title: The coiled-coil domain of zebrafish TRPM7 regulates Mg·nucleotide sensitivity.
abstract: TRPM7 is a member of the Transient-Receptor-Potential Melastatin ion channel family. TRPM7 is a unique fusion protein of an ion channel and an α-kinase. Although mammalian TRPM7 is well characterized biophysically and its pivotal role in cancer, ischemia and cardiovascular disease is becoming increasingly evident, the study of TRPM7 in mouse models has been hampered by embryonic lethality of transgenic ablations. In zebrafish, functional loss of TRPM7 (drTRPM7) manifests itself in an array of non-lethal physiological malfunctions. Here, we investigate the regulation of wild type drTRPM7 and multiple C-terminal truncation mutants. We find that the biophysical properties of drTRPM7 are very similar to mammalian TRPM7. However, pharmacological profiling reveals that drTRPM7 is facilitated rather than inhibited by 2-APB, and that the TRPM7 inhibitor waixenicin A has no effect. This is reminiscent of the pharmacological profile of human TRPM6, the sister channel kinase of TRPM7. Furthermore, using truncation mutations, we show that the coiled-coil domain of drTRPM7 is involved in the channel's regulation by magnesium (Mg) and Mg·adenosine triphosphate (Mg·ATP). We propose that drTRPM7 has two protein domains that regulate inhibition by intracellular magnesium and nucleotides, and one domain that is concerned with sensing magnesium only.
authors.affiliation: Center for Biomedical Research, The Queen's Medical Center and University of Hawaii, Honolulu, HI-96813, USA.|University of Hawaii Cancer Center and John A. Burns School of Medicine, University of Hawaii, Honolulu, HI-96813, USA.
authors.forename: Chad
authors.initials: C
authors.lastname: Jansen
authors.affiliation: Center for Immunity and Immunotherapies, Seattle Children's Research Institute, 1900 9th Ave, Seattle, WA 98101, USA.
authors.forename: Jaya
authors.initials: J
authors.lastname: Sahni
authors.affiliation: Center for Biomedical Research, The Queen's Medical Center and University of Hawaii, Honolulu, HI-96813, USA.
authors.forename: Sayuri
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: Laboratory of Marine Biological Chemistry, Department of Natural Sciences, Hawaii Pacific University, Kaneohe, HI 96744, USA.
authors.forename: F David
authors.initials: FD
authors.lastname: Horgen
authors.affiliation: Center for Biomedical Research, The Queen's Medical Center and University of Hawaii, Honolulu, HI-96813, USA.|University of Hawaii Cancer Center and John A. Burns School of Medicine, University of Hawaii, Honolulu, HI-96813, USA.
authors.forename: Reinhold
authors.initials: R
authors.lastname: Penner
authors.affiliation: Center for Biomedical Research, The Queen's Medical Center and University of Hawaii, Honolulu, HI-96813, USA.|University of Hawaii Cancer Center and John A. Burns School of Medicine, University of Hawaii, Honolulu, HI-96813, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Fleig
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D055592:Biophysical Phenomena; D001896:Boron Compounds / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002645:Chickens; D004553:Electric Conductivity; D057809:HEK293 Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D050505:Mutant Proteins / Q000494:pharmacology; D009994:Osmolar Concentration; D000072417:Protein Domains; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D050053:TRPM Cation Channels / Q000737:chemistry* / Q000378:metabolism*; D015027:Zebrafish / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: C538758:2-aminoethyl diphenylborinate; D001896:Boron Compounds; D050505:Mutant Proteins; D050053:TRPM Cation Channels; D029961:Zebrafish Proteins; D000255:Adenosine Triphosphate; D017346:Protein Serine-Threonine Kinases; C501875:Trpm7 protein, zebrafish; D008274:Magnesium