Nucleotide substitutions at the p.Gly117 and p.Thr180 mutational hot-spots of SKI alter molecular dynamics and may affect cell cycle.

Heterozygous deleterious variants in SKI cause Shprintzen-Goldberg Syndrome, which is mainly characterized by craniofacial features, neurodevelopmental disorder and thoracic aorta dilatations/aneurysms. The encoded protein is a member of the transforming growth factor beta signaling. Paucity of reported studies exploring the SGS molecular pathogenesis hampers disease recognition and clinical interpretation of private variants. Here, the unpublished c.349G>A, p.[Gly117Ser] and the recurrent c.539C>T, p.[Thr180Met] SKI variants were studied combining in silico and in vitro approach. 3D comparative modeling and calculation of the interaction energy predicted that both variants alter the SKI tertiary protein structure and its interactions. Computational data were functionally corroborated by the demonstration of an increase of MAPK phosphorylation levels and alteration of cell cycle in cells expressing the mutant SKI. Our findings confirmed the effects of SKI variants on MAPK and opened the path to study the role of perturbations of the cell cycle in SGS.

The Notch1 signaling pathway directly modulates the human RANKL-induced osteoclastogenesis.

Notch signaling is an evolutionary conserved pathway with a key role in tissue homeostasis, differentiation and proliferation. It was reported that Notch1 receptor negatively regulates mouse osteoclast development and formation by inhibiting the expression of macrophage colony-stimulating factor in mesenchymal cells. Nonetheless, the involvement of Notch1 pathway in the generation of human osteoclasts is still controversial. Here, we report that the constitutive activation of Notch1 signaling induced a differentiation block in human mononuclear CD14+ cells directly isolated from peripheral blood mononuclear cells (PBMCs) upon in vitro stimulation to osteoclasts. Additionally, using a combined approach of single-cell RNA sequencing (scRNA-Seq) simultaneously with a panel of 31 oligo-conjugated antibodies against cell surface markers (AbSeq assay) as well as unsupervised learning methods, we detected four different cell stages of human RANKL-induced osteoclastogenesis after 5 days in which Notch1 signaling enforces the cell expansion of specific subsets. These cell populations were characterized by distinct gene expression and immunophenotypic profiles and active Notch1, JAK/STAT and WNT signaling pathways. Furthermore, cell-cell communication analyses revealed extrinsic modulators of osteoclast progenitors including the IL7/IL7R and WNT5a/RYK axes. Interestingly, we also report that Interleukin-7 receptor (IL7R) was a downstream effector of Notch1 pathway and that Notch1 and IL7R interplay promoted cell expansion of human RANKL-induced osteoclast progenitors. Taken together, these findings underline a novel cell pattern of human osteoclastogenesis, outlining the key role of Notch1 and IL-7R signaling pathways.

Gut Microbiota, Inflammatory Bowel Disease, and Cancer: The Role of Guardians of Innate Immunity.

Inflammatory bowel diseases (IBDs) are characterized by a persistent low-grade inflammation that leads to an increased risk of colorectal cancer (CRC) development. Several factors are implicated in this pathogenetic pathway, such as innate and adaptive immunity, gut microbiota, environment, and xenobiotics. At the gut mucosa level, a complex interplay between the immune system and gut microbiota occurs; a disequilibrium between these two factors leads to an alteration in the gut permeability, called 'leaky gut'. Subsequently, an activation of several inflammatory pathways and an alteration of gut microbiota composition with a proliferation of pro-inflammatory bacteria, known as 'pathobionts', take place, leading to a further increase in inflammation. This narrative review provides an overview on the principal Pattern Recognition Receptors (PRRs), including Toll-like receptors (TLRs) and NOD-like receptors (NLRs), focusing on their recognition mechanisms, signaling pathways, and contributions to immune responses. We also report the genetic polymorphisms of TLRs and dysregulation of NLR signaling pathways that can influence immune regulation and contribute to the development and progression of inflammatory disease and cancer.

A functional role of Ephrin type-B receptor 6 (EPHB6) in T-cell acute lymphoblastic leukemia.

