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Supplementary Figures 1-7, Table 1 from Overcoming Hypoxia-Induced Apoptotic Resistance through Combinatorial Inhibition of GSK-3β and CDK1

In this issue of Cell Chemical Biology, Cheng et al. (2021) identify a class of drugs that activate a mitotic stress-dependent signaling cascade, which culminates in p53 activation and Wnt pathway inhibition (PAWI). PAWI compounds may therefore be effective in cancers associated with loss of p53 and activation of Wnt signaling.

Significance COVID-19 is taking a major toll on personal health, healthcare systems, and the global economy. With three betacoronavirus epidemics in less than 20 y, there is an urgent need for therapies to combat new and existing coronavirus outbreaks. Our analysis of clinical data from over 300,000 patients in three major health systems demonstrates a 50% reduced risk of COVID-19 in patients taking lithium, a direct inhibitor of glycogen synthase kinase-3 (GSK-3). We further show that GSK-3 is essential for phosphorylation of the SARS-CoV-2 nucleocapsid protein and that GSK-3 inhibition blocks SARS-CoV-2 infection in human lung epithelial cells. These findings suggest an antiviral strategy for COVID-19 and new coronaviruses that may arise in the future., The coronaviruses responsible for severe acute respiratory syndrome (SARS-CoV), COVID-19 (SARS-CoV-2), Middle East respiratory syndrome-CoV, and other coronavirus infections express a nucleocapsid protein (N) that is essential for viral replication, transcription, and virion assembly. Phosphorylation of N from SARS-CoV by glycogen synthase kinase 3 (GSK-3) is required for its function and inhibition of GSK-3 with lithium impairs N phosphorylation, viral transcription, and replication. Here we report that the SARS-CoV-2 N protein contains GSK-3 consensus sequences and that this motif is conserved in diverse coronaviruses, raising the possibility that SARS-CoV-2 may be sensitive to GSK-3 inhibitors, including lithium. We conducted a retrospective analysis of lithium use in patients from three major health systems who were PCR-tested for SARS-CoV-2. We found that patients taking lithium have a significantly reduced risk of COVID-19 (odds ratio = 0.51 [0.35–0.74], P = 0.005). We also show that the SARS-CoV-2 N protein is phosphorylated by GSK-3. Knockout of GSK3A and GSK3B demonstrates that GSK-3 is essential for N phosphorylation. Alternative GSK-3 inhibitors block N phosphorylation and impair replication in SARS-CoV-2 infected lung epithelial cells in a cell-type–dependent manner. Targeting GSK-3 may therefore provide an approach to treat COVID-19 and future coronavirus outbreaks.

Mucopolysaccharidosis (MPS) I is a lysosomal storage disease characterized by deficient activity of the enzyme alpha-L-iduronidase, leading to abnormal accumulation of heparan and dermatan sulfate glycosaminoglycans in cells and tissues. Patients commonly exhibit progressive skeletal abnormalities, in part due to failures of endochondral ossification during postnatal growth. Previously, using the naturally-occurring canine model, we showed that bone and cartilage cells in MPS I exhibit elevated lysosomal storage from an early age and that animals subsequently exhibit significantly diminished vertebral trabecular bone formation. Wnts are critical regulators of endochondral ossification that depend on glycosaminoglycans for signaling. The objective of this study was to examine whether lithium, a glycogen synthase kinase-3 inhibitor and stimulator of Wnt/beta-catenin signaling, administered during postnatal growth could attenuate progression of vertebral trabecular bone disease in MPS I. MPS I dogs were treated orally with therapeutic levels of lithium carbonate from 14 days to 6 months-of-age. Untreated heterozygous and MPS I dogs served as controls. Serum was collected at 3 and 6 months for assessment of bone turnover markers. At the study end point, thoracic vertebrae were excised and assessed using microcomputed tomography and histology. Lithium-treated animals exhibited significantly improved trabecular spacing, number and connectivity density, and serum bone-specific alkaline phosphatase levels compared to untreated animals. Growth plates from lithium-treated animals exhibited increased numbers of hypertrophic chondrocytes relative to both untreated MPS I and heterozygous animals. These findings suggest that bone and cartilage cells in MPS I are still capable of responding to exogenous osteogenic signals even in the presence of significant lysosomal storage, and that targeted osteogenic therapies may represent a promising approach for attenuating bone disease progression in MPS I.

Techniques that allow single cell analysis are gaining widespread attention, and most of these studies utilize genomics-based approaches. While nanofluidic technologies have enabled mass spectromet...

Lithium salts have been in the therapeutic toolbox for better or worse since the 19th century, with purported benefit in gout, hangover, insomnia, and early suggestions that lithium improved psychiatric disorders. However, the remarkable effects of lithium reported by John Cade and subsequently by Mogens Schou revolutionized the treatment of bipolar disorder. The known molecular targets of lithium are surprisingly few and include the signaling kinase glycogen synthase kinase-3 (GSK-3), a group of structurally related phosphomonoesterases that includes inositol monophosphatases, and phosphoglucomutase. Here we present a brief history of the therapeutic uses of lithium and then focus on GSK-3 as a therapeutic target in diverse diseases, including bipolar disorder, cancer, and coronavirus infections.

