The transcription factor XBP1 in dendritic cells promotes the TH2 cell response in airway allergy.

Dendritic cells (DCs) that express T cell immunoglobulin domain molecule-4 (TIM4), a cell surface receptor for phosphatidylserine, induce T helper 2 (TH2) cell responses and allergic reactions. We elucidated the role of the transcription factor X-box-binding protein-1 (XBP1) in the induction of the TH2 cell response through its role in generating TIM4+ DCs. We found that XBP1 was required for TIM4 mRNA and protein expression in airway DCs in response to the cytokine interleukin-2 (IL-2) and that this pathway was required for TIM4 expression on DCs in response to the allergens PM2.5 and Derf1. The IL-2-XBP1-TIM4 axis in DCs contributed to Derf1/PM2.5-induced, aberrant TH2 cell responses in vivo. An interaction between the guanine nucleotide exchange factor Son of sevenless-1 (SOS1) and the GTPase RAS promoted XBP1 and TIM4 production in DCs. Targeting the XBP1-TIM4 pathway in DCs prevented or alleviated experimental airway allergy. Together, these data suggest that XBP1 is required for TH2 cell responses by inducing the development of TIM4+ DCs, which depends on the IL-2-XBP1-SOS1 axis. This signaling pathway provides potential therapeutic targets for the treatment of TH2 cell-dependent inflammation or allergic diseases.

Upregulation of Wnt2b exerts neuroprotective effect by alleviating mitochondrial dysfunction in Alzheimer's disease.

AIMS: This study investigated the relationship between plasma Wnt2b levels and Alzheimer's disease (AD), and explored the effect of Wnt2b on mitochondrial dysfunction in AD. METHODS: Healthy and AD subjects, AD transgenic mice, and in vitro models were used to investigate the roles of Wnt2b in abnormalities in canonical Wnt signaling and mitochondria in AD. RT-qPCR, immunoblotting, and immunofluorescence analysis were performed to assay canonical Wnt signaling. Mitochondrial structure was analyzed by electron microscopy. Flow cytometry was used to examine the intracellular calcium and neuronal apoptosis. RESULTS: Plasma Wnt2b levels were lower in AD patients and positively correlated with cognitive performance. Similarly, Wnt2b was reduced in the hippocampus of AD mice and in vitro models. Next, Wnt2b overexpression and recombinant Wnt2b were used to endogenously and exogenously upregulate Wnt2b levels. Upregulation of Wnt2b could effectively prevent downregulation of canonical Wnt signaling, mitochondrial dysfunction in in vitro AD models. Subsequently, intracellular calcium overload and neuronal damage were ameliorated. CONCLUSIONS: Our study highlights that Wnt2b decline is associated with cognitive impairment in AD, and upregulation of Wnt2b can exert neuroprotective effects in AD, particularly in ameliorating mitochondrial dysfunction.

Carnosic Acid Attenuates AßOs-Induced Apoptosis and Synaptic Impairment via Regulating NMDAR2B and Its Downstream Cascades in SH-SY5Y Cells.

Neuronal death and synaptic loss are principal pathological features of Alzheimer's disease (AD). Amyloid beta oligomers (AßOs) constitute the main neurotoxin underscoring AD pathology. AßOs interact with N-methyl-D-aspartate receptors (NMDARs), resulting in neurotoxic events, including activation of apoptosis and synaptic impairment. Carnosic acid (CA), extracted from Salvia rosmarinus, has been verified its neuroprotective effects in AD. However, the precise mechanisms by which CA induces synaptic protection remain unclear. In this study, we established an in vitro AD model using SH-SY5Y human neuroblastoma cells. We observed that CA improved neuronal survival by suppressing apoptosis. Moreover, CA restored synaptic impairments by increasing expression levels of brain-derived neurotrophic factor (BDNF), postsynaptic density protein-95 (PSD-95), and synaptophysin (Syn). Furthermore, we found these protective effects were dependent on inhibiting the phosphorylation of NMDAR subtype 2B (NMDAR2B), which further suppressed calcium overload and promoted activation of the extracellular signal-regulated kinase (ERK)-cAMP response element-binding protein (CREB) pathway. Administration of N-methyl-D-aspartic acid (NMDA), an agonist of NMDARs, abolished these effects of CA. Our findings demonstrate that CA exerts neuroprotective effects in an in vitro model of AD by regulating NMDAR2B and its downstream cascades, highlighting the therapeutic potential of CA as a NMDARs-targeted candidate in the treatment of AD.

