The polarization of renal epithelia is crucial for proper kidney development and function. Recent work from our laboratory and others has pointed to an important role for the Crumbs family of proteins in development and maintenance of epithelial cell polarity. Our work has focused on Crumbs3 which is the predominant form in renal epithelia. Crumbs3 is a small apical transmembrane protein that exists as two different splice isoforms. One isoform, Crumbs3a, uses an evolutionarily conserved carboxy-terminal tail to organize two important polarity complexes, the Crumbs/PALS/PATJ complex and the PAR3/PAR6/aPKC complex. Loss of Crumbs3 expression or overexpression of Crumbs3 can lead to a loss of cell polarity and tight junction formation. It is felt that Crumbs3 functions as a transmembrane anchor that localizes signaling molecules such as aPKC to define the apical domain via reciprocal phosphorylation steps with kinases localized on the basolateral membrane. However a fundamental question is how is Crumbs3 initially localized to instruct creation of the apical membrane. Our newest studies in three-dimensional culture demonstrate that Crumbs3 initiates apical membrane and lumen formation very early in cell division during the cytokinetic process. We hypothesize that the ability of Crumbs3 to target to the mid-body during the cytokinetic process is a crucial step in initial apical membrane and lumen formation. This hypothesis will be tested in the first specific aim where we will examine if factors that regulate membrane trafficking to the midbody during cytokinesis also regulate initial apical membrane formation. In the second specific aim, we will examine the regulation of Crumbs3 expression and trafficking in established polarized epithelia and in epithelia undergoing mesenchymal transition. The last specific aim will examine these processes in vivo by generating a GFP knock in Crumbs3 mouse. This will allow us to determine if our hypothesis generated in tissue culture models holds during kidney development, normal kidney function and during renal recovery from injury.

Public Health Relevance

The goal of this work is to understand the steps that lead to polarized epithelia and kidney tube formation. The proposal focuses on a protein called Crumbs that is crucial in this process. Proper tube formation is important in many diseases including polycystic kidney disease and in recovery from kidney failure. Our data will delineate the basic steps utilized by the Crumbs protein to initiate epithelial polarization.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK069605-09
Application #
8516022
Study Section
Special Emphasis Panel (ZRG1-DKUS-F (02))
Program Officer
Rasooly, Rebekah S
Project Start
2005-02-15
Project End
2014-06-30
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
9
Fiscal Year
2013
Total Cost
$299,791
Indirect Cost
$101,556
Name
University of Michigan Ann Arbor
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Whiteman, Eileen L; Fan, Shuling; Harder, Jennifer L et al. (2014) Crumbs3 is essential for proper epithelial development and viability. Mol Cell Biol 34:43-56
Schluter, Marc A; Margolis, Ben (2012) Apicobasal polarity in the kidney. Exp Cell Res 318:1033-9
Pieczynski, Jay; Margolis, Ben (2011) Protein complexes that control renal epithelial polarity. Am J Physiol Renal Physiol 300:F589-601
Fan, Shuling; Margolis, Ben (2011) The Ran importin system in cilia trafficking. Organogenesis 7:147-53
Grosse, Ann S; Pressprich, Mark F; Curley, Lauren B et al. (2011) Cell dynamics in fetal intestinal epithelium: implications for intestinal growth and morphogenesis. Development 138:4423-32
Teoh, Kim-Tat; Siu, Yu-Lam; Chan, Wing-Lim et al. (2010) The SARS coronavirus E protein interacts with PALS1 and alters tight junction formation and epithelial morphogenesis. Mol Biol Cell 21:3838-52
Schluter, Marc A; Pfarr, Catherine S; Pieczynski, Jay et al. (2009) Trafficking of Crumbs3 during cytokinesis is crucial for lumen formation. Mol Biol Cell 20:4652-63
Schluter, Marc A; Margolis, Ben (2009) Apical lumen formation in renal epithelia. J Am Soc Nephrol 20:1444-52
Whiteman, E L; Liu, C-J; Fearon, E R et al. (2008) The transcription factor snail represses Crumbs3 expression and disrupts apico-basal polarity complexes. Oncogene 27:3875-9
Fan, Shuling; Fogg, Vanessa; Wang, Qian et al. (2007) A novel Crumbs3 isoform regulates cell division and ciliogenesis via importin beta interactions. J Cell Biol 178:387-98

Showing the most recent 10 out of 13 publications