Proliferation-independent role of NF2 (merlin) in limiting biliary morphogenesis

Benhamouche-Trouillet, Samira; O’Loughlin, Evan; Liu, Ching-Hui; Polacheck, William J.; Fitamant, Julien; McKee, Mary; El-Bardeesy, Nabeel; Chen, Christopher; McClatchey, Andrea I.

doi:10.1242/dev.162123

Cited by 16 publications

(21 citation statements)

References 61 publications

(85 reference statements)

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“…1c). This observation is consistent with published shapes of both MDCK (Bryant et al, 2010;Cerruti et al, 2013;Ferrari et al, 2008;O'Brien et al, 2001) and other lumens observed in intact organisms (Benhamouche-Trouillet et al, 2018;Hoijman et al, 2015;Oteiza et al, 2008;Shahbazi et al, 2016;Strilić et al, 2010;Wong et al, 2010), though the irregularity of shape was not previously commented upon or explored in detail.…”

Section: Introductionsupporting

confidence: 90%

Physical basis of lumen shape and stability in a simple epithelium

Vasquez

Vachharajani

Garzón-Coral

et al. 2019

Preprint

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A continuous sheet of epithelial cells surrounding a hollow opening, or lumen, defines the basic topology of numerous organs. De novo lumen formation is a central feature of embryonic development whose dysregulation leads to congenital and acquired diseases of the kidney and other organs. While prior work has described the hydrostatic pressure-driven expansion of lumens when they are large, the physical mechanisms that promote the formation and maintenance of small, nascent lumens are less explored. In particular, models that rely solely on pressure-driven expansion face a potential challenge in that the Laplace pressure, which resists lumen expansion, is predicted to scale inversely with lumen radius. We investigated the cellular and physical mechanisms responsible for stabilizing the initial stages of lumen growth using a 3D culture system in which epithelial cells spontaneously form hollow lumens. Our experiments revealed that neither the actomyosin nor microtubule cytoskeletons are required to stabilize lumen geometry, and that a positive intraluminal pressure is not necessary for lumen stability. Instead, our observations are in agreement with a quantitative model in which cells maintain lumen shape due to topological and geometrical factors tied to the establishment of apicobasolateral polarity. We suggest that this model may provide a general physical mechanism for the formation of luminal openings in a variety of physiological contexts. Lumen shapes for small-and intermediate-size MDCK spheroids are inconsistent with a Laplace model of lumen stabilityWe seeded MDCK cells expressing a fluorescent marker for actin filaments (Lifeact-RFP) in the recombinant extracellular matrix Matrigel. Under these culture conditions, MDCK cells spontaneously form hollow spheroids within 24 hours. To obtain high-resolution images of nascent lumens, we imaged young (18-24 hours) spheroids using lattice light sheet microscopy (LLSM). This acquisition method produced images in which the two opposing apical cortices of the lumen are clearly distinguishable and separated by ~200-300 nm (Fig. 1b,c). We infer that cellular apical surfaces are intrinsically non-adherent, as even small fluctuations in cell shape would allow apposing apical surfaces to contact and potentially adhere. This "non-stick" behavior may reflect the enrichment of negatively charged sialoglycoproteins such as

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Section: Introductionsupporting

confidence: 90%

Physical basis of lumen shape and stability in a simple epithelium

Vasquez

Vachharajani

Garzón-Coral

et al. 2019

Preprint

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“…Measuring and comparing cell apical and basal membranes, we observed a widely variable, increased apical:basal ratio in the Lats1/2 PanKO (S4D Fig). We calculated this ratio based on an analytical method previously published to examine defects in bile duct lumenogenesis [32], in which variable or high apical:basal ratio measurements indicated failure of apical constriction. To assess apical constriction, which is critical for microlumen formation [4, 31], we immunostained for phosphorylated myosin light chain 2 (pMYL2) and found its complete absence at the apical membrane of pancreatic epithelial cells (S4E Fig), suggesting the absence of expected rosette formation and loss of lumen size control.…”

Section: Resultsmentioning

confidence: 99%

LATS1/2 suppress NFκB and aberrant EMT initiation to permit pancreatic progenitor differentiation

