The central histaminergic neurons in vitro, and their neuroprotective role in excitotoxic cell death in the postnatal rat hippocampus.

Histamine acts as a neurotransmitter in the central nervous system. Brain histamine in synthesized in neurons located to the posterior hypothalamus, from where these neurons send their projections to different parts of the brain. Released histamine participates in the regulation of several physiological functions such as arousal, attention and body homeostasis. Disturbances in the histaminergic system have been detected in diseases such as epilepsy, sleep disorders, anxiety, depression, Alzheimer’s disease, and schizophrenia. The purpose of this thesis was to develop optimal culture conditions for the histaminergic neurons, to study their detailed morphology, and to find out their significance in the kainic acid (KA)-induced neuronal death in the immature rat hippocampus. The morphology of the histaminergic neurons in vitro was comparable with the earlier findings. Histamine-containing vesicles were found in the axon but also in the cell body and dendrites suggesting a possibility for the somatodendritic release. Moreover, histamine was shown to be colocalized with the vesicular monoamine transporter 2 (VMAT2) suggesting that VMAT2 transports histamine to the subcellular storage vesicles. Furthermore, histamine was localized with γ-aminobutyric acid (GABA) in distinct storage vesicles and with neuropeptide galanin partly in the same storage vesicles suggesting different corelease mechanisms for GABA and galanin with histamine. In the organotypic hippocampal slice cultures, KA-induced neuronal death was first detected 12 h after the treatment being restricted mainly to the CA3 subregion. Moreover, cell death was irreversible, since the 48 h recovery period did not save the cells, but instead increased the damage. Finally, neuronal death was suggested to be necrotic, since intracellular apoptotic pathways were not activated, and the morphological changes detected with the electron microscopy were characteristic for necrosis. In the coculture system of the hippocampal and posterior hypothalamic slices, histaminergic neurons significantly decreased epileptiform burst activity and neuronal death in the hippocampal slices, this effect being mediated by histamine 1 (H1) and 3 (H3) receptors. In conclusion, the histaminergic neurons were maintained succesfully in the in vitro conditions exhibiting comparable morphological characteristics as detected earlier in vivo. Moreover, they developed functional innervations within the hippocampal slices in the coculture system. Finally, the KA-induced regionspecific, irreversible and necrotic hippocampal pyramidal cell damage was significantly decreased by the histaminergic neurons through H1 and H3 receptors.

Repetitive Deliberate Fires: Critical Review of the Situation and Proposal of a Follow-Up Process and Systematic Analysis

Deliberate fires appear to be borderless and timeless events creating a serious security problem. There have been many attempts to develop approaches to tackle this problem, but unfortunately acting effectively against deliberate fires has proven a complex challenge. This article reviews the current situation relating to deliberate fires: what do we know, how serious is the situation, how is it being dealt with, and what challenges are faced when developing a systematic and global methodology to tackle the issues? The repetitive nature of some types of deliberate fires will also be discussed. Finally, drawing on the reality of repetition within deliberate fires and encouraged by successes obtained in previous repetitive crimes (such as property crimes or drug trafficking), we will argue that the use of the intelligence process cycle as a framework to allow a follow-up and systematic analysis of fire events is a relevant approach. This is the first article of a series of three articles. This first part is introducing the context and discussing the background issues in order to provide a better underpinning knowledge to managers and policy makers planning on tackling this issue. The second part will present a methodology developed to detect and identify repetitive fire events from a set of data, and the third part will discuss the analyses of these data to produce intelligence.

A cellular system for spatial signal decoding in chemical gradients.

Directional cell growth requires that cells read and interpret shallow chemical gradients, but how the gradient directional information is identified remains elusive. We use single-cell analysis and mathematical modeling to define the cellular gradient decoding network in yeast. Our results demonstrate that the spatial information of the gradient signal is read locally within the polarity site complex using double-positive feedback between the GTPase Cdc42 and trafficking of the receptor Ste2. Spatial decoding critically depends on low Cdc42 activity, which is maintained by the MAPK Fus3 through sequestration of the Cdc42 activator Cdc24. Deregulated Cdc42 or Ste2 trafficking prevents gradient decoding and leads to mis-oriented growth. Our work discovers how a conserved set of components assembles a network integrating signal intensity and directionality to decode the spatial information contained in chemical gradients.

