LEONARD R. JOHNSON, Ph.D., B.A.

Professor Emeritus
Physiology

Office: C314 VAN VLEET CANCER CENTER
3 NORTH DUNLAP STREET
MEMPHIS TN 381632113
Tel: (901) 448-4722
ljohns28@uthsc.edu

Education

  • Ph.D., University of Michigan, Ann Arbor, Michigan, Physiology
  • A.B., Wabash College, Crawfordsville, Indiana, Zoology

Research interest/specialty

One is focused on the role of ployamines in programmed cell death or apoptosis of the intestinal mucosa. The other also concerns polyamines and their role in cell migration. We have shown that polyamines are required for both apoptosis and migration and are currently exploring the signaling pathways involved and the molecular interactions of polyamines that regulate those pathways. I am responsible for the gastrointestinal section of the Medical Physiology course.

Research interest/specialty

One is focused on the role of ployamines in programmed cell death or apoptosis of the intestinal mucosa. The other also concerns polyamines and their role in cell migration. We have shown that polyamines are required for both apoptosis and migration and are currently exploring the signaling pathways involved and the molecular interactions of polyamines that regulate those pathways. I am responsible for the gastrointestinal section of the Medical Physiology course.

Publications

  1. Bhattacharya, S, Ray, RM, Johnson, LR. Role of polyamines in p53-dependent apoptosis of intestinal epithelial cells. Cell Signal, 21 (4), 509-22, 2009.
  2. Jin, S, Ray, RM, Johnson, LR. TNF-{alpha}/cycloheximide-induced apoptosis in intestinal epithelial cells requires Rac1-regulated reactive oxygen species. Am J Physiol Gastrointest Liver Physiol, 2008.
  3. Ray, RM, Bhattacharya, S, Johnson, LR. EGFR plays a pivotal role in the regulation of polyamine-dependent apoptosis in intestinal epithelial cells. Cell Signal, 19 (12), 2519-27, 2007.
  4. Bhattacharya, S, Guo, H, Ray, RM, Johnson, LR. Basic helix-loop-helix protein E47-mediated p21Waf1/Cip1 gene expression regulates apoptosis of intestinal epithelial cells. Biochem J, 407 (2), 243-54, 2007.
  5. Deng, W, Shuyu, E, Tsukahara, R, Valentine, WJ, Durgam, G, Gududuru, V, Balazs, L, Manickam, V, Arsura, M, VanMiddlesworth, L, Johnson, LR, Parrill, AL, Miller, DD, Tigyi, G. The lysophosphatidic acid type 2 receptor is required for protection against radiation-induced intestinal injury. Gastroenterology, 132 (5), 1834-51, 2007.
  6. Ray, RM, Guo, H, Patel, M, Jin, S, Bhattacharya, S, Johnson, LR. Role of myosin regulatory light chain and Rac1 in the migration of polyamine-depleted intestinal epithelial cells. Am J Physiol Gastrointest Liver Physiol, 292 (4), G983-95, 2007.
  7. Ray, RM, Vaidya, RJ, Johnson, LR. MEK/ERK regulates adherens junctions and migration through Rac1. Cell Motil Cytoskeleton, 64 (3), 143-56, 2007.
  8. Jin, S, Ray, RM, Johnson, LR. Rac1 mediates intestinal epithelial cell apoptosis via JNK. Am J Physiol Gastrointest Liver Physiol, 291 (6), G1137-47, 2006.
  9. Vaidya, RJ, Ray, RM, Johnson, LR. Akt-mediated GSK-3beta inhibition prevents migration of polyamine-depleted intestinal epithelial cells via Rac1. Cell Mol Life Sci, 63 (23), 2871-9, 2006.
