Analysis on the lineage of adrenocortical cells with 3-dimentional arrangement

肾上腺皮质由髓质和皮质两种功能和个体发育不同的组织组成。中胚层起源的皮层进一步分成三个具有特定功能的同心圆区：肾小球带（zG）、束状带（zF）和网状带（zR）。先前我们在zG和zF之间发现了另一个区（未分化细胞区：zU）；这一层的细胞被认为是肾上腺皮质细胞的干细胞，因为它们不能表达区域特异性的类固醇生成酶，并且在区域周围增殖细胞的行为。然后我们建立了这样的细胞系（祖细胞系）。我们尝试将zU细胞移植到scid小鼠的肾脏，但目前尚未成功。本研究旨在探讨肾上腺皮质细胞的谱系和皮层区维持的机制。通过减法杂交在上述细胞系中发现了一种新的分泌蛋白（后来被命名为肾上腺皮质区化因子1:AZ-1）。该蛋白含有一个分泌信号、egf样重复序列和一个蛋白水解无活性的蛋白酶B相关序列。AZ-1 mRNA仅在zU和zG中检测到。有趣的是，AZ-1 mRNA在肾上腺皮质细胞中的表达与P45011β mRNA的表达呈负相关。AZ-1蛋白存在于整个肾皮质的细胞外部分；它与与血管相关的层粘连蛋白、胶原蛋白和纤维连接蛋白共定位。在皮层发育过程中，AZ-1总是与这些细胞外基质定位。在AZ- I的帮助下，皮质细胞沿细胞外基质迁移和分化。

The adrenal cortex is composed of two functionally and ontogenetically different tissues, the medulla and the cortex. The cortex of mesodermal origin further separates into three concentric zones with specific functions : the zona glomerulosa(zG), the zona fasciculata (zF) and the zona reticularis (zR). Formerly we discovered another zone(undifferentiated cell zone : zU) between zG and zF ; cells in the layer are thought to be stem cells for adrenocortical cells as judged by their inability to express zone-specific steroidogenic enzymes and the behavior of proliferating cells around the zone. We then established such cell-lines(zU-cell line). We tried to transplant the zU cells to the kidney of scid mice, but so far we have not succeeded yet. This study was aimed to investigate the lineage of adrenocortical cells and mechanisms of the maintenance of cortical zones.A new secretory protein(designated later as adrenocortical zonation factor 1 : AZ-1) was identified in the cell line described above by subtractive hybridization. The protein contained a secretory signal, EGF-like repeats, and a proteolytically inactive catepsin B- related sequence. The AZ-1 mRNA was detected only in zU and zG. Interestingly the expression of AZ-1 mRNA in adrenocortical cells was inversely correlated with that of P45011β mRNA. AZ-1 protein, on the other hand, was observed in extracellular portions of whole drenal cortex ; it colocalizes with laminin, collagen, and fibronectin which associate with blood vessels. During development of the cortex, AZ-1 always colocalized with those extracellular matrix. The migration and differentiation of cortical cells may occur along extracellular matrix with the aid of AZ- I.