The Armc10/SVH gene: Genome context, regulation of mitochondrial dynamics and protection against Aβ-induced mitochondrial fragmentation

Mitochondrial function and dynamics are essential for neurotransmission, neural function and neuronal viability. Recently, we showed that the eutherian-specific Armcx gene cluster (Armcx1-6 genes), located in the X chromosome, encodes for a new family of proteins that localise to mitochondria, regulating mitochondrial trafficking. The Armcx gene cluster evolved by retrotransposition of the Armc10 gene mRNA, which is present in all vertebrates and is considered to be the ancestor gene. Here we investigate the genomic organisation, mitochondrial functions and putative neuroprotective role of the Armc10 ancestor gene. The genomic context of the Armc10 locus shows considerable syntenic conservation among vertebrates, and sequence comparisons and CHIP-data suggest the presence of at least three conserved enhancers. We also show that the Armc10 protein localises to mitochondria and that it is highly expressed in the brain. Furthermore, we show that Armc10 levels regulate mitochondrial trafficking in neurons, but not mitochondrial aggregation, by controlling the number of moving mitochondria. We further demonstrate that the Armc10 protein interacts with the KIF5/Miro1-2/Trak2 trafficking complex. Finally, we show that overexpression of Armc10 in neurons prevents A beta-induced mitochondrial fission and neuronal death. Our data suggest both conserved and differential roles of the Armc10/Armcx gene family in regulating mitochondrial dynamics in neurons, and underscore a protective effect of the Armc10 gene against A beta-induced toxicity. Overall, our findings support a further degree of regulation of mitochondrial dynamics in the brain of more evolved mammals.

The Armc10/SVH gene: Genome context, regulation of mitochondrial dynamics and protection against Aβ-induced mitochondrial fragmentation

Mitochondrial function and dynamics are essential for neurotransmission, neural function and neuronal viability. Recently, we showed that the eutherian-specific Armcx gene cluster (Armcx1-6 genes), located in the X chromosome, encodes for a new family of proteins that localise to mitochondria, regulating mitochondrial trafficking. The Armcx gene cluster evolved by retrotransposition of the Armc10 gene mRNA, which is present in all vertebrates and is considered to be the ancestor gene. Here we investigate the genomic organisation, mitochondrial functions and putative neuroprotective role of the Armc10 ancestor gene. The genomic context of the Armc10 locus shows considerable syntenic conservation among vertebrates, and sequence comparisons and CHIP-data suggest the presence of at least three conserved enhancers. We also show that the Armc10 protein localises to mitochondria and that it is highly expressed in the brain. Furthermore, we show that Armc10 levels regulate mitochondrial trafficking in neurons, but not mitochondrial aggregation, by controlling the number of moving mitochondria. We further demonstrate that the Armc10 protein interacts with the KIF5/Miro1-2/Trak2 trafficking complex. Finally, we show that overexpression of Armc10 in neurons prevents A beta-induced mitochondrial fission and neuronal death. Our data suggest both conserved and differential roles of the Armc10/Armcx gene family in regulating mitochondrial dynamics in neurons, and underscore a protective effect of the Armc10 gene against A beta-induced toxicity. Overall, our findings support a further degree of regulation of mitochondrial dynamics in the brain of more evolved mammals.

Post-translational modifications of voltage-gated sodium channels in chronic pain syndromes.

In the peripheral sensory nervous system the neuronal expression of voltage-gated sodium channels (Navs) is very important for the transmission of nociceptive information since they give rise to the upstroke of the action potential (AP). Navs are composed of nine different isoforms with distinct biophysical properties. Studying the mutations associated with the increase or absence of pain sensitivity in humans, as well as other expression studies, have highlighted Nav1.7, Nav1.8, and Nav1.9 as being the most important contributors to the control of nociceptive neuronal electrogenesis. Modulating their expression and/or function can impact the shape of the AP and consequently modify nociceptive transmission, a process that is observed in persistent pain conditions. Post-translational modification (PTM) of Navs is a well-known process that modifies their expression and function. In chronic pain syndromes, the release of inflammatory molecules into the direct environment of dorsal root ganglia (DRG) sensory neurons leads to an abnormal activation of enzymes that induce Navs PTM. The addition of small molecules, i.e., peptides, phosphoryl groups, ubiquitin moieties and/or carbohydrates, can modify the function of Navs in two different ways: via direct physical interference with Nav gating, or via the control of Nav trafficking. Both mechanisms have a profound impact on neuronal excitability. In this review we will discuss the role of Protein Kinase A, B, and C, Mitogen Activated Protein Kinases and Ca++/Calmodulin-dependent Kinase II in peripheral chronic pain syndromes. We will also discuss more recent findings that the ubiquitination of Nav1.7 by Nedd4-2 and the effect of methylglyoxal on Nav1.8 are also implicated in the development of experimental neuropathic pain. We will address the potential roles of other PTMs in chronic pain and highlight the need for further investigation of PTMs of Navs in order to develop new pharmacological tools to alleviate pain.

