Christophe Hue - Academia.edu (original) (raw)

Papers by Christophe Hue

Research paper thumbnail of Transcriptome Profiling in Rat Inbred Strains and Experimental Cross Reveals Discrepant Genetic Architecture of Genome-Wide Gene Expression

G3 (Bethesda, Md.), Jan 19, 2016

To test the impact of genetic heterogeneity on cis- and trans-mediated mechanisms of gene express... more To test the impact of genetic heterogeneity on cis- and trans-mediated mechanisms of gene expression regulation, we profiled the transcriptome of adipose tissue in 20 inbred congenic strains derived from diabetic Goto-Kakizaki (GK) rats and Brown-Norway (BN) controls, which contain well-defined blocks (1Mb-183Mb) of genetic polymorphisms, and in 123 genetically heterogeneous rats of an (GKxBN)F2 offspring. Within each congenic we identified 73 to 1,351 differentially expressed genes (DEG), only 7.7% of which mapped within the congenic blocks, and which may be regulated in cis The remainder localised outside the blocks, and therefore must be regulated in trans Most trans-regulated genes exhibited approximately two-fold expression changes, consistent with mono-allelic expression. Altered biological pathways were replicated between congenics sharing blocks of genetic polymorphisms, but polymorphisms at different loci also had redundant effects on transcription of common distant genes a...

Research paper thumbnail of retroviral gene therapy: a balance between efficiency and toxicity Long-term immune reconstitution in RAG1-deficient mice treated by

Research paper thumbnail of Adaptive Expression of MicroRNA-125a in Adipose Tissue in Response to Obesity in Mice and Men

PLoS ONE, 2014

MicroRNAs are emerging as new mediators in the regulation of adipose tissue biology and the devel... more MicroRNAs are emerging as new mediators in the regulation of adipose tissue biology and the development of obesity. An important role of microRNA-125a has been suggested in the pathogenesis of insulin resistance (IR). Here, we characterized the function of microRNA-125a in adipose tissue in a context of experimentally-induced IR and obesity in mice and in obese patients. We showed time dependent overexpression of the microRNA in adipose tissue of BALB/c and C57BL/6J mice in response to high fat diet (HFD) feeding. MicroRNA-125a expression was downregulated in vitro in insulin resistant 3T3-L1 adipocytes and ex vivo in adipose tissue of obese patients. In vitro modulation of microRNA-125a expression in 3T3-L1 adipocytes did not affect glucose uptake. Gene set enrichment analysis (GSEA) identified significantly altered expression patterns of predicted microRNA-125a gene targets in transcriptomic datasets of adipose tissue from HFD-fed mice and obese patients. Among genes that contributed to global enrichment of altered expression of microRNA-125a targets, Thyrotroph embryonic factor (Tef ), Mannan-binding lectin serine peptidase 1, Reticulon 2 and Ubiquitin-conjugating enzyme E2L3 were significantly differentially expressed in adipose tissue in these groups. We showed that Tef expression is reduced in adipose tissue of obese patients following gastric bypass surgery. Our findings indicate that microRNA-125a expression in adipose tissue adapts to IR and may play a role in the development of obesity in mice and obese subjects through uncoupled regulation of the expression of microRNA-125a and its targets.

Research paper thumbnail of Sustained Correction of X-Linked Severe Combined Immunodeficiency by ex Vivo Gene Therapy

New England Journal of Medicine, 2002

Conclusions Ex vivo gene therapy with g c can safely correct the immune deficiency of patients wi... more Conclusions Ex vivo gene therapy with g c can safely correct the immune deficiency of patients with X-linked severe combined immunodeficiency. (N Engl

Research paper thumbnail of Eculizumab in an anephric patient with atypical haemolytic uraemic syndrome and advanced vascular lesions

Nephrology Dialysis Transplantation, 2013

Research paper thumbnail of O81 Impact de métabolites dérivés de la flore bactérienne intestinale sur la sécrétion d’insuline in vitro et in vivo

Diabetes & Metabolism, 2014

Research paper thumbnail of Topological analysis of metabolic networks integrating co-segregating transcriptomes and metabolomes in type 2 diabetic rat congenic series