Leukemia-initiating cells, also known as leukemic stem cells (LSCs), are experimentally defined by their ability to engraft immunocompromised mice and are believed to be a major cause of relapse in acute myeloid leukemia (AML). Despite the aggressive characteristics of acute leukemia, AML blasts are difficult to culture once removed from the patient, and LSCs, which are a minor fraction of the blast population, are especially difficult to transplant after culture. This impedes development of new therapies for AML that target LSCs. Here, we present a simple strategy to culture LSCs in cytokine-free medium and to perform flow cytometric analysis of the resulting cell population for the characterization of LSCs maintenance and differentiation.

As development proceeds, inductive cues are interpreted by competent tissues in a spatially and temporally restricted manner. While key inductive signaling pathways within competent cells are well-described at a molecular level, the mechanisms by which tissues lose responsiveness to inductive signals are not well understood. Localized activation of Wnt signaling before zygotic gene activation inXenopus laevisleads to dorsal development, but competence to induce dorsal genes in response to Wnts is lost by the late blastula stage. We hypothesize that loss of competence is mediated by changes in histone modifications leading to a loss of chromatin accessibility at the promoters of Wnt target genes. We use ATAC-seq to evaluate genome-wide changes in chromatin accessibility across several developmental stages. Based on overlap with p300 binding, we identify thousands of putative cis-regulatory elements at the gastrula stage, including sites that lose accessibility by the end of gastrulation and are enriched for pluripotency factor binding motifs. Dorsal Wnt target gene promoters are not accessible after the loss of competence in the early gastrula while genes involved in mesoderm and neural crest development maintain accessibility at their promoters. Inhibition of histone deacetylases increases acetylation at the promoters of dorsal Wnt target genes and extends competence for dorsal gene induction by Wnt signaling. Histone deacetylase inhibition, however, is not sufficient to extend competence for mesoderm or neural crest induction. These data suggest that chromatin state regulates the loss of competence to inductive signals in a context-dependent manner.

Therapeutic targeting of initiating oncogenes is the mainstay of precision medicine. Considerable efforts have been expended toward silencing MYC, which drives many human cancers including Burkitt lymphomas (BL). Yet, the effects of MYC silencing on standard-of-care therapies are poorly understood. Here we found that inhibition of MYC transcription renders B-lymphoblastoid cells refractory to chemotherapeutic agents. This suggested that in the context of chemotherapy, stabilization of Myc protein could be more beneficial than its inactivation. We tested this hypothesis by pharmacologically inhibiting glycogen synthase kinase 3β (GSK-3β), which normally targets Myc for proteasomal degradation. We discovered that chemorefractory BL cell lines responded better to doxorubicin and other anti-cancer drugs when Myc was transiently stabilized. In vivo, GSK3 inhibitors (GSK3i) enhanced doxorubicin-induced apoptosis in BL patient-derived xenografts (BL-PDX), as well as in murine MYC-driven lymphoma allografts. This enhancement was accompanied by and required deregulation of several key genes acting in the extrinsic, death-receptor-mediated apoptotic pathway. Consistent with this mechanism of action, GSK3i also facilitated lymphoma cell killing by a death ligand TRAIL and by a death receptor agonist mapatumumab. Thus, GSK3i synergizes with both standard chemotherapeutics and direct engagers of death receptors and could improve outcomes in patients with refractory lymphomas.

Techniques that allow single cell analysis are gaining widespread attention and most of these studies utilize genomics-based approaches. While nanofluidic technologies have enabled mass spectrometric analysis of single cells, these measurements have been limited to metabolomics and lipidomic studies. Single cell proteomics has the potential to improve our understanding of intercellular heterogeneity. However, this approach has faced challenges including limited sample availability, as well as a requirement of highly sensitive methods for sample collection, clean-up and detection. We present a technique to overcome these limitations by combining a micropipette (pulled glass capillary) based sample collection strategy with offline sample preparation and nanoLC-MS/MS to analyze proteins through a bottom-up proteomic strategy. This study explores two types of proteomics data acquisition strategy namely data-dependent (DDA) and data-independent acquisition (DIA) strategy. Results from the study indicate DIA to be more sensitive enabling analysis of >1600 proteins from ~130 μm Xenopus laevis embryonic cells containing

In most species, early germline development occurs in the absence of transcription with germline determinants subject to complex translational and post-translational regulations. Here we report for the first time, that early germline development is influenced by dynamic regulation of the proteasome system, previously thought to be ubiquitously expressed and to serve “house-keeping” roles in controlling protein homeostasis. We show that proteasomes are present in a gradient with highest levels in the animal hemisphere but extending into the vegetal hemisphere of Xenopus oocytes. This distribution changes dramatically during the oocyte-to-embryo transition, with proteasomes becoming enriched in and restricted to the animal hemisphere and therefore separated from vegetally localized germline determinants. We identify Dead-end1 (Dnd1), a master regulator of vertebrate germline development, as a novel substrate of the ubiquitin-independent proteasomes. In the oocyte, ubiquitin-independent proteasomal degradation acts together with translational repression to prevent premature accumulation of Dnd1 protein. In the embryo, artificially increasing ubiquitin-independent proteasomal degradation in the vegetal pole interferes with germline development. Our work thus reveals novel inhibitory functions and spatial regulation of the ubiquitin-independent proteasome during vertebrate germline development.

Wnt signaling plays important roles in stem cell self-renewal and differentiation in adults as well as in embryonic development. Mutations that activate canonical Wnt/β-catenin signaling also initiate and maintain several cancer states, including colorectal cancer and leukemia, and hence Wnt inhibitors are currently being explored as therapeutic options. In this review, we summarize previous studies and update recent findings on canonical Wnt signaling and its components, as well as their roles in somatic stem cell homeostasis and maintenance of cancer initiating cells.

