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Dr. Keith R. Johnson

Title: Professor
NCCS Director

Address
Room: 12730A
987696 Nebraska Medical Center
University of Nebraska Medical Center
Omaha, NE 68198-7696


Oral Biology Department


Telephone: (402) 559-3890
Fax: (402) 559-3888
email: kjohnsonr@unmc.edu

Education:

• B.A. (Major: Chemistry; Minor: Mathematics), University of Minnesota
• B.Ed. (Chemistry, Physics & Math Education), University of Minnesota
• Ph.D. (Major: Cell Biology; Minor: Biochemistry), University of Minnesota

Teaching Responsibilities:

• Course Instructor, Advanced Oral Biology (OBIO 855)

Research Interests:

• The main focus of our laboratory is the role cadherins and catenins play in tumorigenesis. Cadherins are cell-cell adhesion molecules that are the transmembrane component of the adherens junction. Catenins comprise the intracellular plaque proteins of the junction that serve to connect the cadherin to the cytoskeleton. The cadherin family of proteins has been implicated in cell sorting events during normal development. Thus, cells expressing different cadherins sort out from one another. Sorting can depend not only on expression of different family members but also on expression of different levels of a single cadherin. Tumorigenesis is a complex event that involves altered regulation of cell growth patterns and altered interactions of cells with one another and with the extracellular environment.
• Loss of E-cadherin function has been shown to potentiate tumor cell invasion. Loss of function may result from a mutation in the cadherin gene or from mutations in the genes that encode the catenins. Thus loss of any one of these proteins results in a non-adhesive phenotype and increased invasive potential. Interestingly, a large number of invasive tumors do not involve mutations in one of these proteins but rather downregulation of expression or activity of the adhesion complex. We are attempting to understand how the activity of the cadherin complex is regulated.
• One system we have chosen to study is oral squamous cell carcinoma. Oral cancers are more common than cancers of the brain, liver, kidney, thyroid, stomach, ovary or cervix. Risk factors include the use of tobacco and alcohol and exposure to environmental carcinogens. If detected early, the prognosis for survival of oral cancer is better than most cancers. An understanding of the cellular changes that occur in oral squamous cell carcinoma may suggest methods for effective early diagnosis and dramatically improve cure rates. We have shown that expression of an inappropriate member of the cadherin family (N-cadherin) by oral squamous epithelial cells results in down-regulation of the endogenous E-cadherin and generation of a cell with a more invasive phenotype. We are attempting to elucidate the mechanism by which these cellular changes occur by:
  
• 1. Determining which domains of N-cadherin are responsible for down-regulation of the endogenous E-cadherin. These studies involve molecular construction of chimeric cadherins made up of various domains of E-cadherin linked to N-cadherin. These chimeric proteins will be tested for their ability to alter the phenotype of normal squamous epithelial cells.
• 2. Determining if N-cadherin is unique in its ability to induce a more tumorigenic phenotype. Our hypothesis is that other non-epithelial cadherins may act similar to N-cadherin in this regard. We believe that the ability of a cadherin to induce these changes in epithelial cells will depend on its similarity to the cadherins expressed by mesenchymal tissues.
• 3. To determine the mechanisms that confer the more invasive phenotype on N-cadherin-expressing oral squamous epithelial cells. These studies include determining alterations in signaling pathways, cellular migration and cell-substratum interactions.

Grants:

• Source: National Institutes of HealthID number: R01 DE12308 (K.R. Johnson, PI)Title: Cadherins in oral squamous cell carcinomasPeriod of support: 04/01/98-01/31/08The long-term objective of this project is to understand how cell-cell interactions control the behavior of invasive oral squamous cell carcinomas.
• Source: National Institutes of HealthID number: R01 GM51188Title: Aspects of cadherin/catenin complexes (M.J. Wheelock, PI)Period of support: 08/01/94-7/31/10The major goals of this project were to define the roles cadherins and catenins play in cell-cell adhesion, both as structural components of the adherens junction and as signaling molecules.
• Source: Nebraska Research InitiativeNo ID number (M.J. Wheelock, PI)Title: Cell adhesion proteins in cancers of the head and neckPeriod of support: 07/01/02-06/30/06The goals of this project are to identify molecular markers for head and neck cancer for use in the clinic as diagnostic and/or prognostic indicators.
• Source: National Institutes of HealthID number: P20 RR18759Title: Nebraska Center for Cellular Signaling (M.J. Wheelock, PI)Period of support: 9/19/03 – 6/30/08This grant is part of the CoBRE program to mentor junior investigators.