Genome Medicine, 2016

The genetic regulation of metabolic phenotypes (i.e., metabotypes) in type 2 diabetes mellitus oc... more The genetic regulation of metabolic phenotypes (i.e., metabotypes) in type 2 diabetes mellitus occurs through complex organ-specific cellular mechanisms and networks contributing to impaired insulin secretion and insulin resistance. Genome-wide gene expression profiling systems can dissect the genetic contributions to metabolome and transcriptome regulations. The integrative analysis of multiple gene expression traits and metabolic phenotypes (i.e., metabotypes) together with their underlying genetic regulation remains a challenge. Here, we introduce a systems genetics approach based on the topological analysis of a combined molecular network made of genes and metabolites identified through expression and metabotype quantitative trait locus mapping (i.e., eQTL and mQTL) to prioritise biological characterisation of candidate genes and traits. We used systematic metabotyping by (1)H NMR spectroscopy and genome-wide gene expression in white adipose tissue to map molecular phenotypes to genomic blocks associated with obesity and insulin secretion in a series of rat congenic strains derived from spontaneously diabetic Goto-Kakizaki (GK) and normoglycemic Brown-Norway (BN) rats. We implemented a network biology strategy approach to visualize the shortest paths between metabolites and genes significantly associated with each genomic block. Despite strong genomic similarities (95-99 %) among congenics, each strain exhibited specific patterns of gene expression and metabotypes, reflecting the metabolic consequences of series of linked genetic polymorphisms in the congenic intervals. We subsequently used the congenic panel to map quantitative trait loci underlying specific mQTLs and genome-wide eQTLs. Variation in key metabolites like glucose, succinate, lactate, or 3-hydroxybutyrate and second messenger precursors like inositol was associated with several independent genomic intervals, indicating functional redundancy in these regions. To navigate through the complexity of these association networks we mapped candidate genes and metabolites onto metabolic pathways and implemented a shortest path strategy to highlight potential mechanistic links between metabolites and transcripts at colocalized mQTLs and eQTLs. Minimizing the shortest path length drove prioritization of biological validations by gene silencing. These results underline the importance of network-based integration of multilevel systems genetics datasets to improve understanding of the genetic architecture of metabotype and transcriptomic regulation and to characterize novel functional roles for genes determining tissue-specific metabolism.

Research paper thumbnail of The Role of PP2A Methylation in Susceptibility and Resistance to TBI and AD-Induced Neurodegeneration

Research paper thumbnail of Complement Factor B Mutations in Atypical Hemo

Atypical hemolytic uremic syndrome (aHUS) is a genetic ultrarare renal disease associated with ov... more Atypical hemolytic uremic syndrome (aHUS) is a genetic ultrarare renal disease associated with overactivation of the alternative pathway of complement. Four gain-of-function mutations that form a hyperactive or deregulated C3 convertase have been identified in Factor B (FB) ligand binding sites. Here, we studied the functional consequences of 10 FB genetic changes recently identified from different aHUS cohorts. Using several tests for alternative C3 and C5 convertase formation and regulation, we identified two gain-of-function and potentially disease-relevant mutations that formed either an overactive convertase (M433I) or a convertase resistant to decay by FH (K298Q). One mutation (R178Q) produced a partially cleaved protein with no ligand binding or functional activity. Seven genetic changes led to near-normal or only slightly reduced ligand binding and functional activity compared with the most common polymorphism at position 7, R7. Notably, none of the algorithms used to predict the disease relevance of FB mutations agreed completely with the experimental data, suggesting that in silico approaches should be undertaken with caution. These data, combined with previously published results, suggest that 9 of 15 FB genetic changes identified in patients with aHUS are unrelated to disease pathogenesis. This study highlights that functional assessment of identified nucleotide changes in FB is mandatory to confirm disease association. J Am Soc Nephrol 25: ccc-ccc, 2014 ISSN : 1046-6673/2509-ccc RR, homozygous for arginine (R); RW, heterozygous for arginine and tryptophan; NA, not available; FI, Factor I; MCP, membrane cofactor protein; TM, thrombomodulin; RQ, heterozygous for arginine and glutamine.

Research paper thumbnail of Long Term Immune Reconstitution in RAG-1 Deficient Mice Treated by Retroviral Gene Therapy : A Balance Between Efficiency and Toxicity

Severe combined immunodeficiency (SCID) caused by mutations in RAG1 or RAG2 genes is characterize... more Severe combined immunodeficiency (SCID) caused by mutations in RAG1 or RAG2 genes is characterized by a complete block in T-and B-cell development. The only curative treatment is allogeneic hematopoietic stem cell transplantation, which gives a high survival rate (90%) when an HLA-genoidentical donor exists but unsatisfactory results when only partially compatible donors are available. We have thus been interested in the development of a potential alternative treatment by using retroviral gene transfer of a normal copy of RAG1 cDNA. We show here that this approach applied to RAG-1deficient mice restores normal B-and T-cell function even in the presence of a reduced number of mature B cells. The reconstitution is stable over time, attesting to a selective advantage of transduced progenitors. Notably, a high transgene copy number was detected in all lymphoid organs, and this was associated with a risk of lymphoproliferation as observed in one mouse. Altogether, these results demonstrate that correction of RAG-1 deficiency can be achieved by gene therapy in immunodeficient mice but that human application would require the use of self-inactivated vector to decrease the risk of lymphoproliferative diseases. (Blood. 2006;107:63-72)

Research paper thumbnail of Mapping interactions between complement C3 and regulators using mutations in atypical hemolytic uremic syndrome

• C3 mutations in aHUS commonly result in impaired complement regulation, C3 consumption, and a p... more • C3 mutations in aHUS commonly result in impaired complement regulation, C3 consumption, and a poor renal outcome. • C3 mutations tend to cluster at the protein surface and facilitate mapping of putative binding sites for the regulatory proteins.