Chronic lithium treatment stimulates adult hippocampal neurogenesis, but whether increased neurogenesis contributes to its therapeutic mechanism remains unclear. We use a genetic model of neural progenitor cell (NPC) ablation to test whether a lithium-sensitive behavior requires hippocampal neurogenesis. NPC-ablated mice were treated with lithium and assessed in the forced swim test (FST). Lithium reduced time immobile in the FST in NPC-ablated and control mice but had no effect on activity in the open field, a control for the locomotion-based FST. These findings show that hippocampal NPCs that proliferate in response to chronic lithium are not necessary for the behavioral response to lithium in the FST. We further show that 4-6 week old immature hippocampal neurons are not required for this response. These data suggest that increased hippocampal neurogenesis does not contribute to the response to lithium in the forced swim test and may not be an essential component of its therapeutic mechanism.

There is growing concern that the physician-scientist is endangered due to a leaky training pipeline and prolonged time to scientific independence (1). The NIH Physician-Scientist Workforce Working Group has concluded that as many as 1,000 individuals will need to enter the pipeline each year to sustain the workforce (2). Moreover, surveys of postgraduate training programs document considerable variability in disposition and infrastructure (3). Programs can be broadly grouped into two classes: physician-scientist training programs (PSTPs) that span residency and fellowship training, and research-in-residency programs (RiRs), which are limited to residency but trainees are able to match into PSTPs upon transitioning to fellowship (Figure 1). Funding sources for RiRs and PSTPs are varied and include NIH KL2 and T32 awards, charitable foundations, philanthropy, and institutional support. Furthermore, standards for research training and tools for evaluating programmatic success are lacking. Here, we share consensus generated from iterative workshops hosted by the Alliance of Academic Internal Medicine (AAIM) and the student-led American Physician Scientists Association (APSA).

In most species, early germline development occurs in the absence of transcription with germline determinants subject to complex translational and post-translational regulations. Here, we report for the first time that early germline development is influenced by dynamic regulation of the proteasome system, previously thought to be ubiquitously expressed and to serve ‘housekeeping’ roles in controlling protein homeostasis. We show that proteasomes are present in a gradient with the highest levels in the animal hemisphere and extending into the vegetal hemisphere of Xenopus oocytes. This distribution changes dramatically during the oocyte-to-embryo transition, with proteasomes becoming enriched in and restricted to the animal hemisphere and therefore separated from vegetally localized germline determinants. We identify Dead-end1 (Dnd1), a master regulator of vertebrate germline development, as a novel substrate of the ubiquitin-independent proteasomes. In the oocyte, ubiquitin-independent proteasomal degradation acts together with translational repression to prevent premature accumulation of Dnd1 protein. In the embryo, artificially increasing ubiquitin-independent proteasomal degradation in the vegetal pole interferes with germline development. Our work thus reveals novel inhibitory functions and spatial regulation of the ubiquitin-independent proteasome during vertebrate germline development.

Glycogen synthase kinase-3 (GSK-3) is a highly conserved negative regulator of receptor tyrosine kinase, cytokine, and Wnt signaling pathways. Stimulation of these pathways inhibits GSK-3 to modulate diverse downstream effectors that include transcription factors, nutrient sensors, glycogen synthesis, mitochondrial function, circadian rhythm, and cell fate. GSK-3 also regulates alternative splicing in response to T-cell receptor activation, and recent phosphoproteomic studies have revealed that multiple splicing factors and regulators of RNA biosynthesis are phosphorylated in a GSK-3-dependent manner. Furthermore, inhibition of GSK-3 alters the splicing of hundreds of mRNAs, indicating a broad role for GSK-3 in the regulation of RNA processing. GSK-3-regulated phosphoproteins include SF3B1, SRSF2, PSF, RBM8A, nucleophosmin 1 (NPM1), and PHF6, many of which are mutated in leukemia and myelodysplasia. As GSK-3 is inhibited by pathways that are pathologically activated in leukemia and loss of Gsk3 in hematopoietic cells causes a severe myelodysplastic neoplasm in mice, these findings strongly implicate GSK-3 as a critical regulator of mRNA processing in normal and malignant hematopoiesis. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.

SummaryMembers of the Msi family of RNA-binding proteins have recently emerged as potent oncoproteins in a range of malignancies. MSI2 is highly expressed in hematopoietic cancers, where it is required for disease maintenance. In contrast to the hematopoietic system, colorectal cancers can express both Msi family members, MSI1 and MSI2. Here, we demonstrate that, in the intestinal epithelium, Msi1 and Msi2 have analogous oncogenic effects. Further, comparison of Msi1/2-induced gene expression programs and transcriptome-wide analyses of Msi1/2-RNA-binding targets reveal significant functional overlap, including induction of the PDK-Akt-mTORC1 axis. Ultimately, we demonstrate that concomitant loss of function of both MSI family members is sufficient to abrogate the growth of human colorectal cancer cells, and Msi gene deletion inhibits tumorigenesis in several mouse models of intestinal cancer. Our findings demonstrate that MSI1 and MSI2 act as functionally redundant oncoproteins required for the ontogeny of intestinal cancers.

