Avner E D, Sweeney W E, Piesco N P, Ellis D
J Lab Clin Med. 1987 Apr;109(4):441-53.
Previous organ culture investigations into the pathogenesis of renal cyst formation have demonstrated that glucocorticoid-induced proximal tubular cyst formation is associated with increases in renal sodium-potassium adenosine triphosphatase (Na-K-ATPase) activity. To explore the relationship between cyst production and transport enzyme induction, we examined the effects of the potent inducer of Na-K-ATPase activity, L-3,5,3'-triiodothyronine (T3), on renal tubular morphologic and enzymatic development in murine metanephric organ culture. The addition of T3 (2 X 10(-8) mol/L) to completely characterized, serum-free growth medium produced striking proximal tubular cystic abnormalities. Frank cyst development was preceded by ultrastructural alterations consisting of basolateral intercellular spreading, which increased with progressive tubular dilation. Ultrastructural analysis demonstrated no abnormalities of tubular cyst wall basal laminae, and immunohistologic staining with affinity-purified antibodies to the basal lamina glycoproteins fibronectin, laminin, and entactin, revealed no differences between cystic and control tissue. With use of an enzyme-linked kinetic microassay, T3-induced cystic organ culture explants (CY) showed significant increases in Na-K-ATPase when compared with controls from 72 to 120 hours of organ culture incubation. The initial differences in CY Na-K-ATPase occurred contemporaneously with the earliest ultrastructural evidence of cyst formation, and subsequent increases paralleled progressive tubular cyst formation. Tubular cyst formation in CY could be largely prevented by daily incubation of explants with ouabain, 0.2 mmol/L (final concentration) for 120 minutes without deleterious effects on overall metanephric development. We conclude that T3 induces proximal tubular cyst formation in metanephric organ culture, and that T3-induced increases in Na-K-ATPase have a primary role in the pathogenesis of tubular cyst formation in this model system.
以往对肾囊肿形成发病机制的器官培养研究表明，糖皮质激素诱导的近端肾小管囊肿形成与肾钠钾三磷酸腺苷酶（Na-K-ATP酶）活性增加有关。为了探究囊肿产生与转运酶诱导之间的关系，我们研究了Na-K-ATP酶活性的强效诱导剂L-3,5,3'-三碘甲状腺原氨酸（T3）对小鼠后肾器官培养中肾小管形态和酶发育的影响。在完全确定成分的无血清生长培养基中添加T3（2×10⁻⁸mol/L）会导致明显的近端肾小管囊性异常。在明显的囊肿形成之前，会出现超微结构改变，包括基底外侧细胞间扩展，随着肾小管逐渐扩张而增加。超微结构分析显示肾小管囊肿壁基底膜无异常，用针对基底膜糖蛋白纤连蛋白、层粘连蛋白和巢蛋白的亲和纯化抗体进行免疫组织化学染色，结果显示囊性组织和对照组织之间没有差异。使用酶联动力学微量测定法，与器官培养孵育72至120小时的对照组相比，T3诱导的囊性器官培养外植体（CY）的Na-K-ATP酶活性显著增加。CY中Na-K-ATP酶的最初差异与囊肿形成的最早超微结构证据同时出现，随后的增加与肾小管囊肿的逐渐形成平行。通过每天将外植体与0.2 mmol/L（终浓度）的哇巴因孵育120分钟，CY中的肾小管囊肿形成在很大程度上可以得到预防，且对整体后肾发育没有有害影响。我们得出结论，T3在肾后器官培养中诱导近端肾小管囊肿形成，并且T3诱导的Na-K-ATP酶增加在该模型系统中肾小管囊肿形成的发病机制中起主要作用。