Research paper thumbnail of Modulatory role of the anti-apoptotic protein kinase CK2 in the sub-cellular localization of Fas associated death domain protein (FADD)

Biochimica et biophysica acta, Jan 5, 2015

The Fas associated death domain protein (FADD) is the key adaptor molecule of the apoptotic signa... more The Fas associated death domain protein (FADD) is the key adaptor molecule of the apoptotic signal triggered by death receptors of the TNF-R1 superfamily. Besides its crucial role in the apoptotic machinery, FADD has proved to be important in many biological processes like tumorigenesis, embryonic development or cell cycle progression. In a process to decipher the regulatory mechanisms underlying FADD regulation, we identified the anti-apoptotic kinase, CK2, as a new partner and regulator of FADD sub-cellular localization. The blockade of CK2 activity induced FADD re-localization within the cell. Moreover, cytoplasmic FADD was increased when CK2β was knocked down. In vitro kinase and pull down assays confirmed that FADD could be phosphorylated by the CK2 holoenzyme. We found that phosphorylation is weak with CK2α alone and optimal in the presence of stoichiometric amounts of CK2α catalytic and CK2β regulatory subunits, showing that FADD phosphorylation is undertaken by the CK2 holoe...

Research paper thumbnail of Gene Therapy of Human Severe Combined Immunodeficiency (SCID)-X1 Disease

Science, 2000

Severe combined immunodeficiency-X1 (SCID-X1) is an X-linked inherited disorder characterized by ... more Severe combined immunodeficiency-X1 (SCID-X1) is an X-linked inherited disorder characterized by an early block in T and natural killer (NK) lymphocyte differentiation. This block is caused by mutations of the gene encoding the gammac cytokine receptor subunit of interleukin-2, -4, -7, -9, and -15 receptors, which participates in the delivery of growth, survival, and differentiation signals to early lymphoid progenitors. After preclinical studies, a gene therapy trial for SCID-X1 was initiated, based on the use of complementary DNA containing a defective gammac Moloney retrovirus-derived vector and ex vivo infection of CD34+ cells. After a 10-month follow-up period, gammac transgene-expressing T and NK cells were detected in two patients. T, B, and NK cell counts and function, including antigen-specific responses, were comparable to those of age-matched controls. Thus, gene therapy was able to provide full correction of disease phenotype and, hence, clinical benefit.

Research paper thumbnail of Functional mapping of the interactions between complement C3 and regulatory proteins using atypical hemolytic uremic syndrome-associated mutations

Blood, Jan 21, 2015

The pathogenesis of atypical hemolytic uremic syndrome (aHUS) is strongly linked to dysregulation... more The pathogenesis of atypical hemolytic uremic syndrome (aHUS) is strongly linked to dysregulation of the alternative pathway of the complement system. Mutations in complement genes have been identified in about two-thirds of cases with 5-15% being in C3. In this study, 23 aHUS-associated genetic changes in C3 were characterized relative to their interaction with the control proteins Factor H (FH), membrane cofactor protein (MCP; CD46) and complement receptor 1 (CR1; CD35). In surface plasmon resonance experiments, 17 mutant recombinant proteins demonstrated a defect in binding to FH and/or MCP while two demonstrated reduced binding to CR1. In the majority of cases, decreased binding affinity translated to a decrease in proteolytic inactivation (known as cofactor activity) of C3b via FH and MCP. These results were utilized to map the putative binding regions of C3b involved in the interaction with MCP and CR1 and interrogated relative to known FH binding sites. Seventy-six percent of...

Research paper thumbnail of Super C3-convertases, formed by gain-of-function factor B or C3 mutant proteins are associated with atypical haemolytic uraemic syndrome with a poor outcome

Molecular Immunology, 2008

Research paper thumbnail of Fluid phase complement alternative pathway dysregulation: A major physiopathological mechanism in anti-FH autoantibodies-associated HUS

Molecular Immunology, 2010

recorded in C3 deficient mice and in mice treated with the C3 inhibitors CR2-Crry and alternative... more recorded in C3 deficient mice and in mice treated with the C3 inhibitors CR2-Crry and alternative pathway specific CR2-fH. A similar therapeutic effect was also observed by treatment with either C3a or C5a receptor antagonist. Together, these data indicate and important role for the alternative pathway of complement activation in PQ-induced ALI, with a role for the downstream activation products C3a and C5a and receptor signaling. The data suggest that complement inhibition may be an effective clinical intervention for post-exposure treatment of PQ-induced ALI.