T-cell lymphoblastic acute leukemia (T-ALL) is an aggressive blood cancer, characterized by restricted cellular subsets with enriched leukemia initiating cells (LICs). Recently, Ephrin receptors (Eph) were described to be highly expressed in cancer stem cells. Here, using public RNA-Seq datasets of human T-ALL, we reported that EphB6 was the only member within the Eph family overexpressed in over 260 samples. We also found the highest level of EphB6 in a minor cell subpopulation within bulk tumors of patient-derived xenografts, obtained through the injection of primary patient biopsy material into immunocompromised NOD-Scid/IL2Rγc-/- (NSG) mice. Interestingly, this EphB6 positive (EphB6+) subset showed an enriched LIC activity after in vivo transplantation into NSG mice. Additionally, gene expression data at the single-cell level of primary patients' leukemic cells revealed that EphB6 + cells were significantly selected in minimal residual disease up to 30 days from the standard treatments and characterized by high levels of markers related to cell proliferation and poor clinical outcome, such as CCNB1 and KIF20A. Taken together, our data suggest that EphB6 supports LICs' maintenance and progression in T-ALL and, thus, targeting EphB6 + cells could be therapeutically relevant for the treatment of T-ALL patients.

Changes in Lymphocyte Subpopulations after Remdesivir Therapy for COVID-19: A Brief Report.

Remdesivir (RDV) has demonstrated clinical benefit in hospitalized COronaVIrus Disease (COVID)-19 patients. The objective of this brief report was to assess a possible correlation between RDV therapy and the variation in lymphocyte subpopulations. We retrospectively studied 43 hospitalized COVID-19 patients: 30 men and 13 women (mean age 69.3 ± 15 years); 9/43 had received RDV therapy. Six patients had no need for oxygen (severity group 0); 22 were on oxygen treatment with a fraction of inspired oxygen (FiO2) ≤ 50% (group 1); 7 on not-invasive ventilation (group 2); 3 on invasive mechanical ventilation (group 3); and 5 had died (group 4). Cytofluorimetric assessment of lymphocyte subpopulations showed substantial changes after RDV therapy: B lymphocytes and plasmablasts were significantly increased (p = 0.002 and p = 0.08, respectively). Cytotoxic T lymphocytes showed a robust reduction (p = 0.008). No changes were observed in CD4+-T cells and natural killers (NKs). There was a significant reduction in regulatory T cells (Tregs) (p = 0.02) and a significant increase in circulating monocytes (p = 0.03). Stratifying by disease severity, after RDV therapy, patients with severity 0-2 had significantly higher B lymphocyte and monocyte counts and lower memory and effector cytotoxic T cell counts. Instead, patients with severity 3-4 had significantly higher plasmablast and lower memory T cell counts. No significant differences for CD4+-T cells, Tregs, and NKs were observed. Our brief report showed substantial changes in the lymphocyte subpopulations analyzed between patients who did not receive RDV therapy and those after RDV treatment. Despite the small sample size, due to the retrospective nature of this brief report, the substantial changes in lymphocyte subpopulations reported could lead to speculation on the role of RDV treatment both on immune responses against the virus and on the possible downregulation of the cytokine storm observed in patients with more severe disease.

The circadian clock circuitry modulates leukemia initiating cell activity in T-cell acute lymphoblastic leukemia.

BACKGROUND: T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy, characterized by restricted cellular subsets with asymmetrically enriched leukemia initiating cell (LIC) activity. Nonetheless, it is still unclear which signaling programs promote LIC maintenance and progression. METHODS: Here, we evaluated the role of the biological clock in the regulation of the molecular mechanisms and signaling pathways impacting the cellular dynamics in T-ALL through an integrated experimental approach including gene expression profiling of shRNA-modified T-ALL cell lines and Chromatin Immunoprecipitation Sequencing (ChIP-Seq) of leukemic cells. Patient-derived xenograft (PDXs) cell subsets were also genetically manipulated in order to assess the LIC activity modulated by the loss of biological clock in human T-ALL. RESULTS: We report that the disruption of the circadian clock circuitry obtained through shRNA-mediated knockdown of CLOCK and BMAL1 genes negatively impacted the growth in vitro as well as the activity in vivo of LIC derived from PDXs after transplantation into immunodeficient recipient mice. Additionally, gene expression data integrated with ChIP-Seq profiles of leukemic cells revealed that the circadian clock directly promotes the expression of genes, such as IL20RB, crucially involved in JAK/STAT signaling, making the T-ALL cells more responsive to Interleukin 20 (IL20). CONCLUSION: Taken together, our data support the concept that the biological clock drives the expression of IL20R prompting JAK/STAT signaling and promoting LIC activity in T-ALL and suggest that the selective targeting of circadian components could be therapeutically relevant for the treatment of T-ALL patients.

