The protease activity of the paracaspase MALT1 is controlled by monoubiquitination.

The protease activity of the paracaspase MALT1 is central to lymphocyte activation and lymphomagenesis, but how this activity is controlled remains unknown. Here we identify a monoubiquitination of MALT1 on Lys644 that activated the protease function of MALT1. Monoubiquitinated MALT1 had enhanced protease activity, whereas a ubiquitination-deficient MALT1 mutant with replacement of that lysine with arginine (MALT1(K644R)) had less protease activity, which correlated with impaired induction of interleukin 2 (IL-2) via the T cell antigen receptor in activated T cells. Expression of MALT1(K644R) diminished the survival of cells derived from diffuse large B cell lymphoma of the activated B cell-like subtype (ABC DLBCL), which require constitutive protease activity of MALT1 for survival. Thus, monoubiquitination of MALT1 is essential for its catalytic activation and is therefore a potential target for the treatment of ABC-DLBCL and for immunomodulation.

Essential role of platelet activation via protease activated receptor 4 in tissue factor-initiated inflammation.

INTRODUCTION: Tissue factor (TF) activation of the coagulation proteases enhances inflammation in animal models of arthritis and endotoxemia, but the mechanism of this effect is not yet fully understood - in particular, whether this is primarily due to fibrin formation or through activation of protease activated receptors (PARs). METHODS: We induced extravascular inflammation by injection of recombinant soluble murine TF (sTF1-219) in the hind paw. The effects of thrombin inhibition, fibrinogen and platelet depletion were evaluated, as well as the effects of PAR deficiency using knockout mice deficient for each of the PARs. RESULTS: Injection of soluble TF provoked a rapid onset of paw swelling. Inflammation was confirmed histologically and by increased serum IL-6 levels. Inflammation was significantly reduced by depletion of fibrinogen (P < 0.05) or platelets (P = 0.015), and by treatment with hirudin (P = 0.04) or an inhibitor of activated factor VII (P < 0.001) compared with controls. PAR-4-deficient mice exhibited significantly reduced paw swelling (P = 0.003). In contrast, a deficiency in either PAR-1, PAR-2 or PAR-3 did not affect the inflammatory response to soluble TF injection. CONCLUSION: Our results show that soluble TF induces acute inflammation through a thrombin-dependent pathway and both fibrin deposition and platelet activation are essential steps in this process. The activation of PAR-4 on platelets is crucial and the other PARs do not play a major role in soluble TF-induced inflammation.

Modulation of inflammatory pathways by the HIV protease inhibitors

Les inhibiteurs de la protéase du VIH (IP) constituent une des classes de traitements antirétroviraux parmi les plus utilisés au cours de l'infection par le VIH. Leur utilisation est associée à divers effets secondaires, notamment la dyslipidémie, la résistance à l'insuline, la lipodystrophie et certaines complications cardio-vasculaires. Ces molécules ont également des propriétés anti-tumorales, décrites chez des patients non infectés par le VIH. Pourtant, les mécanismes moléculaires à l'origine de ces effets annexes restent méconnus. Dans ce travail, nous démontrons que les IP, comme le Nelfinavir, le Ritonavir, le Lopinavir, le Saquinavir et l'Atazanavir, entrainent la production d'interleukine-lß (IL-lß), une puissante cytokine pro-inflammatoire, connue pour son rôle central dans les maladies inflammatoires. La sécrétion d'IL-lß requiert la formation de l'inflammasome, un complexe protéique intracellulaire servant de plateforme d'activation de la caspase-1 et, par la suite, à la maturation protéolytique de certaines cytokines, dont l'IL-lß. Dans les macrophages murins en culture primaire, ainsi que dans une lignée de monocytes humains, nous démontrons que les IP augmentent la maturation et la sécrétion de l'IL-lß via l'induction d'un inflammasome dépendant de ASC. De plus, nous établissons que les IP induisent spécifiquement l'activation de AIM2, un inflammasome détectant la présence intracytosolique d'ADN viral ou bactérien. Nos résultats démontrent l'existence d'une nouvelle voie d'activation de l'inflammasome AIM2 par un signal endogène dont la nature reste à définir. Ces données suggèrent que AIM2 pourrait jouer un rôle important dans la promotion de l'activité anti-tumorale ainsi que dans les autres effets annexes observés chez les patients traités par IP. -- HIV protease inhibitors (Pis) are among the most often used classes of antiretroviral drugs for HIV infection. Treatment of patients with HIV-PIs is associated with the development of metabolic side effects including dyslipidemia, insulin resistance, lipodystrophy and cardiovascular complications. In addition, these drugs have been reported to have anti¬tumoral properties in non-infected patients, however the molecular mechanisms causing these off-target effects are still unclear. Here we show that the HIV-PIs, such as Nelfinavir, Ritonavir, Lopinavir, Saquinavir and Atazanavir, activate the production of interleukin-lß (IL-lß), a potent pro-inflammatory cytokine that plays a central role in the pathogenesis of inflammatory diseases. The release of IL-lß depends on the activation of the inflammasome, a multiprotein complex that serves as a platform for caspase-1 activation and subsequent proteolytic maturation of cytokines including IL-lß. We found that in mouse primary macrophages as well as in a human monocytic cell line, the HIV-PIs augment the maturation and secretion of IL-lß by triggering an ASC-dependent inflammasome activation. Moreover, we show that the HIV-PIs specifically engage AIM2, a recently characterized inflammasome -forming protein that was described to detect the cytosolic release of bacterial and viral DNA. Our findings demonstrate a new pathway of activation of the AIM2 inflammasome by a yet to be defined endogenous signal and may suggest a possible role for AIM2 in promoting anti¬tumoral activity and off-target effects observed in HIV-PIs treated patients.

