ALKBH3 partner ASCC3 mediates P-body formation and selective clearance of MMS-induced 1-methyladenosine and 3-methylcytosine from mRNA.

BACKGROUND: Reversible enzymatic methylation of mammalian mRNA is widespread and serves crucial regulatory functions, but little is known to what degree chemical alkylators mediate overlapping modifications and whether cells distinguish aberrant from canonical methylations. METHODS: Here we use quantitative mass spectrometry to determine the fate of chemically induced methylbases in the mRNA of human cells. Concomitant alteration in the mRNA binding proteome was analyzed by SILAC mass spectrometry. RESULTS: MMS induced prominent direct mRNA methylations that were chemically identical to endogenous methylbases. Transient loss of 40S ribosomal proteins from isolated mRNA suggests that aberrant methylbases mediate arrested translational initiation and potentially also no-go decay of the affected mRNA. Four proteins (ASCC3, YTHDC2, TRIM25 and GEMIN5) displayed increased mRNA binding after MMS treatment. ASCC3 is a binding partner of the DNA/RNA demethylase ALKBH3 and was recently shown to promote disassembly of collided ribosomes as part of the ribosome quality control (RQC) trigger complex. We find that ASCC3-deficient cells display delayed removal of MMS-induced 1-methyladenosine (m1A) and 3-methylcytosine (m3C) from mRNA and impaired formation of MMS-induced P-bodies. CONCLUSIONS: Our findings conform to a model in which ASCC3-mediated disassembly of collided ribosomes allows demethylation of aberrant m1A and m3C by ALKBH3. Our findings constitute first evidence of selective sanitation of aberrant mRNA methylbases over their endogenous counterparts and warrant further studies on RNA-mediated effects of chemical alkylators commonly used in the clinic.

Impaired oxidative stress response characterizes HUWE1-promoted X-linked intellectual disability.

Mutations in the HECT, UBA and WWE domain-containing 1 (HUWE1) E3 ubiquitin ligase cause neurodevelopmental disorder X-linked intellectual disability (XLID). HUWE1 regulates essential processes such as genome integrity maintenance. Alterations in the genome integrity and accumulation of mutations have been tightly associated with the onset of neurodevelopmental disorders. Though HUWE1 mutations are clearly implicated in XLID and HUWE1 regulatory functions well explored, currently much is unknown about the molecular basis of HUWE1-promoted XLID. Here we showed that the HUWE1 expression is altered and mutation frequency increased in three different XLID individual (HUWE1 p.R2981H, p.R4187C and HUWE1 duplication) cell lines. The effect was most prominent in HUWE1 p.R4187C XLID cells and was accompanied with decreased DNA repair capacity and hypersensitivity to oxidative stress. Analysis of HUWE1 substrates revealed XLID-specific down-regulation of oxidative stress response DNA polymerase (Pol) λ caused by hyperactive HUWE1 p.R4187C. The subsequent restoration of Polλ levels counteracted the oxidative hypersensitivity. The observed alterations in the genome integrity maintenance may be particularly relevant in the cortical progenitor zones of human brain, as suggested by HUWE1 immunofluorescence analysis of cerebral organoids. These results provide evidence that impairments of the fundamental cellular processes, like genome integrity maintenance, characterize HUWE1-promoted XLID.

Exercise induces cerebral VEGF and angiogenesis via the lactate receptor HCAR1.

Physical exercise can improve brain function and delay neurodegeneration; however, the initial signal from muscle to brain is unknown. Here we show that the lactate receptor (HCAR1) is highly enriched in pial fibroblast-like cells that line the vessels supplying blood to the brain, and in pericyte-like cells along intracerebral microvessels. Activation of HCAR1 enhances cerebral vascular endothelial growth factor A (VEGFA) and cerebral angiogenesis. High-intensity interval exercise (5 days weekly for 7 weeks), as well as L-lactate subcutaneous injection that leads to an increase in blood lactate levels similar to exercise, increases brain VEGFA protein and capillary density in wild-type mice, but not in knockout mice lacking HCAR1. In contrast, skeletal muscle shows no vascular HCAR1 expression and no HCAR1-dependent change in vascularization induced by exercise or lactate. Thus, we demonstrate that a substance released by exercising skeletal muscle induces supportive effects in brain through an identified receptor.

PML regulates neuroprotective innate immunity and neuroblast commitment in a hypoxic-ischemic encephalopathy model.

