Post-translational modification of MALT1 and its role in B cell- and T cell-related diseases

Critical and differential roles of eIF4A1 and eIF4A2 in B-cell development and function

Eukaryotic initiation factor 4 A (eIF4A) plays critical roles during translation initiation of cellular mRNAs by forming the cap-binding eIF4F complex, recruiting the 40S small ribosome subunit, and scanning the 5' untranslated region (5' UTR) for the start codon. eIF4A1 and eIF4A2, two isoforms of eIF4A, are highly conserved and exchange freely within eIF4F complexes. The understanding of their biological and molecular functions remains incomplete if not fragmentary. In this study, we showed that eIF4A1 and eIF4A2 exhibit different expression patterns during B-cell development and activation. Mouse genetic analyses showed that they play critical but differential roles during B-cell development and humoral immune responses. While eIF4A1 controls global protein synthesis, eIF4A2 regulates the biogenesis of 18S ribosomal RNA and the 40S ribosome subunit. This study demonstrates the distinct cellular and molecular functions of eIF4A1 and eIF4A2 and reveals a new role of eIF4A2 in controlling 40S ribosome biogenesis.

Sonic hedgehog signaling facilitates pyroptosis in mouse heart following ischemia/reperfusion via enhancing the formation of CARD10-BCL10-MALT1 complex

Pyroptosis has been found to contribute to myocardial ischemia/reperfusion (I/R) injury, but the exact mechanisms that initiate myocardial pyroptosis are not fully elucidated. Sonic hedgehog (SHH) signaling is activated in heart suffered I/R, and intervention of SHH signaling has been demonstrated to protect heart from I/R injury. Caspase recruitment domain-containing protein 10 (CARD10)-B cell lymphoma 10 (BCL10)-mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) (CBM) complex could transduce signals from the membrane and induce inflammatory pathways in non-hematopoietic cells, which could be a downstream effector of SHH signaling pathway. This study aims to explore the role of SHH signaling in I/R-induced myocardial pyroptosis and its relationship with the CBM complex. C57BL/6J mice were subjected to 45 min-ischemia followed by 24 h-reperfusion to establish a myocardial I/R model, and H9c2 cells underwent hypoxia/reoxygenation (H/R) to mimic myocardial I/R model in vitro. Firstly, SHH signaling was significantly activated in heart suffered I/R in an autocrine- or paracrine-dependent manner via its receptor PTCH1, and inhibition of SHH signaling decreased myocardial injury via reducing caspase-11-dependent pyroptosis, concomitant with attenuating CBM complex formation. Secondly, suppression of SHH signaling decreased protein kinase C α (PKCα) level, but inhibition of PKCα attenuated CBM complex formation without impacting the protein levels of SHH and PTCH1. Finally, disruption of the CBM complex prevented MALT1 from recruiting of TRAF6, which was believed to trigger the caspase-11-dependent pyroptosis. Based on these results, we conclude that inhibition of SHH signaling suppresses pyroptosis via attenuating PKCα-mediated CARD10-BCL10-MALT1 complex formation in mouse heart suffered I/R.

The Inhibitors of Mucosa-Associated Lymphoid Tissue Lymphoma Translocation Protein 1 (MALT-1) Protease as Potential Treatment of ABC-DLBCL and Similar Diseases

The invention in this patent application relates to thiazolo[5,4-b]pyridine derivatives represented generally by formula 1. These compounds are inhibitors of the activity of mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT-1) protease and may potentially be useful in the treatment of some forms of cancer, particularly ABC-DLBCL.

