SATB1 dictates expression of multiple genes including IL-5 involved in human T helper cell differentiation

Special AT-rich binding protein 1 (SATB1) is a global chromatin organizer and a transcription factor regulated by interleukin-4 (IL-4) during the early T helper 2 (Th2) cell differentiation. Here we show that SATB1 controls multiple IL-4 target genes involved in human Th cell polarization or function. Among the genes regulated by SATB1 is that encoding the cytokine IL-5, which is predominantly produced by Th2 cells and plays a key role in the development of eosinophilia in asthma. We demonstrate that, during the early Th2 cell differentiation, IL-5 expression is repressed through direct binding of SATB1 to the IL-5 promoter. Furthermore, SATB1 knockdown-induced upregulation of IL-5 is partly counteracted by down-regulating GATA3 expression using RNAi in polarizing Th2 cells. Our results suggest that a competitive mechanism involving SATB1 and GATA3 regulates IL-5 transcription, and provide new mechanistic insights into the stringent regulation of IL-5 expression during human Th2 cell differentiation. (Blood. 2010;116(9):1443-1453

Global Regulator SATB1 Recruits β-Catenin and Regulates TH2 Differentiation in Wnt-Dependent Manner

Chromatin organizer SATB1 and Wnt transducer β-catenin form a complex and regulate expression of GATA3 and TH2 cytokines in Wnt-dependent manner and orchestrate TH2 lineage commitment

Ankylosing spondylitis, chronic fatigue and depression improved after stromal vascular fraction treatment for osteoarthritis: a case report

Abstract Background Osteoarthritis is a prevalent chronic disease that impacts quality of life and imposes a heavy economic burden. Despite this there is no confirmed treatment that could prevent progressive destruction of osteoarthritic joints. Mesenchymal stem cells with their regenerative and immunosuppressive properties have emerged as a potential therapy. Case presentation This case study describes the impact of autologous adipose-derived stromal vascular fraction treatment on a 27-year-old Australian woman with osteoarthritis and multiple comorbidities of ankylosing spondylitis, chronic pain syndrome, and post-traumatic stress disorder as assessed by magnetic resonance imaging, Western Ontario and McMaster Universities Osteoarthritis Index, and Hip Disability and Osteoarthritis Outcome Score. Following standardized stromal vascular fraction treatment protocols for osteoarthritis of her hips and knee, the functional status of her hips was measured by Hip Disability and Osteoarthritis Outcome Score at 3 months, 6 months, and 3 years. Conclusions Our patient showed dramatic improvements to her quality of life and symptoms of osteoarthritis were reduced. Interestingly, along with improvements in her knee and hips her other comorbidities such as ankylosing spondylitis, depression, anxiety, and fatigue exhibited marked improvement. She ceased the use of a wheelchair and walking support and, with increased mobility, had gained independence. These findings are suggestive of the therapeutic effects of stromal vascular fraction

Phosphorylation-dependent regulation of SATB1, the higher-order chromatin organizer and global gene regulator

The chromatin organizer SATB1 regulates distant genes by selectively tethering matrix attachment regions (MARs) to the nuclear matrix. Post-translational modifications (PTMs) are important regulators of functional activities of proteins. Recently, a phosphorylation-dependent molecular switch that provided insights into the molecular mechanism of transcriptional repression and activation by SATB1 was discovered. SATB1 is specifically phosphorylated by protein kinase C (PKC) at serine 185 in vivo, and this modification leads to repression of transcription by SATB1 via increased association with the histone deacetylase 1 (HDAC1) corepressor. In this chapter, we describe methods for overexpression and purification of full length SATB1 protein and for its in vitro phosphorylation. We also describe method for in vivo phosphorylation of SATB1 upon immunoprecipitation using anti-SATB1. Finally, we describe a functional assay to monitor the effect of phosphorylation on transcription activity of SATB1 in vivo using MAR-linked reporter assay, in the presence and absence of PKC inhibitors

Acetylation-Dependent Interaction of SATB1 and CtBP1 Mediates Transcriptional Repression by SATB1▿ †