Braitsch¹,

Azizoglu²,

Htike³

et al. 2019

PLoS Biol

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The Hippo pathway directs cell differentiation during organogenesis, in part by restricting proliferation. How Hippo signaling maintains a proliferation-differentiation balance in developing tissues via distinct molecular targets is only beginning to be understood. Our study makes the unexpected finding that Hippo suppresses nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) signaling in pancreatic progenitors to permit cell differentiation and epithelial morphogenesis. We find that pancreas-specific deletion of the large tumor suppressor kinases 1 and 2 ( Lats1/2 PanKO ) from mouse progenitor epithelia results in failure to differentiate key pancreatic lineages: acinar, ductal, and endocrine. We carried out an unbiased transcriptome analysis to query differentiation defects in Lats1/2 PanKO . This analysis revealed increased expression of NFκB activators, including the pantetheinase vanin1 ( Vnn1 ). Using in vivo and ex vivo studies, we show that VNN1 activates a detrimental cascade of processes in Lats1/2 PanKO epithelium, including (1) NFκB activation and (2) aberrant initiation of epithelial-mesenchymal transition (EMT), which together disrupt normal differentiation. We show that exogenous stimulation of VNN1 or NFκB can trigger this cascade in wild-type (WT) pancreatic progenitors. These findings reveal an unexpected requirement for active suppression of NFκB by LATS1/2 during pancreas development, which restrains a cell-autonomous deleterious transcriptional program and thereby allows epithelial differentiation.

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“…Cystogenesis is characterized by several features 75 , including increased cystic cholangiocyte proliferation 93 , secretion 94 , matrix metalloproteinase activity 95 , autophagy 96 , ciliary and centrosomal abnormalities 97,98 , and alterations in the microRNA expression pattern 99 . An alternative model for initial cyst formation has arisen from work showing that biliary cysts might develop through a proliferation-independent process that involves recruitment and biliary differentiation of nearby hepatoblasts 100,101 . However, further postnatal growth of cysts requires cell proliferation.…”

Section: Polycystic Liver Diseasementioning

confidence: 99%

Pathobiology of inherited biliary diseases: a roadmap to understand acquired liver diseases

Fabris

Fiorotto

Spirlı̀

et al. 2019

Nat Rev Gastroenterol Hepatol

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Bile duct epithelial cells, also known as cholangiocytes, regulate the composition of bile and its flow. Acquired, congenital and genetic dysfunctions in these cells give rise to a set of diverse and complex diseases, often of unknown aetiology, called cholangiopathies. New knowledge has been steadily acquired about genetic and congenital cholangiopathies, and this has led to a better understanding of the mechanisms of acquired cholangiopathies. This Review focuses on findings from studies on Alagille syndrome, polycystic liver diseases, fibropolycystic liver diseases (Caroli disease and congenital hepatic fibrosis) and cystic fibrosis-related liver disease. In particular, knowledge on the role of Notch signalling in biliary repair and tubulogenesis has been advanced by work on Alagille syndrome, and investigations in polycystic liver diseases have highlighted the role of primary cilia in biliary pathophysiology and the concept of biliary angiogenic signalling and its role in cyst growth and biliary repair. In fibropolycystic liver disease, research has shown that loss of fibrocystin generates a signalling cascade that increases β-catenin signalling, activates the NOD-, LRR-and pyrin domain-containing 3 inflammasome, and promotes production of IL-1β and other chemokines that attract macrophages and orchestrate the process of pericystic and portal fibrosis, which are the main mechanisms of progression in cholangiopathies. In cystic fibrosis-related liver disease, lack of cystic fibrosis transmembrane conductance regulator increases the sensitivity of epithelial Toll-like receptor 4 that sustains the secretion of nuclear

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Proliferation-independent role of NF2 (merlin) in limiting biliary morphogenesis

Cited by 16 publications

References 61 publications

Physical basis of lumen shape and stability in a simple epithelium

Physical basis of lumen shape and stability in a simple epithelium

LATS1/2 suppress NFκB and aberrant EMT initiation to permit pancreatic progenitor differentiation

Pathobiology of inherited biliary diseases: a roadmap to understand acquired liver diseases

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