Project description:Intestinal stem cells (ISCs) are responsible for maintaining the physiological function of the intestinal epithelium through the production of differentiated absorptive and secretory cellular lineages. In addition to producing specialized functional cells, ISCs must also drive constant proliferation in order to maintain the especially high rate of cellular turnover in the intestinal epithelium, which undergoes near total renewal every 5-7 days. Understanding the transcriptional mechanisms that control how ISCs and transit-amplifying progenitors (TAs) balance differentiation and proliferation in the intestine may provide valuable insight into common pathologies, such as inflammatory bowel disease and cancer. Here, we show that the Sry¬¬-box containing transcription factor, Sox4, is involved in the regulation of proliferation in the ISC/TA zone, the expression of ISC-associated genes, and the differentiation of enteroendocrine (EE) cells. Interestingly, we also observed a significant reduction in the expression of the methylcytosine dioxygenase, Tet1, in Sox4-deficient intestines. We find that Tet1, which initiates derepression of target genes via DNA demethylation, is specifically upregulated in ISC populations in wild-type animals. Additionally, Sox4-deficient intestines showed a significant reduction in levels of 5-hydroxymethylcytosine, the catalytic byproduct of TET protein activity, in the ISC/TA zone. Together, our data demonstrate that Sox4 regulates differentiation and proliferation in the intestinal epithelium, and suggests that it may influence these processes through induction of Tet1 and subsequent derepression of target genes through epigenetic mechanisms.
Project description:The mammalian intestinal epithelium has a unique organization where crypts harboring stem cells produce progenitors and finally clonal populations of differentiated cells. Remarkably, the epithelium is replaced every three to five days throughout adult life. Disrupted maintenance of the intricate balance of proliferation and differentiation leads to loss of epithelial integrity, barrier function, or cancer. There is a tight correlation between epigenetic status of genes and expression changes during differentiation; however, the mechanism of how changes in DNA methylation direct gene expression and the progression from stem cells to their differentiated descendants is unclear. Using conditional gene ablation of the maintenance methyltransferase Dnmt1, we demonstrate that reducing DNA methylation causes intestinal crypt expansion in vivo. Determination of the base-resolution DNA methylome in stem cells and their differentiated descendants shows that DNA methylation is dynamic at enhancers, which are often associated with genes important for both stem cell maintenance and differentiation. We establish that the loss of DNA methylation at intestinal stem cell gene enhancers causes inappropriate gene expression and delayed differentiation.
Project description:Sox4 is expressed in intestinal stem cells (ISCs) and early intestinal progenitors. The regulatory role for Sox4 in intestinal homeostasis is currently unknown. Here, we used RNA-seq to determine the role of Sox4 in the intestinal epithelium using a conditional knockout model.
Project description:We developed a compartmental model of the small intestinal epithelium that describes stem and progenitor cell proliferation and differentiation and cell migration onto the villus. The model includes a negative feedback loop from villus cells to regulate crypt proliferation and integrates heterogeneous epithelial-related processes, such as the transcriptional profile, citrulline kinetics and probability of diarrhea.
Project description:Intestinal stem cells are required for proliferation, differentiation, and regeneration of the intestinal epithelium. Krüppel-like factor 5 regulates intestinal stem cells in both physiologic and pathological conditions and may be a treatment target in certain diseases of the intestine.
Project description:Acetylcholine (ACh) has been considered a neurotransmitter residing in central, parasympathetic and neuromuscular synapses of mammals. Here, experiments using crypt-villus organoids that lack nerve and immune cells in culture led us to suggest that endogenous ACh is synthesized in the intestinal epithelium to evoke growth and differentiation of the organoids through activation of muscarinic ACh receptors (mAChRs). The extracts of the cultured organoids exhibit a noticeable capacity for ACh synthesis that is sensitive to a potent inhibitor of choline acetyltransferase (ChAT). Imaging mass spectrometry reveals distribution of endogenous ACh that is localized in intestinal epithelial layer in the cultured organoids as well as in mouse small intestinal epithelium in vivo, suggesting non-neural resources of ACh. Treatment of organoids with carbachol down-regulates growth of organoids and expression of marker gene for each epithelial cell. On the other hand, antagonists for mAChRs enhances growth and differentiation of organoids, indicating involvement of mAChRs in regulating proliferation and differentiation of Lgr5-positive stem cells. Collectively, our data provide evidence that endogenous ACh released from intestinal epithelium maintains homeostasis of intestinal epithelial cell growth and differentiation via mAChRs in mice. Gene expression patters of gut, crypt, y-organoid and o-organoid, respectively
Project description:SOX4 is a critical developmental transcription factor in vertebrates and is required for precise differentiation and proliferation in multiple tissues. In addition, SOX4 is overexpressed in many human malignancies, but the precise role of SOX4 in cancer progression is not well understood. Here we have either eliminated SOX4 using siRNA or overexpressed a SOX4 cDNA and compared the gene expression patterns against control GFP transfections to identify SOX4 target genes. Data described in manuscript P. Liu et al., Cancer Res 46, 4011 (April 15, 2006) Experiment Overall Design: LNCaP prostate cancer cells were transfected with either a SOX4 cDNA, a pool of SOX4 siRNAs or a control GFP expression vector. Each transfection was performed in duplicate on two separate days. Total RNA was harvested 24 hours post-transfection
Project description:SOX4 is a critical developmental transcription factor in vertebrates and is required for precise differentiation and proliferation in multiple tissues. In addition, SOX4 is overexpressed in many human malignancies, but the precise role of SOX4 in cancer progression is not well understood. Here we have either eliminated SOX4 using siRNA or overexpressed a SOX4 cDNA and compared the gene expression patterns against control GFP transfections to identify SOX4 target genes. Data described in manuscript P. Liu et al., Cancer Res 46, 4011 (April 15, 2006) Keywords: Gene Expression
Project description:The early retinal progenitor-expressed gene Sox11 regulates the timing of the differentiation of retinal cells. Sry-related HMG box (Sox) proteins play diverse and critical roles in a variety of morphogenetic processes during embryonic development. Sox11 and Sox4 are members of the SoxC subtype, and we found that Sox11 was strongly expressed in early retinal progenitor cells, and that when expression of Sox11 subsided around birth, Sox4 expression began. To analyze the role of Sox11 and Sox4 in retinal development, we perturbed their expression pattern by expressing them ectopically in retinal explant culture. Overexpression of Sox11 or Sox4 in retinal progenitors resulted in similar phenotypes, that is, increased cone cells and decreased Muller glia. Sox11-knockout retinas showed delayed onset and progress of differentiation of early-born retinal cells during the embryonic period. After birth, retinal differentiation took place relatively normally, probably because of the redundant activity of Sox4, which starts to differentiate around birth. Neither overexpression nor loss-of-function analysis gave any evidence that Sox11 and Sox4 directly regulate transcription of genes critical to early-born retinal cells. However, histone H3 acetylation status of the early neurogenic genes was lowered in knockout retinas, suggesting that Sox11 regulates the timing of differentiation in early-born retinas by creating an epigenetic state that helps to establish the competency to differentiate. We also found that the unique expression patterns of Sox11 and Sox4 may be achieved by the Notch signaling pathway and by epigenetic regulation. Taking our findings together, we propose that the precise regulation of Sox11 and Sox4 expression during retinogenesis by multiple mechanisms leads to the fine adjustment of retinal differentiation. To delineate the molecular mechanisms underlying the retinal action of Sox11, we performed microarray analysis of E18 retinas from wild-type and Sox11 knockout mice. Total RNA was obtained from each one retina of Sox11 knockout and wild-type littermate embryos at E18.