TRPγ Channels Are Inhibited by cAMP and Contribute to Pacemaking in Neurosecretory Insect Neurons
| Autor: | Roland Schönherr, Dieter Wicher, Hans-Jürgen Agricola, Christian Derst, Stefan H. Heinemann |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Nervous system
DNA Complementary Insecta Blotting Western Genetic Vectors Molecular Sequence Data 8-Bromo Cyclic Adenosine Monophosphate Down-Regulation Nervous System Biochemistry Ion Channels Cell Line Transient receptor potential channel Transient Receptor Potential Channels Complementary DNA Cyclic AMP medicine Consensus sequence Animals Drosophila Proteins Humans Periplaneta Amino Acid Sequence Protein kinase A Molecular Biology Ions Neurons Binding Sites Sequence Homology Amino Acid biology Reverse Transcriptase Polymerase Chain Reaction cDNA library Sodium Cell Biology Anatomy biology.organism_classification Immunohistochemistry Protein Structure Tertiary Cell biology Electrophysiology Alternative Splicing medicine.anatomical_structure Microscopy Fluorescence Calcium Drosophila Photoreceptor Cells Invertebrate Heterologous expression Peptides |
| Zdroj: | Journal of Biological Chemistry. 281:3227-3236 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m511741200 |
| Popis: | From a neuronal cDNA library of the cockroach Periplaneta americana we isolated a 3585-bp cDNA sequence encoding Periplaneta transient receptor potential gamma (pTRPgamma), a protein of 1194 amino acids showing 65% identity to the orthologous Drosophila channel protein dTRPgamma. Heterologous expression of pTRPgamma in HEK293 cells produced a constitutively active, non-selective cation channel with a Ca2+:Na+ permeability ratio of 2. In contrast to dTRPgamma-mediated currents, pTRPgamma currents were partially inhibited by 8-bromo-cAMP, and this effect was not mediated by protein kinase A (PKA) activation. pTRPgammab, a truncated pTRPgamma splice variant missing most of the C terminus, was insensitive to 8-bromo-cAMP. Thus, the critical cAMP-binding site seems to be located in the C-terminal part of pTRPgamma, although there is no common cAMP-binding consensus sequence. While dTRPgamma is only expressed in the photoreceptors, pTRPgamma is expressed throughout the nervous system. In particular it is expressed in dorsal unpaired median (DUM) neurons. In these octopamine-releasing, neurosecretory cells a Ca2+ background current contributing to pacemaker activity was found to be up-regulated by the reduction of cAMP level. In addition, the Ca2+ background current was inhibited by LOE-908, 2-APB, and La3+, which similarly affected the pTRPgamma current. We thus propose that the pTRPgamma protein is involved in forming the channel passing the Ca2+ pakemaking background current in DUM neurons. |
| Databáze: | OpenAIRE |
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