Noncanonical ß-catenin interactions promote leukemia-initiating activity in early T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is a T-cell malignancy characterized by cell subsets and enriched with leukemia-initiating cells (LICs). ß-Catenin modulates LIC activity in T-ALL. However, its role in maintaining established leukemia stem cells remains largely unknown. To identify functionally relevant protein interactions of ß-catenin in T-ALL, we performed coimmunoprecipitation followed by liquid chromatography-mass spectrometry. Here, we report that a noncanonical functional interaction of ß-catenin with the Forkhead box O3 (FOXO3) transcription factor positively regulates LIC-related genes, including the cyclin-dependent kinase 4, which is a crucial modulator of cell cycle and tumor maintenance. We also confirm the relevance of these findings using stably integrated fluorescent reporters of ß-catenin and FOXO3 activity in patient-derived xenografts, which identify minor subpopulations with enriched LIC activity. In addition, gene expression data at the single-cell level of leukemic cells of primary patients at the time of diagnosis and minimal residual disease (MRD) up to 30 days after the standard treatments reveal that the expression of ß-catenin- and FOXO3-dependent genes is present in the CD82+CD117+ cell fraction, which is substantially enriched with LICs in MRD as well as in early T-cell precursor ALL. These findings highlight key functional roles for ß-catenin and FOXO3 and suggest novel therapeutic strategies to eradicate aggressive cell subsets in T-ALL.

Extracellular vesicle microRNAs contribute to Notch signaling pathway in T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive T-cell malignancy characterized by genotypically-defined and phenotypically divergent cell populations, governed by adaptive landscapes. Clonal expansions are associated to genetic and epigenetic events, and modulation of external stimuli that affect the hierarchical structure of subclones and support the dynamics of leukemic subsets. Recently, small extracellular vesicles (sEV) such as exosomes were also shown to play a role in leukemia. Here, by coupling miRNome, bulk and single cell transcriptome profiling, we found that T-ALL-secreted sEV contain NOTCH1-dependent microRNAs (EV-miRs), which control oncogenic pathways acting as autocrine stimuli and ultimately promoting the expansion/survival of highly proliferative cell subsets of human T-cell leukemias. Of interest, we found that NOTCH1-dependent EV-miRs mostly comprised members of miR-17-92a cluster and paralogues, which rescued in vitro the proliferation of T-ALL cells blocked by γ-secretase inhibitors (GSI) an regulated a network of genes characterizing patients with relapsed/refractory early T-cell progenitor (ETP) ALLs. All these findings suggest that NOTCH1 dependent EV-miRs may sustain the growth/survival of immunophenotypically defined cell populations, altering the cell heterogeneity and the dynamics of T-cell leukemias in response to conventional therapies.

Effectiveness of Booster Dose of Anti SARS-CoV-2 BNT162b2 in Cirrhosis: Longitudinal Evaluation of Humoral and Cellular Response.

Background: LC has been associated with hyporesponsiveness to several vaccines. Nonetheless, no data on complete serological and B- and T-cell immune response are currently available. Aims: To assess, in comparison with healthy controls of the same age and gender, both humoral and cellular immunoresponses of patients with LC after two or three doses of the mRNA Pfizer-BioNTech vaccine against SARS-CoV-2 and to investigate clinical features associated with non-response. Material and methods: 179 patients with LC of CTP class A in 93.3% and viral etiology in 70.1% of cases were longitudinally evaluated starting from the day before the first dose to 4 weeks after the booster dose. Their antibody responses were compared to those of healthcare workers without co-morbidities. In a subgroup of 40 patients, B- and T-cell responses were also compared to controls. Results: At d31, d90 and d180 after BNT162b2 vaccine, no detectable SARS-CoV-2 IgG response was observed in 5.9%, 3.9% and 7.2% of LC patients as compared to 0 controls (p < 0.03). A delay in B-cell and lack of prompt T-cell response compared to healthcare workers was also registered. A significant correlation between antibody titers and cellular response was observed. A MELD score > 8 was the only independent predictor of poor d31 response (p = 0.028). Conclusions: Our results suggest that cirrhotic patients have a slower and in <10% suboptimal immune response to SARS-CoV-2 vaccination. Rates of breakthrough infections were comparable between cirrhotics and controls. The booster dose was critical in inducing both humoral and cellular responses comparable to controls.

