Keith R. Johnson, PhD
Dr. Keith Johnson

Professor

Nebraska Center for Cellular Signaling, Director
Oral Biology Department

Contact Information

Room 9.12.394, Buffett Cancer Center
987696 Nebraska Medical Center
Omaha, NE 68198-7696
402-559-3890

Education

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 Health ID number: P20 GM103489 Title: Nebraska Center for Cellular Signaling (M.J. Wheelock, PI) Period of support: 9/19/03 – 6/30/13 The purpose of this grant is to provide career development support for junior investigators.
  • Source: National Institutes of Health ID number: P50 CA127297 Title: SPORE in gastrointestinal cancer: Project 2, Inhibitors of N-cadherin in the treatment of Pancreatic Cancer (M. A. Hollingsworth, PI) Period of Support: 9/16/08-9/1/13 The purpose of this grant is to study the role N-cadherin expression in pancreatic tumor cells plays in metastasis.
  • Source: National Institutes of Health ID number: U54 CA163120 Title: Pancreatic Tumor Micro-environment Network (S. Batra, PI) Period of Support: 9/26/11-7/31/16 The purpose of this grant is study the role N-cadherin expression in cells in the tumor microenvironment plays in tumor growth and metastasis.
  • Source: Department of Defense ID number: W81XWH-12-1-0390 Title: Connexin and Cadherin Cross-talk in the Pathogenesis of Prostate Cancer (Dr. Parmender Mehta, co-PI) Period of Support: 9/1/12-8/31/15 The purpose of these studies is to characterize how cadherins influence the assembly of gap junctions. 
  • Source: National Institutes of Health ID number: R01 DE12308 (K.R. Johnson, PI)Title: Cadherins in oral squamous cell carcinomas Period 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 Health ID number: R01 GM51188 Title: 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 Initiative No ID number (M.J. Wheelock, PI) Title: Cell adhesion proteins in cancers of the head and neck Period 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 Health ID number: P20 RR18759 Title: 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.
Selected Publications 
  • Huang, H., Svoboda, R.A., Lazenby, A.J., Saowapa, J., Chaika, N., Ding, K., Wheelock, M.J. and Johnson, K.R. Up-Regulation of N-cadherin by Collagen I-activated Discoidin Domain Receptor I in Pancreatic Cancer Requires the Adaptor Molecule Shc1. 2016. J of Biological Chemistry 291(44):23208-23223. PMID: 27605668. PMCID: PMC5087738.
  • Roberts, B.J., Svoboda, R.A., Overmiller, A.M. Lewis, J.D., Kowalczyk, A.P., Mahoney, M.G., Johnson, K.R. and Wahl III, J.K. Palmitoylation of Desmoglein 2 is a Regulator of Assembly Dynamics and Protein Turnover. 2016. J Biol Chem 291(48):24857-24865. PMID: 27703000. PMCID: PMC5122758.
  • Katoch, P., Mitra, S., Ray, A., Kelsey, L., Roberts, B.J., Wahl, J.K., Johnson, K.R. and Mehta, P.P. The Carboxyl Tail of Connexin32 Regulates gap junction assembly in human prostate and pancreatic cancer cells. 2015. MBC 290:4647-62. PMID: 25548281. PMCID: PMC4335205.
  • Liu, X., Yi, C., Wen, Y., Radhakrishnan, P., Tremayne, J.R., Dao, T., Johnson, K.R., Hollingsworth, M.A. Interactions between MUC1 and p120 catenin regulate dynamic features of cell adhesion, motility and metastasis. 2014. Cancer Res 74:1609-20.  PMCID: PMC4076167.
  • Roberts, B.J., Johnson, K.E., McGuinn, K.P., Saowapa, J., Svoboda, R.A., Mahoney, M.G., Johnson, K.R., Wahl, J.K. 3rd. Palmitoylation of plakophilin is required for desmosome assembly. 2014. J Cell Sci 127:3782-93. PMCID: PMC4150063.
  • Johnson, K.E., Mitra, S., Katoch, P., Kelsey, L.S., Johnson, K.R. and Mehta, P.P. Phosphorylation on serines 279 and 282 of connexin43 regulates endocytosis and gap junction assembly in pancreatic cancer cells. Molecular Biology of the Cell 24:715-33, 2013. PMCID: PMC3596244.
  • Chaika, N.V., Gebregiworgis, T., Lewallen, M.E., Purohit, V., Radhakrishnan, P., Liu, X., Zhang, B., Mehla, K., Brown, R.B., Caffrey, T., Yu, F., Johnson, K.R., Powers, R., Hollingsworth, M.A., Singh, P.K. MUC1 stabilizes and activates HIF1α to regulate metabolism in pancreatic cancer. Proceedings of the National Academy of Science USA 109:13787-92.  PMCID: PMC3427054, 2012.
  • Chaika, N.V, Yu, F., Purohit, V., Mehla, K., Lazenby, A.J., DiMaio, D., Anderson, J.M., Yeh, J.J., Johnson, K.R., Hollingsworth, M.A., Singh, P.K. Differential expression of metabolic genes in tumor and stromal components of primary and metastatic loci in pancreatic adenocarcinoma. 2012. PLoS One 7(3):e32996. PMCID: PMC3296773
  • Roberts, B.J., Pashaj, A., Johnson, K.R., Wahl, J.K. 3rd Desmosome dynamics in migrating epithelial cells requires the actin cytoskeleton. 2011. Exp Cell Res 317:2814-22. PMCID: PMC3215790
