Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB131

Poster Communications

Control of cellular shape by actomyosin-dependent apical constriction

A. Hofherr1, C. Seger1, E. Dixon2, S. L. Svendsen3, A. Bohn1, K. Runge1, B. Fajen1, C. Consoli1, O. Woodward2, J. Leipziger3, M. Köttgen1

1. Medical Center - University of Freiburg, Freiburg im Breisgau, Germany. 2. Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States. 3. Biomedicine, Physiology, Aarhus University, Aarhus, Denmark.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic cause of end-stage renal disease affecting approximately 1 in 500 adults. Mutations in two genes cause ADPKD. Polycystic kidney disease 1 (PKD1) accounts for 85 % of patients and PKD2 accounts for the remaining 15 % of patients. Elegant experiments in model organisms have uncovered three evolutionarily conserved core principles of PKD function: 1) the respective proteins, Polycystin-1 (PC1) and transient receptor potential Polycystin-2 (TRPP2), form a receptor-ion channel complex; 2) the PC1/TRPP2 complex localizes to primary cilia; and 3) both genes are part of morphogenetic programs controlling elementary functions in vertebrates ranging from angiogenesis and kidney development to left-right organ patterning. However, the precise molecular relation between these loosely connected key insights has remained largely enigmatic. Or more specifically, the intracellular effectors translating PC1/TRPP2 receptor-ion channel activity into three-dimensional tissue organization connecting genetics, cellular output, and tissue mechanics are unknown. We have addressed this issue for the kidney with an unbiased high-resolution mass spectrometry-based screen for TRPP2-binding proteins in polarized renal epithelial cells followed by targeted analyses of PC1/TRPP2 function in vitro and in vivo. In vitro analyses of PC1/TRPP2 and candidate proteins were performed using CRISPR/Cas- and TALEN-based gene-specific knock-out and knock-in Madin-Darby canine kidney (MDCK) cell models. Wild-type and mutant zebrafish, mice, and human samples were used to validate results in vivo. Here we identify an apical junction associated multi protein signaling complex as functional PC1/TRPP2 effector and show: 1) how the PC1/TRPP2 complex controls cellular shape by actomyosin-dependent apical constriction; 2) that this cellular contraction translates on a tissue-scale into a coordinated fine-tuning of renal tubular diameter in vivo; and 3) that in human ADPKD kidneys, tubular shape is lost, because of impaired signal integration disconnecting mutant cells from their healthy surroundings.

Where applicable, experiments conform with Society ethical requirements