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Vann Bennett, M.D., Ph.D.
(Johns Hopkins School of Medicine)

James B. Duke Professor, Departments of Cell Biology, Biochemistry, and Neurobiology

Investigator, Howard Hughes Medical Institute

Programs: CMB, Molecular Cancer Biology

A major interest of this laboratory is in understanding how cells in metazoan organisms manage to target ion channels to physiological sites that optimize their physiological efficiency. Our research began with discovery of the ankyrin family of membrane-adapter proteins, which interact with structurally diverse membrane proteins (Na/K ATPase, Na/Ca exchanger, anion exchanger, voltage-gated Na channels, IP3 R, L1 cell adhesion molecules, E- and N-cadherins) and couple these proteins to the spectrin-based membrane skeleton. Ankyrins interact with these proteins through a motif known as ANK repeats, which are found in many different proteins and operate in protein recognition for multiple structurally unrelated ligands. In collaboration with Piotr Marszalek of Mechanical Engineering we have discovered that ank repeats can function as nanosprings. Ankyrin thus may act as a mechanosensor in addition to its role in protein recognition.

We have made several discoveries establishing the physiological and clinical significance of ankyrins in the nervous system and heart. We have identified a new cardiac arrhythmia syndrome associated with sudden cardiac death that is caused by loss-of function mutations in ankyrin-B, and have a mouse model for this syndrome. We also have discovered that conditional knockout of ankyrin-G in the mouse cerebellum results in severe ataxia accompanied by coordinate loss of the sodium channel Nav1.6, neurofascin (a member of the L1CAM family), and KCNQ2/3 channels from axon initial segments. We have recently discovered that a mutation in the ankyrin-binding site of principal voltage-gated sodium channel in the heart (Nav1.5) causes cardiac arrhythmia and loss of targeting of Nav1.5 to the cell surface of cardiomyocytes. These studies demonstrate a requirement for ankyrins in localization of a variety of ion channels in excitable membranes in the heart and nervous system, and suggest a new class of functional channelopathies due to abnormal cellular localization.



E-mail
benne012@mc.duke.edu

361 CARL Building
Box 3892 Duke University Medical Center
Durham, NC 27710

Telephone
919-684-3538, 919-684-3105
Fax
919-684-3590


Selected Publications
Bennett V, Healy J. (2008) Being there: cellular targeting of voltage-gated sodium channels in the heart. J Cell Biol. 180(1):13-5. -PDF-

Bennett V, Healy J. (2008) Organizing the fluid membrane bilayer: diseases linked to spectrin and ankyrin. Trends Mol Med. 14(1):28-36. -PDF-

Abdi KM, Bennett V. (2008) Adducin Promotes Micrometer-Scale Organization of {beta}2-Spectrin in Lateral Membranes of Bronchial Epithelial Cells. Mol Biol Cell 19(2):536-45. -PDF-

Mohler PJ, Healy JA, Xue H, Puca AA, Kline CF, Allingham RR, Kranias EG, Rockman HA, Bennett V. Ankyrin-B syndrome: enhanced cardiac function balanced by risk of cardiac death and premature senescence. (2007) PLoS ONE. 2(10):e1051. -PDF-

Kizhatil K, Davis JQ, Davis L, Hoffman J, Hogan BL, Bennett V. (2007) Ankyrin-G is a molecular partner of E-cadherin in epithelial cells and early embryos. J Biol Chem. 282(36):26552-61. -PDF-

Kizhatil K, Yoon W, Mohler PJ, Davis LH, Hoffman JA, Bennett V. (2007) Ankyrin-G and beta2-spectrin collaborate in biogenesis of lateral membrane of human bronchial epithelial cells. J Biol Chem. 282(3):2029-37. -PDF-

Lee G, Abdi K, Jiang Y, Michaely P, Bennett V, Marszalek PE. (2006) Nanospring behaviour of ankyrin repeats. Nature.440:246-9. -PDF-

Abdi KM, Mohler PJ, Davis JQ, Bennett V. (2006) Isoform specificity of ankyrin-B: a site in the divergent C-terminal domain is required for intramolecular association. J Biol Chem. 281:5741-9. -PDF-

Pan Z, Kao T, Horvath Z, Lemos J, Sul JY, Cranstoun SD, Bennett V, Scherer SS, Cooper EC. (2006) A common ankyrin-G-based mechanism retains KCNQ and NaV channels at electrically active domains of the axon. J Neurosci. 26:2599-613. -PDF-

Mohler, PJ, Davis, JQ, Bennett, V. (2005) Ankyrin-B coordinates the Na/K ATPase, Na/Ca exchanger, and InsP3 receptor in a specialized microdomain of cardiac T-tubules. Plos Biology 3:e423. -PDF-

Mohler, P.J., Splawski, I., Napolitano, C., Botteli, G., Sharpe, L., Timothy, K., Priori, S.G., Keatiing, M.T., and Bennett, V. (2004) A cardiac arrhythmia syndrome caused by loss of ankyrin-B function. Proc. Nat. Acad. Sci. USA. 101:9137-42. -PDF-

Mohler PJ, Rivolta I, Napolitano C, LeMaillet G, Lambert S, Priori SG, Bennett V. (2004) Nav1.5 E1053K mutation causing Brugada syndrome blocks binding to ankyrin-G and expression of Nav1.5 on the surface of cardiomyocytes. Proc Natl Acad Sci USA. 101:17533-8. -PDF-

Mohler, P. J et al. (2003) Ankyrin-B mutation causes type 4 long QT cardiac arrhythmia and sudden cardiac death. Nature 421:634-639. -PDF-

Future Directions
Our current research is addressing three general questions: 1. Physiological roles of ankyrins. We are currently exploring ankyrin function in insulin release by pancreatic beta cells, targeting components of the dystrophin complex in striated muscle, and in establishing membrane domains in photoreceptors in the retina. 2. Cellular mechanisms underlying ankyrin-dependent protein localization. One experimental model for these studies is human bronchial epithelial cells where ankyrin-G and beta-2 spectrin are required for biogenesis of the lateral membrane. We also will develop adult cardiomyocytes as an experimental system. We plan to elucidate the ankyrin/spectrin pathways in cardiomyocytes and epithelial cells using a variety of techniques including proteomics, live cell imaging, and siRNA knockdowns. 3. Role of ankyrin-B in aging-related diseases in humans and mice. We have found that ankyrin-B (+/-) mice have reduced life-span and exhibit accelerated senescence in multiple tissues. We also have found that loss-of-function mutations in ankyrin-B are surprisingly common in human populations (2 percent of Europeans). Our working model is that these human ankyrin-B mutations represent balanced polymorphisms with benefits (increased cardiac performance) balanced by costs (risk of sudden cardiac death and reduced life span). At a clinical level, we are exploring roles of ankyrin-B in aging-related diseases including diabetes and atherosclerosis. In addition, we are developing mouse models with knock-in of two of the human ankyrin-B variants. We also are exploring the hypothesis that ankyrin-B-dependent aging is due to stem cell exhaustion.

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