Mitochondria, the organelle critical for cell survival and metabolism, are exploited by cancer cells and provide an important therapeutic target in cancers. Mitochondria dynamically undergo fission ...and fusion to maintain their diverse functions. Proteins controlling mitochondrial fission and fusion have been recognized as essential regulators of mitochondrial functions, mitochondrial quality control, and cell survival. In a recent proteomic study, we identified the key mitochondrial fission factor, MFF, as a new interacting protein of TRAF3, a known tumor suppressor of multiple myeloma and other B cell malignancies. This interaction recruits the majority of cytoplasmic TRAF3 to mitochondria, allowing TRAF3 to regulate mitochondrial morphology, mitochondrial functions, and mitochondria-dependent apoptosis in resting B lymphocytes. Interestingly, recent transcriptomic, metabolic and lipidomic studies have revealed that TRAF3 also vitally regulates multiple metabolic pathways in B cells, including phospholipid metabolism, glucose metabolism, and ribonucleotide metabolism. Thus, TRAF3 emerges as a novel regulator of mitochondrial physiology and metabolic pathways in B lymphocytes and B cell malignancies. Here we review current knowledge in this area and discuss relevant clinical implications.
The BTK inhibitors ibrutinib and acalabrutinib are FDA-approved drugs for the treatment of B cell malignances. Both drugs have demonstrated clinical efficacy and safety profiles superior to ...chemoimmunotherapy regimens in patients with chronic lymphocytic leukemia. Mounting preclinical and clinical evidence indicates that both ibrutinib and acalabrutinib are versatile and have direct effects on many immune cell subsets as well as other cell types beyond B cells. The versatility and immunomodulatory effects of both drugs have been exploited to expand their therapeutic potential in a wide variety of human diseases. Over 470 clinical trials are currently registered at ClinicalTrials.gov to test the efficacy of ibrutinib or acalabrutinib not only in almost every type of B cell malignancies, but also in hematological malignancies of myeloid cells and T cells, solid tumors, chronic graft
versus
host disease (cGHVD), autoimmune diseases, allergy and COVID-19 (
http:www.clinicaltrials.gov
). In this review, we present brief discussions of the clinical trials and relevant key preclinical evidence of ibrutinib and acalabrutinib as monotherapies or as part of combination therapies for the treatment of human diseases beyond B cell malignancies. Adding to the proven efficacy of ibrutinib for cGVHD, preliminary results of clinical trials have shown promising efficacy of ibrutinib or acalabrutinib for certain T cell malignancies, allergies and severe COVID-19. However, both BTK inhibitors have no or limited efficacy for refractory or recurrent solid tumors. These clinical data together with additional pending results from ongoing trials will provide valuable information to guide the design and improvement of future trials, including optimization of combination regimens and dosing sequences as well as better patient stratification and more efficient delivery strategies. Such information will further advance the precise implementation of BTK inhibitors into the clinical toolbox for the treatment of different human diseases.
Crystals of monosodium urate monohydrate (MSU) and calcium pyrophosphate dihydrate (CPPD) are known to induce arthropathic diseases called gout and pseudogout, respectively. These crystals are ...deposited in various joints or tissues, causing severe pain. Correct identification of crystals is crucial for the appropriate treatment of gout and pseudogout, which exhibit very similar symptoms. Herein, a novel approach of laser desorption/ionization time-of-flight (LDI-ToF) mass spectrometry (MS) was introduced to analyze MSU and CPPD crystals with three different types of nanostructured TiO2 materials including TiO2 nanoparticles (P25), TiO2 nanowires synthesized from wet-corrosion method, and the mixture of P25 and TiO2 nanowires (P25/TiO2 nanowires) as inorganic solid matrices. Furthermore, the feasibility of LDI-ToF MS based on these TiO2 nanostructures for the analysis of the two arthropathy-related crystals was tested using spiked samples in synovial fluid at known crystal concentrations. The mass analysis results of MSU and CPPD crystals demonstrated that (1) the electrostatic interaction between analytes and solid matrices was key for the analyte ionization and (2) LDI-ToF MS with nanostructured TiO2 materials has the potential to be a practical approach for the diagnosis of gout and pseudogout.
