Chromatin remodeling by the SWI/SNF complex is essential for transcription mediated by the yeast cell wall integrity MAPK pathway

Abstract

The SWI/SNF complex is a key element of the yeast CWI MAPK pathway, which mediates the chromatin remodeling necessary for an adequate transcriptional response to cell wall stress. The MAPK Slt2 mediates, through Rlm1, nucleosome rearrangements at cell wall stress–responsive genes by targeting the SWI/SNF complex.

Rlm1 mediates positive autoregulatory transcriptional feedback that is essential for Slt2-dependent gene expression

“…Under these conditions, the MAPK Slt2 is phosphorylated and activates the transcription factor Rlm1, which is interdependently recruited with the chromatin-remodelling complex SWI-SNF to the promoters of the CWI-responsive genes -such as KDX1 (also known as MLP1), SRL3 and YLR194C -to regulate gene expression (Sanz et al, 2012). Expression of both RLM1 and SLT2 is also up-regulated under these stress conditions in an Rlm1-dependent manner (García et al, 2004).…”

“…Regulation of the CWI pathway. Upon cell wall stress, the MAPK Slt2 mediates, through Rlm1 and the SWI-SNF chromatin remodelling complex, the induction of the CWI transcriptional programme (Sanz et al, 2012). Modulation of CWI signaling outputs requires both positive-and negative-feedback mechanisms.…”

“…This transcriptional response is largely dependent on the transcription factor Rlm1 and the MAPK Slt2 (García et al, 2004(García et al, , 2009Jung and Levin, 1999;Sanz et al, 2012). Rlm1 is a MADS-box transcription factor, which shares homology and in vitro DNA-binding specificity with mammalian MEF2 orthologues.…”

“…In addition to Rlm1 and Slt2, the SWI-SNF ATP chromatin remodelling complex is required for yeast transcriptional reprogramming under cell wall stress conditions. Through a direct interaction with Rlm1, this complex is recruited to the promoters of genes that are responsive to cell wall stress, mediating the necessary nucleosome eviction (Sanz et al, 2012).…”

“…Genome-wide transcriptional profiles have revealed that expression of the genes encoding the MAPK Slt2 and the transcription factor Rlm1 increases under conditions of CWI activation, such as overexpression of PKC1 (Roberts et al, 2000), treatment with Congo Red (García et al, 2004;Sanz et al, 2012) and overexpression of a hyperactive allele of MKK1 and temperature upshift (Jung and Levin, 1999), indicating the existence of internal feedback autoregulatory circuits of amplification of the cell wall stress response in order to control adaptation through this pathway. Simultaneous monitoring of gene expression programmes of other signal transduction pathways in yeast by performing genome-wide transcript analysis has also uncovered that the genes encoding the MAPKs Fus3 and Kss1 are induced by stimulation of the respective mating and invasive growth pathways (Roberts et al, 2000).…”