Waddlia: An emerging pathogen and a model organism to study the biology of chlamydiae.

Waddlia chondrophila is an emerging pathogen associated with abortion in cattle. In humans, a growing body of evidence supports its pathogenic role in miscarriage and in respiratory tract infection. The human pathogenicity of W. chondrophila is further supported by the presence of several virulence factors including a catalase, a functional T3SS and several adhesins. Despite this medical importance, no commercial tests are available and diagnostic of this strict intracellular bacterium mainly relies on serology, PCR and immunohistochemistry. So far, the epidemiology of W. chondrophila remains largely unexplored and zoonotic, waterborne or interhuman transmission has been considered. Apart from its pathogenic role, chlamydiologists are also interested in W. chondrophila in order to better understand biological mechanisms conserved and shared with Chlamydia spp. Indeed, W. chondrophila proved to be a useful model organism to study the pathobiology of chlamydiae thanks to its rapid replication, its large size allowing precise subcellular protein localization, as well as its growth in Dictyostelium amoebae.

Role of Munc18c in SNARE-mediated exocytosis

Background: The SNARE (Soluble N-ethylmaleimide-sensitive factor Attachment protein Receptors) and SM (Sec1/Munc18) family of proteins form the core machinery that drives the fusion of vesicles in different membrane trafficking steps. They are highly conserved, implying a similar mode of binding and function. In vertebrates, Munc18a is essential for neuronal exocytosis. It binds to its partner syntaxin1a (Syx1a) at both its N-peptide and closed conformation, and thereby inhibits SNARE complex formation in vitro. By contrast, its close homolog Munc18c is thought to interact with only the N-peptide of its partner Syx4. Moreover, different effects of Munc18c on SNARE complex formation have been reported, suggesting that the two Munc18/Syx pairs act differently. Objective: The aim of the present study was to investigate whether the mechanism of action of Munc18c indeed deviates from that of Munc18a by using sensitive biochemical and biophysical methods. Results: I found that Munc18c does have a similar binding mode as Munc18a and interacts tightly with Syx4 at both the N-peptide and closed conformation. Moreover, I established, through a novel assay, that Munc18c inhibits SNARE complex assembly, with both the binding sites contributing to inhibition, similar to Munc18a. However, there were several subtle differences between the two Munc18/Syx pairs. Munc18a exerted stronger inhibition than Munc18c. Also their respective Syx partners were found to differ in the rate of binding to SNAP25, suggesting that the equilibrium of their open and closed conformations is different. Moreover, Munc18a was found to interact with Syx 1, 2, 3 but not 4, while Munc18c bound to Syx 2, 4 and 1 but not 3. By comparing the kinetics of interaction of Syx with either Munc18 or SNAP25, I found that the block of SNARE complex assembly by Munc18 is effective on a shorter time scale, but SNAP25 eventually binds to Syx resulting in SNARE complex formation. Nevertheless, these findings do not explain how Syx can escape the tight grip of Munc18, suggesting that other proteins or mechanisms are needed for this step. I also discovered that Munc18 is able to bind on the surface of the SNARE core complex; however, this observation needs to be tested more rigorously. Conclusion: Munc18c was found to be similar to Munc18a in its mode of binding to Syx and inhibition of SNARE complex assembly. However, differences in kinetics and interaction specificities were observed between the different Munc18/Syx pairs. -- Contexte : Les familles des protéines SNARE (Soluble N-ethylmaleimide-sensitive factor At- tachment protein Receptors) et SM (Sec1/Munc18) forment le coeur de la machinerie chargée de la fusion vésiculaire au cours des différentes étapes du trafic intracellulaire. Elles sont très conservées, suggérant un mode d'interaction et des fonctions semblables. Chez les Verté- brés, Munc18a est essentielle à l'exocytose neuronale. Elle se lie à sa partenaire d'interaction syntaxin1a (Syx1a) à la fois via un peptide N-terminal et la conformation fermée de celle-ci, inhibant ainsi