title: A splice form of polycystin-2, lacking exon 7, does not interact with polycystin-1.
abstract: Polycystin-2 (or polycystic kidney disease gene 2 product, PKD2) and its homologues are calcium-regulated ion channels. Mutations in PKD2 are causative for autosomal dominant polycystic kidney disease. Alternative splicing has been documented for the 'PKD2-like' genes as a naturally occurring event and for PKD2 in pathologic context. Here we studied naturally occurring PKD2/Pkd2 (human/murine) splice forms on the mRNA and protein levels. Systematic scanning of PKD2/Pkd2 cDNAs obtained through RT-PCR from murine tissues and human cell lines revealed alternative splice forms that were sequenced and checked for translation. We identified three major alternative transcripts of PKD2/Pkd2, PKD2/Pkd2Delta6, PKD2/Pkd2Delta7 and PKD2/Pkd2Delta9, and one minor splice form, PKD2/Pkd2Delta12-13, numbered according to deleted exons or parts thereof. A transcript lacking exon 7 (PKD2/Pkd2Delta7) generated significantly altered protein variant. This polycystin-2Delta7 protein appeared stable, when expressed in cell culture and apparently did not interact with polycyctin-1, which should be due to the reversed topology (extracellular) of the interacting C-terminus (intracellular in polycystin-2). Pkd2Delta7 transcript was predominantly expressed in brain and amounted to 3-6.4% of Pkd2 transcripts in the relevant organ. Moreover, both Pkd2 and Pkd2Delta7 were developmentally regulated. Polycystin-2Delta7 adds on to the number of identified polycystin molecules. The predominant expression in brain indicates a function in this organ. The inability to interact with polycystin-1 expands further the PKD1-independent functions of polycystin-2 forms.
authors.affiliation: Institut für Humangenetik, Universitätsklinikum Münster, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Hackmann
authors.forename: Arseni
authors.initials: A
authors.lastname: Markoff
authors.forename: Feng
authors.initials: F
authors.lastname: Qian
authors.forename: Nadia
authors.initials: N
authors.lastname: Bogdanova
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Germino
authors.forename: Petra
authors.initials: P
authors.lastname: Pennekamp
authors.forename: Bernd
authors.initials: B
authors.lastname: Dworniczak
authors.forename: Jürgen
authors.initials: J
authors.lastname: Horst
authors.forename: Volker
authors.initials: V
authors.lastname: Gerke
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons / Q000235:genetics; D005455:Fluorescent Antibody Technique; D006801:Humans; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011506:Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D050396:TRPP Cation Channels
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D008565:Membrane Proteins; D011506:Proteins; D050396:TRPP Cation Channels