The polycystin-1 C-terminal fragment triggers branching morphogenesis and migration of tubular kidney epithelial cells
Christian Nickel, … , Lloyd G. Cantley, Gerd Walz
Christian Nickel, … , Lloyd G. Cantley, Gerd Walz
Published February 15, 2002
Citation Information: J Clin Invest. 2002;109(4):481-489. https://doi.org/10.1172/JCI12867.
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Article

The polycystin-1 C-terminal fragment triggers branching morphogenesis and migration of tubular kidney epithelial cells

Abstract

Mutations of either PKD1 or PKD2 cause autosomal dominant polycystic kidney disease, a syndrome characterized by extensive formation of renal cysts and progressive renal failure. Homozygous deletion of Pkd1 or Pkd2, the genes encoding polycystin-1 and polycystin-2, disrupt normal renal tubular differentiation in mice but do not affect the early steps of renal development. Here, we show that expression of the C-terminal 112 amino acids of human polycystin-1 triggers branching morphogenesis and migration of inner medullary collecting duct (IMCD) cells, and support in vitro tubule formation. The integrity of the polycystin-2–binding region is necessary but not sufficient to induce branching of IMCD cells. The C-terminal domain of polycystin-1 stimulated protein kinase C-α (PKC-α), but not the extracellular signal–regulated kinases ERK1 or ERK2. Accordingly, inhibition of PKC, but not ERK, prevented polycystin-1–mediated IMCD cell morphogenesis. In contrast, HGF-mediated morphogenesis required ERK activation but was not dependent on PKC. Our findings demonstrate that the C-terminal domain of polycystin-1, acting in a ligand-independent fashion, triggers unique signaling pathways for morphogenesis, and likely plays a central role in polycystin-1 function.

Authors

Christian Nickel, Thomas Benzing, Lorenz Sellin, Peter Gerke, Anil Karihaloo, Zhen-Xiang Liu, Lloyd G. Cantley, Gerd Walz

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Figure 7

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Mutational analysis reveals that the integrity of two distinct regions o...
Mutational analysis reveals that the integrity of two distinct regions of the cytoplasmic domain of human polycystin-1 is necessary to trigger branching morphogenesis. (a) Depicted are the two N-terminal heptad repeats (blue line, blue arrow) and the five C-terminal heptad repeats (red line, red arrow), intersected by the proline-rich region of the C-terminus of polycystin-1. The mutated amino acids (L4196, V4235, and L4238) are shown in red text. The position of the patient truncation mutant R4227X is marked with a single asterisk. (b–d) IMCD cells were transduced with a retrovirus expressing CD16.7 fused to the cytoplasmic tail of polycystin-1 (PKD1 WT), or to three mutations (PKD1 L4196D), the double mutation (PKD1 V4235D/L4238D), and the triple mutation (PKD1 L4196D/V4235D/L4238D). A retrovirus expressing CD16.7 was used as a control. The coiled-coils prediction reveals that the L4196D mutation dramatically reduces the coiled-coils probability for the N-terminal heptad repeats (b), and the V4235D/L4238D double mutation abolishes the coiled-coils probability for the C-terminal heptad repeats (c). Accordingly, the triple mutation L4196D/V4235D/L4238D virtually eliminates the coiled-coils probability for the entire region (d). All three mutations completely abrogate branching morphogenesis of IMCD cells. **P < 0.01.