Profile

Emily R. Liman

Professor
Department of Biological Sciences,
Section of Neurobiology

Emily R. Liman

Research Topics

  • Ion channel biophysics
  • Sensory biology
  • Pain and taste transduction

Research Images

Expression of the TRPM5 ion channel in taste cells (unpublished). Taste buds from mouse circumvallate papillae were labeled with anti-TRPM5 (purple) and anti-PLCb2 (green) antibodies. Co-localization is shown in white.
Expression of the TRPM5 ion channel in taste cells (unpublished). Taste buds from mouse circumvallate papillae were labeled with anti-TRPM5 (purple) and anti-PLCb2 (green) antibodies. Co-localization is shown in white.
The taste channel TRPM5 is activated by micromolar concentrations of Ca2+.  Activation by 40 mM Ca2+ of an inward current in a patch excised from a TRPM5-transfected CHO-K1 cell (Vm = 80 mV).  Neither 10 mM IP3 nor 100 mM OAG nor 10 mM PIP2 elicited a current in the same patch. (Modified from Liu and Liman, PNAS, 2003).
The taste channel TRPM5 is activated by micromolar concentrations of Ca2+. Activation by 40 mM Ca2+ of an inward current in a patch excised from a TRPM5-transfected CHO-K1 cell (Vm = 80 mV). Neither 10 mM IP3 nor 100 mM OAG nor 10 mM PIP2 elicited a current in the same patch. (Modified from Liu and Liman, PNAS, 2003).

Research Overview

SENSORY TRANSDUCTION AND ION CHANNEL BIOPHYSICS

We are interested in how organisms detect and respond to sensory stimuli, particularly as it pertains to the detection of chemical stimuli. Animals respond to sensory stimuli using one of several different sensory organs: the olfactory epithelium (smell), taste buds (taste), vomeronasal organ (pheromones) or noiceptors (painful chemicals and pungent tastes). Our lab uses a combination of electrophysiology, molecular biology, genetics and genomics to identify the receptors for sensory stimuli and to understand how they function. Professor Liman trained with Linda Buck, in whose lab she cloned and characterized sensory transduction components of the main olfactory and vomeronasal sysmtes (see Liman and Buck, 1992). As a research assistant professor at Harvard she identified an ion channel essential for pheromone detection in vertebrates (TRPC2; see Liman, Corey and Dulac, 1999). Interestingly, this protein is not found in humans (it is encoded by a pseudogene), indicating that humans have lost much of their ability to respond to pheromones. Work in the Liman lab showed that the functional protein was lost in human evolution at the same time that humans developed trichromatic vision, suggesting that vision has replaced pheromone detection in human reproductive biology (Liman and Innan, 2003).

Current work in the Liman lab is focused on mechanisms of taste and pain signaling and the identification of ion channels that contribute to these processes. In one line of investigation, the lab showed that an ion channel responsible for the detection of spicy mustards, TRPA1, is also activated by carbon dioxide (Wang et al, 2010). This may explain some of the pungency we feel when we drink carbonated beverages. In a separate study, the lab examined the mechanism of taste transduction using genetically modified mice in which subsets of taste cells are fluorescently labeled. Using patch clamp electrophysiology and uv-uncaging of protons, the lab showed that sour taste is mediated by an apically located proton channel (Chang et al, 2010; Bushman et al, 2015)). More recently, we showed that the K+ channel KIR2.1 is a component of taste tranduction (Ye et al, 2016).

See http://www.usc.edu/uscnews/story.php?id=8704 and http://www.usc.edu/uscnews/story.php?id=9616
for recent news coverage of work in the liman lab

Contact Information

Mailing Address University of Southern California
HNB 301
3614 Watt Way
Los Angeles, CA 90089-2520
Office Location HNB 301
Office Phone (213) 821-1454
Lab Location HNB 307
Lab Phone (213) 821-1453
Fax
Office Location HNB 301

Websites

Education

  • B.A., Princeton University, 1985.
  • Ph.D., Harvard University, 1992.

Selected Publications

View a complete PubMed searchView a complete Google Scholar search
  • Ye W, Chang RB, Bushman JD, Tu YH, Mulhall EM, Wilson CE, Cooper AJ, Chick WS, Hill-Eubanks DC, Nelson MT, Kinnamon SC, Liman ER. (2016). The K+ channel KIR2.1 functions in tandem with proton influx to mediate sour taste transduction. PNAS;113(2):E229-38. (featured on the cover)
    PubMed
  • Bushman JD, Ye W, Liman ER. (2015) A proton current associated with sour taste: distribution and functional properties. FASEB J:3014-26. PubMed
  • Liman ER, Zhang YV, Montell C. (2014) Peripheral coding of taste. Neuron. 81(5):984-1000. doi: 10.1016/j.neuron.2014.02.022. PubMed
  • Chang, R. B., Waters, H., and Liman, E. R. (2010). A proton current drives action potentials in genetically identified sour taste cells. PNAS, 468, 603; 2010, Featured on the cover and in "This week in PNAS", Featured in  Nature "Research Highlights" PubMed Link
  • Wang, Y. Y., Chang, R. B., and Liman, E. R. (2010). TRPA1 is a component of the nociceptive response to CO2. J Neurosci 30, 12958-12963. Featured on the cover and in "This week in the journal." Selected for a "ScienceShot" in Science PubMed Link
  • Wang, Y. Y., Chang, R. B., Waters, H. N., McKemy, D. D., and Liman, E. R. (2008). The Nociceptor Ion Channel TRPA1 Is Potentiated and Inactivated by Permeating Calcium Ions. J Biol Chem 283, 32691-32703. PubMed Link
  • Zhang, Z., Zhao, Z., Margolskee, R., and Liman, E. (2007) The transduction channel TRPM5 is gated by intracellular calcium in taste cells. J Neurosci. 27(21):5777-86. PubMed Link
  • E. R. Liman and H. Innan (2003). Relaxed selective pressure on an essential component of pheromone transduction in primate evolution PNAS. 100:3328-3332. PubMed Link
  • D. Liu and Liman, E.R. (2003) Intracellular Ca2+ and the phospholipid PIP2 regulate the taste transduction channel TRPM5. PNAS. 100(25):15160-15165. PubMed
  • Liman, E.R., Corey, D.P., and Dulac, C. (1999) TRP2, a candidate transduction channel for mammalian pheromone sensory signalling. PNAS. 96:5791-5796 PubMed