Research paper thumbnail of Restoration of Human B-cell Differentiation Into NOD-SCID Mice Engrafted With Gene-corrected CD34+ Cells Isolated From Artemis or RAG1-deficient Patients

Molecular Therapy, 2008

Severe combined immunodeficiency (SCID) caused by mutation of the recombination-activating gene 1... more Severe combined immunodeficiency (SCID) caused by mutation of the recombination-activating gene 1 (RAG1) or Artemis gene lead to the absence of B- and T-cell differentiation. The only curative treatment is allogeneic bone marrow (BM) transplantation, which displays a high survival rate when an HLA compatible donor is available but has a poorer prognosis when the donor is partially compatible. Consequently, gene therapy may be a promising alternative strategy for these diseases. Here, we report that lentiviral gene-corrected BM CD34(+) cells (isolated from Artemis- or RAG1-deficient patients) sustain human B-cell differentiation following injection into non-obese diabetic/SCID (NOD-SCID) mice previously infused with anti-interleukin-2 receptor beta chain monoclonal antibody. In most of the mice BM, engrafted with Artemis-transduced cells, human B-cell differentiation occurred until the mature stage. The B cells were functional as human immunoglobulin M (IgM) was present in the serum. Following injection with RAG1-transduced cells, human engraftment occurred in vivo but B-cell differentiation until the mature stage was less frequent. However, when it occurred, it was always associated with human IgM production. This overall approach represents a useful tool for evaluating gene transfer efficiency in human SCID forms affecting B-cell development (such as Artemis deficiency) and for testing new vectors for improving in vivo RAG1 complementation.

Research paper thumbnail of Further evidence for a paradoxical role of the alternative pathway C3 convertase in atypical haemolytic Uremic Syndrome

Molecular Immunology, 2009

including skin and wound infections as well as live threatening septicemia.

Research paper thumbnail of Novel C3 convertase gain of function in atypical haemolytic uraemic syndrome, caused by a frequent mutation in C3

Molecular Immunology, 2010

C3 is a key component of the complement cascade, common to all three activation pathways. Mutatio... more C3 is a key component of the complement cascade, common to all three activation pathways. Mutations in C3 are related to a rare renal thrombotic microangiopatic disease -atypical haemolytic uraemic syndrome (aHUS). C3 sequencing of a large aHUS cohort (n = 282) led to the identification of 27 patients with C3 mutations, 12 of which carried the same mutation R139W, not found in healthy controls (n = 160). Most of the 12 patients come from the same geographic region and might have a common ancestor. In these patients the clinical outcome was unfavorable with 70% of patients progressing to end stage renal disease immediately or within the first years after the onset of the disease. Therefore it was important to find out whether and how this mutation is related to the disease pathogenesis. The R139 position in C3 is located in proximity to the FH SCR1-4 binding site. Accordingly, the R139W mutation resulted in weaker interaction with FH and MCP binding (studied by SPR and ELISA). In addition, real time monitoring of the C3-convertase formation demonstrated that the R139W-C3 formed a hyperactive convertase, depositing more C3 on the surface compared to the wild type. In order to understand how this mutation was related to the aHUS pathogenesis, endothelial cells models were applied. Adherent HUVEC and glomerular endothelial cells (GEnC) were incubated with normal sera (n = 40) or aHUS R139W patients sera (n = 3). Marked increase in C3 depositions was detected upon incubation of patients' sera in the case of TNFa/IFNg activated EC. The augmented C3 deposition was accompanied by increased C5a and sC5b-9 release and increased tissue factor (TF) expression on EC membrane. In conclusion, this is the first demonstration of a direct gain of function mutation in C3, leading to hyperactive C3 convertase. The abnormal R139W convertase deposited high amounts of C3 on EC and resulted in a pro-coagulant phenotype -a hallmark of aHUS.

Research paper thumbnail of Complement Factor B Mutations in Atypical Hemolytic Uremic Syndrome--Disease-Relevant or Benign?

Journal of the American Society of Nephrology, 2014

Atypical hemolytic uremic syndrome (aHUS) is a genetic ultrarare renal disease associated with ov... more Atypical hemolytic uremic syndrome (aHUS) is a genetic ultrarare renal disease associated with overactivation of the alternative pathway of complement. Four gain-of-function mutations that form a hyperactive or deregulated C3 convertase have been identified in Factor B (FB) ligand binding sites. Here, we studied the functional consequences of 10 FB genetic changes recently identified from different aHUS cohorts. Using several tests for alternative C3 and C5 convertase formation and regulation, we identified two gain-of-function and potentially disease-relevant mutations that formed either an overactive convertase (M433I) or a convertase resistant to decay by FH (K298Q). One mutation (R178Q) produced a partially cleaved protein with no ligand binding or functional activity. Seven genetic changes led to near-normal or only slightly reduced ligand binding and functional activity compared with the most common polymorphism at position 7, R7. Notably, none of the algorithms used to predict the disease relevance of FB mutations agreed completely with the experimental data, suggesting that in silico approaches should be undertaken with caution. These data, combined with previously published results, suggest that 9 of 15 FB genetic changes identified in patients with aHUS are unrelated to disease pathogenesis. This study highlights that functional assessment of identified nucleotide changes in FB is mandatory to confirm disease association. J Am Soc Nephrol 25: ccc-ccc, 2014 ISSN : 1046-6673/2509-ccc RR, homozygous for arginine (R); RW, heterozygous for arginine and tryptophan; NA, not available; FI, Factor I; MCP, membrane cofactor protein; TM, thrombomodulin; RQ, heterozygous for arginine and glutamine.

