Render C L, Hull K L, Harvey S
Department of Physiology, University of Alberta, T6G 2H7, Edmonton, Alberta, Canada.
Endocrine. 1995 Oct;3(10):729-35. doi: 10.1007/BF03000205.
It is well established that growth hormone (GH)-like proteins and mRNA are present in immune tissues, but it is not known whether this reflects ectopic transcription of the GH gene or the expression of a closely related gene. This possibility was, therefore, investigated. Immunoreactive (IR) GH-like proteins were readily measured by radioimmunoassay and immunoblotting in the spleen, bursa of Fabricius and thymus of immature White Leghorn chickens, in which IR-GH was similar in size and antigenicity to the major GH moieties present in the pituitary gland. RT-PCR of mRNA from these immune tissues, with oligonucleotide primers spanning the coding region of pituitary GH cDNA, also generated cDNA fragments identical in size (689 bp) to pituitary GH cDNA.BamHI andRsaI cleavage sites were located in these cDNA sequences in the same position as those in pituitary GH cDNA. These amplified cDNA sequences also contained sequences that hybridized, by Southern blotting, with a chicken pituitary GH cDNA probe, thus suggesting a high degree of homology between pituitary and immune GH transcripts. The nucleotide sequence of the PCR products generated from these immune tissues, determined by a modified cycle dideoxy chain termination method, were also identical to pituitary GH cDNA. This homology extended over 593 bp of the spleen cDNA (spanning nucleotides 70-663 of the pituitary GH cDNA and its coding region for amino acids 5-201), 613 bp of the bursa cDNA fragment (spanning nucleotides 63-676 of the pituitary GH cDNA and its coding region for amino acids 3-207) and 607 bp of the thymic cDNA fragment (spanning nucleotides 61-665 of pituitary GH cDNA and its coding region for amino acids 4-203). These results clearly establish that the GH mRNA is present in immune tissues, in which GH-IR proteins are present. The local production of GH within the immune system of the domestic fowl, therefore, suggests it has paracrine or autocrine roles in modulating immune function.
生长激素（GH）样蛋白和mRNA存在于免疫组织中，这一点已得到充分证实，但尚不清楚这是反映了GH基因的异位转录还是密切相关基因的表达。因此，对这种可能性进行了研究。通过放射免疫测定和免疫印迹法，很容易在未成熟白来航鸡的脾脏、法氏囊和胸腺中检测到免疫反应性（IR）GH样蛋白，其中IR-GH在大小和抗原性上与垂体中存在的主要GH部分相似。用跨越垂体GH cDNA编码区的寡核苷酸引物对这些免疫组织的mRNA进行RT-PCR，也产生了与垂体GH cDNA大小相同（689 bp）的cDNA片段。BamHI和RsaI切割位点在这些cDNA序列中的位置与垂体GH cDNA中的位置相同。这些扩增的cDNA序列还包含通过Southern印迹与鸡垂体GH cDNA探针杂交的序列，因此表明垂体和免疫GH转录本之间具有高度同源性。通过改良的循环双脱氧链终止法测定，这些免疫组织产生的PCR产物的核苷酸序列也与垂体GH cDNA相同。这种同源性延伸至脾脏cDNA的593 bp（跨越垂体GH cDNA的核苷酸70-663及其氨基酸5-201编码区）、法氏囊cDNA片段的613 bp（跨越垂体GH cDNA核苷酸63-676及其氨基酸3-207编码区）和胸腺cDNA片段的607 bp（跨越垂体GH cDNA核苷酸61-665及其氨基酸4-203编码区）。这些结果清楚地表明，GH mRNA存在于存在GH-IR蛋白的免疫组织中。因此，家禽免疫系统中GH的局部产生表明它在调节免疫功能中具有旁分泌或自分泌作用。
