Dalton Cardiovascular Research Center

University of Missouri

Lane L. Clarke, DVM, PhD

Professor, Department of Biomedical Sciences
Office Location: 324D DCRC
Office Phone: 573-882-7049
ClarkeL@missouri.edu

Research Interests

Cystic fibrosis; stem cell biology; goblet cell differentiation/function and epithelial transport of ions and nutrients

Research Description

Our laboratory investigates abnormalities of acid-base transporters in cystic fibrosis and other genetic diseases that contribute to epithelial hyperproliferation and dysfunction of secretory cells in the intestinal crypts, i.e., the site of stem cell activity and cell differentiation. Studies of mice with gene-targeted deletion of CFTR (the cystic fibrosis gene) or other acid-base transporters employ in vivo, ex vivo or primary murine or human organoid culture. Mechanistic studies of molecular interactions are performed using cell lines. Functional activity of acid-base or nutrient transporters is measured in real time using fluorescence confocal or conventional microscopy and electrophysiological methods. Gene or protein expression is measured using quantitative real-time PCR, microarrays, immunoblots, immunofluorescence and laser capture microdissection. Currently, three major projects in the laboratory are funded by NIDDK or the Cystic Fibrosis Foundation. The first project investigates the role of CFTR in down-regulating the cell cycle dynamics and Wnt/b-catenin signaling in intestinal stem cells (ISCs). Loss of this regulation in cystic fibrosis (CF) results in intestinal hyperproliferation which likely contributes to the six-fold increase in the incidence of gastrointestinal cancer in the relatively young population of CF patients. The second project investigates the acid-base transporters expressed in ISCs that determine intracellular pH (pH_i). Manipulation of pH_i is used to control proliferation in a timed manner to offset the “bystander” damage to ISCs resulting from therapeutic doses of chemotherapeutic reagents and radiation during cancer treatment. The third project investigates goblet cell (mucus secreting) dysfunction in the CF intestine, i.e., mucoviscidosis. The goals are to investigate the factors contributing to hyperplasia of goblet cells and the causes of abnormal exocytosis. To facilitate the translational potential of the above projects, our laboratory is developing a human CFTR “rescue” mouse model in which murine CFTR is replaced by the human ortholog of the gene. This humanized CFTR mouse will also enable pharmacological testing of reagents designed to correct defective function CFTR in CF patients and pharmacological/probiotic strategies designed to combat infectious diarrheal diseases in humans.

Professional Background

• Obtained PhD from North Carolina State University.
• Obtained DVM from University of Missouri.
• Post-doctoral training at the Cystic Fibrosis Research Center, Department of Medicine, North Carolina University at Chapel Hill. Postdoctoral mentor: R. C. Boucher, M.D.

Selected Publications

• Cftr Modulates Wnt/β-Catenin Signaling and Stem Cell Proliferation in Murine Intestine. Strubberg AM, Liu J, Walker NM, Stefanski CD, MacLeod RJ, Magness ST, Clarke LL. Cell Mol Gastroenterol Hepatol. 2017 Dec 7;5(3):253-271. doi: 10.1016/j.jcmgh.2017.11.013. eCollection 2018 Mar. PMID: 29675451
• Cellular chloride and bicarbonate retention alters intracellular pH regulation in Cftr KO crypt epithelium. Walker NM, Liu J, Stein SR, Stefanski CD, Strubberg AM, Clarke LL. Am J Physiol Gastrointest Liver Physiol. 2016 Jan 15;310(2):G70-80. doi: 10.1152/ajpgi.00236.2015. Epub 2015 Nov 5. PMID: 26542396
• Defective goblet cell exocytosis contributes to murine cystic fibrosis-associated intestinal disease. Liu J, Walker NM, Ootani A, Strubberg AM, Clarke LL. J Clin Invest. 2015 Mar 2;125(3):1056-68. doi: 10.1172/JCI73193. Epub 2015 Feb 2. PMID: 25642775
• Liu, J, Walker, NM, Williams, AM, Clarke, LL. Defective and ectopic exocytosis by goblet cells in the CF mouse intestine. Pediatr. Pulmonol. Suppl. 36: 257-8, 2013.
• Liu, J, Walker, NM, Williams, AM, Clarke, LL. Intracellular pH is normal in CF goblet cells but not in adjacent epithelial cells of murine intestinal organoids. Pediatr. Pulmonol. Suppl. 35: 266, 2012.

• Liu, J, Walker, NM, Clarke, LL. Hyperproliferation is an intrinsic property of the intestinal epithelium in Cftr-null mice. Gastroenterology 142 (Suppl. 1): S334, 2012.

