Benditt E P, Meek R L
Department of Pathology, University of Washington, Seattle 98195.
J Exp Med. 1989 May 1;169(5):1841-6. doi: 10.1084/jem.169.5.1841.
Three homologous genes that code for three related proteins comprise the serum amyloid A (SAA) family in the mouse. Endotoxin induces equally vigorous expression of mRNAs for the three SAA genes in liver. In extrahepatic tissues SAA1 and/or SAA2 mRNAs have been found only in kidney and intestine, however, SAA3 is expressed in all extrahepatic tissues thus far examined. This observation raised the question: is SAA3 mRNA expressed by a single cell system dispersed throughout all tissues, or by differentiated cells of each tissue? This question was explored in various tissues by in situ hybridization with a single-stranded cRNA probe specific for SAA3 mRNA. We found expression in the liver of SAA3 mRNA by other cells as well as by hepatocytes. A common feature among extrahepatic tissues was SAA3 mRNA expression in adipocytes. SAA3 mRNA was also found in two nonadipose cells, Leydig cells of the testis, and some of the cells located in parafollicular zones of the spleen.
编码三种相关蛋白质的三个同源基因构成了小鼠的血清淀粉样蛋白A（SAA）家族。内毒素可同等强烈地诱导肝脏中三个SAA基因的mRNA表达。然而，在肝外组织中，仅在肾脏和肠道中发现了SAA1和/或SAA2的mRNA，而SAA3在迄今为止检查的所有肝外组织中均有表达。这一观察结果引发了一个问题：SAA3 mRNA是由分散在所有组织中的单一细胞系统表达，还是由每个组织的分化细胞表达？我们通过用针对SAA3 mRNA的单链cRNA探针进行原位杂交，在各种组织中探讨了这个问题。我们发现，除肝细胞外，肝脏中的其他细胞也表达SAA3 mRNA。肝外组织的一个共同特征是脂肪细胞中表达SAA3 mRNA。在两种非脂肪细胞中也发现了SAA3 mRNA，即睾丸的间质细胞和脾脏滤泡旁区的一些细胞。