la formation du complexe SNARE in vitro. Son homologue proche Munc18c au contraire, est supposée interagir seulement avec le peptide N-terminal de sa partenaire Syx4. En outre, différents effets de Munc18c sur la formation du complexe SNARE ont été décrits, suggérant que les deux paires Munc18/Syx fonctionnent différemment. Objectif : Le but de cette étude est de tester si les mécanismes de fonctionnement de Munc18c diffèrent vraiment de ceux de Munc18a par le biais de méthodes biochimiques et biophysiques très précises. Résultats : J'ai pu démontrer que Munc18c se comporte en effet de façon semblable à Munc18a, et interagit étroitement avec Syx4 à ses deux sites de liaison. J'ai pu de surcroît montrer par une nouvelle méthode que Munc18c inhibe l'assemblage du complexe SNARE en impliquant ces deux sites de liaison, comme le fait Munc18a. il existe cependant de subtiles différences entre les deux paires Munc18/Syx : Munc18a exerce une inhibition plus forte que Munc18c ; leurs Syx partenaires diffèrent également dans leur degré de liaison à SNAP25, ce qui suggère un équilibre different de leurs conformations ouverte et fermée. De plus, Munc18a interagit avec Syx 1, 2 et 3 mais pas Syx 4, alors que Munc18c se lie à Syx 2, 4 et 1 mais pas Syx 3. En comparant les cinétiques d'interaction de Syx avec Munc18 ou SNAP25, j'ai découvert que le blocage par Munc18 de l'assemblage du complexe SNARE est effectif de façon brève, bien que SNAP25 finisse par se lier à Syx et aboutir ainsi à la formation du complexe SNARE. Ces découvertes n'expliquent cependant pas comment Syx parvient à échapper à la solide emprise de Munc18, et suggèrent ainsi l'intervention nécessaire d'autres protéines ou mécanismes à cette étape. J'ai également découvert que Munc18 peut se lier à la surface de la partie centrale du complexe SNARE - cette observation reste à être testée de façon plus stringente. Conclusion : Il a pu être établi que Munc18c est semblable à Munc18a quant à son mode de liaison à Syx et d'inhibition de l'assemblage du complexe SNARE. Des différences de cinétique et de spécificité d'interaction entre les diverses paires Munc18/Syx ont cependant été identifiées.

Chemical profiling: a tool to decipher the structure and organisation of illicit drugs markets: an 8-year study in Western Switzerland

Illicit drug analyses usually focus on the identification and quantitation of questioned material to support the judicial process. In parallel, more and more laboratories develop physical and chemical profiling methods in a forensic intelligence perspective. The analysis of large databases resulting from this approach enables not only to draw tactical and operational intelligence, but may also contribute to the strategic overview of drugs markets. In Western Switzerland, the chemical analysis of illicit drug seizures is centralised in a laboratory hosted by the University of Lausanne. For over 8 years, this laboratory has analysed 5875 cocaine and 2728 heroin specimens, coming from respectively 1138 and 614 seizures operated by police and border guards or customs. Chemical (major and minor alkaloids, purity, cutting agents, chemical class), physical (packaging and appearance) as well as circumstantial (criminal case number, mass of drug seized, date and place of seizure) information are collated in a dedicated database for each specimen. The study capitalises on this extended database and defines several indicators to characterise the structure of drugs markets, to follow-up on their evolution and to compare cocaine and heroin markets. Relational, spatial, temporal and quantitative analyses of data reveal the emergence and importance of distribution networks. They enable to evaluate the cross-jurisdictional character of drug trafficking and the observation time of drug batches, as well as the quantity of drugs entering the market every year. Results highlight the stable nature of drugs markets over the years despite the very dynamic flows of distribution and consumption. This research work illustrates how the systematic analysis of forensic data may elicit knowledge on criminal activities at a strategic level. In combination with information from other sources, such knowledge can help to devise intelligence-based preventive and repressive measures and to discuss the impact of countermeasures.

