Three-dimensional polarization sensitizes hepatocytes to Fas/CD95 apoptotic signalling

Abstract

Maintenance of epithelial cell shape and polarity determines many vital cell functions, including the appropriate response to external stimuli. Murine hepatocytes cultured in a three-dimensional Matrigel matrix formed highly polarized organoids characterized by specific localization of an ERM (ezrin/radixin/moesin) protein, radixin, at microvillus-lined membrane domains. These apical domains surrounded a lumen and were bordered by tight junctions. The hepatocyte organoids were functional as judged by the high level of albumin secretion and accumulation of bilirubin. Stimulation of the Fas/CD95 death receptor, which is highly hepatotoxic in vivo, was a strong inducer of apoptosis in the polarized organoids. This was in sharp contrast to the monolayer hepatocyte cultures, which were protected from death by exacerbated NF-κB signalling following engagement of the death receptors. Thus, hepatocytes in polarized, functional organoids modulate an intracellular signal transduction pathway, allowing the recapitulation of their physiological response to an apoptotic stimulus.

Transforming Growth Factor β Controls the Directional Migration of Hepatocyte Cohorts by Modulating Their Adhesion to Fibronectin

“…However, high levels of active TGF-␤ can be found in well-differentiated HCC, with no signs of EMT, suggesting that acquisition of the mesenchymal phenotype is not the sole mechanism of escape from the antiproliferative and proapoptotic TGF-␤ signaling (Idobe et al, 2003). Similarly, we show that the mhAT3F hepatocytes, which retain a high level of differentiation (Antoine et al, 1992;Haouzi et al, 2005), are resistant to apoptotic effects of TGF-␤ without undergoing EMT. They are nevertheless sensitive to this cytokine, because even a short pulse of TGF-␤ initiates longlasting changes in the expression of integrins and their ligands.…”

“…We have studied the effect of TGF-␤ treatment on mhAT3F, an immortalized, highly differentiated mouse hepatocyte cell line (Antoine et al, 1992;Haouzi et al, 2005). We show that these cells undergo little, if any, apoptosis and no EMT in response to TGF-␤.…”

“…However, it has been reported that either the constitutive Erk (Pinkas and Leder, 2002) or TGF-␤ signaling (Han et al, 2005) alone, in the absence of demonstrable EMT, could increase metastasis in experimentally inoculated tumors. Moreover, epithelial tumor cells are capable of collective migration and intravasation into blood vessels, moving as sheets or cohorts (Friedl et al, 2004;Wicki et al, 2006), suggesting that the EMT is not the sole means by which epithelial cells can become motile and invade local and distant sites.We have studied the effect of TGF-␤ treatment on mhAT3F, an immortalized, highly differentiated mouse hepatocyte cell line (Antoine et al, 1992;Haouzi et al, 2005). We show that these cells undergo little, if any, apoptosis and no EMT in response to TGF-␤.…”

Mammalian Target of Rapamycin Activation Impairs Hepatocytic Differentiation and Targets Genes Moderating Lipid Homeostasis and Hepatocellular Growth

“…drug-induced liver toxicity, and three-dimensional polarization sensitizes hepatocytes to Fas apoptotic signaling (25). Therefore, sustained activation of mTOR may contribute to neoplastic cell expansion by altering receptor-induced apoptosis sensitivity.…”

Hepatic Differentiation of Human Embryonic and Induced Pluripotent Stem Cells for Regenerative Medicine

“…Using matrigel or collagen gel, it has been shown that static 3D culture conditions prolong hepatic function of primary hepatocytes (Kono et al 1997). It has been proposed that the 3D structure allows more physiological cellto-cell interactions, and induces polarity in hepatocytes (Haouzi et al 2005). Baharvand et al demonstrated that hESCs are more efficiently differentiated to hepatic cells under static 3D culture conditions than conventional 2D culture conditions (Baharvand et al 2008).…”