NMDA Receptor GluN2B Subunit Is Involved in Excitotoxicity Mediated by Death-Associated Protein Kinase 1 in Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is the most common form of neurodegenerative dementia among the elderly. Excitotoxicity has been implicated as playing a dominant role in AD, especially related to the hyperactivation of excitatory neurons. Death-associated protein kinase 1 (DAPK1) is a calcium/calmodulin-dependent kinase and involved in the pathogenesis of AD, but the roles and mechanisms of DAPK1 in excitotoxicity in AD are still uncertain. OBJECTIVE: We mainly explored the underlying mechanisms of DAPK1 involved in the excitotoxicity of AD and its clinical relevance. METHODS: Differentiated SH-SY5Y human neuroblastoma cells, PS1 V97 L transgenic mice, and human plasma samples were used. Protein expression was assayed by immunoblotting, and intracellular calcium and neuronal damage were analyzed by flow cytometry. Plasma DAPK1 was measured by ELISA. RESULTS: We found that DAPK1 was activated after amyloid-ß oligomers (AßOs) exposure in differentiated SH-SY5Y cells. Besides, we found the phosphorylation of GluN2B subunit at Ser1303 was increased, which contributing to excitotoxicity and Ca2+ overload in SH-SY5Y cells. Inhibiting DAPK1 activity, knockdown of DAPK1 expression, and antagonizing GluN2B subunits could effectively prevent AßOs-induced activation of GluN2B subunit, Ca2+ overload, and neuronal apoptosis. Additionally, we found that DAPK1 was elevated in the brain of AD transgenic mouse and in the plasma of AD patients. CONCLUSION: Our finding will help to understand the mechanism of DAPK1 in the excitotoxicity in AD and provide a reference for the diagnosis and therapy of AD.

CaMKIIα Signaling Is Required for the Neuroprotective Effects of Dl-3-n-Butylphthalide in Alzheimer's Disease.

Alzheimer's disease (AD) is the most common form of neurodegenerative disease and most anti-AD drugs have failed in clinical trials; hence, it is urgent to find potentially effective drugs against AD. DL-3-n-butylphthalide (NBP) is a compound extracted from celery seed and is a multiple-target drug. Several studies have demonstrated the neuroprotective effects of NBP on cognitive impairment, but the mechanisms of NBP remains relatively unexplored. In this study, we found that NBP could alleviated the increase of intracellular Ca2+ and reversed down-regulation of Ca2+/calmodulin-dependent protein kinase alpha (CaMKIIα) signaling and rescued neuronal apoptosis in SH-SY5Y cells treated by Aß oligomers. However, these neuroprotective effects of NBP on neuronal damage and CaMKIIα signaling were abolished when CaMKIIα expression was knocked down or its activity was inhibited. Thus, our findings suggested that CaMKIIα signaling was required for the neuroprotective effects of NBP in AD and provided an improved basis for elucidating the mechanism and treatment of NBP in AD.

Decreased Levels of Insulin-Like Growth Factor-1 Are Associated with Alzheimer's Disease: A Meta-Analysis.

BACKGROUND: Alterations in levels of peripheral insulin-like growth factor-1 (IGF-1) in Alzheimer's disease (AD) have been reported in several studies, and results are inconsistent. OBJECTIVE: We conducted a meta-analysis to investigate the relationship between peripheral and cerebrospinal fluid IGF-1 levels and AD or mild cognitive impairment (MCI). METHODS: A systematic search in PubMed, Medline, Web of Science, Embase, and Cochrane Library was conducted and 18 studies were included. RESULTS: Results of random-effects meta-analysis showed that there was no significant difference between AD patients and healthy control (17 studies; standard mean difference [SMD], -0.01; 95%CI, -0.35 to 0.32) and between MCI patients and healthy control (6 studies; SMD, -0.20; 95%CI, -0.52 to 0.13) in peripheral IGF-1 levels. Meta-regression analyses identified age difference might explain the heterogeneity (p = 0.017). However, peripheral IGF-1 levels were significantly decreased in AD subjects (9 studies; SMD, -0.44; 95%CI, -0.81 to -0.07) and MCI subjects exhibited a decreasing trend (4 studies; SMD, -0.31; 95%CI, -0.72 to 0.11) in studies with sample size≥80. Cerebrospinal fluid IGF-1 levels also significantly decreased in AD subjects (3 studies; SMD, -2.40; 95%CI, -4.36 to -0.43). CONCLUSION: These findings suggest that decreased peripheral and cerebrospinal fluid IGF-1 levels might be a potential marker for the cognitive decline and progression of AD.