Differential Recognition of Old World and New World Arenavirus Envelope Glycoproteins by Subtilisin Kexin Isozyme 1 (SKI-1)/Site 1 Protease (S1P).

The arenaviruses are an important family of emerging viruses that includes several causative agents of severe hemorrhagic fevers in humans that represent serious public health problems. A crucial step of the arenavirus life cycle is maturation of the envelope glycoprotein precursor (GPC) by the cellular subtilisin kexin isozyme 1 (SKI-1)/site 1 protease (S1P). Comparison of the currently known sequences of arenavirus GPCs revealed the presence of a highly conserved aromatic residue at position P7 relative to the SKI-1/S1P cleavage side in Old World and clade C New World arenaviruses but not in New World viruses of clades A and B or cellular substrates of SKI-1/S1P. Using a combination of molecular modeling and structure-function analysis, we found that residueY285 of SKI-1/S1P, distal from the catalytic triad, is implicated in the molecular recognition of the aromatic "signature residue" at P7 in the GPC of Old World Lassa virus. Using a quantitative biochemical approach, we show that Y285 of SKI-1/S1P is crucial for the efficient processing of peptides derived from Old World and clade C New World arenavirus GPCs but not of those from clade A and B New World arenavirus GPCs. The data suggest that during coevolution with their mammalian hosts, GPCs of Old World and clade C New World viruses expanded the molecular contacts with SKI-1/S1P beyond the classical four-amino-acid recognition sequences and currently occupy an extended binding pocket.

Autosomal Recessive Posterior Microphthalmos/Nanophthalmos is Caused by Loss-of-function Mutations in LOC646960, a Novel Gene Encoding a Trypsin-like Serine Protease

Purpose: Posterior microphthalmos (MCOP)/nanophthalmos (NNO) is a developmental anomaly characterized by extreme hyperopia due to short axial length. The population of the Faroe Islands shows a high prevalence of an autosomal recessive form (arMCOP). The gene mutated in arMCOP is not yet known.Methods: Genetic mapping by linkage analysis using microsatellite and single nucleotide polymorphisms, mutation analysis by PCR and sequencing, molecular modellingResults: Having refined the position of the disease locus (MCOP6) in an interval of 250 kb in chromosome 2q37.1 in Faroese families, we detected 3 mutations in a novel gene, LOC646960: Patients of 10 different Faroese families were either homozygous (n=22) for c.926G>C (p.Trp309Ser) or compound heterozygous (n=6) for c.926G>C and c.526C>G (p.Arg176Gly), whereas a homozygous 1 bp duplication (c.1066dupC) was identified in patients with arNNO from a Tunisian family. In two unrelated patients with MCOP, no LOC646960 mutation was found. LOC646960 is expressed in the human adult retina and RPE. The expression of the mouse homologue in the eye can be first detected at E17 and is highest in adults. The predicted protein is a 603 amino acid long secreted trypsin-like serine peptidase. c.1066dupC should result in a functional null allele. Molecular modelling of the p.Trp309Ser mutant suggests that both affinity and reactivity of the enzyme towards in vivo substrates are substantially reduced.Conclusions: Postnatal growth of the eye is important for proper development of the refractive components (emmetropization), and is mainly due to elongation of the posterior segment from 10-11 mm at birth to 15-16 mm at the age of 13 years. Optical defocus leads to changes in axial length by moving the retina towards the image plane. arMCOP may theoretically be explained, in line with the expression pattern of LOC646960, by a postnatal growth retardation of the posterior segment.