Recent Publications:

• Curtis, M.W., Johnson, K.R. and Wheelock, M.J. E-cadherin/catenin complexes are formed cotranslationally in the endoplasmic reticulum/Golgi compartments. Cell Commun Adhes 15(4):365-78, 2008 Nov. PMID: 18937087 PubMed - in process
• Mandal, S., Johnson, K.R. and Wheelock, M.J. TGF-beta induces formation of F-actin cores and matrix degradation in human breast cancer cells via distinct signaling pathways. Exp Cell Res Epub ahead of print 2008 Sep 26. PMID: 18848540 PubMed - as supplied by publisher
• Keim, S.A., Johnson, K.R., Wheelock, M.J. and Wahl III, J.K. Generation and characterization of monoclonal antibodies against the proregion of human desmoglein-2. Hybridoma 2008 (In Press)
• Shintani, Y., Fukumoto, Y., Chaika, N., Svoboda, R., Wheelock, M.J. and Johnson, K.R. Collagen I-mediated up-regulation of N-cadherin requires cooperative signals from integrins and discoidin domain receptor 1. J Cell Biol 180:1277-89, 2008.
• Wheelock, M.J., Shintani, Y., Maeda, M., Fukumoto, Y. and Johnson, K.R. Cadherin switching. J Cell Sci 121:727-35, 2008.
• Shintani, Y., Fukumoto, Y., Chaika, N., Grandgenett, P.M., Hollingsworth, M.A., Wheelock, M.J. and Johnson, K.R. ADH-1 suppresses N-cadherin-dependent pancreatic cancer progression. Int J Cancer 122:71-7, 2008.
• Fukumoto, Y., Shintani, Y., Reynolds, A.B., Johnson, K.R. and Wheelock, M.J. The regulatory or phosphorylation domain of p120 catenin controls E-cadherin dynamics at the plasma membrane. Exp Cell Res 314:52-67, 2008.
• Shintani, Y., Maeda, M., Chaika, N., Johnson, K.R. and Wheelock, M.J. Collagen I promotes epithelial-to-mesenchymal transition in lung cancer cells via transforming growth factor-beta signaling. Am J Respir Cell Mol Biol 38:95-104, 2008.
• Theisen, C.S., Wahl, J.K., Johnson, K.R. and Wheelock, M.J. NHERF links the N-cadherin/catenin complex to the PDGF receptor to modulate the actin cytoskeleton and regulate cell motility. Mol Biol Cell 18:1220-32. 2007.
• Pyo, S.W., Hashimoto, M., Kim, Y.S., Kim, C.H., Lee, S.H., Johnson, K.R., Wheelock, M.J. and Park, J.U. Expression of E-cadherin, P-cadherin and N-cadherin in oral squamous cell carcinoma: Correlation with the clinicopathologic features and patient outcome. J Craniomaxillofac Surg 35:1-9, 2007.
• Curtis, M.W., Ly, Q.P., Wheelock, M.J. and Johnson, K.R. Evidence that the V832M E-cadherin germ-line missense mutation does not influence the affinity of alpha-catenin for the cadherin/catenin complex. Cell Commun Adhes 14:45-55, 2007.
• Maeda, M., Shintani, Y., Wheelock, M.J. and Johnson, K.R. SRC activation is not necessary for TGF-beta-mediated EMT in mammary epithelial cells; PP1 directly inhibits TGF-beta receptors l and ll. J Biol Chem 281:59-68, 2006.
• Shintani, Y., Wheelock, M.J. and Johnson, K.R. PI3K-Rac1-JNK signaling mediates collagen-induced cell scattering and up-regulation of N-cadherin expression in mouse mammary epithelial cells. Mol Biol Cell 17:2963-75, 2006.
• Maeda, M., Johnson, E., Mandal, S.H., Lawson, K.R., Keim, S.A., Svoboda, R.A., Caplan, S., Wahl, J.K. III, Wheelock, M.J. and Johnson, K.R. Expression of inappropriate cadherins by epithelial tumor cells promotes endocytosis and degradation of E-cadherin via competition for p120ctn. Oncogene 25:4594-4604, 2006.