The role of endothelial enzymes NOS, VAP-1 and CD73 in acute lung injury

Acute lung injury (ALI) is a syndrome of acute hypoxemic respiratory failure with bilateral pulmonary infiltrates that is not caused by left atrial hypertension. Since there is no effective treatment available, this frequent clinical syndrome significantly contributes to mortality of both medical and surgical patients. Great majority of the patients with the syndrome suffers from indirect ALI caused by systemic inflammatory response syndrome (SIRS). Sepsis, trauma, major surgery and severe burns, which represent the most common triggers of SIRS, often induce an overwhelming inflammatory reaction leading to dysfunction of several vital organs. Studies of indirect ALI due to SIRS revealed that respiratory dysfunction results from increased permeability of endothelium. Disruption of endothelial barrier allows extravasation of protein-rich liquid and neutrophils to pulmonary parenchyma. Both under normal conditions and in inflammation, endothelial barrier function is regulated by numerous mechanisms. Endothelial enzymes represent one of the critical control points of vascular permeability and leukocyte trafficking. Some endothelial enzymes prevent disruption of endothelial barrier by production of anti-inflammatory substances. For instance, nitric oxide synthase (NOS) down-regulates leukocyte extravasation in inflammation by generation of nitric oxide. CD73 decreases vascular leakage and neutrophil emigration to inflamed tissues by generation of adenosine. On the other hand, vascular adhesion protein-1 (VAP-1) mediates leukocyte trafficking to the sites of inflammation both by generation of pro-inflammatory substances and by physically acting as an adhesion molecule. The aims of this study were to define the role of endothelial enzymes NOS, CD73 and VAP-1 in acute lung injury. Our data suggest that increasing substrate availability for NOS reduces both lung edema and neutrophil infiltration and this effect is not enhanced by concomitant administration of antioxidants. CD73 protects from vascular leakage in ALI and its up-regulation by interferon-β represents a novel therapeutic strategy for treatment of this syndrome. Enzymatic activity of VAP-1 mediates neutrophil infiltration in ALI and its inhibition represents an attractive approach to treat ALI.

Role of Myotonic Dystrophy Protein Kinase [DMPK] in Glucose Homeostasis and Muscle Insulin Action

Myotonic dystrophy 1 (DM1) is caused by a CTG expansion in the 3′-unstranslated region of the DMPK gene, which encodes a serine/threonine protein kinase. One of the common clinical features of DM1 patients is insulin resistance, which has been associated with a pathogenic effect of the repeat expansions. Here we show that DMPK itself is a positive modulator of insulin action. DMPK-deficient (dmpk−/−) mice exhibit impaired insulin signaling in muscle tissues but not in adipocytes and liver, tissues in which DMPK is not expressed. Dmpk−/− mice display metabolic derangements such as abnormal glucose tolerance, reduced glucose uptake and impaired insulin-dependent GLUT4 trafficking in muscle. Using DMPK mutants, we show that DMPK is required for a correct intracellular trafficking of insulin and IGF-1 receptors, providing a mechanism to explain the molecular and metabolic phenotype of dmpk−/− mice. Taken together, these findings indicate that reduced DMPK expression may directly influence the onset of insulin-resistance in DM1 patients and point to dmpk as a new candidate gene for susceptibility to type 2-diabetes.

Role of Myotonic Dystrophy Protein Kinase [DMPK] in Glucose Homeostasis and Muscle Insulin Action

Myotonic dystrophy 1 (DM1) is caused by a CTG expansion in the 3′-unstranslated region of the DMPK gene, which encodes a serine/threonine protein kinase. One of the common clinical features of DM1 patients is insulin resistance, which has been associated with a pathogenic effect of the repeat expansions. Here we show that DMPK itself is a positive modulator of insulin action. DMPK-deficient (dmpk−/−) mice exhibit impaired insulin signaling in muscle tissues but not in adipocytes and liver, tissues in which DMPK is not expressed. Dmpk−/− mice display metabolic derangements such as abnormal glucose tolerance, reduced glucose uptake and impaired insulin-dependent GLUT4 trafficking in muscle. Using DMPK mutants, we show that DMPK is required for a correct intracellular trafficking of insulin and IGF-1 receptors, providing a mechanism to explain the molecular and metabolic phenotype of dmpk−/− mice. Taken together, these findings indicate that reduced DMPK expression may directly influence the onset of insulin-resistance in DM1 patients and point to dmpk as a new candidate gene for susceptibility to type 2-diabetes.