  • Singh, P.K., Mehla, K., Hollingsworth, M.A., Johnson, K.R. Regulation of Aerobic Glycolysis by microRNAs in Cancer. 2011. Molec Cell Pharmacol 3:125-134.
  • Chakraborty, S., Mitra, S., Falk, M.M., Caplan, S.H., Wheelock, M.J., Johnson, K.R., Mehta, P.P. E-cadherin differentially regulates the assembly of connexin43 and connexin32 into gap junctions in human squamous carcinoma cells. 2010. J Biol Chem 285:10761. PMCID: PMC2856283
  • Govindarajan, R., Chakraborty, S., Johnson, K.E., Falk, M.M., Wheelock, M.J., Johnson, K.R., Mehta, P.P. Assembly of connexin43 into gap junctions is regulated differentially by E-cadherin and N-cadherin in rat liver epithelial cells. 2010. Mol Biol Cell 21:4089-107. PMCID: PMC2993739
  • Fukunaga, Y., Svoboda, R.A., Cerny, R.L., Johnson, K.R., Wheelock, M.J. Expression artifact with retroviral vectors based on pBMN. Anal Biochem 2009. 395:49-53. PMCID: PMC275348
  • Curtis, M.W., Johnson, K.R. and Wheelock, M.J. E-cadherin/catenin complexes are formed co-translationally in the endoplasmic reticulum/Golgi compartments. Cell Commun Adhes 15(4):365-78, 2008 Nov. PMID: 18937087
  • 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  2008 Sep 26. PMID: 18848540 Abstract
  • 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. 2008. Hybridoma 2008 27:249-58. PMCID: PMC3186698.
  • 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 65:483-492, 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 Adhes12:23-39, 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. 
Selected Abstracts 
  • Huang, H., Svoboda, R., Saowapa, J. and Johnson, K. Up-regulation of N-cadherin by collagen I-activated DDR1 requires SHC1. Midwest Student Biomedical Research Forum, February 28, 2015, Omaha, NE.
  • Purohit, V., Nina V. Chaika, Teklab Gebregiworgis, Prakash Radhakrishnan, Bo Zhang, Kamiya Mehla, Fang Yu, Keith R. Johnson, Robert Powers, Michael A. Hollingsworth, and Pankaj K. Singh. MUC1 and HIF-1α signaling interactions modulate glucose flux in pancreatic cancer. American Association of Cancer Research Annual Meeting, Washington DC. Cancer Research 73:5391, 2013.
  • Fukumoto, Y., Shintani, Y., Johnson, K.R. and Wheelock, M.J. The phosphorylation domain of p120catenin modulates E-cadherin dynamics at the plasma membrane. 47th Annual ASCB Meeting, December 2007.
  • Keim, S.A., Wheelock, M.J., Johnson, K.R. and Wahl, J.K. MMP cleavage of the desmosomal cadherins contributes to desmosome disassembly during TGF-beta-induced EMT. 47thAnnual ASCB Meeting, December 2007.
  • Mandal, S., Wheelock, M.J. and Johnson, K.R. TGF-beta induces invadopodia formation in human breast cancer cells. 47thAnnual ASCB Meeting, December 2007.
  • Shintani, Y., Johnson, K.R., and Wheelock, MJ.  N-cadherin expression and epithelial-to-mesenchymal transition in pancreatic cancer. AACR 97th Annual Meeting, April 2006.
  • Lawson, K.R., Wheelock, M.J. and Johnson, K.R.  Modulation of E- and N-cadherin levels in oral squamous carcinoma cells reveals N-cadherin-specific increases in invasion-related signaling pathways. AACR 97th Annual Meeting, April 2006.
  • Shintani, Y., Wheelock, M.J. and Johnson, K.R. Cross talk between cadherins and integrins. Gordon Conference on Signaling by Adhesion Receptors, June 2006.
  • Shintani, Y., Johnson, K.R. and Wheelock, M.J.  Collagen I promotes metastasis in pancreatic cancer by up regulating N-cadherin expression via JNK1.  ASCB 46th Annual Meeting, December 2006.
  • Lawson, K.R., Myers, J.N., Wheelock, M.J. and Johnson, K.R.  Modulation of E- and N-cadherin levels in oral squamous carcinoma cells reveals N-cadherin-specific increases in invasion-related signaling pathways. ASCB 46th Annual Meeting, December 2006
  • Mandal, S., Johnson, K.R., and Wheelock, M.J. The role of alpha-catenin in invadopodia assembly in human breast cancer. ASCB 46th Annual Meeting, December 2006.
  • Theisen, C., Johnson, K.R., and Wheelock, M.J.  NHERF-2 bridges N-cadherin and the platelet derived growth factor receptor via beta-catenin and regulated cell migration. ASCB 46thAnnual Meeting, December 2006.
  • Fukumoto, Y., Johnson, K.R. and Wheelock, M.J. The role of serine/threonine phosphorylation of p120: Does it alter E-cadherin dynamics at the plasma membrane?  ASCB 46th Annual Meeting, December 2006.
  • Keim, S.A., Wahl, K.J., Wheelock, M.J. and Johnson, K.R. TGF-beta effects on desmosomal components in MCF10A cells. ASCB 46th Annual Meeting, December 2006.
  • 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.