Research paper thumbnail of Transcriptome Profiling in Rat Inbred Strains and Experimental Cross Reveals Discrepant Genetic Architecture of Genome-Wide Gene Expression

G3 (Bethesda, Md.), Jan 19, 2016

To test the impact of genetic heterogeneity on cis- and trans-mediated mechanisms of gene express... more To test the impact of genetic heterogeneity on cis- and trans-mediated mechanisms of gene expression regulation, we profiled the transcriptome of adipose tissue in 20 inbred congenic strains derived from diabetic Goto-Kakizaki (GK) rats and Brown-Norway (BN) controls, which contain well-defined blocks (1Mb-183Mb) of genetic polymorphisms, and in 123 genetically heterogeneous rats of an (GKxBN)F2 offspring. Within each congenic we identified 73 to 1,351 differentially expressed genes (DEG), only 7.7% of which mapped within the congenic blocks, and which may be regulated in cis The remainder localised outside the blocks, and therefore must be regulated in trans Most trans-regulated genes exhibited approximately two-fold expression changes, consistent with mono-allelic expression. Altered biological pathways were replicated between congenics sharing blocks of genetic polymorphisms, but polymorphisms at different loci also had redundant effects on transcription of common distant genes a...

Research paper thumbnail of retroviral gene therapy: a balance between efficiency and toxicity Long-term immune reconstitution in RAG1-deficient mice treated by

Research paper thumbnail of Adaptive Expression of MicroRNA-125a in Adipose Tissue in Response to Obesity in Mice and Men

PLoS ONE, 2014

MicroRNAs are emerging as new mediators in the regulation of adipose tissue biology and the devel... more MicroRNAs are emerging as new mediators in the regulation of adipose tissue biology and the development of obesity. An important role of microRNA-125a has been suggested in the pathogenesis of insulin resistance (IR). Here, we characterized the function of microRNA-125a in adipose tissue in a context of experimentally-induced IR and obesity in mice and in obese patients. We showed time dependent overexpression of the microRNA in adipose tissue of BALB/c and C57BL/6J mice in response to high fat diet (HFD) feeding. MicroRNA-125a expression was downregulated in vitro in insulin resistant 3T3-L1 adipocytes and ex vivo in adipose tissue of obese patients. In vitro modulation of microRNA-125a expression in 3T3-L1 adipocytes did not affect glucose uptake. Gene set enrichment analysis (GSEA) identified significantly altered expression patterns of predicted microRNA-125a gene targets in transcriptomic datasets of adipose tissue from HFD-fed mice and obese patients. Among genes that contributed to global enrichment of altered expression of microRNA-125a targets, Thyrotroph embryonic factor (Tef ), Mannan-binding lectin serine peptidase 1, Reticulon 2 and Ubiquitin-conjugating enzyme E2L3 were significantly differentially expressed in adipose tissue in these groups. We showed that Tef expression is reduced in adipose tissue of obese patients following gastric bypass surgery. Our findings indicate that microRNA-125a expression in adipose tissue adapts to IR and may play a role in the development of obesity in mice and obese subjects through uncoupled regulation of the expression of microRNA-125a and its targets.

Research paper thumbnail of Sustained Correction of X-Linked Severe Combined Immunodeficiency by ex Vivo Gene Therapy

New England Journal of Medicine, 2002

Conclusions Ex vivo gene therapy with g c can safely correct the immune deficiency of patients wi... more Conclusions Ex vivo gene therapy with g c can safely correct the immune deficiency of patients with X-linked severe combined immunodeficiency. (N Engl

Research paper thumbnail of Eculizumab in an anephric patient with atypical haemolytic uraemic syndrome and advanced vascular lesions

Nephrology Dialysis Transplantation, 2013

Research paper thumbnail of O81 Impact de métabolites dérivés de la flore bactérienne intestinale sur la sécrétion d’insuline in vitro et in vivo

Diabetes & Metabolism, 2014

Research paper thumbnail of Topological analysis of metabolic networks integrating co-segregating transcriptomes and metabolomes in type 2 diabetic rat congenic series