Glycogen synthase kinase-3 (GSK-3) is a constitutively active, ubiquitously expressed protein kinase that regulates multiple signaling pathways. In vitro kinase assays and genetic and pharmacological manipulations of GSK-3 have identified more than 100 putative GSK-3 substrates in diverse cell types. Many more have been predicted on the basis of a recurrent GSK-3 consensus motif ((pS/pT)XXX(S/T)), but this prediction has not been tested by analyzing the GSK-3 phosphoproteome. Using stable isotope labeling of amino acids in culture (SILAC) and MS techniques to analyze the repertoire of GSK-3–dependent phosphorylation in mouse embryonic stem cells (ESCs), we found that ∼2.4% of (pS/pT)XXX(S/T) sites are phosphorylated in a GSK-3–dependent manner. A comparison of WT and Gsk3a;Gsk3b knock-out (Gsk3 DKO) ESCs revealed prominent GSK-3–dependent phosphorylation of multiple splicing factors and regulators of RNA biosynthesis as well as proteins that regulate transcription, translation, and cell division. Gsk3 DKO reduced phosphorylation of the splicing factors RBM8A, SRSF9, and PSF as well as the nucleolar proteins NPM1 and PHF6, and recombinant GSK-3β phosphorylated these proteins in vitro. RNA-Seq of WT and Gsk3 DKO ESCs identified ∼190 genes that are alternatively spliced in a GSK-3–dependent manner, supporting a broad role for GSK-3 in regulating alternative splicing. The MS data also identified posttranscriptional regulation of protein abundance by GSK-3, with ∼47 proteins (1.4%) whose levels increased and ∼78 (2.4%) whose levels decreased in the absence of GSK-3. This study provides the first unbiased analysis of the GSK-3 phosphoproteome and strong evidence that GSK-3 broadly regulates alternative splicing.

Hematopoietic stem cells (HSCs) are able to self-renew and to differentiate into all blood cells. HSCs reside in a low-perfusion niche and depend on local signals to survive and to maintain the capacity for self-renewal. HSCs removed from the niche are unable to survive without addition of hematopoietic cytokines and rapidly lose their ability to self-renew. We reported previously that inhibition of both GSK-3 and mTORC1 is essential to maintain long-term HSCs ex vivo. Although Wnt/β-catenin signaling downstream of GSK-3 is required for this response, the downstream effectors of mTORC1 remain undefined. We now report that HSCs express a pro-autophagic gene signature and accumulate LC3 puncta only when both mTORC1 and GSK-3 are inhibited, identifying autophagy as a signature for a signaling network that maintains HSCs ex vivo. In addition, these conditions sustain HSC repopulating function despite an increased rate of global translation. Together, these findings provide new insight into the relative contributions of various mTORC1 outputs toward the maintenance of HSC function and build upon the growing body of literature implicating autophagy and tightly controlled protein synthesis as important modulators of diverse stem cell populations.

Hematopoiesis is maintained throughout life by self-renewing hematopoietic stem cells (HSCs) that differentiate to produce both myeloid and lymphoid cells. The NR4A family of orphan nuclear receptors, which regulates cell fate in many tissues, appears to play a key role in HSC proliferation and differentiation. Using a NR4A1GFP BAC transgenic reporter mouse we have investigated NR4A1 expression and its regulation in early hematopoiesis. We show that NR4A1 is most highly expressed in a subset of Lin−Sca-1+c-Kit+ CD48−CD150+ long-term (LT) HSCs, and its expression is tightly associated with HSC quiescence. We also show that NR4A1 expression in HSCs is induced by PGE2, a known enhancer of stem cell engraftment potential. Finally, we find that both NR4A1GFP+ and NR4A1GFP− HSCs successfully engraft primary and secondary irradiated hosts; however, NR4A1GFP+ HSCs are distinctly myeloid-biased. These results show that NR4A1 expression identifies a highly quiescent and distinct population of myeloid-biased LT-HSCs. Stem Cells 2015;33:278–288

The regulation of behavior by the molecular components of the circadian clock is not well understood. Here we report that mice lacking the nuclear receptor Rev-erbα, a potent transcriptional repressor and core clock component, displayed marked hyperactivity and impaired response habituation in novel environments. In addition, Rev-erbα knockout (KO) mice were deficient in short-term, long-term, and contextual memories and also showed impairment in nest-building ability. Together, these results suggest that Rev-erbα KO mice manifest defective hippocampal function. Interestingly, the changes in novelty-induced locomotor activity of Rev-erbα KO mice were comparable at multiple times of day, potentially due to the muted amplitude of Rev-erbα oscillation in the hippocampus of wild-type mice. Hippocampal dopamine turnover was increased in Rev-erbα KO mice, due to up-regulation of tyrosine hydroxylase, the rate-limiting enzyme in dopamine production, and pharmacologic inhibition of tyrosine hydroxylase activity partially rescued locomotor hyperactivity. These findings reveal a novel, nonredundant function for Rev-erbα that links a core component of the circadian gene-regulatory network to the control of dopaminergic and hippocampus-dependent behaviors.

Summary Wnts are a family of 19 extracellular ligands that regulate cell fate, proliferation, and migration during metazoan embryogenesis and throughout adulthood. Wnts are acylated post-translationally at a conserved serine and bind the extracellular cysteine-rich domain (CRD) of Frizzled (FZD) seven-pass transmembrane receptors. Although crystal structures suggest that acylation is essential for Wnt binding to FZDs, we show here that several Wnts can promote signaling in Xenopus laevis and Danio rerio embryos, as well as in an in vitro cell culture model, without acylation. The non-acylated Wnts are expressed at levels similar to wild-type counterparts and retain CRD binding. By contrast, we find that certain other Wnts do require acylation for biological activity in Xenopus embryos, although not necessarily for FZD binding. Our data argue that acylation dependence of Wnt activity is context specific. They further suggest that acylation may underlie aspects of ligand-receptor selectivity and/or control other aspects of Wnt function.