Functional associations between polymorphic regions of the human 3'IgH locus and COVID-19 disease.

PURPOSE: The pandemic diffusion of Coronavirus Disease 2019 (COVID-19) has highlighted significant gender-related differences in disease severity. Despite several hypotheses being proposed, how the genetic background of COVID-19 patients might impact clinical outcomes remains largely unknown. METHODS: We collected blood samples from 192 COVID-19 patients (115 men, 77 women, mean age 67 ± 19 years) admitted between March and June 2020 at two different hospital centers in Italy, and determined the allelic distribution of nine Single Nucleotide Polymorphisms (SNPs), located at the 3'Regulatory Region (3'RR)-1 in the immunoglobulin (Ig) heavy chain locus, including *1 and *2 alleles of polymorphic hs1.2 enhancer region. RESULTS: In COVID-19 patients, the genotyped SNPs exhibited strong Linkage Disequilibrium and produced 7 specific haplotypes, associated to different degrees of disease severity, including the occurrence of pneumonia. Additionally, the allele *2, which comprises a DNA binding site for the Estrogen receptor alpha (ERα) in the polymorphic enhancer hs1.2 of 3'RR-1, was significantly enriched in women with a less severe disease. CONCLUSIONS: These findings document genetic variants associated to individual clinical severity of COVID-19 disease. Most specifically, a novel genetic protective factor was identified that might explain the sex-related differences in immune response to Sars-COV-2 infection in humans.

Cellular and Humoral Immune Responses and Breakthrough Infections After Two Doses of BNT162b Vaccine in Healthcare Workers (HW) 180 Days After the Second Vaccine Dose.

Background: Immunity and clinical protection induced by mRNA vaccines against SARS-CoV-2 have been shown to decline overtime. To gather information on the immunity profile deemed sufficient in protecting against hospitalization, we tested IgG levels, interferon-gamma (IFN-γ) secretion, and neutralizing antibodies 180 days (d180) after the second shot of BNT162b vaccine, in HW. Methods: A total of 392 subjects were enrolled. All received BioNTech/Pfizer from February 2020 to April 2021. The vaccine-specific humoral response was quantitatively determined by testing for IgG anti-S1 domain of SARS-CoV-spike protein. Live virus microneutralization (MN) was evaluated by an assay performing incubation of serial 2-fold dilution of human serum samples, starting from 1:10 to 1:5120, with an equal volume of Wuhan strain and Delta VOC viral solution and assessing the presence/absence of a cytopathic effect. SARS-CoV-2-spike protein-specific T-cell response was determined by a commercial IFN-γ release assay. Results: In 352 individuals, at d180, IgG levels decreased substantially but no results below the assay's positivity threshold were observed. Overall, 22 naive (8.1%) had values above the highest threshold. Among COVID-naive, the impact of age, which was observed at earlier stages, disappeared at d180, while it remained significant for 81 who had experienced a previous infection. Following the predictive model of protection by Khoury, we transformed the neutralizing titers in IU/ml and used a 54 IU/ml threshold to identify subjects with 50% protective immunity. Overall, live virus MN showed almost all subjects with previous exposure to SARS-CoV-2 neutralized the virus as compared to 33% of naive double-dosed subjects (p < 0.0001). All previously exposed subjects had strong IFN-γ secretion (>200 mIU/ml); among 271 naive, 7 (2.58%) and 17 (6.27%) subjects did not show borderline or strong secretion, respectively. Conclusions: In naive subjects, low IgG titers are relatively long-lasting. Only a third of naive subjects maintain neutralizing responses. After specific stimulation, a very limited number of naive were unable to produce IFN-γ. The results attained in the small group of subjects with breakthrough infection suggest that simultaneous neutralizing antibody titers <20, binding antibody levels/ml <200, and IFN-γ <1,000 mIU/ml in subjects older than 58 may identify at-risk groups.

Log reduction of leukemic cells and minimal residual disease by flow cytometry represent effective predictors of clinical outcome in elderly patients with acute myeloid leukemia.

