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Animireddy, S.

Publications and source records attributed to Animireddy, S..

2 recordsLinked to original sources

An RNA binding module of SWI/SNF is required for activation of cell-type specific enhancers and super-enhancers in early development

The mammalian SWI/SNF complex is an ATP-dependent chromatin remodeler and master regulator in development that when mutated is the cause for several human diseases including cancer. Although SWI/SNF is highly enriched at enhancers and its basic chromatin remodeling activities have been studied for over 30 years, there is little known about how it regulates enhancer activity or enhancer-promoter interactions. We find a putative RNA binding module located near the C-terminus of the catalytic subunit of SWI/SNF required for SWI/SNF recruitment to cell-type specific enhancers and super-enhancers in naive and cell lineage primed pluripotent cells. The AT-hook is required for acquisition of the active histone marks H3K27ac and H3K4me1 and recruitment of the MLL3/4 co-activator to these enhancers and super-enhancers. Consistent with changes in enhancer architecture, loss of the AT-hook interferes with activation of genes involved in cell lineage priming as well as genes normally activated in naive pluripotent cells.

genomics↗

Cytoplasm localized ARID1B promotes oncogenesis in pancreatic cancer by activating RAF-ERK signaling

The ARID1B/BAF250b subunit of the human SWI/SNF chromatin remodeling complex is a canonical nuclear tumor suppressor. Immunohistochemistry on a pancreatic cancer tissue microarray revealed significant ARID1B cytoplasmic localization that correlated with advanced tumor stage and lymph node positivity. Identification of the nuclear localization signal (NLS) using in silico prediction and subcellular localization studies facilitated evaluation of a possible cytoplasmic function for ARID1B. A cytoplasm-restricted ARID1B-NLS mutant was significantly compromised to regulate transcription activation and tumor suppression functions, as expected. Surprisingly however, cytoplasm-localized ARID1B could bind c-RAF and PPP1CA causing stimulation of RAS-RAF-ERK signaling and {beta}-catenin transcription activity in pancreatic cancer cells. More importantly, cytoplasmic ARID1B resulted in an induction of cell growth and migration in pancreatic cancer cell lines that was dependent on ERK signaling and caused increased tumorigenesis in nude mice. NLS peptides representing mutations identified from pancreatic cancer samples exhibiting ARID1B cytoplasmic localization or curated from cancer somatic mutation database were significantly compromised to effect nuclear localization of a reporter protein. ARID1B cytoplasmic localization correlated significantly with active forms of ERK and {beta}-catenin in primary pancreatic tumor samples. ARID1B may therefore promote oncogenesis through non-canonical cytoplasm-based gain of function mechanisms in addition to dysregulation in the nucleus.

cell biology↗