Background: Histone deacetylases (HDACs) regulate multiple developmental processes and cellular functions. However, their roles in blood development have not been determined, and in Xenopus laevis a specific function for HDACs has yet to be identified. Here, we employed the class I selective HDAC inhibitor, valproic acid (VPA), to show that HDAC activity is required for primitive hematopoiesis. Results: VPA treatment during gastrulation resulted in a complete absence of red blood cells (RBCs) in Xenopus tadpoles, but did not affect development of other mesodermal tissues, including myeloid and endothelial lineages. These effects of VPA were mimicked by Trichostatin A (TSA), a well-established pan-HDAC inhibitor, but not by valpromide, which is structurally similar to VPA but does not inhibit HDACs. VPA also caused a marked, dose-dependent loss of primitive erythroid progenitors in mouse yolk sac explants at clinically relevant concentrations. In addition, VPA treatment inhibited erythropoietic development downstream of bmp4 and gata1 in Xenopus ectodermal explants. Conclusions: These findings suggest an important role for class I HDACs in primitive hematopoiesis. Our work also demonstrates that specific developmental defects associated with exposure to VPA, a significant teratogen in humans, arise through inhibition of class I HDACs. Developmental Dynamics 242:108–121, 2013. © 2012 Wiley Periodicals,Inc.

Following fertilization, vertebrate embryos delay large-scale activation of the zygotic genome from several hours in fish and amphibians to several days in mammals. Externally developing embryos also undergo synchronous and extraordinarily rapid cell divisions that are accelerated by promiscuous licensing of DNA replication origins, absence of gap phases and cell cycle checkpoints, and preloading of the egg with maternal RNAs and proteins needed to drive early development. After a species-specific number of cell divisions, the cell cycle slows and becomes asynchronous, gap phases appear, checkpoint functions are acquired, and large-scale zygotic gene activation begins. These events, along with clearance of maternal RNAs and proteins, define the maternal to zygotic transition and are coordinated at a developmental milestone termed the midblastula transition (MBT). Despite the relative quiescence of the zygotic genome in vertebrate embryos, genes required for clearance of maternal RNAs and for the initial steps in mesoderm induction are robustly transcribed before MBT. The coordination and timing of the MBT depends on a mechanism that senses the ratio of nuclear to cytoplasmic content as well as mechanisms that are independent of the nuclear-cytoplasm ratio. Changes in chromatin architecture anticipate zygotic gene activation, and maternal transcription factors identified as regulators of pluripotency play critical roles in kick-starting the transition from the proliferative, pluripotent state of the early embryo to the more lineage-committed phase of development after the MBT. This chapter describes the regulation of the cell cycle and the activation of zygotic gene expression before and after the MBT in vertebrate embryos.

Following fertilization, vertebrate embryos delay large-scale activation of the zygotic genome from several hours in fish and amphibians to several days in mammals. Externally developing embryos also undergo synchronous and extraordinarily rapid cell divisions that are accelerated by promiscuous licensing of DNA replication origins, absence of gap phases and cell cycle checkpoints, and preloading of the egg with maternal RNAs and proteins needed to drive early development. After a species-specific number of cell divisions, the cell cycle slows and becomes asynchronous, gap phases appear, checkpoint functions are acquired, and large-scale zygotic gene activation begins. These events, along with clearance of maternal RNAs and proteins, define the maternal to zygotic transition and are coordinated at a developmental milestone termed the midblastula transition (MBT). Despite the relative quiescence of the zygotic genome in vertebrate embryos, genes required for clearance of maternal RNAs and for the initial steps in mesoderm induction are robustly transcribed before MBT. The coordination and timing of the MBT depends on a mechanism that senses the ratio of nuclear to cytoplasmic content as well as mechanisms that are independent of the nuclear–cytoplasm ratio. Changes in chromatin architecture anticipate zygotic gene activation, and maternal transcription factors identified as regulators of pluripotency play critical roles in kick-starting the transition from the proliferative, pluripotent state of the early embryo to the more lineage-committed phase of development after the MBT. This chapter describes the regulation of the cell cycle and the activation of zygotic gene expression before and after the MBT in vertebrate embryos.