  10. Bhattacharya, S, Ray, RM, Johnson, LR. Integrin beta3-mediated Src activation regulates apoptosis in IEC-6 cells via Akt and STAT3. Biochem J, 397 (3), 437-47, 2006.
  11. Bhattacharya, S, Ray, RM, Johnson, LR. STAT3-mediated transcription of Bcl-2, Mcl-1 and c-IAP2 prevents apoptosis in polyamine-depleted cells. Biochem J, 392 (Pt 2), 335-44, 2005.
  12. Ray, RM, Bhattacharya, S, Johnson, LR. Protein phosphatase 2A regulates apoptosis in intestinal epithelial cells. J Biol Chem, 280 (35), 31091-100, 2005.
  13. Deng, W, Viar, MJ, Johnson, LR. Polyamine depletion inhibits irradiation-induced apoptosis in intestinal epithelia. Am J Physiol Gastrointest Liver Physiol, 289 (3), G599-606, 2005.
  14. Bhattacharya, S, Ray, RM, Johnson, LR. Decreased apoptosis in polyamine depleted IEC-6 cells depends on Akt-mediated NF-kappaB activation but not GSK3beta activity. Apoptosis, 10 (4), 759-76, 2005.
  15. Vaidya, RJ, Ray, RM, Johnson, LR. MEK1 restores migration of polyamine-depleted cells by retention and activation of Rac1 in the cytoplasm. Am J Physiol Cell Physiol, 288 (2), C350-9, 2005.
  16. Deng, W, Poppleton, H, Yasuda, S, Makarova, N, Shinozuka, Y, Wang, DA, Johnson, LR, Patel, TB, Tigyi, G. Optimal lysophosphatidic acid-induced DNA synthesis and cell migration but not survival require intact autophosphorylation sites of the epidermal growth factor receptor. J Biol Chem, 279 (46), 47871-80, 2004.
  17. Johnson, DA, Sharma, RK, Allan, K, Ray, R, Johnson, LR. Immunocytochemical localization of polyamines during attachment and spreading of retinal pigment epithelial and intestinal epithelial cells. Cell Motil Cytoskeleton, 58 (4), 269-80, 2004.
  18. Zhang, C, Baker, DL, Yasuda, S, Makarova, N, Balazs, L, Johnson, LR, Marathe, GK, McIntyre, TM, Xu, Y, Prestwich, GD, Byun, HS, Bittman, R, Tigyi, G. Lysophosphatidic acid induces neointima formation through PPARgamma activation. J Exp Med, 199 (6), 763-74, 2004.
  19. Bhattacharya, S, Ray, RM, Johnson, LR. Prevention of TNF-alpha-induced apoptosis in polyamine-depleted IEC-6 cells is mediated through the activation of ERK1/2. Am J Physiol Gastrointest Liver Physiol, 286 (3), G479-90, 2004.
  20. Bhattacharya, S, Ray, RM, Viar, MJ, Johnson, LR. Polyamines are required for activation of c-Jun NH2-terminal kinase and apoptosis in response to TNF-alpha in IEC-6 cells. Am J Physiol Gastrointest Liver Physiol, 285 (5), G980-91, 2003.
  21. Guo, H, Ray, RM, Johnson, LR. RhoA stimulates IEC-6 cell proliferation by increasing polyamine-dependent Cdk2 activity. Am J Physiol Gastrointest Liver Physiol, 285 (4), G704-13, 2003.
  22. Du, H, Viar, MJ, Johnson, LR, Watsky, MA. Polyamines in cultured rabbit corneal cells. Invest Ophthalmol Vis Sci, 44 (6), 2512-7, 2003.
  23. Deng, W, Wang, DA, Gosmanova, E, Johnson, LR, Tigyi, G. LPA protects intestinal epithelial cells from apoptosis by inhibiting the mitochondrial pathway. Am J Physiol Gastrointest Liver Physiol, 284 (5), G821-9, 2003.
  24. Ray, RM, McCormack, SA, Covington, C, Viar, MJ, Zheng, Y, Johnson, LR. The requirement for polyamines for intestinal epithelial cell migration is mediated through Rac1. J Biol Chem, 278 (15), 13039-46, 2003.