BACKGROUND: Nowadays minimal residual disease (MRD) and log-reduction of leukemic cells are poorly investigated in elderly patients with acute myeloid leukemia (AML) treated with hypometilating agents (HMAs). Studies focusing on MRD in elderly AML patients who received HMAs are scant and devoid of rigorous criteria for both enrollment and monitoring. Log-reduction has never been investigated in these patients. Thus, the purpose of our study was to compare the prognostic impact of MRD and log-reduction of leukemic cells at the optimal time of assessment in older AML patients. METHODS: Elderly patients who completed at least six cycles of HMAs and showed suitable leukemia-associated immunophenotypes (LAIPs) for the MRD and log-reduction assessment by flow cytometry were enrolled in the study. RESULTS: After comparing the times of assessment C4 (4-cycles) and C6 (6-cycles), C6 has been chosen as optimal. Patients who achieved MRD negativity or 2-log-reduction of leukemic cells at C6 had a significantly longer DFS. Particularly, results of 2-log-reduction were confirmed a multivariate analysis. Patients with MRD negativity or 2-log reduction of leukemic cells showed an improvement of their OS, although not significantly. CONCLUSIONS: Our data confirmed the predictive role of MRD and 2-log reduction also in older AML patients treated with HMAs.

COVID-19 Specific Immune Markers Revealed by Single Cell Phenotypic Profiling.

COVID-19 is a viral infection, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and characterized by a complex inflammatory process and clinical immunophenotypes. Nowadays, several alterations of immune response within the respiratory tracts as well as at the level of the peripheral blood have been well documented. Nonetheless, their effects on COVID-19-related cell heterogeneity and disease progression are less defined. Here, we performed a single-cell RNA sequencing of about 400 transcripts relevant to immune cell function including surface markers, in mononuclear cells (PBMCs) from the peripheral blood of 50 subjects, infected with SARS-CoV-2 at the diagnosis and 27 healthy blood donors as control. We found that patients with COVID-19 exhibited an increase in COVID-specific surface markers in different subsets of immune cell composition. Interestingly, the expression of cell receptors, such as IFNGR1 and CXCR4, was reduced in response to the viral infection and associated with the inhibition of the related signaling pathways and immune functions. These results highlight novel immunoreceptors, selectively expressed in COVID-19 patients, which affect the immune functionality and are correlated with clinical outcomes.

Associations between Allelic Variants of the Human IgH 3' Regulatory Region 1 and the Immune Response to BNT162b2 mRNA Vaccine.

The escalation of Coronavirus disease 2019 (COVID-19) has required the development of safe and effective vaccines against the severe acute respiratory syndrome coronavirus 2-associated (SARS-CoV-2), which is the causative agent of the disease. Here, we determined the levels of antibodies, antigen-specific B cells, against a recombinant GFP-tagged SARS-CoV-2 spike (S) protein and total T and NK cell subsets in subjects up to 20 days after the injection of the BNT162b2 (Pfizer-BioNTech) vaccine using a combined approach of serological and flow cytometry analyses. In former COVID-19 patients and highly responsive individuals, a significant increase of antibody production was detected, simultaneous with an expansion of antigen-specific B cell response and the total number of NK-T cells. Additionally, through a genetic screening of a specific polymorphic region internal to the 3' regulatory region 1 (3'RR1) of human immunoglobulin constant-gene (IgH) locus, we identified different single-nucleotide polymorphic (SNP) variants associated with either highly or lowly responsive subjects. Taken together, these results suggest that favorable genetic backgrounds and immune profiles support the progression of an effective response to BNT162b2 vaccination.

Early Serological Response to BNT162b2 mRNA Vaccine in Healthcare Workers.

