The hSNF5 chromatin-remodeling factor is a tumor suppressor that is inactivated in malignant rhabdoid tumors (MRTs). A number of studies have shown that hSNF5 re-expression blocks MRT cell proliferation. However, the pathway through which hSNF5 acts remains unknown. To address this question, we generated MRT-derived cell lines in which restoration of hSNF5 expression leads to an accumulation in G 0 /G 1 , induces cellular senescence and increased apoptosis.

Polycomb group (PcG) proteins function through cis-acting DNA elements called PcG response elements (PREs) to stably silence developmental regulators, including the homeotic genes. However, the mechanism by which they are targeted to PREs remains largely unclear. Pleiohomeotic (PHO) is a sequence-specific DNAbinding PcG protein and therefore may function to tether other PcG proteins to the DNA. Here, we show that PHO can directly bind to a Polycomb (PC)-containing complex as well as the Brahma (BRM) chromatinremodeling complex. PHO contacts the BRM complex through its zinc finger DNA-binding domain and a short N-terminal region. A distinct domain of PHO containing a conserved motif contacts the PcG proteins PC and Polyhomeotic (PH). With mobility shift assays and DNA pulldown experiments, we demonstrated that PHO is able to link PC, which lacks sequence-specific DNA-binding activity, to the DNA. Importantly, we found that the PC-binding domain of PHO can mediate transcriptional repression in transfected Drosophila Schneider cells. Concomitant overexpression of PC resulted in stronger PHO-directed repression that was dependent on its PC-binding domain. Together, these results suggest that PHO can contribute to PRE-mediated silencing by direct recruitment of a PC complex to repress transcription.

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Our results suggest that factors found to be associated with noncompliant behavior (e.g., being a newly treated patient, self-reported compliance, regimen complexity) can be assessed by physicians and pharmacists as a routine practice.

The quality of the compliance research was generally poor. These low scores reflect very important shortcomings in the methodology. Such oversights make it difficult for the reader to critically assess the validity of the conclusions.