  25. Withrow, C, Ashraf, S, O'Leary, T, Johnson, LR, Fitzgerald, ME, Johnson, DA. Effect of polyamine depletion on cone photoreceptors of the developing rabbit retina. Invest Ophthalmol Vis Sci, 43 (9), 3081-90, 2002.
  26. Deng, W, Balazs, L, Wang, DA, Van Middlesworth, L, Tigyi, G, Johnson, LR. Lysophosphatidic acid protects and rescues intestinal epithelial cells from radiation- and chemotherapy-induced apoptosis. Gastroenterology, 123 (1), 206-16, 2002.
  27. Ray, RM, Patel, A, Viar, MJ, McCormack, SA, Zheng, Y, Tigyi, G, Johnson, LR. RhoA inactivation inhibits cell migration but does not mediate the effects of polyamine depletion. Gastroenterology, 123 (1), 196-205, 2002.
  28. Yuan, Q, Ray, RM, Johnson, LR. Polyamine depletion prevents camptothecin-induced apoptosis by inhibiting the release of cytochrome c. Am J Physiol Cell Physiol, 282 (6), C1290-7, 2002.
  29. Johnson, DA, Fields, C, Fallon, A, Fitzgerald, ME, Viar, MJ, Johnson, LR. Polyamine-dependent migration of retinal pigment epithelial cells. Invest Ophthalmol Vis Sci, 43 (4), 1228-33, 2002.
  30. Pfeffer, LM, Yang, CH, Murti, A, McCormack, SA, Viar, MJ, Ray, RM, Johnson, LR. Polyamine depletion induces rapid NF-kappa B activation in IEC-6 cells. J Biol Chem, 276 (49), 45909-13, 2001.
  31. McCormack, SA, Johnson, LR. Polyamines and cell migration. J Physiol Pharmacol, 52 (3), 327-49, 2001.
  32. Ray, RM, Viar, MJ, McCormack, SA, Johnson, LR. Focal adhesion kinase signaling is decreased in polyamine-depleted IEC-6 cells. Am J Physiol Cell Physiol, 281 (2), C475-85, 2001.
  33. Ray, RM, McCormack, SA, Johnson, LR. Polyamine depletion arrests growth of IEC-6 and Caco-2 cells by different mechanisms. Am J Physiol Gastrointest Liver Physiol, 281 (1), G37-43, 2001.
  34. Yuan, Q, Ray, RM, Viar, MJ, Johnson, LR. Polyamine regulation of ornithine decarboxylase and its antizyme in intestinal epithelial cells. Am J Physiol Gastrointest Liver Physiol, 280 (1), G130-8, 2001.
  35. Ray, RM, Viar, MJ, Yuan, Q, Johnson, LR. Polyamine depletion delays apoptosis of rat intestinal epithelial cells. Am J Physiol Cell Physiol, 278 (3), C480-9, 2000.
  36. Pfeffer, LM, Yang, CH, Pfeffer, SR, Murti, A, McCormack, SA, Johnson, LR. Inhibition of ornithine decarboxylase induces STAT3 tyrosine phosphorylation and DNA binding in IEC-6 cells. Am J Physiol Cell Physiol, 278 (2), C331-5, 2000.
  37. Yuan, Q, Viar, MJ, Ray, RM, Johnson, LR. Putrescine does not support the migration and growth of IEC-6 cells. Am J Physiol Gastrointest Liver Physiol, 278 (1), G49-56, 2000.
  38. Ray, RM, Zimmerman, BJ, McCormack, SA, Patel, TB, Johnson, LR. Polyamine depletion arrests cell cycle and induces inhibitors p21(Waf1/Cip1), p27(Kip1), and p53 in IEC-6 cells. Am J Physiol, 276 (3 Pt 1), C684-91, 1999.
  39. Ray, RM, Viar, MJ, Patel, TB, Johnson, LR. Interaction of asparagine and EGF in the regulation of ornithine decarboxylase in IEC-6 cells. Am J Physiol, 276 (3 Pt 1), G773-80, 1999.
  40. McCormack, SA, Ray, RM, Blanner, PM, Johnson, LR. Polyamine depletion alters the relationship of F-actin, G-actin, and thymosin beta4 in migrating IEC-6 cells. Am J Physiol, 276 (2 Pt 1), C459-68, 1999.