Special AT-rich binding protein 1 (SATB1) acts as a global regulator of gene expression by recruiting various corepressor or coactivator complexes, thereby establishing a unique chromatin structure at its genomic targets in a context-dependent manner. Although SATB1 acts predominantly as a repressor via recruitment of histone deacetylase 1 (HDAC1) complexes, the precise mechanism of global repression is not clear. Here we report that SATB1 and C-terminal binding protein 1 (CtBP1) form a repressor complex in vivo. The interaction occurs via the CtBP1 interaction consensus motif PVPLS within the PDZ-like domain of SATB1. The acetylation of SATB1 upon LiCl and ionomycin treatments disrupts its association with CtBP1, resulting in enhanced target gene expression. Chromatin immunoprecipitation analysis indicated that the occupancy of CtBP1 and HDAC1 is gradually decreased and the occupancy of PCAF is elevated at the SATB1 binding sites within the human interleukin-2 and mouse c-Myc promoters. Moreover, gene expression profiling studies using cells in which expression of SATB1 and CtBP1 was silenced indicated commonly targeted genes that may be coordinately repressed by the SATB1-CtBP1 complex. Collectively, these results provide a mechanistic insight into the role of SATB1-CtBP1 interaction in the repression and derepression of SATB1 target genes during Wnt signaling in T cells

Phosphorylation of SATB1, a global gene regulator, acts as a molecular switch regulating its transcriptional activity In vivo

SATB1 regulates gene expression by acting as a "docking site" for several chromatin remodeling enzymes and also by recruiting corepressors (HDACs) or coactivators (HATs) directly to promoters. However, how these contrasting effectors act at the level of SATB1 is not clear. We show here that phosphorylation by PKC acts as a switch to determine whether SATB1 interacts with HDAC1 or PCAF. Phosphorylation and dephosphorylation of SATB1 exerted opposing effects on MAR-linked reporter activity in vivo. SATB1 interacted with both CBP/p300 and PCAF HATs; however, these interactions resulted in the acetylation of the PDZ-like domain of SATB1 by PCAF but not by CBP/p300 and resulted in loss of its DNA binding activity. Using the T cell activation model, we provide mechanistic insights into how IL-2 transcription is reciprocally governed by the phosphorylation status of SATB1 and propose that a similar mechanism may dictate the ability of SATB1 to function as a global regulator

Modulation of signal transduction pathways in lymphocytes due to sub-lethal toxicity of chlorinated phenol

Chlorophenols and their derivatives are a major component of environmental pollutants that are potential immunotoxicants. Deaminase assay performed on peripheral blood mononuclear cells (PBMCs) exposed to chlorophenolic compounds and its derivatives demonstrated a decreased proliferation rate and cell death. Chlorophenolic exposure also led to impaired production of IL-21 and IL-9 along with many other cytokines and chemokines that potentiate the inflammatory response. Using the PBMC activation model and gene expression profiling we provide insights into mechanisms by which the chlorophenolic compounds and their derivatives, especially pentachlorophenol (PCP) dysregulate the inflammatory response. We have shown here that PCP represses IL21 and IL9 expression thus affecting various downstream signaling pathways. We propose that PCP, a potent pollutant, imparts its cytotoxicity by evading the immune response by simultaneously affecting multiple signaling pathways in lymphocytes

SATB1 dictates expression of multiple genes including IL-5 involved in human T helper cell differentiation

Special AT-rich binding protein 1 (SATB1) is a global chromatin organizer and a transcription factor regulated by interleukin-4 (IL-4) during the early T helper 2 (Th2) cell differentiation. Here we show that SATB1 controls multiple IL-4 target genes involved in human Th cell polarization or function. Among the genes regulated by SATB1 is that encoding the cytokine IL-5, which is predominantly produced by Th2 cells and plays a key role in the development of eosinophilia in asthma. We demonstrate that, during the early Th2 cell differentiation, IL-5 expression is repressed through direct binding of SATB1 to the IL-5 promoter. Furthermore, SATB1 knockdown-induced up-regulation of IL-5 is partly counteracted by down-regulating GATA3 expression using RNAi in polarizing Th2 cells. Our results suggest that a competitive mechanism involving SATB1 and GATA3 regulates IL-5 transcription, and provide new mechanistic insights into the stringent regulation of IL-5 expression during human Th2 cell differentiation