Polycomb repressive complex 2 impedes intestinal cell terminal differentiation

Abstract

SummaryThe crypt-villus axis constitutes the functional unit of the small intestine, where mature absorptive cells are confined to the villi, and stem cells and transit amplifying and differentiating cells are restricted to the crypts. The polycomb group (PcG) proteins repress differentiation and promote self-renewal in embryonic stem cells. PcGs prevent transcriptional activity by catalysing epigenetic modifications, such as the covalent addition of methyl groups on histone tails, through the action of the polycomb repressive complex 2 (PRC2). Although a role for PcGs in the preservation of stemness characteristics is now well established, recent evidence suggests that they may also be involved in the regulation of differentiation. Using intestinal epithelial cell models that recapitulate the enterocytic differentiation programme, we generated a RNAi-mediated stable knockdown of SUZ12, which constitutes a cornerstone for PRC2 assembly and functionality, in order to analyse intestinal cell proliferation and differentiation. Expression of SUZ12 was also investigated in human intestinal tissues, revealing the presence of SUZ12 in most proliferative epithelial cells of the crypt and an increase in its expression in colorectal cancers. Moreover, PRC2 disruption led to a significant precocious expression of a number of terminal differentiation markers in intestinal cell models. Taken together, our data identified a mechanism whereby PcG proteins participate in the repression of the enterocytic differentiation program, and suggest that a similar mechanism exists in situ to slow down terminal differentiation in the transit amplifying cell population.

Altered epigenetic regulation of homeobox genes in human oral squamous cell carcinoma cells

“…The cells were treated with 1 µM RA or vehicle in the growth medium for 6 days and counted using a cell and particle counter (Coulter Z; Beckman Coulter, Inc., Fullerton, CA). Stable Suz12 knockdown (shRNA sequence TRCN0000038728) and control cell populations were established as described [25]. …”

Laminin Receptor 37/67LR Regulates Adhesion and Proliferation of Normal Human Intestinal Epithelial Cells

“…Typical cell markers identified in the lower crypt in the intact intestine are also expressed in HIEC cells including adhesion and signaling molecules [61–63], metabolism [64] and inflammatory response [65,66]. Furthermore, while HIEC cells are undifferentiated, studies have shown that reintroduction of the intestine-specific pro-differentiation factors CDX2, HFN-1α and GATA-4 can induce enterocytic differentiation [67,68]. Taken together, HIEC cells represent a valid human intestinal crypt cell model.…”

Ezh2 maintains a key phase of muscle satellite cell expansion but does not regulate terminal differentiation

“…Conditional deletion of Ezh2, for example, in B cells (Su et al, 2003), neuronal stem cells (Hirabayashi et al, 2009;Pereira et al, 2010), epidermal progenitors (Ezhkova et al, 2011;Ezhkova et al, 2009;Lien et al, 2011) and pancreatic islet b cells (Chen et al, 2009) has provided insights into the function of PRC2 within lineage restricted somatic cells. However, the differing phenotypes within these studies indicate that Ezh2 action may be highly dependent on the differentiation stage of the stem cell and may even regulate the differentiation programme (Benoit et al, 2012). Interestingly, loss of Ezh2 within cardiac progenitors leads to an upregulation of Six1 dependent skeletal muscle genes (Delgado-Olguín et al, 2012), suggesting that Ezh2 may not only be required for stem cell function but may also act to ensure the correct lineage choice of a stem cell.…”