Background: Aromatase Inhibitors (AI) are well established as adjuvant treatment for postmenopausal (PMP) women with hormone receptor positive (HR+) early breast cancer (EBC). However, phase III clinical trials have reported higher rates of arthralgia associated with AI than tamoxifen. This study aims to collect real world data on the effects of AI-associated arthralgia on patient compliance, patient outcomes and on treatment of arthralgia. Methods: COMPACT is an open, prospective, non-interventional, non-randomized study (NCT00857012) run in Germany. PMP women with HR+ EBC who had been on adjuvant anastrozole (ANA) for 3–6 months were enrolled and stratified by initial adjuvant ANA or switch from tamoxifen. All patients received regular standardized information about breast cancer from baseline to week 20 to support treatment compliance. Data on demographics, arthralgia, related therapies, other side effects and QoL were collected at baseline, 3, 6 and 9 months. Primary endpoints are scaled data on arthralgia and compliance within the first year of ANA therapy. Secondary endpoints include incidence of arthralgia, therapy costs, reasons for non-compliance, and influence of arthralgia on clinical outcome. Results: Between Apr 2009 and Mar 2011, 2313 patients were enrolled, 2007 on upfront ANA and 306 on switch from tamoxifen. The mean age at baseline was 64.5 years, mean BMI 27.7. Only 17.0% of patients had received HRT prior to their EBC. At baseline, 41.9% reported symptoms relating to skeleton or musculature. 12.0% reported arthralgia existing prior to ANA treatment and 13.2% stated a worsening of pre-existing arthralgia or new arthralgia after starting ANA. Predictors for non-adherence to AI therapy were former non-adherence, general symptom load on the side effect scale GASE, and low benefit expectation at treatment start. Risk of arthralgia was related to BMI (lowest for patients with BMI ≤24.1 kg/m2, highest with BMI >30.5 kg/m2 at all time points; OR>1) and upfront therapy (switch patients had a reduced risk of 68% at 6 and 61% at 9 months compared to patients with ANA upfront, p = 0.002). Patients with prior chemotherapy had lower rates of arthralgia before start of ANA (10.4% vs 13.3%, p = 0.036) but higher rates after the start of ANA and before study start (27.0% vs 22.5%, p = 0.013). Patients with arthralgia showed higher compliance rates at all time points (p < 0.001). Conclusion: COMPACT identified arthralgia and musculoskeletal symptoms as common complaints in PMP women with EBC. ANA treatment both increased the number of women with such symptoms and aggravated these in some patients. Higher BMI and upfront AI predicted for risk of AI associated arthralgia. However, COMPACT also showed that AI-associated arthralgia did not lead to non-compliance in most patients. This data may help to better understand compliance issues with adjuvant AI treatment. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-09-08.

Hematopoietic stem cell (HSC) self-renewal and lineage commitment depend on complex interactions with the microenvironment, and the ability to maintain or expand HSCs for clinical applications or for basic research has been significantly limited because these interactions are not well defined. Recent evidence suggests that HSCs reside in a low perfusion, reduced nutrient niche and that nutrient sensing pathways contribute to HSC homeostasis. Here we report that suppression of the mammalian target of rapamycin (mTOR) pathway, an established nutrient sensor, combined with activation of canonical Wnt/β-catenin signaling, allows the ex vivo maintenance of human and mouse long-term HSCs under cytokine-free conditions. We also show that combining two clinically approved medications that activate Wnt/β-catenin signaling and inhibit mTOR increases the number (but not the proportion) of long-term HSCs in vivo.

Glycogen synthase kinase-3 (GSK-3) is essential for many signaling pathways and cellular processes. As Adenomatous Polyposis Coli (APC) functions in many of the same processes, we investigated a role for APC in the regulation of GSK-3-dependent signaling. We find that APC directly enhances GSK-3 activity. Furthermore, knockdown of APC mimics inhibition of GSK-3 by reducing phosphorylation of glycogen synthase and by activating mTOR, revealing novel roles for APC in the regulation of these enzymes. Wnt signaling inhibits GSK-3 through an unknown mechanism, and this results in both stabilization of β-catenin and activation of mTOR. We therefore hypothesized that Wnts may regulate GSK-3 by disrupting the interaction between APC and the Axin-GSK-3 complex. We find that Wnts rapidly induce APC dissociation from Axin, correlating with β-catenin stabilization. Furthermore, Axin interaction with the Wnt co-receptor LRP6 causes APC dissociation from Axin. We propose that APC regulates multiple signaling pathways by enhancing GSK-3 activity, and that Wnts induce APC dissociation from Axin to reduce GSK-3 activity and activate downstream signaling. APC regulation of GSK-3 also provides a novel mechanism for Wnt regulation of multiple downstream effectors, including β-catenin and mTOR.

Familial hemophagocytic lymphohistiocytosis (HLH) is a rare primary immunodeficiency disorder characterized by defects in cell-mediated cytotoxicity that results in fever, hepatosplenomegaly, and cytopenias. Familial HLH is well recognized in children but rarely diagnosed in adults. We conducted a retrospective review of genetic and immunologic test results in patients who developed HLH in adulthood. Included in our study were 1531 patients with a clinical diagnosis of HLH; 175 patients were 18 years or older. Missense and splice-site sequence variants in PRF1, MUNC13-4, and STXBP2 were found in 25 (14%) of the adult patients. The A91V-PRF1 genotype was found in 12 of these patients (48%). The preponderance of hypomorphic mutations in familial HLH–causing genes correlates with the later-onset clinical symptoms and the more indolent course in adult patients. We conclude that late-onset familial HLH occurs more commonly than was suspected previously.

Lithium is the first-line therapy for bipolar disorder. However, its therapeutic target remains controversial. Candidates include inositol monophosphatases, glycogen synthase kinase-3 (GSK-3), and a β-arrestin-2/AKT/protein phosphatase 2A (β-arrestin-2/AKT/PP2A) complex that is known to be required for lithium-sensitive behaviors. Defining the direct target(s) is critical for the development of new therapies and for elucidating the molecular pathogenesis of this major psychiatric disorder. Here, we show what we believe to be a new link between GSK-3 and the β-arrestin-2 complex in mice and propose an integrated mechanism that accounts for the effects of lithium on multiple behaviors. GSK-3β (Gsk3b) overexpression reversed behavioral defects observed in lithium-treated mice and similar behaviors observed in Gsk3b+/- mice. Furthermore, immunoprecipitation of striatial tissue from WT mice revealed that lithium disrupted the β-arrestin-2/Akt/PP2A complex by directly inhibiting GSK-3. GSK-3 inhibitors or loss of one copy of the Gsk3b gene reduced β-arrestin-2/Akt/PP2A complex formation in mice, while overexpression of Gsk3b restored complex formation in lithium-treated mice. Thus, GSK-3 regulates the stability of the β-arrestin-2/Akt/PP2A complex, and lithium disrupts the complex through direct inhibition of GSK-3. We believe these findings reveal a new role for GSK-3 within the β-arrestin complex and demonstrate that GSK-3 is a critical target of lithium in mammalian behaviors.