  41. Johnson, LR, McCormack, SA, Yang, CH, Pfeffer, SR, Pfeffer, LM. EGF induces nuclear translocation of STAT2 without tyrosine phosphorylation in intestinal epithelial cells. Am J Physiol, 276 (2 Pt 1), C419-25, 1999.
  42. Johnson, LR, McCormack, SA. Healing of Gastrointestinal Mucosa: Involvement of Polyamines. News Physiol Sci, 14, 12-17, 1999.
  43. Langkamp-Henken, B, Johnson, LR, Viar, MJ, Geller, AM, Kotb, M. Differential effect on polyamine metabolism in mitogen- and superantigen-activated human T-cells. Biochim Biophys Acta, 1425 (2), 337-47, 1998.
  44. Banan, A, McCormack, SA, Johnson, LR. Polyamines are required for microtubule formation during gastric mucosal healing. Am J Physiol, 274 (5 Pt 1), G879-85, 1998.
  45. McCormack, SA, Blanner, PM, Zimmerman, BJ, Ray, R, Poppleton, HM, Patel, TB, Johnson, LR. Polyamine deficiency alters EGF receptor distribution and signaling effectiveness in IEC-6 cells. Am J Physiol, 274 (1 Pt 1), C192-205, 1998.
  46. Santos, MF, Viar, MJ, McCormack, SA, Johnson, LR. Polyamines are important for attachment of IEC-6 cells to extracellular matrix. Am J Physiol, 273 (1 Pt 1), G175-83, 1997.
  47. Santos, MF, McCormack, SA, Guo, Z, Okolicany, J, Zheng, Y, Johnson, LR, Tigyi, G. Rho proteins play a critical role in cell migration during the early phase of mucosal restitution. J Clin Invest, 100 (1), 216-25, 1997.
  48. Banan, A, Wang, JY, McCormack, SA, Johnson, LR. Relationship between polyamines, actin distribution, and gastric healing in rats. Am J Physiol, 271 (5 Pt 1), G893-903, 1996.
  49. McCormack, SA, Viar, MJ, Tague, L, Johnson, LR. Altered distribution of the nuclear receptor RAR beta accompanies proliferation and differentiation changes caused by retinoic acid in Caco-2 cells. In Vitro Cell Dev Biol Anim, 32 (1), 53-61, 1996.
  50. Wang, JY, Wang, H, Johnson, LR. Gastrin stimulates expression of protooncogene c-myc through a process involving polyamines in IEC-6 cells. Am J Physiol, 269 (6 Pt 1), C1474-81, 1995.
  51. McCormack, SA, Zimmerman, BJ, Israel, M, Blanner, P, Johnson, LR. Structural requirements of analogues of polyamines for migration and growth of IEC-6 cells. Mol Pharmacol, 48 (4), 724-9, 1995.
  52. Wang, JY, McCormack, SA, Viar, MJ, Johnson, LR. Inhibition of ornithine decarboxylase activity but not expression of the gene by cimetidine in intestinal mucosal cells. J Pharmacol Exp Ther, 274 (1), 521-9, 1995.
  53. Johnson, LR, Brockway, PD, Madsen, K, Hardin, JA, Gall, DG. Polyamines alter intestinal glucose transport. Am J Physiol, 268 (3 Pt 1), G416-23, 1995.
  54. McCormack, SA, Wang, JY, Johnson, LR. Polyamine deficiency causes reorganization of F-actin and tropomyosin in IEC-6 cells. Am J Physiol, 267 (3 Pt 1), C715-22, 1994.
  55. McCormack, SA, Wang, JY, Viar, MJ, Tague, L, Davies, PJ, Johnson, LR. Polyamines influence transglutaminase activity and cell migration in two cell lines. Am J Physiol, 267 (3 Pt 1), C706-14, 1994.
  56. Wang, JY, McCormack, SA, Viar, MJ, Johnson, LR. Secretin inhibits induction of ornithine decarboxylase activity by gastrin in duodenal mucosa and IEC-6 cells. Am J Physiol, 267 (2 Pt 1), G276-84, 1994.