Regulation of innate immune responses and activation of tissue regenerative processes are key elements in the pathophysiology of brain injuries. The promyelocytic leukemia (PML) gene was originally identified on a breakpoint of chromosomal translocation t(15;17) associated with acute PML. We have studied the role of PML protein during acute and regenerative phases after hypoxia-ischemia (HI) in brains of neonatal mice. We found that PML prevents tissue loss and apoptotic cell death selectively in subcortical regions of the brain at early stages after damage. In accordance with this, we revealed that PML is important for microglia activation and production of key inflammatory cytokines such as IL1α, IL1ß, IL1RN, CXCL10, CCL12 and TNFα. During the regenerative phase, PML-depleted mice were found to have impaired transformation of transit-amplifying precursors into migratory progenitors. This was accompanied by increased ratios of symmetric versus asymmetric neural progenitor cell divisions during tissue repair and a specific defect in tissue restoration within the striatum 42 days after HI. The data demonstrate a dual role of PML in protection and recovery after brain injury.

Promyelocytic leukemia bodies tether to early endosomes during mitosis.

During mitosis the nuclear envelope breaks down, leading to potential interactions between cytoplasmic and nuclear components. PML bodies are nuclear structures with tumor suppressor and antiviral functions. Early endosomes, on the other hand, are cytoplasmic vesicles involved in transport and growth factor signaling. Here we demonstrate that PML bodies form stable interactions with early endosomes immediately following entry into mitosis. The 2 compartments remain stably associated throughout mitosis and dissociate in the cytoplasm of newly divided daughter cells. We also show that a minor subset of PML bodies becomes anchored to the mitotic spindle poles during cell division. The study demonstrates a stable mitosis-specific interaction between a cytoplasmic and a nuclear compartment.

Expression of Bcl2L12 in chronic lymphocytic leukemia patients: association with clinical and molecular prognostic markers.

Dysregulation of apoptosis is a distinctive feature of chronic lymphocytic leukemia (CLL), although a unique mechanism underlying apoptosis resistance of CLL B lymphocytes has not been identified yet. Aberrant expression as well as genetic and epigenetic alterations of numerous genes involved in different pathways of apoptosis regulation has been described in CLL. Here, we report the expression analysis of Bcl2L12 (Bcl2-like 12), a novel apoptotic gene belonging to Bcl2 family, in 58 Serbian CLL patients. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) analysis revealed a significant overexpression of Bcl2L12 mRNA in CLL samples compared to non-leukemic samples, implying its role in the pathogenesis of the disease. Receiver operating characteristic (ROC) analysis showed that Bcl2L12 expression efficiently discriminates CLL cases from healthy controls. However, relatively homogenous Bcl2L12 mRNA expression among patients did not reflect their clinical characteristics (with the exception of lactate dehydrogenase status and time from diagnosis to treatment) and failed to show association with the most informative prognostic markers, namely the mutational status of rearranged immunoglobulin heavy chain variable region genes, CD38 and lipoprotein lipase gene (LPL) expression.

Mutational status and gene repertoire of IGHV-IGHD-IGHJ rearrangements in Serbian patients with chronic lymphocytic leukemia.