The CAP1/Prss8 catalytic triad is not involved in PAR2 activation and protease nexin-1 (PN-1) inhibition.

Serine proteases, serine protease inhibitors, and protease-activated receptors (PARs) are responsible for several human skin disorders characterized by impaired epidermal permeability barrier function, desquamation, and inflammation. In this study, we addressed the consequences of a catalytically dead serine protease on epidermal homeostasis, the activation of PAR2 and the inhibition by the serine protease inhibitor nexin-1. The catalytically inactive serine protease CAP1/Prss8, when ectopically expressed in the mouse, retained the ability to induce skin disorders as well as its catalytically active counterpart (75%, n=81). Moreover, this phenotype was completely normalized in a PAR2-null background, indicating that the effects mediated by the catalytically inactive CAP1/Prss8 depend on PAR2 (95%, n=131). Finally, nexin-1 displayed analogous inhibitory capacity on both wild-type and inactive mutant CAP1/Prss8 in vitro and in vivo (64% n=151 vs. 89% n=109, respectively), indicating that the catalytic site of CAP1/Prss8 is dispensable for nexin-1 inhibition. Our results demonstrate a novel inhibitory interaction between CAP1/Prss8 and nexin-1, opening the search for specific CAP1/Prss8 antagonists that are independent of its catalytic activity.-Crisante, G., Battista, L., Iwaszkiewicz, J., Nesca, V., Mérillat, A.-M., Sergi, C., Zoete, V., Frateschi, S., Hummler, E. The CAP1/Prss8 catalytic triad is not involved in PAR2 activation and protease nexin-1 (PN-1) inhibition.

Vasopressin-inducible ubiquitin-specific protease 10 increases ENaC cell surface expression by deubiquitylating and stabilizing sorting nexin 3

Adjustment of Na+ balance in extracellular fluids is achieved by regulated Na+ transport involving the amiloride-sensitive epithelial Na+ channel (ENaC) in the distal nephron. In this context, ENaC is controlled by a number of hormones, including vasopressin, which promotes rapid translocation of water and Na+ channels to the plasma membrane and long-term effects on transcription of vasopressin-induced and -reduced transcripts. We have identified a mRNA encoding the deubiquitylating enzyme ubiquitin-specific protease 10 (Usp10), whose expression is increased by vasopressin at both the mRNA and the protein level. Coexpression of Usp10 in ENaC-transfected HEK-293 cells causes a more than fivefold increase in amiloride-sensitive Na+ currents, as measured by whole cell patch clamping. This is accompanied by a three- to fourfold increase in surface expression of alpha- and gamma-ENaC, as shown by cell surface biotinylation experiments. Although ENaC is well known to be regulated by its direct ubiquitylation, Usp10 does not affect the ubiquitylation level of ENaC, suggesting an indirect effect. A two-hybrid screen identified sorting nexin 3 (SNX3) as a novel substrate of Usp10. We show that it is a ubiquitylated protein that is degraded by the proteasome; interaction with Usp10 leads to its deubiquitylation and stabilization. When coexpressed with ENaC, SNX3 increases the channel's cell surface expression, similarly to Usp10. In mCCD(cl1) cells, vasopressin increases SNX3 protein but not mRNA, supporting the idea that the vasopressin-induced Usp10 deubiquitylates and stabilizes endogenous SNX3 and consequently promotes cell surface expression of ENaC

Mice carrying ubiquitin-specific protease 2 (Usp2) gene inactivation maintain normal sodium balance and blood pressure.