  57. Wang, JY, Johnson, LR. Expression of protooncogenes c-fos and c-myc in healing of gastric mucosal stress ulcers. Am J Physiol, 266 (5 Pt 1), G878-86, 1994.
  58. Wang, JY, Viar, MJ, Johnson, LR. Regulation of transglutaminase activity by polyamines in the gastrointestinal mucosa of rats. Proc Soc Exp Biol Med, 205 (1), 20-8, 1994.
  59. Wang, JY, McCormack, SA, Viar, MJ, Wang, H, Tzen, CY, Scott, RE, Johnson, LR. Decreased expression of protooncogenes c-fos, c-myc, and c-jun following polyamine depletion in IEC-6 cells. Am J Physiol, 265 (2 Pt 1), G331-8, 1993.
  60. McCormack, SA, Viar, MJ, Johnson, LR. Polyamines are necessary for cell migration by a small intestinal crypt cell line. Am J Physiol, 264 (2 Pt 1), G367-74, 1993.
  61. Wang, JY, Viar, MJ, Johnson, LR. Transglutaminase in response to hypertonic NaCl-induced gastric mucosal injury in rats. Gastroenterology, 104 (1), 65-74, 1993.
  62. Wang, JY, Viar, MJ, McCormack, SA, Johnson, LR. Effect of putrescine on S-adenosylmethionine decarboxylase in a small intestinal crypt cell line. Am J Physiol, 263 (4 Pt 1), G494-501, 1992.
  63. McCormack, SA, Viar, MJ, Johnson, LR. Migration of IEC-6 cells: a model for mucosal healing. Am J Physiol, 263 (3 Pt 1), G426-35, 1992.
  64. Wang, JY, Johnson, LR. Role of transglutaminase and protein cross-linking in the repair of mucosal stress erosions. Am J Physiol, 262 (5 Pt 1), G818-25, 1992.
  65. Wang, JY, Johnson, LR. Luminal polyamines substitute for tissue polyamines in duodenal mucosal repair after stress in rats. Gastroenterology, 102 (4 Pt 1), 1109-17, 1992.
  66. Johnson, LR, Wang, P, Haddox, K. Ornithine decarboxylase in large bowel mucosa: regulation by gastrin, secretin and EGF. J Physiol Pharmacol, 43 (1), 33-41, 1992.
  67. Wang, H, Wang, JY, Johnson, LR, Scott, RE. Selective induction of c-jun and jun-B but not c-fos or c-myc during mitogenesis in SV40-transformed cells at the predifferentiation growth arrest state. Cell Growth Differ, 2 (12), 645-52, 1991.
  68. Wang, JY, McCormack, SA, Viar, MJ, Johnson, LR. Stimulation of proximal small intestinal mucosal growth by luminal polyamines. Am J Physiol, 261 (3 Pt 1), G504-11, 1991.
  69. McCormack, SA, Johnson, LR. Putrescine uptake and release by a normal rat small intestine crypt cell line, IEC-6. Exp Cell Res, 193 (2), 241-52, 1991.
  70. Wang, JY, Johnson, LR. Polyamines and ornithine decarboxylase during repair of duodenal mucosa after stress in rats. Gastroenterology, 100 (2), 333-43, 1991.
  71. Johnson, LR, Farmer, JG. Use of human metabolic studies and urinary arsenic speciation in assessing arsenic exposure. Bull Environ Contam Toxicol, 46 (1), 53-61, 1991.
  72. Wang, JY, Johnson, LR. Luminal polyamines stimulate repair of gastric mucosal stress ulcers. Am J Physiol, 259 (4 Pt 1), G584-92, 1990.
  73. McCormack, SA, Tague, LL, Gragoe, EJ, Johnson, LR. Regulation of ornithine decarboxylase activity in LoVo cells. Am J Physiol, 258 (6 Pt 1), G934-41, 1990.
  74. Wang, JY, Johnson, LR. Gastric and duodenal mucosal ornithine decarboxylase and damage after corticosterone. Am J Physiol, 258 (6 Pt 1), G942-50, 1990.