Genome Medicine, 2016

The genetic regulation of metabolic phenotypes (i.e., metabotypes) in type 2 diabetes mellitus oc... more The genetic regulation of metabolic phenotypes (i.e., metabotypes) in type 2 diabetes mellitus occurs through complex organ-specific cellular mechanisms and networks contributing to impaired insulin secretion and insulin resistance. Genome-wide gene expression profiling systems can dissect the genetic contributions to metabolome and transcriptome regulations. The integrative analysis of multiple gene expression traits and metabolic phenotypes (i.e., metabotypes) together with their underlying genetic regulation remains a challenge. Here, we introduce a systems genetics approach based on the topological analysis of a combined molecular network made of genes and metabolites identified through expression and metabotype quantitative trait locus mapping (i.e., eQTL and mQTL) to prioritise biological characterisation of candidate genes and traits. We used systematic metabotyping by (1)H NMR spectroscopy and genome-wide gene expression in white adipose tissue to map molecular phenotypes to genomic blocks associated with obesity and insulin secretion in a series of rat congenic strains derived from spontaneously diabetic Goto-Kakizaki (GK) and normoglycemic Brown-Norway (BN) rats. We implemented a network biology strategy approach to visualize the shortest paths between metabolites and genes significantly associated with each genomic block. Despite strong genomic similarities (95-99 %) among congenics, each strain exhibited specific patterns of gene expression and metabotypes, reflecting the metabolic consequences of series of linked genetic polymorphisms in the congenic intervals. We subsequently used the congenic panel to map quantitative trait loci underlying specific mQTLs and genome-wide eQTLs. Variation in key metabolites like glucose, succinate, lactate, or 3-hydroxybutyrate and second messenger precursors like inositol was associated with several independent genomic intervals, indicating functional redundancy in these regions. To navigate through the complexity of these association networks we mapped candidate genes and metabolites onto metabolic pathways and implemented a shortest path strategy to highlight potential mechanistic links between metabolites and transcripts at colocalized mQTLs and eQTLs. Minimizing the shortest path length drove prioritization of biological validations by gene silencing. These results underline the importance of network-based integration of multilevel systems genetics datasets to improve understanding of the genetic architecture of metabotype and transcriptomic regulation and to characterize novel functional roles for genes determining tissue-specific metabolism.

Research paper thumbnail of The Role of PP2A Methylation in Susceptibility and Resistance to TBI and AD-Induced Neurodegeneration

Research paper thumbnail of Complement Factor B Mutations in Atypical Hemo

Atypical hemolytic uremic syndrome (aHUS) is a genetic ultrarare renal disease associated with ov... more Atypical hemolytic uremic syndrome (aHUS) is a genetic ultrarare renal disease associated with overactivation of the alternative pathway of complement. Four gain-of-function mutations that form a hyperactive or deregulated C3 convertase have been identified in Factor B (FB) ligand binding sites. Here, we studied the functional consequences of 10 FB genetic changes recently identified from different aHUS cohorts. Using several tests for alternative C3 and C5 convertase formation and regulation, we identified two gain-of-function and potentially disease-relevant mutations that formed either an overactive convertase (M433I) or a convertase resistant to decay by FH (K298Q). One mutation (R178Q) produced a partially cleaved protein with no ligand binding or functional activity. Seven genetic changes led to near-normal or only slightly reduced ligand binding and functional activity compared with the most common polymorphism at position 7, R7. Notably, none of the algorithms used to predict the disease relevance of FB mutations agreed completely with the experimental data, suggesting that in silico approaches should be undertaken with caution. These data, combined with previously published results, suggest that 9 of 15 FB genetic changes identified in patients with aHUS are unrelated to disease pathogenesis. This study highlights that functional assessment of identified nucleotide changes in FB is mandatory to confirm disease association. J Am Soc Nephrol 25: ccc-ccc, 2014 ISSN : 1046-6673/2509-ccc RR, homozygous for arginine (R); RW, heterozygous for arginine and tryptophan; NA, not available; FI, Factor I; MCP, membrane cofactor protein; TM, thrombomodulin; RQ, heterozygous for arginine and glutamine.

Research paper thumbnail of Long Term Immune Reconstitution in RAG-1 Deficient Mice Treated by Retroviral Gene Therapy : A Balance Between Efficiency and Toxicity

Severe combined immunodeficiency (SCID) caused by mutations in RAG1 or RAG2 genes is characterize... more Severe combined immunodeficiency (SCID) caused by mutations in RAG1 or RAG2 genes is characterized by a complete block in T-and B-cell development. The only curative treatment is allogeneic hematopoietic stem cell transplantation, which gives a high survival rate (90%) when an HLA-genoidentical donor exists but unsatisfactory results when only partially compatible donors are available. We have thus been interested in the development of a potential alternative treatment by using retroviral gene transfer of a normal copy of RAG1 cDNA. We show here that this approach applied to RAG-1deficient mice restores normal B-and T-cell function even in the presence of a reduced number of mature B cells. The reconstitution is stable over time, attesting to a selective advantage of transduced progenitors. Notably, a high transgene copy number was detected in all lymphoid organs, and this was associated with a risk of lymphoproliferation as observed in one mouse. Altogether, these results demonstrate that correction of RAG-1 deficiency can be achieved by gene therapy in immunodeficient mice but that human application would require the use of self-inactivated vector to decrease the risk of lymphoproliferative diseases. (Blood. 2006;107:63-72)

Research paper thumbnail of Mapping interactions between complement C3 and regulators using mutations in atypical hemolytic uremic syndrome

• C3 mutations in aHUS commonly result in impaired complement regulation, C3 consumption, and a p... more • C3 mutations in aHUS commonly result in impaired complement regulation, C3 consumption, and a poor renal outcome. • C3 mutations tend to cluster at the protein surface and facilitate mapping of putative binding sites for the regulatory proteins.