UNLABELLED: The mutational status and configuration of immunoglobulin heavy variable (IGHV) gene rearrangements was analyzed in 85 Serbian patients with chronic lymphocytic leukemia (CLL). We found that 55.3% of cases belonged to mutated and 44.7% to unmutated CLL, progressive disease predominating in the unmutated subset. IGHV gene use resembled that obtained for Mediterranean countries, except for underrepresentation of the IGHV4 subgroup in our cohort. BACKGROUND: Chronic lymphocytic leukemia (CLL) results from the clonal expansion of mature B lymphocytes and is characterized by extreme clinical heterogeneity. One of the most reliable prognostic markers in chronic lymphocytic leukemia (CLL) is the mutational status of immunoglobulin heavy variable (IGHV) genes, which defines 2 subsets, mutated CLL (M-CLL) and unmutated CLL (U-CLL), with different clinical courses. Biased IGHV gene use between M-CLL and U-CLL clones, as well as population differences in the IGHV gene repertoire have been reported. PATIENTS AND METHODS: In this study, mutational status and configuration of IGHV-IGHD-IGHJ rearrangements in 85 Serbian patients were analyzed using reverse transcriptase-polymerase chain reaction (RT-PCR) and sequencing methodology. RESULTS: We found that 55.3% of cases belonged to M-CLL and 44.7% belonged to U-CLL, with progressive disease predominating in the unmutated subset. Most frequently expressed was the IGHV3 subgroup (55.7%), followed by IGHV1 (27.3%), IGHV4 (12.5%), IGHV5 (2.3%), IGHV2 (1.1%), and IGHV6 (1.1%). The distribution of IGHD subgroups was as follows: IGHD3, 39.1%; IGHD2, 21.8%; IGHD6, 12.6%; IGHD1, 10.3%; IGHD4, 8%; IGHD5, 6.9%; and IGHD7, 1.1%. The most frequent IGHJ gene was IGHJ4 (48.9%), followed by IGHJ6 (28.4%), IGHJ3 (11.4%), and IGHJ5 (11.4%). In 15.3% of cases, heavy complementarity-determining region 3 (VH CDR3) amino acid sequences could be assigned to previously defined stereotyped clusters. CONCLUSIONS: Our study showed a strong correlation between IGHV gene mutational status and clinical course of CLL. IGHV gene use was comparable to that obtained for Mediterranean countries, with the exception of the IGHV4 subgroup, which was underrepresented in our cohort.

[Progression of nodal marginal zone lymphoma into diffuse large B cell lymphoma in a patient with Sjögren's syndrome].

INTRODUCTION: Sjögren's syndrome is a chronic autoimmune disorder carrying the risk of the development of non-Hodgkin's lymphoma, most frequently marginal zone lymphoma. CASE OUTLINE: A 66-year-old male patient with Sjögren's syndrome, after a year of the disease, developed a nodal marginal zone lymphoma with lymphoma cells in peripheral blood which had the following immunophenotype: CD19, CD20, CD22, CD19/kappa, CD79b+. After six cycles of chemotherapy according to CHOP protocol (cyclophosphamide, doxorubicin, vincristine and prednisone) disease remission was achieved lasting four months, followed by enlargement of lymph nodes in all areas (generalized lymphadenopathy), splenomegaly and enlargement of the right parotid gland. Bone marrow biopsy and histology confirmed lymphoma of the same morphologic and immunohistochemic profile. Biopsy of a very enlarged hard right parotid gland, by using histology and immunohistochemistry, showed lymphoid tumour tissue with blast appearance and a number of nucleoli corresponding to centroblasts and less to immunoblasts. Immunophenotypes of these cells were as follows: CD79alfa+, CD20+, CD3-, bcl-2-; proliferative activity measured with KI-67 was high rating 60%. Histology and immunohistochemistry showed the co-existence of a diffuse large B cell lymphoma with marginal zone lymphoma. In spite of aggressive chemotherapy treatment according to protocol ESHAP (Vepesid 200 mg i.v. on 1st and 2nd day and 100 mg on 3rd, 4th and 5th day; Cisplatin 20-20-10 mg on 1st to 4th day) the disease showed a progressive course. CONCLUSION: In patients with Sjögren's syndrome, the possibility of lymphoma should be kept in mind and in suspected cases timely diagnostic and therapeutic measures should be undertaken.

FGF-R3 and OPG expression in patient with multiple myeloma following systemic sclerosis: case report and review of the literature.

The presence of multiple myeloma (MM) in a patient with systemic sclerosis is a rare and unusual occurrence with unclear significance. We report the case of a 55-year-old woman with a 20-year history of systemic sclerosis, who subsequently presented with clinical stage IIIA IgG-λ MM. The systemic sclerosis was diagnosed and treated in 1988 with D: -penicillamine and methotrexate. Twenty years later, in December 2008, she presented with symptoms of Raynaud's phenomenon and intense facial pruritus. Immunoelectrophoresis confirmed the presence of a IgG-λ paraprotein (71.90 g/l) and Bence Jones proteinuria of the lambda light chains. Bone marrow histology revealed infiltrates of plasmocytes and lymphoplasmocytes which were on immunohistochemistry CD38+, FGF-R3+ and OPG+. An extensive X-ray skeletal survey did not show any osteolytic lesions or fractures. The patient was treated according to the CTD protocol (cyclophosphamide, thalidomide, and dexamethasone) which was effective against the myeloma as well as the systemic sclerosis and patient achieved complete remission.