• Liu, J, Walker, NM, Clarke, LL. Hyperproliferation in the CF mouse intestine is associated with increased Wnt/b-catenin signaling. Pediatr. Pulmonol. Suppl. 34: 255, 2011.

• *Liu, J, Walker, NM, Clarke, LL. Abnormal mucus release but not hyperplasia is an intrinsic property of goblet cells in the CF mouse intestine. Pediatr. Pulmonol. Suppl. 34: 236, 2011.

• Liu, J, Walker, NM, Cook, MT, Ootani, A, Clarke, LL. Functional Cftr in crypt epithelium of organotypic enteroid cultures from murine small intestine. Am. J. Physiol. Cell Physiol. 302: C1492-C1503, 2012.
• Alper SL, Stewart AK, Vandorpe DH, Clark JS, Horack RZ, Simpson JE, Walker NM, Clarke LL., Native and recombinant Slc26a3 (downregulated in adenoma, Dra) do not exhibit properties of 2Cl-/1HCO3- exchange., Am J Physiol Cell Physiol. 2011 Feb;300(2):C276-86. Epub 2010 Nov 10.,PMID: 21068358
• Walker NM, Simpson JE, Hoover EE, Brazill JM, Schweinfest CW, Soleimani M, Clarke LL., Functional activity of Pat-1 (Slc26a6) Cl(−)/HCO₃(−) exchange in the lower villus epithelium of murine duodenum., Acta Physiol (Oxf). 2011 Jan;201(1):21-31. doi: 10.1111/j.1748-1716.2010.02210.x. Epub 2010 Nov 12.PMID: 20969732
• Simpson JE, Walker NM, Supuran CT, Soleimani M, Clarke LL., Putative anion transporter-1 (Pat-1, Slc26a6) contributes to intracellular pH regulation during H+-dipeptide transport in duodenal villous epithelium., Am J Physiol Gastrointest Liver Physiol. 2010 May;298(5):G683-91. Epub 2010 Feb 11.,PMID: 20150244
• Clarke LL., A guide to Ussing chamber studies of mouse intestine., Am J Physiol Gastrointest Liver Physiol. 2009 Jun;296(6):G1151-66. Epub 2009 Apr 2. Review.PMID: 19342508
• Walker NM, Simpson JE, Brazill JM, Gill RK, Dudeja PK, Schweinfest CW, Clarke LL., Role of down-regulated in adenoma anion exchanger in HCO3- secretion across murine duodenum., Gastroenterology. 2009 Mar;136(3):893-901. Epub 2008 Nov 8.,PMID: 19121635
• Walker NM, Simpson JE, Yen PF, Gill RK, Rigsby EV, Brazill JM, Dudeja PK, Schweinfest CW, Clarke LL., Down-regulated in adenoma Cl/HCO3 exchanger couples with Na/H exchanger 3 for NaCl absorption in murine small intestine., Gastroenterology. 2008 Nov;135(5):1645-1653.e3. Epub 2008 Aug 7.PMID:18930060
• Gawenis, LR, Hut, H, Bot, AGM, Shull, GE, De Jonge, HR, Stein, X, Miller, ML and Clarke, LL. Electroneutral sodium absorption and electrogenic anion secretion across murine small intestine are regulated in parallel. Am. J. Physiol. 287: G1140-G1149, 2004.
• Clarke, LL, Gawenis, LR, Hwang, T-C, Gruis, DB and Price, EM. A domain mimic increases DF508 CFTR trafficking and restores cAMP-stimulated anion secretion in cystic fibrosis epithelia. Am. J. Physiol. 287: C192-C199, 2004.
• Gawenis, LR, Boyle, KT, Palmer, BA, Walker, NM, and Clarke, LL. Lateral intercellular space volume as a determinant of CFTR-mediated anion secretion across small intestinal mucosa. Am. J. Physiol. 286: G1015-G1023, 2004.
• Gawenis, LR, Franklin, CL, Simpson, JE, Palmer, BA, Walker, NM, Wiggins, TM and Clarke, LL. cAMP inhibition of murine intestinal Na⁺/H⁺ exchange requires CFTR-mediated cell shrinkage of villus epithelium. Gastroenterology 125: 1124-1148, 2003.
• Clarke LL, Grubb BR, Yankaskas JR, Cotton CU, McKenzie A, and Boucher RC. Relationship of a non-CFTR-mediated chloride conductance to organ-level disease in cftr (-/-) mice. Proc. Natl. Acad. Sci. 91(2):479-483, 1994.
• Clarke LL, Grubb BR, Gabriel SE, Smithies O, Koller BH, and Boucher RC. Defective epithelial chloride transport in a gene-targeted mouse model of cystic fibrosis. Science, 257:1125-1128. 1992.