Ubiquitylation plays an important role in the control of Na⁺ homeostasis by the kidney. It is well established that the epithelial Na⁺ channel ENaC is regulated by the ubiquitin-protein ligase NEDD4-2, limiting ENaC cell surface expression and activity. Ubiquitylation can be reversed by the action of deubiquitylating enzymes (DUBs). One such DUB, USP2-45, was identified previously as an aldosterone-induced protein in the kidney and is also a circadian output gene. In heterologous expression systems, USP2-45 binds to ENaC, deubiquitylates it, and enhances channel density and activity at the cell surface. Because the role of USP2-45 in renal Na⁺ transport had not been studied in vivo, we investigated here the effect of Usp2 gene inactivation in this process. We demonstrate first that USP2-45 protein has a rhythmic expression with a peak at ZT12. Usp2-KO mice did not show any differences from wild-type littermates with respect to the diurnal control of Na⁺ or K⁺ urinary excretion and plasma levels either on a standard diet or after acute and chronic changes to low- and high-Na⁺ diets, respectively. Moreover, they had similar aldosterone levels on either a low- or high-Na⁺ diet. Blood pressure measurements using telemetry did not reveal variations compared with control mice. Usp2-KO mice did not display alterations in expression of genes involved in sodium homeostasis or the ubiquitin system, as evidenced by transcriptome analysis in the kidney. Our data suggest that USP2 does not play a primary role in the control of Na⁺ balance or blood pressure.

Orosomucoid (alpha1-acid glycoprotein) plasma concentration and genetic variants: effects on human immunodeficiency virus protease inhibitor clearance and cellular accumulation.

BACKGROUND AND OBJECTIVE: Protease inhibitors are highly bound to orosomucoid (ORM) (alpha1-acid glycoprotein), an acute-phase plasma protein encoded by 2 polymorphic genes, which may modulate their disposition. Our objective was to determine the influence of ORM concentration and phenotype on indinavir, lopinavir, and nelfinavir apparent clearance (CL(app)) and cellular accumulation. Efavirenz, mainly bound to albumin, was included as a control drug. METHODS: Plasma and cells samples were collected from 434 human immunodeficiency virus-infected patients. Total plasma and cellular drug concentrations and ORM concentrations and phenotypes were determined. RESULTS: Indinavir CL(app) was strongly influenced by ORM concentration (n = 36) (r2 = 0.47 [P = .00004]), particularly in the presence of ritonavir (r2 = 0.54 [P = .004]). Lopinavir CL(app) was weakly influenced by ORM concentration (n = 81) (r2 = 0.18 [P = .0001]). For both drugs, the ORM1 S variant concentration mainly explained this influence (r2 = 0.55 [P = .00004] and r2 = 0.23 [P = .0002], respectively). Indinavir CL(app) was significantly higher in F1F1 individuals than in F1S and SS patients (41.3, 23.4, and 10.3 L/h [P = .0004] without ritonavir and 21.1, 13.2, and 10.1 L/h [P = .05] with ritonavir, respectively). Lopinavir cellular exposure was not influenced by ORM abundance and phenotype. Finally, ORM concentration or phenotype did not influence nelfinavir (n = 153) or efavirenz (n = 198) pharmacokinetics. CONCLUSION: ORM concentration and phenotype modulate indinavir pharmacokinetics and, to a lesser extent, lopinavir pharmacokinetics but without influencing their cellular exposure. This confounding influence of ORM should be taken into account for appropriate interpretation of therapeutic drug monitoring results. Further studies are needed to investigate whether the measure of unbound drug plasma concentration gives more meaningful information than total drug concentration for indinavir and lopinavir.

Characterization of a surface metalloprotease from Herpetomonas samuelpessoai and comparison with Leishmania major promastigote surface protease.

The monogenetic kinetoplastid protozoan parasite Herpetomonas samuelpessoai expresses a surface-exposed metalloprotease. Comparable to the Leishmania promastigote surface protease, or PSP, the protease of Herpetomonas is active at the surface of fixed and live organisms, and both enzymes display an identical cleavage specificity toward a nonapeptide substrate. The protease was enriched 440 times by partition into Triton X-114 followed by 2 steps of anion exchange chromatography. The 56-kDa enzyme is inhibited by the metal chelator 1,10-phenanthroline and is susceptible to cleavage by glycosyl-phosphatidylinositol phospholipase C (GPI-PLC). The conservation of an identical surface protease activity in these monogenetic and digenetic trypanosomatids suggests that the enzyme has a physiological function in the promastigote (insect) stage of these parasites.