Systemic immunization with altered myelin basic protein peptide produces sustained antidepressant-like effects.

Immune dysregulation, specifically of inflammatory processes, has been linked to behavioral symptoms of depression in both human and rodent studies. Here, we evaluated the antidepressant effects of immunization with altered peptide ligands of myelin basic protein (MBP)-MBP87-99[A91, A96], MBP87-99[A91], and MBP87-99[R91, A96]-in different models of depression and examined the mechanism by which these peptides protect against stress-induced depression. We found that a single dose of subcutaneously administered MBP87-99[A91, A96] produced antidepressant-like effects by decreasing immobility in the forced swim test and by reducing the escape latency and escape failures in the learned helplessness paradigm. Moreover, immunization with MBP87-99[A91, A96] prevented and reversed depressive-like and anxiety-like behaviors that were induced by chronic unpredictable stress (CUS). However, MBP87-99[R91, A96] tended to aggravate CUS-induced anxiety-like behavior. Chronic stress increased the production of peripheral and central proinflammatory cytokines and induced the activation of microglia in the prelimbic cortex (PrL), which was blocked by MBP87-99[A91, A96]. Immunization with MBP-derived altered peptide ligands also rescued chronic stress-induced deficits in p11, phosphorylated cyclic adenosine monophosphate response element binding protein, and brain-derived neurotrophic factor expression. Moreover, microinjections of recombinant proinflammatory cytokines and the knockdown of p11 in the PrL blunted the antidepressant-like behavioral response to MBP87-99[A91, A96]. Altogether, these findings indicate that immunization with altered MBP peptide produces prolonged antidepressant-like effects in rats, and the behavioral response is mediated by inflammatory factors (particularly interleukin-6), and p11 signaling in the PrL. Immune-neural interactions may impact central nervous system function and alter an individual's response to stress.

Chimeric specific antigen epitope-carrying dendritic cells induce interleukin-17(+) regulatory T cells to suppress food allergy.

BACKGROUND: The on-purpose-modulated dendritic cells (DCs) have shown charming effects on restoring immune regulatory functions in subjects with immune diseases. OBJECTIVE: This study aims to construct DCs carrying chimerical antigen (Ag) peptides (CAP-DCs) to induce interleukin (IL)-17+ inducible Tregs (iTregs) to alleviate food allergy (FA) in a murine model. METHODS: In this study, we constructed CAP-DCs. The CAP is a fusion protein, consisting of a segment of recombinant scFv of anti-DEC205 antibody and an ovalbumin (OVA) epitope (IC). A murine OVA-FA model was developed to test the effects of CAP-DCs on suppressing the allergic response in the intestine. RESULTS: The CAP-DCs are characterized as that a complex of scFv-IC is presented on the surface of the cells, moderately express CD80 and CD86 as well as IL-6, IL-23, transforming growth factor (TGF)-ß and CCR9. After being passively transferred with CAP-DCs or injection of scFv-IC, Ag-specific IL-17+ Foxp3+ iTregs were induced in the intestinal lamina propria of FA mice. The iTregs showed immune suppressive effects on Ag-specific Th2 response. FA mice were adoptively transferred with the CAP-DCs or scFv-IC injection, which resulted in a significant decrease in the number of Ag-specific Th2 cells and suppression of FA response in an Ag-specific manner. CONCLUSIONS AND CLINICAL RELEVANCE: CAP-DCs can ameliorate FA response by inducing Ag-specific IL-17+ Foxp3+ iTregs and suppressing Ag-specific Th2 response. To generate CAP-DCs has the translational potential in the treatment of FA.

Correction: EphB2 in the medial prefrontal cortex regulates vulnerability to stress.

Following publication of the above article, the authors noticed that an incorrect version of Figs. 2f, 3f, 5h and 7d was presented.

DAPK1: a Novel Pathology and Treatment Target for Alzheimer's Disease.