PURPOSE: Clinical significance and durability of serological response after mRNA COVID-19 vaccines is under investigation. Data on early virological response are limited. To iden-tify potential predictors of antibody durability, circulating antibody levels were longitudinally ex-plored in healthcare workers included in a follow-up program for SARS-CoV-2 infection. Meth-ods: Subjects meeting the inclusion criteria signed an informed consent. Serum samples were col-lected at baseline, before the first BNT162b2 vaccine, at days 7, 21, 31, 90, and 180 days after the first dose. Serological evaluation was performed by QuantiVac Euroimmune anti-S1 antibody as-say. Only subjects followed-up until day 90 are here considered. RESULTS: Of 340 taken into consid-eration, 265 subjects were naive, and 75 COVID-19 experienced. The former showed a progres-sive increase in their antibody levels before day 90 decline, while the latter showed antibody levels reaching a plateau at day 7 and slightly declining at day 90. All showed antibody levels higher than the assay cut-off at day 31 and 90. Among naive, 108 had an early response whose predic-tors were younger age and female gender (OR 0.94, 95% CI 0.91-0.96, p < 0.0001; and OR 2.58, 95% CI 1.48-4.51, p = 0.0009). Naive subjects experienced a day 30/90 decline in antibody levels, whereas experienced did not. Early response was an independent predictor of higher day 30/90 antibody levels decline (OR = 2.05, 95% CI 1.04-4.02; p = 0.037). CONCLUSIONS: Our results suggest that in healthcare workers early response might be inversely associated with antibody levels 90 days after BNT162b2 vaccine.

The Histone Variant MacroH2A1 Impacts Circadian Gene Expression and Cell Phenotype in an In Vitro Model of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. A foremost risk factor for HCC is obesity/metabolic syndrome-related non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH), which is prompted by remarkable changes in transcription patterns of genes enriching metabolic, immune/inflammatory, and circadian pathways. Epigenetic mechanisms play a role in NAFLD-associated HCC, and macroH2A1, a variant of histone H2A, is involved in the pathogenesis modulating the expression of oncogenes and/or tumor suppressor genes and interacting with SIRT1, which crucially impacts the circadian clock circuitry. Hence, we aimed to appraise if and how macroH2A1 regulated the expression patterns of circadian genes in the setting of NAFLD-associated HCC. We took advantage of an in vitro model of liver cancer represented by HepG2 (human hepatocarcinoma) cells stably knocked down for macroH2A1 and conducted whole transcriptome profiling and deep phenotyping analysis. We found up-regulation of PER1 along with several deregulated circadian genes, enriching several important pathways and functions related to cancer onset and progression, such as epithelial-to-mesenchymal transition, cell cycle deregulation, and DNA damage. PER1 silencing partially mitigated the malignant phenotype induced by the loss of macroH2A1 in HCC cells. In conclusion, our findings suggest a modulatory role for the core circadian protein PER1 in liver carcinogenesis in the context of a lack of the macroH2A1 epigenetic and transcriptional landscape.

Protein Tyrosine Kinases: Their Roles and Their Targeting in Leukemia.

Protein kinases constitute a large group of enzymes catalysing protein phosphorylation and controlling multiple signalling events. The human protein kinase superfamily consists of 518 members and represents a complicated system with intricate internal and external interactions. Protein kinases are classified into two main families based on the ability to phosphorylate either tyrosine or serine and threonine residues. Among the 90 tyrosine kinase genes, 58 are receptor types classified into 20 groups and 32 are of the nonreceptor types distributed into 10 groups. Tyrosine kinases execute their biological functions by controlling a variety of cellular responses, such as cell division, metabolism, migration, cell-cell and cell matrix adhesion, cell survival and apoptosis. Over the last 30 years, a major focus of research has been directed towards cancer-associated tyrosine kinases owing to their critical contributions to the development and aggressiveness of human malignancies through the pathological effects on cell behaviour. Leukaemia represents a heterogeneous group of haematological malignancies, characterised by an uncontrolled proliferation of undifferentiated hematopoietic cells or leukaemia blasts, mostly derived from bone marrow. They are usually classified as chronic or acute, depending on the rates of their progression, as well as myeloid or lymphoblastic, according to the type of blood cells involved. Overall, these malignancies are relatively common amongst both children and adults. In malignant haematopoiesis, multiple tyrosine kinases of both receptor and nonreceptor types, including AXL receptor tyrosine kinase (AXL), Discoidin domain receptor 1 (DDR1), Vascular endothelial growth factor receptor (VEGFR), Fibroblast growth factor receptor (FGFR), Mesenchymal-epithelial transition factor (MET), proto-oncogene c-Src (SRC), Spleen tyrosine kinase (SYK) and pro-oncogenic Abelson tyrosine-protein kinase 1 (ABL1) mutants, are implicated in the pathogenesis and drug resistance of practically all types of leukaemia. The role of ABL1 kinase mutants and their therapeutic inhibitors have been extensively analysed in scientific literature, and therefore, in this review, we provide insights into the impact and mechanism of action of other tyrosine kinases involved in the development and progression of human leukaemia and discuss the currently available and emerging treatment options based on targeting these molecules.