Development of Potent MALT1 Inhibitors Featuring a Novel "2-Thioxo-2,3-dihydrothiazolo[4,5-d]pyrimidin-7(6H)-one" Scaffold for the Treatment of B Cell Lymphoma

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) has emerged as a novel and promising therapeutic target for the treatment of lymphomas and autoimmune diseases. Herein, we reported a new class of MALT1 inhibitors featuring a novel "2-thioxo-2,3-dihydrothiazolo[4,5-d]pyrimidin-7(6H)-one" scaffold developed by structure-based drug design. Structure-activity relationship studies finally led to the discovery of MALT1 inhibitor 10m, which covalently and potently inhibited MALT1 protease with the IC50 value of 1.7 μM. 10m demonstrated potent and selective antiproliferative activity against ABC-DLBCL and powerful ability to induce HBL1 apoptosis. 10m also effectively downregulated the activities of MALT1 and its downstream signal pathways. Furthermore, 10m induced upregulation of mTOR and PI3K-Akt signals and exhibited a synergistic antitumor effect with Rapamycin in HBL1 cells. More importantly, 10m remarkably suppressed the tumor growth both in the implanted HBL1 and TMD8 xenograft models. Collectively, this work provides valuable MALT1 inhibitors with a distinct core structure.

MALT1 Positively Relates to T Helper 1 and T Helper 17 cells, and Serves as a Potential Biomarker for Predicting 30-Day Mortality in Stanford Type A Aortic Dissection Patients

Mucosa-associated lymphoid tissue 1 (MALT1) regulates inflammation and T helper (Th) cell differentiation, which may participate in the progression of Stanford type A aortic dissection (TAAD). This study intended to assess the association of MALT1 expression with prognosis in TAAD patients. In this prospective study, MALT1 expression was measured by reverse transcription-quantitative polymerase chain reaction assay from peripheral blood samples in 100 TAAD patients and 100 non-AD controls (non-AD patients with chest pain) before treatment. Besides, Th1, Th2, and Th17 cells of TAAD patients before treatment were measured by flow cytometry assay, and their 30-day mortality was recorded. MALT1 expression was ascended in TAAD patients vs. non-AD controls (P < 0.001). In TAAD patients, elevated MALT1 expression was linked with hypertension complication (P = 0.009), increased systolic blood pressure (r = 0.291, P = 0.003), C-reactive protein (CRP) (r = 0.286, P = 0.004), and D-dimer (r = 0.359, P < 0.001). Additionally, MALT1 expression was positively correlated with Th1 cells (r = 0.312, P = 0.002) and Th17 cells (r = 0.397, P < 0.001), but not linked with Th2 cells (r = -0.166, P = 0.098). Notably, the 30-day mortality of TAAD patients was 28.0%. MALT1 expression [odds ratio (OR) = 1.936, P = 0.004], CRP (OR = 1.108, P = 0.002), D-dimer (OR = 1.094, P = 0.003), and surgery timing (emergency vs. selective) (OR = 8.721, P = 0.024) independently predicted increased risk of death within 30 days in TAAD patients. Furthermore, the combination of the above-mentioned independent factors had an excellent ability in predicting 30-day mortality with the area under curve of 0.949 (95% confidence interval: 0.909-0.989). MALT1 expression relates to increased Th1 cells, Th17 cells, and 30-day mortality risk in TAAD patients.

Telaprevir Improves Memory and Cognition in Mice Suffering Ischemic Stroke via Targeting MALT1-Mediated Calcium Overload and Necroptosis

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) has been confirmed to contribute to brain injury in ischemic stroke via promoting excitotoxicity and necroptosis. Telaprevir, a hepatitis C virus protease inhibitor, is predicted to be a potential MALT1 inhibitor. Here, we showed that telaprevir protected against cerebral ischemic injury via inhibiting MALT1, thereby preventing glutamate receptor ionotropic NMDA 2B (GluN2B) activation, limiting calcium overload, and suppressing necroptosis. In ischemic stroke mice, telaprevir reduced infarct volume, improved the long-term survival rate, and enhanced sensorimotor, memory, and cognitive functions. In hypoxia-treated nerve cells, telaprevir decreased the intracellular calcium concentrations and reduced LDH release. Mechanistically, telaprevir inhibited MALT1 protease activity, thus decreasing the membrane protein level of GluN2B and its phosphorylation through reducing the level of STEP61. Moreover, telaprevir was able to inhibit the levels of necroptosis-associated proteins. According to these results, it can be concluded that telaprevir alleviates neuronal brain injury in stroke mice via restraining GluN2B activation and suppresses the receptor-interacting protein kinase 1 (RIPK1)/receptor-interacting protein kinase 3 (RIPK3)/mixed lineage kinase domain-like pseudokinase (MLKL) pathway through inhibiting MALT1. Thus, telaprevir might have a novel indication for treating patients with ischemic stroke.