Demand response (DR) is one of the major benefits that utility companies can derive from the advanced metering infrastructure (AMI). In particular, the dynamic rate plan with DR is attracting ...attention as an electricity rate system suitable for the future power environment. In order for electricity consumers to select an appropriate electricity rate plan, it is necessary to provide information such as whether electricity bills are reduced by the plan and the estimated amount of electricity bill savings. In this paper, we first comparatively analyze the current progressive rate plan and a dynamic rate plan of the time-of-use (TOU). We next propose several prediction methods for households to provide information on whether the electricity bill amount can be reduced in advance when changing to the TOU rate plan from the progressive rate plan by using only the current monthly electricity usages and bills. In order to develop three different prediction methods based on statistical learning, we use the support vector machine, linear regression, and deep neural network techniques. As a ground truth training sequence, we use hourly electricity usages and bills obtained from ten apartment complexes through AMI, and an apartment complex is used for testing the designed methods. The decision accuracy for the test complex was more than 0.98 and the root mean square error of the saving prediction was 1.7%.
Proteins controlling mitochondrial fission have been recognized as essential regulators of mitochondrial functions, mitochondrial quality control and cell apoptosis. In the present study, we ...identified the critical B cell survival regulator TRAF3 as a novel binding partner of the key mitochondrial fission factor, MFF, in B lymphocytes. Elicited by our unexpected finding that the majority of cytoplasmic TRAF3 proteins were localized at the mitochondria in resting splenic B cells after
culture for 2 days, we found that TRAF3 specifically interacted with MFF as demonstrated by co-immunoprecipitation and GST pull-down assays. We further found that in the absence of stimulation, increased protein levels of mitochondrial TRAF3 were associated with altered mitochondrial morphology, decreased mitochondrial respiration, increased mitochondrial ROS production and membrane permeabilization, which eventually culminated in mitochondria-dependent apoptosis in resting B cells. Loss of TRAF3 had the opposite effects on the morphology and function of mitochondria as well as mitochondria-dependent apoptosis in resting B cells. Interestingly, co-expression of TRAF3 and MFF resulted in decreased phosphorylation and ubiquitination of MFF as well as decreased ubiquitination of TRAF3. Moreover, lentivirus-mediated overexpression of MFF restored mitochondria-dependent apoptosis in TRAF3-deficient malignant B cells. Taken together, our findings provide novel insights into the apoptosis-inducing mechanisms of TRAF3 in B cells: as a result of survival factor deprivation or under other types of stress, TRAF3 is mobilized to the mitochondria through its interaction with MFF, where it triggers mitochondria-dependent apoptosis. This new role of TRAF3 in controlling mitochondrial homeostasis might have key implications in TRAF3-mediated regulation of B cell transformation in different cellular contexts. Our findings also suggest that mitochondrial fission is an actionable therapeutic target in human B cell malignancies, including those with
deletion or relevant mutations.
The clinical success of the two BTK inhibitors, ibrutinib and acalabrutinib, represents a major breakthrough in the treatment of chronic lymphocytic leukemia (CLL) and has also revolutionized the ...treatment options for other B cell malignancies. Increasing evidence indicates that in addition to their direct effects on B lymphocytes, both BTK inhibitors also directly impact the homeostasis, phenotype and function of many other cell subsets of the immune system, which contribute to their high efficacy as well as adverse effects observed in CLL patients. In this review, we attempt to provide an overview on the overlapping and differential effects of ibrutinib and acalabrutinib on specific receptor signaling pathways in different immune cell subsets other than B cells, including T cells, NK cells, monocytes, macrophages, granulocytes, myeloid-derived suppressor cells, dendritic cells, osteoclasts, mast cells and platelets. The shared and distinct effects of ibrutinib
versus
acalabrutinib are mediated through BTK-dependent and BTK-independent mechanisms, respectively. Such immunomodulatory effects of the two drugs have fueled myriad explorations of their repurposing opportunities for the treatment of a wide variety of other human diseases involving immune dysregulation.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (NP) participates in viral genome packaging and abundantly produced when infected. In this work, SPR biosensor ...for the detection of SARS-CoV-2 in viral fluid using Fv-antibodies with the binding affinity to nucleocapsid protein (NP) of SARS-CoV-2. The F
V
-antibodies with a specific binding activity to the SARS-CoV-2 NP were screened using the F
V
-antibody library, which was expressed on the outer membrane of
E. coli
. F
V
-antibodies comprised three complementarity-determining regions (CDRs) and four frame regions (FRs) of the heavy chain at the binding pocket of IgG. The F
V
-antibody library was prepared by performing site-directed mutagenesis and by using the autodisplay technology; F
V
-antibodies with specific binding activities to the nucleocapsid protein (NP) of SARS-CoV-2 were screened using NP-immobilized magnetic beads. First,
E. coli
isolates with the target F
V
-antibody were screened, and the binding affinity (K
D
) was estimated for the screened
E. coli
clones using FACS analysis. Then, the outer membrane (OM) of the screened
E. coli
clones with autodisplayed Fv-antibodies was obtained and layered on an SPR biosensor, and the binding curves of four different coronavirus (CoV) culture fluids, SARS-CoV-2, SARS-CoV, MERS-CoV, and CoV strain 229E, were compared. Finally, the F
V
-antibodies of the screened
E. coli
clones were synthesized as peptides (11 amino acid residues), and the binding constants (K
D
) to NP as well as the binding curves of the CoV strains in culture fluids were estimated. Using docking simulation, binding sites and interaction types between NP and each synthetic peptide were investigated.