Research paper thumbnail of Modulatory role of the anti-apoptotic protein kinase CK2 in the sub-cellular localization of Fas associated death domain protein (FADD)

Biochimica et biophysica acta, Jan 5, 2015

The Fas associated death domain protein (FADD) is the key adaptor molecule of the apoptotic signa... more The Fas associated death domain protein (FADD) is the key adaptor molecule of the apoptotic signal triggered by death receptors of the TNF-R1 superfamily. Besides its crucial role in the apoptotic machinery, FADD has proved to be important in many biological processes like tumorigenesis, embryonic development or cell cycle progression. In a process to decipher the regulatory mechanisms underlying FADD regulation, we identified the anti-apoptotic kinase, CK2, as a new partner and regulator of FADD sub-cellular localization. The blockade of CK2 activity induced FADD re-localization within the cell. Moreover, cytoplasmic FADD was increased when CK2β was knocked down. In vitro kinase and pull down assays confirmed that FADD could be phosphorylated by the CK2 holoenzyme. We found that phosphorylation is weak with CK2α alone and optimal in the presence of stoichiometric amounts of CK2α catalytic and CK2β regulatory subunits, showing that FADD phosphorylation is undertaken by the CK2 holoe...

Research paper thumbnail of Gene Therapy of Human Severe Combined Immunodeficiency (SCID)-X1 Disease

Science, 2000

Severe combined immunodeficiency-X1 (SCID-X1) is an X-linked inherited disorder characterized by ... more Severe combined immunodeficiency-X1 (SCID-X1) is an X-linked inherited disorder characterized by an early block in T and natural killer (NK) lymphocyte differentiation. This block is caused by mutations of the gene encoding the gammac cytokine receptor subunit of interleukin-2, -4, -7, -9, and -15 receptors, which participates in the delivery of growth, survival, and differentiation signals to early lymphoid progenitors. After preclinical studies, a gene therapy trial for SCID-X1 was initiated, based on the use of complementary DNA containing a defective gammac Moloney retrovirus-derived vector and ex vivo infection of CD34+ cells. After a 10-month follow-up period, gammac transgene-expressing T and NK cells were detected in two patients. T, B, and NK cell counts and function, including antigen-specific responses, were comparable to those of age-matched controls. Thus, gene therapy was able to provide full correction of disease phenotype and, hence, clinical benefit.

Research paper thumbnail of Functional mapping of the interactions between complement C3 and regulatory proteins using atypical hemolytic uremic syndrome-associated mutations

Blood, Jan 21, 2015

The pathogenesis of atypical hemolytic uremic syndrome (aHUS) is strongly linked to dysregulation... more The pathogenesis of atypical hemolytic uremic syndrome (aHUS) is strongly linked to dysregulation of the alternative pathway of the complement system. Mutations in complement genes have been identified in about two-thirds of cases with 5-15% being in C3. In this study, 23 aHUS-associated genetic changes in C3 were characterized relative to their interaction with the control proteins Factor H (FH), membrane cofactor protein (MCP; CD46) and complement receptor 1 (CR1; CD35). In surface plasmon resonance experiments, 17 mutant recombinant proteins demonstrated a defect in binding to FH and/or MCP while two demonstrated reduced binding to CR1. In the majority of cases, decreased binding affinity translated to a decrease in proteolytic inactivation (known as cofactor activity) of C3b via FH and MCP. These results were utilized to map the putative binding regions of C3b involved in the interaction with MCP and CR1 and interrogated relative to known FH binding sites. Seventy-six percent of...

Research paper thumbnail of Super C3-convertases, formed by gain-of-function factor B or C3 mutant proteins are associated with atypical haemolytic uraemic syndrome with a poor outcome

Molecular Immunology, 2008

Research paper thumbnail of Fluid phase complement alternative pathway dysregulation: A major physiopathological mechanism in anti-FH autoantibodies-associated HUS

Molecular Immunology, 2010

recorded in C3 deficient mice and in mice treated with the C3 inhibitors CR2-Crry and alternative... more recorded in C3 deficient mice and in mice treated with the C3 inhibitors CR2-Crry and alternative pathway specific CR2-fH. A similar therapeutic effect was also observed by treatment with either C3a or C5a receptor antagonist. Together, these data indicate and important role for the alternative pathway of complement activation in PQ-induced ALI, with a role for the downstream activation products C3a and C5a and receptor signaling. The data suggest that complement inhibition may be an effective clinical intervention for post-exposure treatment of PQ-induced ALI.

