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Marshall H. Montrose, PhD
Professor and Dean of the Graduate School
marshall.montrose@uc.edu

Our laboratory is interested in the cellular and sub-cellular physiology of epithelial cells lining the gastrointestinal tract. We have a number of ongoing projects which are described briefly below. In all our projects we explore the role of specific proteins thru the use of normal and mutant mice as well as tissue culture models. Our favorite tool is the use of high resolution (confocal and two-photon) light microscopy, to help us explore events in living cells and tissues.

In the small and large intestines, epithelial cells are responsible for the absorption of nutrients and fluid. Within this topic area, we want to know how sodium absorption in the large intestine (colon) is stimulated by short-chain fatty acids (abundant monocarboxylates created from bacterial fermentation in the colonic lumen). More specifically, we are investigating two questions concerning (1) which Na/H exchanger isoforms are responsible for sodium absorption in the colon, and (2) how these sodium transporters are differentially regulated by the short-chain fatty acids. We have found that the NHE2 isoform has previously unsuspected roles in sodium transport in the colonic crypt, and have also identifed two general mechanisms that lead to activation of this and other NHE isoforms. First, microdomains of pH in the extracellular and intracellular environment near the transport proteins provide unusual kinetic activation of the exchangers. In other words, the pH that the Na/H exchanger sees is not the same as the bulk pH in either the cytosol or the outside bathing solution. The second mechanism is a translocation of the Na/H exchangers in response to ionic conditions that signal a need for altered absorption.

In the stomach, we are exploring the reason that the stomach does not digest itself despite having a caustic environment imposed on the epithelial cells lining the stomach. Part of the gastric defenses include pH microdomain near the tissue surface, which we detect with confocal microscopy in vivo. The epithelial cells are responsible for both acid and alkali secretion, and here we are exploring how changes in the luminal pH of the stomach regulate the dramatic transition from net-acid to net-alkali secretion, and its impact on gastric defense. We are also using the two-photon microscope to cause microlesions in the stomach (damaging 2-5 cells) and following in real-time the process of expanding damage and repair.

Since all the epithelial cells lining the GI tract are being constantly replaced every week, we are also fascinated with the mechanisms which allow cell proliferation, death, migration and differentiation to occur during normal tissue function. We are questioning the sites and extent of apoptosis and cell shedding in living tissue. Our initial work has focused on the small intestine but we hope to expand studies to other tissues as our knowledge expands.



Selected Publications:
  • Ralf Kiesslich, Martin Goetz, Elizabeth M Angus, Qiuping Hu, Yanfang Guan, Chris Potten, Terry Allen, Markus F Neurath, Noah F Shroyer, Marshall H Montrose and Alastair J M Watson (2008) Identification of epithelial gaps in human small and large intestine by confocal endomicroscopy. Gastroenterology 133, 1769-1778.
    View original publication via Elsevier.com.
  • Olga T Starodub, Elise S Demitrack, Heidi K Baumgartner and Marshall H Montrose (2007) Disruption of Cox-1 gene slows repair of microscopic lesions of the mouse gastric epithelium. Am J Physiol Cell Physiol 294, C223-C232.
    View original publication at AJP:Cell Online.
  • J Scott Gens, Hongwei Du, Lixuan Tackett, Shen-Shen Kong, Shaoyou Chu and Marshall H Montrose (2007) Different ionic conditions prompt NHE2 and NHE3 translocation to the plasma membrane. Biochim Biophys Acta 1768, 1023-1035.
    View original publication at ScienceDirect.com
  • Yanfang Guan, Jin Dong, Lixuan Tackett, Jamie W Meyer, Gary E Shull and Marshall H Montrose (2006) NHE2 is the main apical NHE in mouse colonic crypts but an alternative Na+-dependent acid extrusion mechanism is upregulated in NHE2-null mice. Am J Physiol Gastrointest Liver Physiol 291, G689-G699.
    View original publication at AJP:GI Online.
  • Alastair J M Watson, Shaoyou Chu, Leah Sieck, Oleg Gerasimenko, Tim Bullen, Fiona Campbell, Michael McKenna, Tracy Rose and Marshall H Montrose (2005) Epithelial barrier function in vivo is sustained despite gaps in epithelial layers. Gastroenterology 129, 902-912.
    View original publication at GastroJournal.org.

Publications, Complete List at PubMed


Other Publications, Not Listed in PubMed:
  • Marshall H Montrose, Yasutada Akiba, Koji Takeuchi, and Jonathan D Kaunitz (2006) Gastroduodenal mucosal defense, ch 50 in: Physiology of the Gastrointestinal Tract, vol 1-2, 4e, Leonard R Johnson (Ed-in-Chief), Kim E Barrett, Fayez K Ghishan, Juanita L Merchant, Hamid M Said, and Jackie D Wood (Eds), Academic Press, Burlington, pp 1259-1292 (Review).
    View details at Elsevier.com.
    Buy the book at Amazon.com.


Postdoctoral positions are currently available in the Montrose laboratory. For information and application details, click here.


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