Mechanical stimuli induce cleavage and nuclear translocation of the polycystin-1 C terminus
Veronique Chauvet, Xin Tian, Herve Husson, David H. Grimm, Tong Wang, Thomas Hieseberger, Peter Igarashi, Anton M. Bennett, Oxana Ibraghimov-Beskrovnaya, Stefan Somlo, Michael J. Caplan
Veronique Chauvet, Xin Tian, Herve Husson, David H. Grimm, Tong Wang, Thomas Hieseberger, Peter Igarashi, Anton M. Bennett, Oxana Ibraghimov-Beskrovnaya, Stefan Somlo, Michael J. Caplan
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Article Nephrology

Mechanical stimuli induce cleavage and nuclear translocation of the polycystin-1 C terminus

Abstract

Polycystin-1, which is encoded by a gene that is mutated in autosomal dominant polycystic kidney disease (ADPKD), is involved in cell-matrix interactions as well as in ciliary signaling. The precise mechanisms by which it functions, however, remain unclear. Here we find that polycystin-1 undergoes a proteolytic cleavage that releases its C-terminal tail (CTT), which enters the nucleus and initiates signaling processes. The cleavage occurs in vivo in association with alterations in mechanical stimuli. Polycystin-2, the product of the second gene mutated in ADPKD, modulates the signaling properties of the polycystin-1 CTT. These data reveal a novel pathway by which polycystin-1 transmits messages directly to the nucleus.

Authors

Veronique Chauvet, Xin Tian, Herve Husson, David H. Grimm, Tong Wang, Thomas Hieseberger, Peter Igarashi, Anton M. Bennett, Oxana Ibraghimov-Beskrovnaya, Stefan Somlo, Michael J. Caplan

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The CTT of polycystin-1 accumulates in nuclei and activates the AP-1 pat...
The CTT of polycystin-1 accumulates in nuclei and activates the AP-1 pathway. (A) Schematic diagram of the structure of polycystin-1 CTT constructs. The predicted CTT includes residues 4,048–4,302. The p200 construct contains the final 200 amino acids of the polycystin-1 tail, extending from residue 4,102 to residue 4,302. The putative NLS, located between residues 4,134 and 4,154, is deleted in the p200Ø construct. (B) Comparison of the molecular weights of p200 and the CTT generated from full-length polycystin-1 expressed in MDCK cells. The p200 protein migrates with an apparent molecular weight of about 28 kDa, whereas the CTT derived from full-length polycystin-1 migrates as a protein with a molecular weight of about 34 kDa. (C) When expressed in Cos-7 cells the p200 protein accumulates mainly in the nucleus, as detected with polycystin-1 and Xpress antibodies (left center panel). Nuclei are labeled with a histone deacetylase-1 antibody (Hd; right center panel). (D) In contrast, the p200Ø protein is excluded from the nucleus in transfected Cos-7 cells, as observed with the polycystin-1 and Xpress antibodies (left panels), and distributes instead in a pattern suggestive of association with the ER, as seen by colocalization using Serca-2 and polycystin-1 antibodies (right panels). Original magnification, ×1000 (C and D). (E) Expression of p200 considerably elevates the activity of a coexpressed AP-1 reporter system over the background detected in cells transfected with an empty vector (Mock). This activation is not observed with the p200Ø construct or with the PLAP-p200 construct, in which p200 is attached to a membrane anchor. Thus, p200 must be free to enter the nucleus in order to activate the AP-1 pathway. The AP-1 activity for each condition is normalized to the activity observed in p200-expressing cells. RLU, relative light units. Each bar is the average of six experiments performed in triplicate. (F) Although p200Ø does not activate AP-1 activity, it is expressed at a level comparable to or greater than that of p200, as determined by Western blotting with an antibody directed against the Xpress tag.