• Shintani, Y., Hollingsworth, M.A., Wheelock, M.J. and Johnson, K.R. Collagen I promotes metastasis in pancreatic cancer by activating JNK1 and up regulating N-cadherin expression. Cancer Res 66:11745-53, 2006.
• Shintani, Y., Wheelock, M.J. and Johnson, K.R. Phosphoinositide-3 kinase-rac1-c-jun NH2-terminal kinase signaling mediates collagen I-induced cell scattering and up-regulation of N-cadherin expression in mouse mammary epithelial cells. Mol Biol Cell 17:2963-2975, 2006.
• Jaggi, M., Rao, P.S., Smith, D.J., Wheelock, M.J., Johnson, K.R., Hemstreet, G.P. and Balaji, K.C. E-cadherin phosphorylation by protein kinase D1/protein kinase CM is associated with altered cellular aggregation and motility in prostate cancer. Cancer Res 65:483–92, 2005.
• Maeda, M., Johnson, K.R. and Wheelock, M.J. Cadherin switching: Essential for behavioral but not morphological changes in epithelial to mesenchymal transition. J Cell Sci 118:873-87, 2005.
• Kim, Y.J., Sauer, C., Testa, K., Wahl, J.K., Svoboda, R.A., Johnson, K.R., Wheelock, M.J., Knudsen, K.A. Modulating the strength of cadherin adhesion: evidence for a novel adhesion complex. J Cell Sci 118:3883-94, 2005.
• Knudsen, K.A., Sauer, C., Johnson, K.R. and Wheelock, M.J. Effect of N-cadherin misexpression by the mammary epithelium in mice. J Cell Biochem 95:1093-107, 2005.
• Kim Y.J., Johnson, K.R. and Wheelock, M.J. N-cadherin-mediated cell motility requires cis dimers. Cell Commun Adhes 12:23-39, 2005.
• Maeda, M., Shintani, Y., Wheelock, M.J. and Johnson, K.R. SRC activation is not necessary for transforming growth factor (TGF)-beta-mediated epithelial to mesenchymal transition (EMT) in mammary epithelial cells. PP1 directly inhibits TGF-beta receptors I and II. J Biol Chem 281:59-68, 2005.
• Johnson. E., Theisen, C.S., Johnson, K.R. and Wheelock, M.J. R-cadherin influences cell motility via Rho family GTPases. J Biol Chem 279:31041-31049, 2004.
• Wheelock, M.J. and Johnson, K.R. Cadherins as modulators of cellular phenotype. Annu Rev Cell Dev Biol 19: 207-235, 2003.
• Wheelock, M.J. and Johnson, K.R. Cadherin-mediated cellular signaling. Curr Opin Cell Biol 15:509-514, 2003.
• Wen Y., Caffrey T.C., Wheelock M.J., Johnson, K.R. and Hollingsworth M.A. Nuclear association of the cytoplasmic tail of MUC1 and -catenin. J Biol Chem 278:38029-38039, 2003.

Abstracts:

• Shintani, Y, Johnson, K.R., Wheelock, M.J. Cross talk between cadherins and integrins. Cell Contact and Adhesion Gordon Conference, New Hampshire, June 2005.
• Shintani, Y, Johnson, K.R., Wheelock, M.J. Collagen-induced epithelial to mesenchymal transition in pancreatic cancer. American Society for Cell Biology 45th Annual Meeting, San Francisco, December 2005.
• Keim, S.A., Johnson, K.R., Wheelock, M.J. TGF-beta effects on desmosomal components in MCF10A cells. American Society for Cell Biology 45th Annual Meeting, San Francisco, December 2005.
• Theisen, C., Johnson, K.R., Wheelock, M.J. A role for N-cadherin in endothelial cell migration via PDGF-R signaling. American Society for Cell Biology 45th Annual Meeting, San Francisco, December 2005.
• Mandal, S., Maeda, M., Johnson, K.R., Wheelock, M.J. Expression of inappropriate cadherins by epithelial tumor cells promotes endocytosis and degradation of E-cadherin via competition for p120 catenin. American Society for Cell Biology 45th Annual Meeting, San Francisco, December 2005.