Tumor hypoxia is an inherent impediment to cancer treatment that is both clinically significant and problematic. In this study, we conducted a cell-based screen to identify small molecules that could reverse the apoptotic resistance of hypoxic cancer cells. Among the compounds, we identified were a structurally related group that sensitized hypoxic cancer cells to apoptosis by inhibiting the kinases GSK-3β and cyclin-dependent kinase (CDK) 1. Combinatorial inhibition of these proteins in hypoxic cancer cells and tumors increased levels of c-Myc and decreased expression of c-IAP2 and the central hypoxia response regulator hypoxia-inducible factor (HIF) 1α. In mice, these compounds augmented the hypoxic tumor cell death induced by cytotoxic chemotherapy, blocking angiogenesis and tumor growth. Taken together, our findings suggest that combinatorial inhibition of GSK-3β and CDK1 augment the apoptotic sensitivity of hypoxic tumors, and they offer preclinical validation of a novel and readily translatable strategy to improve cancer therapy. Cancer Res; 71(15); 5265–75. ©2011 AACR.

Post-transcriptional control of mRNA stability and translation is central to multiple developmental pathways. This control can be linked to cytoplasmic polyadenylation in certain settings. In maturing Xenopus oocytes, specific mRNAs are targeted for polyadenylation via recruitment of the Cytoplasmic Polyadenylation Element (CPE) binding protein (CPEB) to CPE(s) within the 3′ UTR. Cytoplasmic polyadenylation is also critical to early embryonic events, although corresponding determinants are less defined. Here, we demonstrate that the Xenopus ortholog of the poly(rC) binding protein αCP2 can recruit cytoplasmic poly(A) polymerase activity to mRNAs in Xenopus post-fertilization embryos, and that this recruitment relies on cis sequences recognized by αCP2. We find that the hα-globin 3′ UTR, a validated mammalian αCP2 target, constitutes an effective target for cytoplasmic polyadenylation in Xenopus embryos, but not during Xenopus oocyte maturation. We further demonstrate that the cytoplasmic polyadenylation activity is dependent on the action of the C-rich αCP-binding site in conjunction with the adjacent AAUAAA. Consistent with its ability to target mRNA for poly(A) addition, we find that XαCP2 associates with core components of the Xenopus cytoplasmic polyadenylation complex, including the cytoplasmic poly(A) polymerase XGLD2. Furthermore, we observe that the C-rich αCP-binding site can robustly enhance the activity of a weak canonical oocyte maturation CPE in early embryos, possibly via a direct interaction between XαCP2 and CPEB1. These studies establish XαCP2 as a novel cytoplasmic polyadenylation trans factor, indicate that C-rich sequences can function as noncanonical cytoplasmic polyadenylation elements, and expand our understanding of the complexities underlying cytoplasmic polyadenylation in specific developmental settings.

Honey is a rich conventional natural resource of sweetness and energy for human beings. A protocol for the determination of two important monosaccharide sugars (fructose and glucose) in honey was established in the current study by using normal phase partition liquid chromatography and 1–5% combined working standard of glucose, fructose and sucrose.

Carboxylic acids with known central nervous system and histone deacetylase (HDAC) inhibitory activities were converted to hydroxamic acids and tested using a suite of in vitro biochemical assays with recombinant HDAC isoforms, cell based assays in human cervical carcinoma HeLa cells and primary cultures from mouse forebrain, and a whole animal (Xenopus laevis) developmental assay. Relative to the parent carboxylic acids, two of these analogues exhibited enhanced potency, and one analogue showed altered HDAC isoform selectivity and in vivo activity in the Xenopus assay. We discuss potential uses of these novel hydroxamic acids in studies aimed at determining the utility of HDAC inhibitors as memory enhancers and mood stabilizers.

In vertebrates, canonical Wnt signaling controls posterior neural cell lineage specification. Although Wnt signaling to the neural plate is sufficient for posterior identity, the source and timing of this activity remain uncertain. Furthermore, crucial molecular targets of this activity have not been defined. Here, we identify the endogenous Wnt activity and its role in controlling an essential downstream transcription factor, Meis3. Wnt3a is expressed in a specialized mesodermal domain, the paraxial dorsolateral mesoderm, which signals to overlying neuroectoderm. Loss of zygotic Wnt3a in this region does not alter mesoderm cell fates, but blocks Meis3 expression in the neuroectoderm, triggering the loss of posterior neural fates. Ectopic Meis3 protein expression is sufficient to rescue this phenotype. Moreover, Wnt3a induction of the posterior nervous system requires functional Meis3 in the neural plate. Using ChIP and promoter analysis, we show that Meis3 is a direct target of Wnt/β-catenin signaling. This suggests a new model for neural anteroposterior patterning, in which Wnt3a from the paraxial mesoderm induces posterior cell fates via direct activation of a crucial transcription factor in the overlying neural plate.