β1 integrin regulation

Integrins are heterodimeric adhesion receptors mediating adhesion to extracellular matrix proteins and to other cells. Integrins are important in embryonic development, structural integrity of connective tissue, blood thrombus formation, and immune defense system. Integrins are transmembrane proteins whose ligand binding capacity (activity) is regulated by large conformational changes. Extracellular ligand binding or intracellular effector binding to integrin cytoplasmic face regulate integrin activity. Integrins are thus able to mediate bi-directional signaling. Integrin function is also regulated by intracellular location. Integrins are constantly recycled from endocytic vesicles to plasma membrane, and this has been shown to be important for cell migration and invasion as well. Deregulation of integrin functionality can lead to deleterious illnesses, such as bleeding or inflammatory disorders. It is also evident that integrin deregulation is associated with cancer progression. In this study, a novel Beta1 integrin associating protein, Rab21, was characterized. Rab21 binding to integrin cytoplasmic tail was shown to be important for Beta1 integrin endo- and exocytosis – intracellular trafficking. It was furher shown that this interaction has an important role in cell adhesion, migration, as well as in the final step of cell division, cytokinesis. This work showed that abrogation of Rab21 function or β1 integrin endocytic traffic, can lead to defects in cell division and results in formation of multinucleated cells. Multinucleation and especially tetraploidy can be a transient pathway to aneuploidy and tumorigenesis. This work characterized chromosomal deletions in rab21 locus in ovarian and prostate cancer samples and showed that a cell line with rab21 deletion also had impairment in cell division, which could be rescued by Rab21 re-expression. The work demonstrates an important role for Rab21 and Beta1 integrin traffic regulation in cell adhesion and division, and suggests a probable associaton with tumorigenesis. In this study, Beta1 integrin activity regulation was also addressed. A novel cell array platform for genome-scale RNAi screenings was characterized here. More than 4500 genes were knocked-down in prostate cancer cells using siRNA-mediated silencing. The effects on Beta1 integrin activity were analyzed upon knock-downs. The screen identified more that 400 putative regulators of Beta1 integrin activity in prostate cancer. In conclusion, this work will help us to understand complex regulatory pathways involved in cancer cell adhesion and migration.

Potential of caveolae in the therapy of cardiovascular and neurological diseases.

Caveolae are membrane micro-domains enriched in cholesterol, sphingolipids and caveolins, which are transmembrane proteins with a hairpin-like structure. Caveolae participate in receptor-mediated trafficking of cell surface receptors and receptor-mediated signaling. Furthermore, caveolae participate in clathrin-independent endocytosis of membrane receptors. On the one hand, caveolins are involved in vascular and cardiac dysfunction. Also, neurological abnormalities in caveolin-1 knockout mice and a link between caveolin-1 gene haplotypes and neurodegenerative diseases have been reported. The aim of this article is to present the rationale for considering caveolae as potential targets in cardiovascular and neurological diseases.

Cytoplasmic accumulation of NCoR in malignant melanoma: Consequences of altered gene repression and prognostic significance

Invasive malignant melanoma (MM) is an aggressive tumor with no curative therapy available in advanced stages. Nuclear corepressor (NCoR) is an essential regulator of gene transcription, and its function has been found deregulated in different types of cancer. In colorectal cancer cells, loss of nuclear NCoR is induced by Inhibitor of kappa B kinase (IKK) through the phosphorylation of specific serine residues. We here investigate whether NCoR function impacts in MM, which might have important diagnostic and prognostic significance. By IHC, we here determined the subcellular distribution of NCoR in a cohort of 63 primary invasive MM samples, and analyzed its possible correlation with specific clinical parameters. We therefore used a microarray-based strategy to determine global gene expression differences in samples with similar tumor stage, which differ in the presence of cytoplasmic or nuclear NCoR. We found that loss of nuclear NCoR results in upregulation of a specific cancer-related genetic signature, and is significantly associated with MM progression. Inhibition of IKK activity in melanoma cells reverts NCoR nuclear distribution and specific NCoR-regulated gene transcription. Analysis of public database demonstrated that inactivating NCoR mutations are highly prevalent in MM, showing features of driver oncogene.