Compartmentalized secretory leukocyte protease inhibitor expression and hormone responses along the reproductive tract of postmenopausal women

Immunity and hormonal responses in the reproductive tissues of postmenopausal women are poorly understood. Secretory leukocyte protease inhibitor (SLPI), a multifunctional antimicrobial protein expressed at mucosal surfaces, is thought to play a key role in infectious and inflammatory contexts. The aim of this study was to measure SLPI production along the female reproductive tract in postmenopausal women with and without hormonal treatment. We additionally quantified estrogen receptor alpha (ERα) and progesterone receptor A (PRA) in these tissues. Expression of SLPI was decreased in the vagina and ectocervix of women under hormonal treatment. Endocervical ERα mRNA expression was increased while this did not reach significance at the protein level. SLPI expression in the endometrium was not influenced by hormonal treatment. We observed attenuated ERα expression in the cervix and endometrium of hormonally treated women, whereas vaginal expression was increased. PRA expression was augmented in the cervix and endometrium and unchanged in the vagina. Taken together, our results indicate that hormonal responses and receptor expression are differentially regulated in vaginal tissue compared with the cervix and endometrium.

Malt1 protease inactivation efficiently dampens immune responses but causes spontaneous autoimmunity.

The protease activity of the paracaspase Malt1 has recently gained interest as a drug target for immunomodulation and the treatment of diffuse large B-cell lymphomas. To address the consequences of Malt1 protease inactivation on the immune response in vivo, we generated knock-in mice expressing a catalytically inactive C472A mutant of Malt1 that conserves its scaffold function. Like Malt1-deficient mice, knock-in mice had strong defects in the activation of lymphocytes, NK and dendritic cells, and the development of B1 and marginal zone B cells and were completely protected against the induction of autoimmune encephalomyelitis. Malt1 inactivation also protected the mice from experimental induction of colitis. However, Malt1 knock-in mice but not Malt1-deficient mice spontaneously developed signs of autoimmune gastritis that correlated with an absence of Treg cells, an accumulation of T cells with an activated phenotype and high serum levels of IgE and IgG1. Thus, removal of the enzymatic activity of Malt1 efficiently dampens the immune response, but favors autoimmunity through impaired Treg development, which could be relevant for therapeutic Malt1-targeting strategies.

Ubiquitin-specific protease 2-45 (Usp2-45) binds to epithelial Na+ channel (ENaC)-ubiquitylating enzyme Nedd4-2.

Regulation of the epithelial Na(+) channel (ENaC) by ubiquitylation is controlled by the activity of two counteracting enzymes, the E3 ubiquitin-protein ligase Nedd4-2 (mouse ortholog of human Nedd4L) and the ubiquitin-specific protease Usp2-45. Previously, Usp2-45 was shown to decrease ubiquitylation and to increase surface function of ENaC in Xenopus laevis oocytes, whereas the splice variant Usp2-69, which has a different N-terminal domain, was inactive toward ENaC. It is shown here that the catalytic core of Usp2 lacking the N-terminal domain has a reduced ability relative to Usp2-45 to enhance ENaC activity in Xenopus oocytes. In contrast, its catalytic activity toward the artificial substrate ubiquitin-AMC is fully maintained. The interaction of Usp2-45 with ENaC exogenously expressed in HEK293 cells was tested by coimmunoprecipitation. The data indicate that different combinations of ENaC subunits, as well as the α-ENaC cytoplasmic N-terminal but not C-terminal domain, coprecipitate with Usp2-45. This interaction is decreased but not abolished when the cytoplasmic ubiquitylation sites of ENaC are mutated. Importantly, coimmunoprecipitation in HEK293 cells and GST pull-down of purified recombinant proteins show that both the catalytic domain and the N-terminal tail of Usp2-45 physically interact with the HECT domain of Nedd4-2. Taken together, the data support the conclusion that Usp2-45 action on ENaC is promoted by various interactions, including through binding to Nedd4-2 that is suggested to position Usp2-45 favorably for ENaC deubiquitylation.

