Multiple cellular pathways are dysregulated in autosomal dominant polycystic kidney disease (ADPKD), but mechanisms initiating cyst formation are unknown. ADPKD is caused by mutations in Pkd1/Pkd2 genes that encode for polycystins that localize to primary cilia. The primary cilium is a miniscule subcellular compartment for generating signaling outputs that profoundly affect cellular function. Severe cystogenesis from polycystin loss is mostly cilia dependent. However, the polycystin-repressed ciliary signals that promote cyst growth are unknown and have been challenging to uncouple from downstream cystogenic pathways. Here we aimed at differentiating ciliary adenylyl cyclase signaling from total cellular changes in second messenger cAMP implicated in cystogenesis. We studied an Ankyrin repeat and MYND domain protein, ANKMY2 that we previously implicated in maturation and ciliary localization of adenylyl cyclases in fibroblasts. We studied kidney-specific conditional knockout mouse models of Ankmy2/Pkd1 and ciliary localization of adenylyl cyclases in kidney epithelial cells. We found suppression of early postnatal renal cystogenesis and prolonged survival in an embryonic onset Pkd1 deletion model from ANKMY2 loss. Phosphorylated CREB formation, from elevated cellular cAMP levels, remained unaffected. Cyst load in male mice in an adult inducible conditional Pkd1 deletion model was suppressed from ANKMY2 loss. Mechanistically, ANKMY2 determined ciliary trafficking of adenylyl cyclases in kidney epithelial cells without disrupting cilia. Further, ANKMY2 loss prevented ciliary length increase in ADPKD mouse models irrespective of cyst load or sex. Cilia length increase was seen preceding cystogenesis. Our results suggest that targeting of adenylyl cyclases to renal epithelial cilia promotes PC1/2-inhibited cilia-dependent cyst activation distinct from cyst progression involving cellular cAMP.

在常染色体显性多囊肾病（ADPKD）中，多个细胞通路失调，但引发囊肿形成的机制尚不清楚。ADPKD是由Pkd1/Pkd2基因突变引起的，这些基因编码位于纤毛中的多囊蛋白。初级纤毛是生成信号输出的微小亚细胞区室，对细胞功能有深远影响。由于多囊蛋白丢失而导致的严重囊肿形成主要依赖于纤毛。然而，被多囊蛋白抑制并促进囊肿生长的纤毛信号尚不清楚，并且难以从下游囊肿形成的通路中分离出来。在这里，我们旨在区分纤毛腺苷酸环化酶信号与在囊肿生成过程中涉及的整体细胞二酰基甘油（cAMP）变化。我们研究了一种含有ANKMY结构域的蛋白质——ANKMY2，先前已将其与成纤维细胞中的腺苷酸环化酶成熟和纤毛定位相关联。我们还研究了肾特异性条件敲除小鼠模型Ankmy2/Pkd1以及肾上皮细胞中腺苷酸环化酶的纤毛定位情况。我们发现，ANKMY2丢失可以抑制胚胎期Pkd1基因缺失模型中的早期出生后肾囊肿形成，并延长了生存时间。从升高的细胞cAMP水平形成的磷酸化的CREB（激活调节增殖的cAMP反应元件结合蛋白）没有受到影响。在成年诱导条件性敲除Pkd1的小鼠模型中，ANKMY2丢失可以抑制雄性小鼠的囊肿负荷量。机制上，ANKMY2决定了肾上皮细胞中腺苷酸环化酶向纤毛的转运而不破坏纤毛。此外，在ADPKD小鼠模型中，不论囊肿负荷或性别如何，ANKMY2丢失均可防止纤毛长度增加。在囊肿形成之前就观察到了纤毛长度的增加。我们的结果表明，将腺苷酸环化酶靶向到肾上皮细胞中的纤毛会促进PC1/2抑制的纤毛依赖性囊泡激活，这与涉及细胞内cAMP的囊肿进展过程是不同的。