Early low blood MALT1 expression levels forecast better efficacy of PD‑1 inhibitor‑based treatment in patients with metastatic colorectal cancer

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) modulates colorectal cancer (CRC) malignant behaviors and tumor immune escape. The present study aimed to explore the association of MALT1 with treatment response and survival time among patients with metastatic CRC (mCRC) after programmed cell death protein-1 (PD-1) inhibitor-based treatment. MALT1 from the blood samples of 75 patients with unresectable mCRC receiving PD-1 inhibitor-based treatment at baseline and after 2-cycle treatment, as well as 20 healthy controls (HCs), was detected by reverse transcription-quantitative PCR. In the patients with mCRC, the objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS) and overall survival (OS) were calculated. MALT1 expression was elevated in patients with mCRC compared with that in HCs (P<0.001). In patients with mCRC, MALT1 expression was positively correlated with multiple (vs. single) metastasis (P=0.032) and peritoneum metastasis (P=0.029). MALT1 levels before treatment were decreased in ORR patients vs. non-ORR patients (P=0.043) and in DCR patients vs. non-DCR patients (P=0.007). Additionally, MALT1 expression was reduced after treatment compared with that before treatment (P<0.001). Meanwhile, MALT1 expression after treatment was notably decreased in ORR patients vs. non-ORR patients (P<0.001) and in DCR patients vs. non-DCR patients (P<0.001). Furthermore, a low MALT1 level before treatment was associated with longer PFS (P=0.030) and OS (P=0.025) times. Decreased MALT1 expression after treatment and a decline in MALT1 expression of >30% after treatment (ratio to MALT1 before treatment) (both P≤0.001) presented more significant associations with prolonged PFS and OS times. In conclusion, early low levels of blood MALT1 during therapy may predict an improved response to PD-1 inhibitor-based treatment and survival time in patients with mCRC.

The Weakened Interaction Between HECTD4 and GluN2B in Ischemic Stroke Promotes Calcium Overload and Brain Injury Through a Mechanism Involving the Decrease of GluN2B and MALT1 Ubiquitination

Glutamate receptor ionotropic NMDA 2B (GluN2B) plays an essential role in calcium overload during excitotoxicity. Reverse-phase nano-liquid chromatography-tandem mass spectrometry has revealed an interaction between GluN2B and HECT domain E3 ubiquitin protein ligase 4 (HECTD4), an E3 ubiquitin ligase highly expressed in the brain. As a potential substrate for HECTD4, mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) acts as a scaffold with hydrolysis activity. This study explores the relationship between HECTD4, GluN2B, and MALT1, focusing on their role in brain injury in ischemic stroke. Rats were subjected to 2 h-ischemia followed by 24-h reperfusion to establish an ischemic stroke model. We observed the downregulation of HECTD4 and the upregulation of MALT1. Additionally, an increased GluN2B phosphorylation was concomitant with weakened interactions between HECTD4 and GluN2B, followed by decreased striatal-enriched protein phosphatase (STEP61). Knockdown of HECTD4 exacerbated hypoxia- or NMDA-induced injury in nerve cells coincident with a decrease in GluN2B and MALT1 ubiquitination, and an increase in GluN2B phosphorylation as well as an increase in intracellular calcium level, which were counteracted by MALT1 siRNA. Blockage of MALT1 with its inhibitor or siRNA reduced STEP61 degradation, accompanied by a decrease in GluN2B phosphorylation, intracellular calcium concentration, and brain cell injury, which were reversed by overexpression of MALT1. Based on these observations, we conclude that the downregulation of HECTD4 in ischemic stroke rat brain accounts for calcium overload and brain injury due to activating GluN2B directly and indirectly through a mechanism involving the reduced ubiquitination of GluN2B and MALT1, respectively.

