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TRP channels Tibor Rohacs
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Calcium Three major compartments: Intracellular: signaling ion, very low concentration (~ 100 nM) Extracellular: ~2.5 mM total, ~1.25 mM ionized Bones: hydroxyapatite crystals: Ca 10 (PO 4 ) 6 (OH) 2
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Calcium signaling From: Clapham, D.E., et al. Nat. Rev. Neurosci. 2, 387-396 (2001). GPCR-s: Angiotensin II Acetylcholine (M1 M3) Adrenergic alpha-1 Thrombin Metabotropic GluR RTK-s EGF, NGF, BDNF etc Other factors Sperm oocyte Light (invertebrates)
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Capacitative (store operated) Ca 2+ entry (Putney) From: Putney, J.W., Jr. Cell Calcium 11, 611-624 (1990).
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Calcium Release Activated Calcium current (I CRAC ) From: Hoth, M. & Penner, R. Nature 355, 353-356 (1992).
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From: Minke, B. & Cook, B. Physiol Rev. 82, 429-472 (2002). Invertebrate Phototransduction
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Transient Receptor Potential From: Minke, B. & Cook, B. Physiol Rev. 82, 429-472 (2002).
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TRP channels and capacitative calcium entry From: Zhu, X., et al. Cell 85, 661-671 (1996). From: Vaca, L., et al. Am. J. Physiol. 267 C1501-C1505 (1994). +thapsigargin
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I CRAC and TRP channels I CRAC TRP Ca 2+ selectiveNon selective cation channel Inwardly rectifyingOutwardly rectifying Very small single channel conductance Measurable single channel conductance Store depletion activates Store depletion activates (sometimes)
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Direct activation of TRP channels by the IP 3 receptor From: Kiselyov, K., et al. Nature 396, 478-482 (1998).
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DAG activation of TRPC3,6,7 From: Hofmann,T., et al. Nature 397, 259-263 (1999).
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PIP 2 inhibition of TRPL From: Estacion, M., et al. J. Physiol 530, 1-19 (2001).
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The TRPC (Classical) family Homologues of TRP and TRPL Seven members TRPC1-7 Are activated upon PLC activation –Store Operated –DAG TRPC3,6,7 –IP 3 receptor direct interaction –PIP 2 inhibits TRPL channels, other TRPC-s are not tested yet No general paradigm on how PLC activates these TRPC channels
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Thermosensation Hot Cold Capsaicin (chili pepper) sensitizes to warm temperature Menthol sensitizes to cold temperature
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Cloning of the capsaicin receptor From: Caterina, M.J., et al. Nature 389, 816-824 (1997). 2:4 x 10 6 independent bacterial clones were divided into 144 pools.
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TRPV1 integrates pain producing stimuli From: Tominaga, M., et al. Neuron 21, 531-543 (1998).
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TRPV1 KO mouse From: Caterina, M.J., et al. Science 288, 306-313 (2000).
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Cloning of the cold menthol receptor: TRPM8 From: McKemy, D.D., et al. Nature 416, 52-58 (2002). From: Peier, A.M., et al. Cell 108, 705-715 (2002).
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Heat sensitive TRP channels From: Jordt, S.E., et al. Curr. Opin. Neurobiol. 13, 487-492 (2003).
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TRPV4 is a mechanosensor From: Liedtke,W., et al. Cell 103, 525-535 (2000). TRPV4 -/- mice have impaired osmoregulation and pressure sensation
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Epithelial calcium channels From: Hoenderop, J.G., et al. Physiol Rev. 85, 373-422 (2005).
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TRPV5-6 Biophysical properties TRPV5 From: Hoenderop, J.G., et al. Physiol Rev. 85, 373-422 (2005).
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The TRPV5 Knockout mouse From: Hoenderop, J.G., et al. J. Clin. Invest 112, 1906-1914 (2003).
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The TRPV (Vanilloid) family The first cloned member (1997): capsaicin receptor (TRPV1) ”heat” receptor, “chili pepper” TRPV2-3 also temperature receptors –(insensitive to capsaicin) TRPV4 osmosensor (also temperature sensitive) TRPV5-6 Epithelial calcium transporters (only Ca 2+ selective TRP-s)
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The TRPM (Melastain) family Melastatin TRPM1 tumor suppressor TRPM2 ADP ribose activated Ca 2+ permeable channel TRPM3 TRPM4 Ca 2+ activated non selective TRPM5 taste tissues TRPM6 Mg 2+ homeostasis, disease !! TRPM7 Mg 2+ homeostasis, PIP 2 activates TRPM8 Cold receptor
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Some TRPM channels are also enzymes From: Yamaguchi, H., et al. Mol. Cell 7, 1047-1057 (2001).From: Fleig, A. & Penner, R. Trends Pharmacol. Sci. 25, 633- 639 (2004). Kinase Domain
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From: Walder, R.Y., et al. Nat. Genet. 31, 171-174 (2002). Hypomagnesemia, hypocalcemia, Seizures Caused by impaired intestinal Mg 2+ absorption abnormal renal Mg 2+ excretion Can be overcome by high-dose Mg 2+ supplementation
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From: Chubanov,V., et al. Proc. Natl. Acad. Sci. U. S. A 101, 2894-2899 (2004).
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Is there anything common among the regulation of TRP channels ?
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From: Runnels, L.W., et al. Nat. Cell Biol. 4, 329-336 (2002).
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TRPM8 From: Rohacs, T., et al. Nature Neuroscience in press
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The role of the TRP domain as a PIP 2 interacting site From: Rohacs, T., et al. Nature Neuroscience in press
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Extended TRP superfamily From: Montell, C., et al. Mol. Cell 9, 229-231 (2002). From: Clapham, D.E. Nature 426, 517-524 (2003).
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Another cold receptor: ANKTM1 (TRPA1) From: Story, G.M., et al. Cell 112, 819-829 (2003). From: Jordt, S.E., et al. Nature 427, 260-265 (2004).
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Mechano-sensitive channels and hearing From: Frolenkov, G.I., et al. Nat. Rev. Genet. 5, 489-498 (2004).
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From: Corey, D.P., et al. Nature 432, 723-730 (2004). SiRNA TRPA
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http://peir.path.uab.edu/iplab/messages/598/467.html?1002303218 From: Wilson, P.D. N. Engl. J. Med. 350, 151-164 (2004). From: Igarashi, P. & Somlo, S. J. Am. Soc. Nephrol. 13, 2384-2398 (2002). Polycystic Kidney Disease
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