Research paper thumbnail of Restoration of Human B-cell Differentiation Into NOD-SCID Mice Engrafted With Gene-corrected CD34+ Cells Isolated From Artemis or RAG1-deficient Patients

Molecular Therapy, 2008

Severe combined immunodeficiency (SCID) caused by mutation of the recombination-activating gene 1... more Severe combined immunodeficiency (SCID) caused by mutation of the recombination-activating gene 1 (RAG1) or Artemis gene lead to the absence of B- and T-cell differentiation. The only curative treatment is allogeneic bone marrow (BM) transplantation, which displays a high survival rate when an HLA compatible donor is available but has a poorer prognosis when the donor is partially compatible. Consequently, gene therapy may be a promising alternative strategy for these diseases. Here, we report that lentiviral gene-corrected BM CD34(+) cells (isolated from Artemis- or RAG1-deficient patients) sustain human B-cell differentiation following injection into non-obese diabetic/SCID (NOD-SCID) mice previously infused with anti-interleukin-2 receptor beta chain monoclonal antibody. In most of the mice BM, engrafted with Artemis-transduced cells, human B-cell differentiation occurred until the mature stage. The B cells were functional as human immunoglobulin M (IgM) was present in the serum. Following injection with RAG1-transduced cells, human engraftment occurred in vivo but B-cell differentiation until the mature stage was less frequent. However, when it occurred, it was always associated with human IgM production. This overall approach represents a useful tool for evaluating gene transfer efficiency in human SCID forms affecting B-cell development (such as Artemis deficiency) and for testing new vectors for improving in vivo RAG1 complementation.

Research paper thumbnail of Further evidence for a paradoxical role of the alternative pathway C3 convertase in atypical haemolytic Uremic Syndrome

Molecular Immunology, 2009

including skin and wound infections as well as live threatening septicemia.

Research paper thumbnail of Novel C3 convertase gain of function in atypical haemolytic uraemic syndrome, caused by a frequent mutation in C3

Molecular Immunology, 2010

C3 is a key component of the complement cascade, common to all three activation pathways. Mutatio... more C3 is a key component of the complement cascade, common to all three activation pathways. Mutations in C3 are related to a rare renal thrombotic microangiopatic disease -atypical haemolytic uraemic syndrome (aHUS). C3 sequencing of a large aHUS cohort (n = 282) led to the identification of 27 patients with C3 mutations, 12 of which carried the same mutation R139W, not found in healthy controls (n = 160). Most of the 12 patients come from the same geographic region and might have a common ancestor. In these patients the clinical outcome was unfavorable with 70% of patients progressing to end stage renal disease immediately or within the first years after the onset of the disease. Therefore it was important to find out whether and how this mutation is related to the disease pathogenesis. The R139 position in C3 is located in proximity to the FH SCR1-4 binding site. Accordingly, the R139W mutation resulted in weaker interaction with FH and MCP binding (studied by SPR and ELISA). In addition, real time monitoring of the C3-convertase formation demonstrated that the R139W-C3 formed a hyperactive convertase, depositing more C3 on the surface compared to the wild type. In order to understand how this mutation was related to the aHUS pathogenesis, endothelial cells models were applied. Adherent HUVEC and glomerular endothelial cells (GEnC) were incubated with normal sera (n = 40) or aHUS R139W patients sera (n = 3). Marked increase in C3 depositions was detected upon incubation of patients' sera in the case of TNFa/IFNg activated EC. The augmented C3 deposition was accompanied by increased C5a and sC5b-9 release and increased tissue factor (TF) expression on EC membrane. In conclusion, this is the first demonstration of a direct gain of function mutation in C3, leading to hyperactive C3 convertase. The abnormal R139W convertase deposited high amounts of C3 on EC and resulted in a pro-coagulant phenotype -a hallmark of aHUS.

Research paper thumbnail of Complement Factor B Mutations in Atypical Hemolytic Uremic Syndrome--Disease-Relevant or Benign?

Journal of the American Society of Nephrology, 2014

Atypical hemolytic uremic syndrome (aHUS) is a genetic ultrarare renal disease associated with ov... more Atypical hemolytic uremic syndrome (aHUS) is a genetic ultrarare renal disease associated with overactivation of the alternative pathway of complement. Four gain-of-function mutations that form a hyperactive or deregulated C3 convertase have been identified in Factor B (FB) ligand binding sites. Here, we studied the functional consequences of 10 FB genetic changes recently identified from different aHUS cohorts. Using several tests for alternative C3 and C5 convertase formation and regulation, we identified two gain-of-function and potentially disease-relevant mutations that formed either an overactive convertase (M433I) or a convertase resistant to decay by FH (K298Q). One mutation (R178Q) produced a partially cleaved protein with no ligand binding or functional activity. Seven genetic changes led to near-normal or only slightly reduced ligand binding and functional activity compared with the most common polymorphism at position 7, R7. Notably, none of the algorithms used to predict the disease relevance of FB mutations agreed completely with the experimental data, suggesting that in silico approaches should be undertaken with caution. These data, combined with previously published results, suggest that 9 of 15 FB genetic changes identified in patients with aHUS are unrelated to disease pathogenesis. This study highlights that functional assessment of identified nucleotide changes in FB is mandatory to confirm disease association. J Am Soc Nephrol 25: ccc-ccc, 2014 ISSN : 1046-6673/2509-ccc RR, homozygous for arginine (R); RW, heterozygous for arginine and tryptophan; NA, not available; FI, Factor I; MCP, membrane cofactor protein; TM, thrombomodulin; RQ, heterozygous for arginine and glutamine.