon in expressing and non-expressing cells. Repression of this promoter activity in both cell types was induced by upstream elements in at least two domains. Am additional upstream inhibitory element present only in non-expressing cells is likely to participate in constitutive repression of LH receptors. Analysis of the 173 bp domain revealed two independent promoter regions. The first domain between -1 and -137 bp carries by typical TATA or CAAT boxes, but does contain SP1 elements and inhibitor sites. A second promoter domain between nucleotides -120 and -173 is predominant in non-expressing cells. Tissue-specific DNA binding proteins, observed only in expressing cells, are present for each of the promoter domains and may be important in tissue-specific regulatory events. A protein common to both expressing and non-expressing cell types (C-box protein) may play a central role in basal transcription. Complex regulatory patterns in LH receptor gene transcription can reflect the alternate activation of these two promoter domains, and may be involved in hormone-induced fluctuations of gene expression during gonadal maturation. Lactogen receptor heterogeneity in the gonads has been defined at the molecular level by the characterization of ovarian cDNA clones coding for distinct receptor isoforms (clone R1, coding for 80 kDa transmembrane form with short cytoplasmic domain; L1, for a 40 kDa transmembrane with long cytoplasmic domain; and R2, a soluble receptor form). Differential hybridization of ovarian mRNA demonstrated that the long form is derived from the 9.7 and the 4.6 mRNA species. Two distinct mRNA species (1.8 and 2.1 kb) correspond to the short transmembrane form with differences their non- coding regions. A 2.6 kb mRNA (not yet cloned or the protein isolated) is a variant of the long transmembrane form with a truncated or altered extracellular domain, and could be a constitutively active gene product. The 9.7 kb species is the only species observed in early development, while the other forms are induced by FSH or LH. All five mRNA species are expressed and regulated in a developmental stage-specific manner during gonadotropin-induced ovarian maturation, luteinization, and desensitization. Coordinate up- and down-regulation of receptor binding activities and mRNA levels by gonadotropin suggest that a common mechanism is involved in the regulation of the two receptor mRNA's.