Project description:HHEX KD led to the differential expression of genes in pathway or cellular function related to cell proliferation and anti-apoptosis
Project description:Memory B cells (MBCs) are essential for long-lived humoral immunity. However, the transcription factors (TFs) involved in MBC differentiation are poorly defined. Here, by single cell RNAseq analysis, we identified a population of germinal center (GC) B cells in the process of differentiating into MBCs. Using an inducible Crispr/Cas9 screening approach we identified the hematopoietically-expressed homeobox gene Hhex as a transcription factor regulating MBC differentiation. The co-repressor Tle3 was also identified in the screen and was found to interact with Hhex to promote MBC development. Bcl6 directly repressed Hhex in GC B cells. Reciprocally, Hhex-deficient MBCs exhibited derepressed Bcl6 and reduced expression of Bcl6-repressed Bcl2. Overexpression of Bcl2 was able to rescue MBC differentiation in Hhex-deficient cells. We also identified Ski as an Hhex-induced transcription factor involved in MBC differentiation. These findings establish an important role for Hhex-Tle3 in regulating the transcriptional circuitry governing MBC differentiation.
Project description:We have identified HHEX as an oncogene to promote proliferation in colorectal cancer. To elucidate the potential mechanism of HHEX in colorectal cancer, RNA-seq analysis was performed in HCT116 cells to analyze differential expressed genes after HHEX knockdown.
Project description:Hhex encodes a homeobox transcriptional regulator that plays a key role in embryonic development and hematopoiesis. Hhex is highly expressed in NK cells and germline deletion of Hhex results in significant defects in lymphoid development, including NK cells. However, whether Hhex is intrinsically required throughout NK cell development or for NK cell function remains unknown. To investigate this, we generated mice that specifically lack Hhex in NK cells. Hhex was intrinsically required for NK cell homeostasis, while NK cell differentiation, IL-15 responsiveness and cytotoxic function were largely normal in the absence of Hhex. Unexpectedly, increased IL-15 availability failed to rescue Hhex-deficient NK cell homeostasis, suggesting that Hhex regulates developmental pathways extrinsic to those dependent on IL-15. Gene expression and functional genetic approaches revealed that Hhex promoted NK cell survival by repressing BIM expression, a key apoptotic mediator in NK cells. This study identifies Hhex as a novel transcription factor essential for NK cell biology.
Project description:Hhex encodes a homeobox transcriptional regulator important for embryonic development and hematopoiesis. Hhex is highly expressed in NK cells and its germline deletion results in significant defects in lymphoid development, including NK cells. To determine if Hhex is intrinsically required throughout NK cell development or for NK cell function, we generated mice that specifically lack Hhex in NK cells. NK cell numbers was dramatically reduced, while NK cell differentiation, IL-15 response and function at the cellular level remained largely normal in the absence of Hhex. Increased IL-15 availability failed to fully reverse NK lymphopenia following conditional Hhex deletion, suggesting that Hhex regulates developmental pathways extrinsic to those dependent on IL-15. Gene expression and functional genetic approaches revealed that Hhex regulates NK cell survival by repressing expression of the key apoptotic mediator, BIM. These data implicates Hhex as a novel transcription factor essential for NK cell homeostasis and immunity.
Project description:The Hematopoietically-expressed homeobox (Hhex) transcription factor is overexpressed in human myeloid leukemias. Conditional knockout models of murine acute myeloid leukemia (AML) indicate that Hhex maintains leukemia stem cell self-renewal by enabling Polycomb-mediated epigenetic repression of the Cdkn2a tumor suppressor locus, encoding p16Ink4a and p19Arf. However, whether Hhex overexpression also affects hematopoietic differentiation is unknown. To study this, we retrovirally overexpressed Hhex in hematopoietic progenitors. This enabled serial replating of myeloid progenitors, leading to the rapid establishment of IL-3-dependent promyelocytic cell lines. Use of a Hhex-ERT2 fusion protein demonstrated that continuous nuclear Hhex is required for transformation, and structure function analysis demonstrated a requirement of the DNA binding and N-terminal repressive domains of Hhex for promyelocytic transformation. This included the N-terminal Pml interaction domain, although deletion of Pml failed to prevent Hhex-induced promyelocyte transformation, implying other critical partners. Furthermore, deletion of p16Ink4a or p19Arf did not promote promyelocyte transformation, indicating that repression of distinct Hhex target genes is required for this process. Indeed, transcriptome analysis showed that Hhex overexpression resulted in repression of several myeloid developmental genes. To test potential for Hhex overexpression to contribute to leukemic transformation, Hhex-transformed promyelocyte lines were rendered growth factor-independent using a constitutively active IL-3 receptor common b subunit (bcV449E). The resultant cell lines resulted in a rapid promyelocytic leukemia in vivo. Thus Hhex overexpression can contribute to myeloid leukemia via multiple mechanisms including differentiation blockade and enabling epigenetic repression of the Cdkn2a locus.
Project description:Background & Aims: Perturbations in pancreatic ductal bicarbonate secretion often result in chronic pancreatitis. Although the physiological mechanism of ductal secretion is known, its transcriptional control is not well characterized. Here, we investigate the role of the transcription factor Hematopoietically-expressed homeobox protein (Hhex) in pancreatic secretion and pancreatitis. Methods: We derived mice with pancreas-specific, Cre-mediated Hhex gene ablation to determine the requirement of Hhex in the pancreatic duct in early life and in adult stages. Histological and immunostaining analyses were used to detect the presence of pathology. Pancreatic primary ductal cells (PDCs) were isolated to discover differentially expressed transcripts upon acute Hhex ablation. Results: Hhex protein was detected throughout the embryonic and adult ductal trees. Ablation of Hhex in pancreatic progenitors resulted in postnatal ductal ectasia associated with acinar-to-ductal metaplasia, a progressive phenotype that ultimately resulted in chronic pancreatitis. Hhex ablation in adult mice, however, did not cause any detectable pathology. Ductal ectasia did not result from perturbations in primary cilia, but was consistent with the effects of primary ductal hypertension. RNA-seq analysis of Hhex-ablated PDCs indicated the G-protein coupled receptor Natriuretic peptide receptor 3, implicated in paracrine signaling, was upregulated 4.70-fold. Conclusions: Although Hhex is dispensable for adult pancreatic function, ablation of Hhex in pancreatic progenitors results in profound pancreatitis that is consistent with primary ductal hypertension. Our data highlight the critical role of paracrine signaling in maintaining ductal homeostasis, especially in early life, and support ductal hypersecretion as a novel etiology of pediatric chronic pancreatitis. Pancreatic primary ductal cells (PDCs) were isolated from uninduced adult HhexL/L;Sox9CreERT2 (n=2) and littermate control HhexL/L (n=2) mice. PDCs were treated with 500nM 4-hydroxytamoxifen in vitro for 4 days, and then RNA was collected for transcriptome analysis.
Project description:To investigate the role of HHEX in regulating human pancreatic endoderm differentiation, we knocked down the HHEX gene in 585A1 cell line-derived pancreatic endoderm cells by siRNA. We then performed gene expression profiling analysis using data obtained from RNA-seq of the 3 cell samples.
Project description:We used high throughput sequencing to identify differential expression in siblings, hhex mutants and hhex-overexpression endothelial cells at 48 hpf.