Targeting Leukemia-Initiating Cells in Acute Lymphoblastic Leukemia.

The concept that different leukemias are developmentally distinct and, like in normal hematopoiesis, generated by restricted populations of cells named leukemia-initiating cells (LIC), is becoming more established. These cancer stem-like cells have been assumed to have unique properties, including the capability of self-renewing and giving rise to "differentiated" or non-LICs that make up the whole tumor. Cell populations enriched with LIC activity have been characterized in different hematopoietic malignancies, including human acute lymphoblastic leukemia (ALL). Related studies have also demonstrated that LICs are functionally distinct from bulk cells and modulated by distinct molecular signaling pathways and epigenetic mechanisms. Here we review several biological and clinical aspects related to LICs in ALL, including (i) immunophenotypic characterization of LIC-enriched subsets in human and mouse models of ALL, (ii) emerging therapeutics against regulatory signaling pathways involved in LIC progression and maintenance in T- and B-cell leukemias, (iii) novel epigenetic and age-related mechanisms of LIC propagation, and (iv) ongoing efforts in immunotherapy to eradicate LIC-enriched cell subsets in relapsed and refractory ALL cases. Current conventional treatments do not efficiently eliminate LICs. Therefore, innovative therapeutics that exclusively target LICs hold great promise for developing an effective cure for ALL.

Insights into the molecular pathogenesis of cardiospondylocarpofacial syndrome: MAP3K7 c.737-7A > G variant alters the TGFß-mediated α-SMA cytoskeleton assembly and autophagy.

Transforming growth factor beta-activated kinase 1 (TAK1) is a highly conserved kinase protein encoded by MAP3K7, and activated by multiple extracellular stimuli, growth factors and cytokines. Heterozygous variants in MAP3K7 cause the cardiospondylocarpofacial syndrome (CSCFS) which is characterized by short stature, dysmorphic facial features, cardiac septal defects with valve dysplasia, and skeletal anomalies. CSCFS has been described in seven patients to date and its molecular pathogenesis is only partially understood. Here, the functional effects of the MAP3K7 c.737-7A > G variant, previously identified in a girl with CSCFS and additional soft connective tissue features, were explored. This splice variant generates an in-frame insertion of 2 amino acid residues in the kinase domain of TAK1. Computational analysis revealed that this in-frame insertion alters protein dynamics in the kinase activation loop responsible for TAK1 autophosphorylation after binding with its interactor TAB1. Co-immunoprecipitation studies demonstrate that the ectopic expression of TAK1-mutated protein impairs its ability to physically bind TAB1. In patient's fibroblasts, MAP3K7 c.737-7A > G variant results in reduced TAK1 autophosphorylation and dysregulation of the downstream TAK1-dependent signaling pathway. TAK1 loss-of-function is associated with an impaired TGFß-mediated α-SMA cytoskeleton assembly and cell migration, and defective autophagy process. These findings contribute to our understanding of the molecular pathogenesis of CSCFS and might offer the rationale for the design of novel therapeutic targets.

TRIM8 interacts with KIF11 and KIFC1 and controls bipolar spindle formation and chromosomal stability.

The faithful inheritance of chromosomes is essential for the propagation of organisms. In eukaryotes, central to this process is the mitotic spindle. Recently, we have identified TRIM8 as a gene aberrantly expressed in gliomas whose expression reduces the clonogenic potential in the patients' glioma cells. TRIM8 encodes an E3 ubiquitin ligase involved in various pathological processes, including hypertrophy, antiviral defense, encephalopathy, and cancer development. To gain insights into the TRIM8 functions, we characterized the TRIM8 interactome in primary mouse embryonic neural stem cells using proteomics. We found that TRIM8 interacts with KIFC1, and KIF11/Eg5, two master regulators of mitotic spindle assembly and cytoskeleton reorganization. By exploring the TRIM8 role in the mitotic spindle machinery, we showed that TRIM8 localizes at the mitotic spindle during mitosis and plays a role in centrosome separation at the beginning of mitosis with a subsequent delay of the mitotic progression and impact on chromosomal stability.