BackgroundThe embryonic stem cell (ESC) factor, SALL4, plays an essential role in both development and leukemogenesis. It is a unique gene that is involved in self-renewal in ESC and leukemic stem cell (LSC).Methodology/Principal FindingsTo understand the mechanism(s) of SALL4 function(s), we sought to identify SALL4-associated proteins by tandem mass spectrometry. Components of a transcription repressor Mi-2/Nucleosome Remodeling and Deacetylase (NuRD) complex were found in the SALL4-immunocomplexes with histone deacetylase (HDAC) activity in ESCs with endogenous SALL4 expression and 293T cells overexpressing SALL4. The SALL4-mediated transcriptional regulation was tested on two potential target genes: PTEN and SALL1. Both genes were confirmed as SALL4 downstream targets by chromatin-immunoprecipitation, and their expression levels, when tested by quantitative reverse transcription polymerase chain reaction (qRT-PCR), were decreased in 293T cells overexpressing SALL4. Moreover, SALL4 binding sites at the promoter regions of PTEN and SALL1 were co-occupied by NuRD components, suggesting that SALL4 represses the transcriptions of PTEN and SALL1 through its interactions with the Mi-2/NuRD complex. The in vivo repressive effect(s) of SALL4 were evaluated in SALL4 transgenic mice, where decreased expressions of PTEN and SALL1 were associated with myeloid leukemia and cystic kidneys, respectively.Conclusions/SignificanceIn summary, we are the first to demonstrate that stem cell protein SALL4 represses its target genes, PTEN and SALL1, through the epigenetic repressor Mi-2/NuRD complex. Our novel finding provides insight into the mechanism(s) of SALL4 functions in kidney development and leukemogenesis.

There is a growing body of evidence supporting that cancer cells share many similarities with embryonic stem cells (ESCs). For example, aggressive cancers and ESCs share a common gene expression signature that includes hundreds of genes. Since ESC genes are not present in most adult tissues, they could be ideal candidate targets for cancer-specific diagnosis and treatment. This is an exciting cancer-targeting model. The major hurdle to test this model is to identify the key factors/pathway(s) within ESCs that are responsible for the cancer phenotype. SALL4 is one of few genes that can establish this link. The first publication of SALL4 is on its mutation in a human inherited disorder with multiple developmental defects. Since then, over 300 papers have been published on various aspects of this gene in stem cells, development, and cancers. This review aims to summarize our current knowledge of SALL4, including a SALL4-based approach to classify and target cancers. Many questions about this important gene still remain unanswered, specifically, on how this gene regulates cell fates at a molecular level. Understanding SALL4’s molecular functions will allow development of specific targeted approaches in the future.

CanadaSALL4, a newly identified zinc-finger transcriptional factor important for embryonic development, is mapped to chromosome 20q13. Previously, we reported that SALL4 was constitutively expressed in acute myeloid leukemia and SALL4 transgenic mice developed acute myeloid leukemia. In this study, we aimed to survey SALL4 protein expression in benign and neoplastic hematopoietic tissues in addition to acute myeloid leukemia using immunostaining with a polyclonal anti-SALL4 antibody. Primary hematological tumors (178) and 15 benign hematopoietic tissues were examined. Reverse transcription-polymerase chain reaction was also performed to detect SALL4 mRNA expression on eight precursor B-cell lymphoblastic leukemia/lymphomas, 10 benign hematopoietic tissues, and seven hematopoietic cancer cell lines. Of the benign tissues, SALL4 expression was detectable only in CD34 þ hematopoietic stem/progenitor cells (2/2 at protein level, 3/3 at RNA level). In neoplastic tissues, only precursor B-cell lymphoblastic leukemia/lymphomas had detectable SALL4 (12/16 at protein level, 7/8 at RNA level), similar to that observed in acute myeloid leukemia. Of the seven cell lines examined, only those derived from acute myeloid leukemia and precursor B-cell lymphoblastic leukemia/ lymphomas were positive. To conclude, SALL4 expression is normally restricted to CD34 þ hematopoietic stem/ progenitor cells. The persistence of SALL4 expression in leukemic blasts in precursor B-cell lymphoblastic leukemia/lymphomas resembles to what we observed in acute myeloid leukemia, and correlates with the maturation arrest of these cells. We have shown in our previous study that the constitutive expression of SALL4 in mice can lead to acute myeloid leukemia development. The similar expression pattern of SALL4 in acute myeloid leukemia and B-cell lymphoblastic leukemia/lymphomas suggests that these two disease entities may share similar biological features and/or mechanisms of leukemogenesis. More definite studies to investigate the role of SALL4 in the pathogenesis of B-cell lymphoblastic leukemia/lymphomas are needed in the future to address this question.