Recent studies have uncovered an unexpected relationship between factors that are essential for germline development in Drosophila melanogaster: the arginine protein methyltransferase 5 (dPRMT5/Csul/Dart5) and its cofactor Valois, methylate the Piwi family protein Aub, enabling it to bind Tudor. The RNA helicase Vasa is another essential protein in germline development. Here, we report that mouse (mouse Vasa homolog), Xenopus laevis, and D. melanogaster Vasa proteins contain both symmetrical and asymmetrical dimethylarginines. We find that dPRMT5 is required for the production of sDMAs of Vasa in vivo. Furthermore, we find that the mouse Vasa homolog associates with Tudor domain-containing proteins, Tdrd1 and Tdrd6, as well as the Piwi proteins, Mili and Miwi. Arginine methylation is thus emerging as a conserved and pivotal post-translational modification of proteins that is essential for germline development.

Purpose This randomized, open-label, parallel-group, multicenter study was designed to compare the efficacy and safety of bendamustine and chlorambucil in previously untreated patients with advanced (Binet stage B or C) chronic lymphocytic leukemia (CLL). Patients and Methods Patients (≤ 75 years of age) were randomly assigned to receive bendamustine 100 mg/m2/d intravenously on days 1 to 2, or chlorambucil 0.8 mg/kg (Broca's normal weight) orally on days 1 and 15; treatment cycles were repeated every 4 weeks for a maximum of six cycles. The response to treatment was assessed according to National Cancer Institute Working Group criteria, and the final determination of response was made by a blinded independent review committee. Results A total of 319 patients were randomly assigned (162 bendamustine, 157 chlorambucil). Complete or partial responses were achieved in 110 (68%) of 162 bendamustine-treated and 48 (31%) of 157 chlorambucil-treated patients (P < .0001). More patients showed complete responses with bendamustine than with chlorambucil (31% v 2%). Median progression-free survival was 21.6 months with bendamustine and 8.3 months with chlorambucil (P < .0001). Bendamustine was also associated with an improvement in duration of remission, compared with chlorambucil (median, 21.8 v 8.0 months). Hematologic National Cancer Institute Common Toxicity Criteria grade 3 to 4 adverse events were more common with bendamustine than with chlorambucil (occurring in 40% v 19% of patients). Severe infections (grade 3 to 4) occurred in 8% of bendamustine-treated patients and 3% of chlorambucil-treated patients. Conclusion Bendamustine offers significantly greater efficacy than chlorambucil, and a manageable toxicity profile, when used as first-line therapy in patients with advanced CLL.

Cholinergic loss is the single most replicated neurotransmitter deficiency in Alzheimer's disease (AD) and has led to the use of acetylcholinesterase inhibitors (AChE-Is) and unselective cholinesterase inhibitors (ChE-Is) as the mainstay of treatment. AChE-Is and ChE-Is, however, induce dose-limiting adverse effects. Recent studies indicate that selective butyrylcholinesterase inhibitors (BuChE-Is) elevate acetylcholine (ACh) in brain, augment long-term potentiation, and improve cognitive performance in rodents without the classic adverse actions of AChE-Is and ChE-Is. BuChE-Is thereby represent a new strategy to ameliorate AD, particularly since AChE activity is depleted in AD brain, in line with ACh levels, whereas BuChE activity is elevated. Our studies have focused on the design and development of cymserine analogues to induce selective time-dependent brain BuChE inhibition, and on the application of innovative and quantitative enzyme kinetic analyses to aid selection of drug candidates. The quantitative interaction of the novel inhibitor, dihydrobenzodioxepine cymserine (DHBDC), with human BuChE was characterized. DHBDC demonstrated potent concentration-dependent binding with BuChE. The IC(50) and specific new kinetic constants, such as K(T50), P(PC), K(T1/2) and R(I), were determined at dual substrate concentrations of 0.10 and 0.60 mM butyrylthiocholine and reaction times, and are likely attainable in humans. Other classical kinetic parameters such as K(ia), K(ma), V(ma) and V(mi) were also determined. In synopsis, DHBDC proved to be a highly potent competitive inhibitor of human BuChE in comparison to its structural analogue, cymserine, and represents an interesting drug candidate for AD.

Glycogen synthase kinase 3 (GSK-3) has been implicated in the generation of multiple pathological lesions associated with Alzheimer's disease (AD), including β-amyloid production, neurofibrillary tangle formation, and neuronal apoptosis. Thus, drugs that inhibit GSK-3 could prevent or reverse AD pathology through multiple mechanisms. This brief review discusses the role of GSK-3 in AD and describes several classes of GSK-3 inhibitors that have been tested in experimental models.

Two leading hypotheses to explain lithium action in bipolar disorder propose either inositol depletion or inhibition of GSK-3 as mechanisms of action. Behavioral effects of lithium are mimicked in Gsk-3β +/− mice, but the contribution of inositol depletion to these behaviors has not been tested. According to the inositol depletion hypothesis, lithium-sensitive behavior is secondary to impaired phosphatidylinositol synthesis caused by inositol deficiency. By disrupting the sodium myo-inositol transporter1 gene, SMIT1 , we show that depletion of brain myo-inositol in SMIT1 +/− mice has no effect on lithium-sensitive behavior. These findings, taken together with our previous work showing that SMIT −/− mice have an even greater depletion of inositol in brain with no reduction in phosphatidylinositol levels, are difficult to reconcile with the current formulation of the inositol depletion hypothesis.