Functional analysis of altered channel-activating protease-1 (CAP1) expression in the skin

Summary : The skin is a complex organ that protects the body against entry of pathogens and supplies a relatively dry and impermeable barrier to water loss. This barrier function is mainly provided by the epidermis, which is the outermost layer of the skin. Serine proteases are involved in skin physiology and it is known that mutations or alterations in their expression can lead to skin diseases. In order to investigate the importance of the regulated expression of CAPI/Prss8, a membrane bound serine protease expressed in the epidermis, we developed transgenic mice ectopically expressing CAPI/Prss8 in the skin. These animals exhibited a phenotype characterized by scaly skin, epidermal hypertrophy, inflammation and scratching behavior. This phenotype could be completely abolished in mice lacking the proteinase activated receptor 2 (PAR2) revealing PAR2 as a potential in vivo downstream target of CAP 1 /Prss8. We could also provide evidence of a CAP1 /Prss8 function independent of its catalytic activity. Additionally, mice ectopically expressing PAR2 in the skin developed a skin phenotype very similar to CAPI/Prss8 transgenic animals, supporting the hypothesis of PAR2 activation by CAPI/Prss8. We could furthermore demonstrate an inhibitory effect of the serine protease inhibitor nexin-I on CAPI/Prss8, since nexin-1 transgenic expression negated the skin phenotype observed in CAPI/Prss8 transgenic mice. CAP1/Prss8 and PAR2 transgenic animals, and the understanding of the interaction between CAPl/Prss8 and PAR2, can be helpful in developing potential CAPI/Prss8 and PAR2 inhibitory molecules that may be used as drugs to treat ichthyoses-like skin diseases. Résumé : La peau est un organe complexe qui protège le corps contre l'entrée des pathogènes et forme une barrière imperméable qui empêche la déshydratation. Cette fonction de barrière est surtout fournie par l'épiderme, la couche la plus superficielle de la peau. Le bon fonctionnement de cet organe est permis, entre autres, par les protéases à sérine qui sont des enzymes dont l'altération peut causer des maladies de la peau. Pour étudier l'importance de la régulation de CAP1/Prss8, une protéase à sérine exprimée au niveau de l'épiderme, des souris génétiquement modifiées, dans lesquelles CAP1/Prss8 est exprimé d'une manière ectopique dans la peau, ont été générées. Les animaux transgéniques pour CAP1/Prss8 présentent une peau squameuse, un épiderme hypertrophique, des processus inflammatoires et se grattent. Ce phénotype a pu être complètement guéri lorsque le gène de PAR2, un récepteur qui règle l'activité des cellules de l'épiderme, est inactivé chez la souris. Ceci montre que PAR2 est une cible de CAP1/Prss8 dans le système étudié. Des études expérimentales suggèrent de plus que l'effet de CAP1/Prss8 dans ce modèle ne dépend pas de son activité enzymatique. En dernière analyse, il a été démontré que l'expression transgénique de nexin-1, un inhibiteur des protéases à sérine exprimé dans la peau, a la capacité d'améliorer la peau squameuse et l'épiderme hypertrophique causés par CAP1/Prss8 transgénique. Les animaux transgéniques pour CAP1/Prss8 et PAR2, et la compréhension du mécanisme d'interaction entre eux, pourraient aider à développer et à tester des molécules inhibitrices de CAP1 /Prss8 et PARI qui pourraient alors être utilisées comme médicaments pour traiter des maladies de la peau comme les ichthyoses.

Essential role of MALT1 protease activity in activated B cell-like diffuse large B-cell lymphoma.

A key element for the development of suitable anti-cancer drugs is the identification of cancer-specific enzymatic activities that can be therapeutically targeted. Mucosa-associated lymphoid tissue transformation protein 1 (MALT1) is a proto-oncogene that contributes to tumorigenesis in diffuse large B-cell lymphoma (DLBCL) of the activated B-cell (ABC) subtype, the least curable subtype of DLBCL. Recent data suggest that MALT1 has proteolytic activity, but it is unknown whether this activity is relevant for tumor growth. Here we report that MALT1 is constitutively active in DLBCL lines of the ABC but not the GCB subtype. Inhibition of the MALT1 proteolytic activity led to reduced expression of growth factors and apoptosis inhibitors, and specifically affected the growth and survival of ABC DLBCL lines. These results demonstrate a key role for the proteolytic activity of MALT1 in DLBCL of the ABC subtype, and provide a rationale for the development of pharmacological inhibitors of MALT1 in DLBCL therapy.