Background Stem cell factor SALL4 is a zinc finger transcription factor. It plays vital roles in the maintenance of embryonic stem cell properties, functions as an oncogene in leukemia, and has been recently proposed to use for cord blood expansion. The mechanism(s) by which SALL4 functions in normal human hematopoiesis, including identification of its target genes, still need to be explored. Study Design and Methods Chromatin-immunoprecipitation followed by microarray hybridization (ChIP-chip) was used for mapping SALL4 global gene targets in normal primary CD34+ cells. The results were then correlated with SALL4 functional studies in the CD34+ cells. Results Over 1,000 potential SALL4 down-stream target genes have been identified, and validation of binding by ChIP-qPCR was performed for 5% of potential targets. These include genes that are involving in hematopoietic differentiation and self-renewal, such as HOXA9, RUNX1, CD34, and PTEN. Down-regulation of SALL4 expression using shRNA in these cells led to decreased in vitro myeloid colony forming abilities and impaired in vivo engraftment. Furthermore, HOXA9 was identified to be a major SALL4 target in normal human hematopoiesis and the loss of either SALL4 or HOXA9 expression in CD34+ cells shared a similar phenotype. Conclusion Taking together, SALL4 is a key regulator in normal human hematopoiesis and the mechanism of its function is at least in part through the HOXA9. Future study will determine whether modulating the SALL4/HOXA9 pathway can be used in cellular therapy such as cord blood expansion and/or myeloid engraftment.

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BACKGROUND & AIMS: Some oncogenes encode transcription factors, but few drugs have been successfully developed to block their activity specifically in cancer cells. The transcription factor SALL4 is aberrantly expressed in solid tumor and leukemia cells. We developed a screen to identify compounds that reduce the viability of liver cancer cells that express high levels of SALL4, and we investigated their mechanisms. METHODS: We developed a stringent high-throughput screening platform comprising unmodified SNU-387 and SNU-398 liver cancer cell

Amphibian neural development occurs as a two-step process:(1) induction specifies a neural fate in undifferentiated ectoderm; and (2) transformation induces posterior spinal cord and hindbrain. Signaling through the Fgf, retinoic acid (RA) and Wnt/β-catenin pathways is necessary and sufficient to induce posterior fates in the neural plate, yet a mechanistic understanding of the process is lacking. Here, we screened for factors enriched in posterior neural tissue and identify spalt-like 4 (sall4), which is induced by Fgf. Knockdown of Sall4 results in loss of spinal cord marker expression and increased expression of pou5f3.2 (oct25), pou5f3.3 (oct60) and pou5f3.1 (oct91) (collectively, pou5f3 genes), the closest Xenopus homologs of mammalian stem cell factor Pou5f1 (Oct4). Overexpression of the pou5f3 genes results in the loss of spinal cord identity and knockdown of pou5f3 function restores spinal cord marker expression in Sall4 morphants. Finally, knockdown of Sall4 blocks the posteriorizing effects of Fgf and RA signaling in the neurectoderm. These results suggest that Sall4, activated by posteriorizing signals, represses the pou5f3 genes to provide a permissive environment allowing for additional Wnt/Fgf/RA signals to posteriorize the neural plate.

Electrophilic biocompatible warheads, particularly cysteine-reactive acrylamides, have enabled the development of covalent inhibitor drugs and chemical biology probes, but cysteine is rarely present in protein binding sites. Therefore, expansion of...