Alzheimer's disease (AD) is the most common neurodegenerative disease and seriously damages the health of elderly population. Clinical drug research targeting at classic pathology hallmarks, such as amyloid-ß (Aß) and tau protein, failed to achieve effective cognitive improvement, suggesting that the pathogenesis of AD is much complicated, and there are still other unknown and undetermined important factors. Death-associated protein kinase 1 (DAPK1) is a calcium/calmodulin-dependent serine/threonine kinase that plays an important role in various neuronal injury models. Mounting evidence has demonstrated that DAPK1 variants are associated with AD risk. The activation of DAPK1 is also involved in AD-related neurodegeneration in the brain. Exploring the roles of DAPK1 in AD might help us understand the pathogenic mechanisms and find a novel promising therapeutic target in AD. Therefore, in this review, we comprehensively summary the main progress of DAPK1 in the AD studies from genetic risk, neuropathological process, and clinical potential implications.

p62/SQSTM1 interacts with vimentin to enhance breast cancer metastasis.

The signalling adaptor p62 is frequently overexpressed in numerous cancer types. Here, we found that p62 expression was elevated in metastatic breast cancer and its overexpression correlated with reduced metastasis- and relapse-free survival times. Analysis of p62 expression in breast cancer cell lines demonstrated that high p62 expression was associated with the invasive phenotypes of breast cancer. Indeed, silencing p62 expression attenuated the invasive phenotypes of highly metastatic cells, whereas overexpressing p62 promoted the invasion of non-metastatic cells in in vitro microfluidic model. Moreover, MDA-MB-231 cells with p62 depletion which were grown in a three-dimensional culture system exhibited a loss of invasive protrusions. Consistently, genetic ablation of p62 suppressed breast cancer metastasis in both zebrafish embryo and immunodeficient mouse models, as well as decreased tumourigenicity in vivo. To explore the molecular mechanism by which p62 promotes breast cancer invasion, we performed a co-immunoprecipitation-mass spectrometry analysis and revealed that p62 interacted with vimentin, which mediated the function of p62 in promoting breast cancer invasion. Vimentin protein expression was downregulated upon p62 suppression and upregulated with p62 overexpression in breast cancer cells. Linear regression analysis of clinical breast cancer specimens showed a positive correlation between p62 and vimentin protein expression. Together, our findings provide strong evidence that p62 functions as a tumour metastasis promoter by binding vimentin and promoting its expression. This finding might help to develop novel molecular therapeutic strategies for breast cancer metastasis treatment.

Predictable Chronic Mild Stress during Adolescence Promotes Fear Memory Extinction in Adulthood.

Early-life stress in adolescence has a long-lasting influence on brain function in adulthood, and it is mostly recognized as a predisposing factor for mental illnesses, such as anxiety and posttraumatic stress disorder. Previous studies also indicated that adolescent predictable chronic mild stress (PCMS) in early life promotes resilience to depression- and anxiety-like behaviors in adulthood. However, the role of PCMS in associated memory process is still unclear. In the present study, we found that adolescent PCMS facilitated extinction and inhibited fear response in reinstatement and spontaneous recovery tests in adult rats, and this effect was still present 1 week later. PCMS in adolescence increased the activity of brain-derived neurotrophic factor (BDNF)-extracellular signal-regulated kinase 1/2 (ERK1/2) signaling in infralimbic cortex (IL) but not prelimbic cortex in adulthood. Intra-IL infusion of BDNF antibody and the ERK1/2 inhibitor U0126 reversed PCMS-induced enhancement of fear extinction. Moreover, we found that PCMS decreased DNA methylation of the Bdnf gene at exons IV and VI and elevated the mRNA levels of Bdnf in the IL. Our findings indicate that adolescent PCMS exposure promotes fear memory extinction in adulthood, which reevaluates the traditional notion of adolescent stress.

Galectin-1 inhibits oral-intestinal allergy syndrome.

