title: Polycystin-1 C-terminal cleavage is modulated by polycystin-2 expression.
abstract: Autosomal dominant polycystic kidney disease is caused by mutations in the genes encoding polycystin-1 (PC-1) and polycystin-2 (PC-2). PC-1 cleavage releases its cytoplasmic C-terminal tail (CTT), which enters the nucleus. To determine whether PC-1 CTT cleavage is influenced by PC-2, a quantitative cleavage assay was utilized, in which the DNA binding and activation domains of Gal4 and VP16, respectively, were appended to PC-1 downstream of its CTT domain (PKDgalvp). Cells cotransfected with the resultant PKDgalvp fusion protein and PC-2 showed an increase in luciferase activity and in CTT expression, indicating that the C-terminal tail of PC-1 is cleaved and enters the nucleus. To assess whether CTT cleavage depends upon Ca2+ signaling, cells transfected with PKDgalvp alone or together with PC-2 were incubated with several agents that alter intracellular Ca2+ concentrations. PC-2 enhancement of luciferase activity was not altered by any of these treatments. Using a series of PC-2 C-terminal truncated mutations, we identified a portion of the PC-2 protein that is required to stimulate PC-1 CTT accumulation. These data demonstrate that release of the CTT from PC-1 is influenced and stabilized by PC-2. This effect is independent of Ca2+ but is regulated by sequences contained within the PC-2 C-terminal tail, suggesting a mechanism through which PC-1 and PC-2 may modulate a novel signaling pathway.
authors.affiliation: Departments of Cellular and Molecular Physiology, New Haven, Connecticut 06510, USA.
authors.forename: Claudia A
authors.initials: CA
authors.lastname: Bertuccio
authors.forename: Hannah C
authors.initials: HC
authors.lastname: Chapin
authors.forename: Yiqiang
authors.initials: Y
authors.lastname: Cai
authors.forename: Kavita
authors.initials: K
authors.lastname: Mistry
authors.forename: Veronique
authors.initials: V
authors.lastname: Chauvet
authors.forename: Stefan
authors.initials: S
authors.lastname: Somlo
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Caplan
mesh_terms: D019943:Amino Acid Substitution / Q000187:drug effects; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000494:pharmacology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002522:Chlorocebus aethiops; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D017930:Genes, Reporter; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D050505:Mutant Proteins / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D013329:Structure-Activity Relationship; D050396:TRPP Cation Channels / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D002118:Calcium; D050505:Mutant Proteins; D046988:Proteasome Endopeptidase Complex; D050396:TRPP Cation Channels