Disease relevance of TRPM5

• MTR1 transcripts are present in a large proportion of WTs and rhabdomyosarcomas [1].

High impact information on TRPM5

• TRPM5, a member of the TRPM subfamily, plays an important role in taste receptors, although its activation mechanism remains controversial and its function in signal transduction is unknown [2].
• TRPM5 can be activated physiologically by inositol 1,4,5-trisphosphate-producing receptor agonists, and it may therefore couple intracellular Ca2+ release to electrical activity and subsequent cellular responses [2].
• Moreover, we demonstrate that TRPM5 is not limited to taste signal transduction, because we detect the presence of TRPM5 in a variety of tissues and we identify endogenous TRPM5-like currents in a pancreatic beta cell line [2].
• Identification and characterization of MTR1, a novel gene with homology to melastatin (MLSN1) and the trp gene family located in the BWS-WT2 critical region on chromosome 11p15.5 and showing allele-specific expression [1].
• RT-PCR analysis of somatic cell hybrids harboring a single human chromosome 11 demonstrated exclusive expression of MTR1 in cell lines carrying a paternal chromosome 11, indicating allele-specific inactivation of the maternal copy by genomic imprinting [1].

Biological context of TRPM5

• We have recently described the occurrence of calcium signaling mechanisms in taste receptor cells via apparent store-operated channels and identified Trpm5, a novel candidate taste transduction element belonging to the mammalian family of transient receptor potential channels [3].

Anatomical context of TRPM5

• Together with TRPM5, these channels are up till now the only molecular candidates for a class of non-selective, Ca(2+)-impermeable cation channels which are activated by elevated Ca2+ levels in the cytosol [4].
• TRPM5, a cation channel of the TRP superfamily, is highly expressed in taste buds of the tongue, where it has a key role in the perception of sweet, umami and bitter tastes [5].
• Mean MTR of both MS lesions and whole brain tissue was lower in patients with frontal lobe impairment (p=0.04) [6].
• Biophysical studies of Trpm5 heterologously expressed in Xenopus oocytes and mammalian CHO-K1 cells indicate that it functions as a store-operated channel that mediates capacitative calcium entry [3].

Associations of TRPM5 with chemical compounds

• Transient receptor potential channel melastatin subfamily (TRPM) 4 and its close homologue, TRPM5, are the only two members of the large transient receptor potential superfamily of cation channels that are impermeable to Ca(2+) [7].
• These results strongly suggest the possibility that arachidonic acid acts as a modulator of TRPM5 in taste signaling pathways [8].
• The ligand specificity of the MT receptor in a normal prostate with minor amounts of progestin receptors was typical of an androgen receptor, and the ligand specificity of the R5020 receptor in a BPH specimen was typical of a progestin receptor [9].
• Mutant MT-receptor complexes dissociate normally even at 42 degrees C; yet, in cells post-incubated at 42 degrees C with cycloheximide and a saturating concentration of ligand, their pool size decays in the rank order, MT greater than MB greater than normal [10].

Other interactions of TRPM5

• TRPM5, which is distantly related to TRPM8, is a Ca2+-activated cation channel expressed in taste cells that is essential for sweet, bitter, and umami tastes [11].
• TRPM5, which is the most homologous channel to TRPM4, was not modulated by DV [12].
• In taste cells, Trpm5 is co-expressed with taste-signaling molecules such as alpha-gustducin, Ggamma(13), phospholipase C beta(2) and inositol 1,4,5-trisphosphate receptor type III [3].

References