BACKGROUND AND AIMS: The pathogenesis of oral-intestinal allergy syndrome (OIAS) has not been well understood. Published data indicate that galectin (Gal) 1 has immune regulatory functions. This study tests a hypothesis that Gal1 inhibits oral-intestinal allergy syndrome. METHODS: Mice were sensitized to peanut extracts (PE) via the buccal mucosa with or without using Gal1 together. RESULTS: Upon re-exposure to specific antigen, the OIAS mice showed the systemic allergic response, the oral allergic reactions, and intestinal allergic inflammation, including increases in serum histamine, drop of the core temperature, higher levels of PE-specific IgE and interleukin (IL)-4. Increases in mast cell and eosinophil in the oral mucosa and intestinal mucosa were also observed. The OIAS was inhibited by co-administration with Gal1 via a mechanism of suppressing micro RNA (miR)-98 and reversing the expression of IL-10 in CD14+ cells in the intestine. CONCLUSIONS: The OIAS can be induced by applying specific antigens to the oral mucosa, which can be inhibited by co-administration with Gal1.

BDNF-GSK-3ß-ß-Catenin Pathway in the mPFC Is Involved in Antidepressant-Like Effects of Morinda officinalis Oligosaccharides in Rats.

Background: Morinda officinalis oligosaccharides have been reported to exert neuroprotective and antidepressant-like effects in the forced swim test in mice. However, the mechanisms that underlie the antidepressant-like effects of Morinda officinalis oligosaccharides are unclear. Methods: Chronic unpredictable stress and forced swim test were used to explore the antidepressant-like effects of Morinda officinalis oligosaccharides and resilience to stress in rats. The phosphoinositide-3 kinase inhibitor LY294002 was microinjected in the medial prefrontal cortex to explore the role of glycogen synthase kinase-3ß in the antidepressant-like effects of Morinda officinalis oligosaccharides. The expression of brain-derived neurotrophic factor, phosphorylated-Ser9-glycogen synthase kinase 3ß, ß-catenin, and synaptic proteins was determined in the medial prefrontal cortex and the orbitofrontal cortex by western blot. Results: We found that Morinda officinalis oligosaccharides effectively ameliorated chronic unpredictable stress-induced depression-like behaviors in the sucrose preference test and forced swim test. The Morinda officinalis oligosaccharides also significantly rescued chronic unpredictable stress-induced abnormalities in the brain-derived neurotrophic factor-glycogen synthase kinase-3ß-ß-catenin pathway and synaptic protein deficits in the medial prefrontal cortex but not orbitofrontal cortex. The activation of glycogen synthase kinase-3ß by the phosphoinositide-3 kinase inhibitor LY294002 abolished the antidepressant-like effects of Morinda officinalis oligosaccharides in the forced swim test. Naïve rats that were treated with Morinda officinalis oligosaccharides exhibited resilience to chronic unpredictable stress, accompanied by increases in the expression of brain-derived neurotrophic factor, phosphorylated-Ser9-glycogen synthase kinase-3ß, and ß-catenin in the medial prefrontal cortex. Conclusion: Our findings indicate that the brain-derived neurotrophic factor-glycogen synthase kinase-3ß-ß-catenin pathway in the medial prefrontal cortex may underlie the antidepressant-like effect of Morinda officinalis oligosaccharides and resilience to stress.

Combination of specific allergen and probiotics induces specific regulatory B cells and enhances specific immunotherapy effect on allergic rhinitis.

The therapeutic efficacy of allergen specific immunotherapy (SIT) on allergic diseases is to be improved. Probiotics can regulate immune response. This study aims to promote the effect of SIT on allergic rhinitis (AR) by co-administration with Clostridium butyricum (Cb). In this study, patients with AR sensitized to mite allergens were enrolled to this study, and treated with SIT or/and Cb. The therapeutic efficacy was evaluated by the total nasal symptom scores (NSS), medication scores, serum specific IgE levels and T helper (Th)2 cytokine levels. The improvement of immune regulation in the AR patients was assessed by immunologic approaches. The results showed that treating AR patients with SIT alone markedly reduced NSS and medication scores; but did not alter the serum specific IgE, Th2 cytokines and skin prick test (SPT) index. The clinical symptoms on AR in SIT group relapsed one month after stopping SIT. Co-administration of Cb significantly enhanced the efficacy of SIT on AR as shown by suppression of NSS, medication scores, serum specific IgE, Th2 cytokines and SPT index; the regulatory B cell frequency was also markedly increased. Such an effect on AR was maintained throughout the observation period even after stopping the treatment. Butyrate blocked the activation of histone deacetylase-1, the downstream activities of epsilon chain promoter activation, and the IgE production in the antigen specific B cells. On the other hand, butyrate induced the IL-10 expression in B cells with a premise of the B cell receptor activation by specific antigens. In conclusion, administration with Cb can markedly enhance the efficacy of SIT on AR.