Tetrahydrocurcumin regulates the tumor immune microenvironment to inhibit breast cancer proliferation and metastasis via the CYP1A1/NF-κB signaling pathway

The NF-κB signaling pathway is overactivated in tumor cells, and the activation of the NF-κB signaling pathway releases a large number of inflammatory factors, which enhance tumor immunosuppression and promote tumor metastasis. The cytochrome P450 (CYP450) system consists of important metabolic enzymes present in different tissues and progressive tumors, which may lead to changes in the pharmacological action of drugs in inflammatory diseases such as tumors. In this study, the anticancer effect of tetrahydrocurcumin (THC), an active metabolite of curcumin, on breast cancer cells and the underlying mechanism were investigated. Result showed that THC selectively inhibited proliferation and triggered apoptosis in breast cancer cells in a concentration- and time-dependent manner. Moreover, THC-induced cell apoptosis via a mitochondria-mediated pathway, as indicated by the upregulated ratio of Bax/Bcl-2 and reactive oxygen species (ROS) induction. In addition, THC could affect the CYP450 enzyme metabolic pathway and inhibit the expression of CYP1A1 and activation of the NF-κB pathway, thereby inhibiting the migration and invasion of breast cancer cells. Furthermore, after overexpression of CYP1A1, the inhibitory effects of THC on the proliferation, metastasis, and induction of apoptosis in breast cancer cells were weakened. The knockdown of CYP1A1 significantly enhanced the inhibitory effect of THC on the proliferation, metastasis, and apoptosis induction of breast cancer cells. Notably, THC exhibited a significant tumor growth inhibition and anti-pulmonary metastasis effect in a tumor mouse model of MCF-7 and 4T1 cells by regulating the tumor immunosuppressive microenvironment. Collectively, these results showed that TH could effectively trigger apoptosis and inhibit the migration of breast cancer cells via the CYP1A1/NF-κB signaling pathway, indicating that THC serves as a potential candidate drug for the treatment of breast cancer.

MALT1 regulates Th2 and Th17 differentiation via NF-κB and JNK pathways, as well as correlates with disease activity and treatment outcome in rheumatoid arthritis

Objective

MALT1 regulates immunity and inflammation in multiple ways, while its role in rheumatoid arthritis (RA) is obscure. This study aimed to investigate the relationship of MALT1 with disease features, treatment outcome, as well as its effect on Th1/2/17 cell differentiation and underlying molecule mechanism in RA.

Methods

Totally 147 RA patients were enrolled. Then their blood Th1, Th2, and Th17 cells were detected by flow cytometry. Besides, PBMC MALT1 expression was detected before treatment (baseline), at week (W) 6, W12, and W24. PBMC MALT1 in 30 osteoarthritis patients and 30 health controls were also detected. Then, blood CD4⁺ T cells were isolated from RA patients, followed by MALT1 overexpression or knockdown lentivirus transfection and Th1/2/17 polarization assay. In addition, IMD 0354 (NF-κB antagonist) and SP600125 (JNK antagonist) were also added to treat CD4⁺ T cells.

Results

MALT1 was increased in RA patients compared to osteoarthritis patients and healthy controls. Meanwhile, MALT1 positively related to CRP, ESR, DAS28 score, Th17 cells, negatively linked with Th2 cells, but did not link with other features or Th1 cells in RA patients. Notably, MALT1 decreased longitudinally during treatment, whose decrement correlated with RA treatment outcome (treatment response, low disease activity, or disease remission). In addition, MALT1 overexpression promoted Th17 differentiation, inhibited Th2 differentiation, less affected Th1 differentiation, activated NF-κB and JNK pathways in RA CD4⁺ T cells; while MALT1 knockdown exhibited the opposite effect. Besides, IMD 0354 and SP600125 addition attenuated MALT1’s effect on Th2 and Th17 differentiation.

Conclusion

MALT1 regulates Th2 and Th17 differentiation via NF-κB and JNK pathways, as well as correlates with disease activity and treatment outcome in RA.