Graphical Abstract
This study aimed to isolate F
-antibodies with biotin-binding activity from a F
-antibody library that was successfully screened on the outer membrane of E. coli. The aims were achieved by (1) ...preparing a library of F
-antibodies on the outer membrane of E. coli using autodisplay technology, (2) screening the F
-antibodies with biotin-binding activity from the F
-antibody library, and (3) synthesizing peptides (molecular weight of several kDa) from the biotin-binding amino acid sequence of F
-antibodies. An F
-antibody library with a diversity of 1.7 × 10
clones was prepared on the outer membrane of E. coli, using a surface display method called autodisplay technology. For the screening of biotin-binding F
-antibodies, the fluorescence-labeled biotin was introduced into the library, and the target E. coli with biotin-binding activity were screened using flow cytometry. For the screened E. coli clones, the binding affinity (K
) of Fv-antibodies against biotin was calculated and the binding properties of the screened F
-antibody were analyzed through competition assay with a synthetic peptide having the biotin-like activity. From the FRET experiment with the synthetic peptide corresponding to the CDR3 region of the screened Fv-antibody, the biotin-binding activity of the screened F
-antibody was proved to be originated from the CDR3. Finally, the applicability of the biotin-binding domain was demonstrated through the co-expression with a protein called Z-domain with antibody binding activity.
The pleiotropic cytokine IL-9 signals to target cells by binding to a heterodimeric receptor consisting of the unique subunit IL-9R and the common subunit γ-chain shared by multiple cytokines of the ...γ-chain family. In the current study, we found that the expression of IL-9R was strikingly upregulated in mouse naive follicular B cells genetically deficient in TNFR-associated factor 3 (TRAF3), a critical regulator of B cell survival and function. The highly upregulated IL-9R on Traf3-/- follicular B cells conferred responsiveness to IL-9, including IgM production and STAT3 phosphorylation. Interestingly, IL-9 significantly enhanced class switch recombination to IgG1 induced by BCR crosslinking plus IL-4 in Traf3-/- B cells, which was not observed in littermate control B cells. We further demonstrated that blocking the JAK-STAT3 signaling pathway abrogated the enhancing effect of IL-9 on class switch recombination to IgG1 induced by BCR crosslinking plus IL-4 in Traf3-/- B cells. Our study thus revealed, to our knowledge, a novel pathway that TRAF3 suppresses B cell activation and Ig isotype switching by inhibiting IL-9R-JAK-STAT3 signaling. Taken together, our findings provide (to our knowledge) new insights into the TRAF3-IL-9R axis in B cell function and have significant implications for the understanding and treatment of a variety of human diseases involving aberrant B cell activation such as autoimmune disorders.
Abstract
The pleiotropic cytokine interleukin-9 (IL-9) signals to target cells by binding to a heterodimeric receptor consisting of the IL-9 receptor (IL-9R) and the common subunit γ chain. In the ...present study, we found that the expression of IL-9R was strikingly up-regulated in mouse naïve follicular B cells genetically deficient in TRAF3, a critical regulator of B cell survival and function. The highly up-regulated IL-9R on Traf3 −/−follicular B cells conferred responsiveness to IL-9, including IgM production and STAT3 phosphorylation. Interestingly, IL-9 significantly enhanced class switch recombination to IgG1 induced by B cell antigen receptor crosslinking plus IL-4 in Traf3 −/−B cells but not in wild type B cells. Blocking the JAK-STAT3 pathway abrogated the effects of IL-9 on Traf3 −/−B cells. Our study thus revealed a novel pathway that TRAF3 suppresses B cell activation and Ig isotype switching by inhibiting IL-9R-JAK-STAT3 signaling. Our findings provide new insights into the TRAF3-IL-9R axis in B cell function and have significant implications for the understanding and treatment of a variety of human diseases involving aberrant B cell activation.
This study was supported by the National Institutes of Health grants R01 CA158402 (P. Xie) and R21 AI128264 (P. Xie), the Department of Defense grant W81XWH-13-1-0242 (P. Xie), and a Busch Biomedical Grant (P. Xie). FACS analyses were supported by the Flow Cytometry Core Facility with funding from NCI-CCSG P30CA072720.
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