Flagellin modulates IgE expression in B cells to initiate food allergy in mice.

The initiation mechanism of IgE expression has not been fully understood. Flagellin (FGN) is an important microbial factor in the regulation of immune responses in the intestine. This study tests a hypothesis that FGN plays a crucial role in the isotype switching of IgE in B cells and the initiation of food allergy. In this study, the expression of IgE in B cells was analyzed by real time RT-PCR, Western blotting and chromatin immunoprecipitation. A mouse model was developed to assess the role of Toll like receptor-5 in the development of IgE-mediated allergic reaction in the intestinal mucosa. The results showed that exposure to FGN suppressed the expression of Bcl6 in B cells via increasing the levels of histone deacetylase (HDAC) 7; the latter up regulated the levels of methylated H3K9 and H3K27, down regulated RNA polymerase II and STAT3 (signal transducer and activator of transcription 3) at the Bcl6 promoter locus. Exposure to FGN and IL-4 markedly increased the expression of IgE in B cells via activating p300, H3K4, Pol II and STAT6 at the IgE promoter locus. As compared with the sensitized wild mice, the sensitized TLR5-deficient mice showed no detectable OVA-specific IgE in the serum; mast cells in the intestinal mucosa were not activated, no apparent allergic symptoms were evoked after the specific antigen challenge. In conclusion, FGN facilitates the initiation of food allergy in mice by triggering IgE transcription in B cells in a Th2 polarization environment via activating HDAC7 and suppressing Bcl6 expression.

Effects of environmental stress on the depression-like behaviors and the diurnal rhythm of corticosterone and melatonin in male rats.

Environmental stress (ES) is commonly used in producing chronic unpredictable mild stress to study pathogenesis of depression, including the regulatory role of circadian system on depression. However, the direct effect of ES on the circadian system has been rarely explored. The present study was aimed to investigate the effect of ES on depression-like behaviors and diurnal rhythm of plasma hormone/peptide levels in male rats. Rats were allocated into control group (CON group), low frequency ES group (LF group) and high frequency ES group (HF group). Sucrose preference test (SPT), open field test (OFT), weight gain, food and water intake were conducted to assess depression- and anxiety-like behaviors. A total of 7 times of the tail venous blood was collected with an interval of 4 h during 24 h from other rats who subjected to the same procedures of ES but not the behavioral tests. The alterations of diurnal rhythm of peripheral plasma corticosterone (CORT) and melatonin, and changes of the cholecystokinin (CCK), neuropeptide Y and leptin levels at zeitgeber time (ZT) 0 were detected by using enzyme-linked immunosorbent assay (ELISA). We found that ES led to a disturbance of diurnal rhythm of CORT and melatonin in the plasma. Besides, it also increased plasma leptin level and decreased body weight gain, but it did not produce depression- and anxiety-like behaviors compared with those rats in the control group. In short, our findings indicated that the ES could induce a disturbance of diurnal rhythm of plasma CORT and melatonin in male rats.

The Philadelphia chromosome in leukemogenesis.

The truncated chromosome 22 that results from the reciprocal translocation t(9;22)(q34;q11) is known as the Philadelphia chromosome (Ph) and is a hallmark of chronic myeloid leukemia (CML). In leukemia cells, Ph not only impairs the physiological signaling pathways but also disrupts genomic stability. This aberrant fusion gene encodes the breakpoint cluster region-proto-oncogene tyrosine-protein kinase (BCR-ABL1) oncogenic protein with persistently enhanced tyrosine kinase activity. The kinase activity is responsible for maintaining proliferation, inhibiting differentiation, and conferring resistance to cell death. During the progression of CML from the chronic phase to the accelerated phase and then to the blast phase, the expression patterns of different BCR-ABL1 transcripts vary. Each BCR-ABL1 transcript is present in a distinct leukemia phenotype, which predicts both response to therapy and clinical outcome. Besides CML, the Ph is found in acute lymphoblastic leukemia, acute myeloid leukemia, and mixed-phenotype acute leukemia. Here, we provide an overview of the clinical presentation and cellular biology of different phenotypes of Ph-positive leukemia and highlight key findings regarding leukemogenesis.