Human testis-expressed (TEX) genes: a review focused on spermatogenesis and male fertility

International audienceAbstract Spermatogenesis is a complex process regulated by a multitude of genes. The identification and characterization of male-germ-cell-specific genes is crucial to understanding the mechanisms through which the cells develop. The term “ TEX gene” was coined by Wang et al. (Nat Genet. 2001; 27: 422–6) after they used cDNA suppression subtractive hybridization (SSH) to identify new transcripts that were present only in purified mouse spermatogonia. TEX ( Testis expressed ) orthologues have been found in other vertebrates (mammals, birds, and reptiles), invertebrates, and yeasts. To date, 69 TEX genes have been described in different species and different tissues. To evaluate the expression of each TEX/tex gene, we compiled data from 7 different RNA-Seq mRNA databases in humans, and 4 in the mouse according to the expression atlas database. Various studies have highlighted a role for many of these genes in spermatogenesis. Here, we review current knowledge on the TEX genes and their roles in spermatogenesis and fertilization in humans and, comparatively, in other species (notably the mouse). As expected, TEX genes appear to have a major role in reproduction in general and in spermatogenesis in humans but also in all mammals such as the mouse. Most of them are expressed specifically or predominantly in the testis. As most of the TEX genes are highly conserved in mammals, defects in the male (gene mutations in humans and gene-null mice) lead to infertility. In the future, cumulative data on the human TEX genes’ physiological functions and pathophysiological dysfunctions should become available and is likely to confirm the essential role of this family in the reproductive process. Thirteen TEX genes are now referenced in the OMIM database, and 3 have been linked to a specific phenotype. TEX11 (on Xq13.1) is currently the gene most frequently reported as being associated with azoospermia.La spermatogenèse est un processus complexe régulé par une multitude de gènes. L’identification et la caractérisation des gènes spécifiques des cellules germinales mâles sont essentielles pour comprendre les mécanismes par lesquels les cellules se développent. Le terme «gène TEX » a été inventé par Wang et al. (Nat Genet. 2001; 27: 422–6) après avoir utilisé l’hybridation soustractive d’ADNc (SSH) pour identifier de nouveaux transcrits qui n’étaient présents que dans la spermatogonie de souris. Puis, des orthologues TEX ont été trouvés chez d’autres vertébrés (mammifères, oiseaux et reptiles), des invertébrés et des levures. À ce jour, 69 gènes TEX ( Testis expressed ) ont été décrits dans différentes espèces et différents tissus. Pour évaluer l’expression de chaque gène TEX/tex , nous avons compilé les données de 7 bases de données différentes d’ARNm RNA-Seq chez l’homme, et 4 chez la souris selon la base de données de l’atlas d’expression. Diverses études ont mis en évidence le rôle de plusieurs de ces gènes dans la spermatogenèse. Ici, nous passons en revue les connaissances actuelles sur les gènes TEX et leurs rôles dans la spermatogenèse et la fécondation chez l’humain et, comparativement, chez d’autres espèces (notamment la souris). Comme prévu, les gènes TEX semblent avoir un rôle majeur dans la reproduction en général et dans la spermatogenèse chez l’homme, mais aussi chez d’autres mammifères comme la souris. La plupart d’entre eux sont exprimés spécifiquement ou principalement dans les testicules. Comme la plupart des gènes TEX sont hautement conservés chez les mammifères, des défauts chez le mâle (mutations géniques chez l’homme et KO murin) conduisent à l’infertilité. À l’avenir, l’accumulation des données sur les fonctions physiologiques et les dysfonctionnements physiopathologiques des gènes TEX humains devraient devenir disponibles et confirmer le rôle essentiel de cette famille dans le processus de reproduction. Treize gènes TEX sont désormais référencés dans la base de données OMIM, et 3 ont été liés à un phénotype spécifique. TEX11 (sur Xq13.1) est. actuellement le gène le plus fréquemment rapporté comme étant associé à l’azoospermie

Les micropolluants dans les eaux pluviales : quelles représentations en ont les acteurs de la gestion ?Micropollutants in stormwater: how do stakeholders address this issue?

International audienceLes eaux pluviales (EP) sont un des principaux vecteurs de contamination diffuse des milieux aquatiques en micropolluants. De nouvelles stratégies de gestion doivent être envisagées par les collectivités pour répondre aux exigences de la DCE en termes de qualité des milieux. Dans ce contexte, une attention est portée à la manière dont les acteurs de la gestion se représentent les enjeux associés aux micropolluants dans les EP et les modalités d’action qu’ils mettent en œuvre ou envisagent. Il s’agit plus particulièrement d’interroger l’efficacité associée aux différents ouvrages de gestion alternative – centralisés et décentralisés – en termes de piégeage de micropolluants. Pour cela, l’exemple du Grand Lyon est choisi. Des enquêtes par entretiens semi-directifs ont été conduits auprès d’acteurs de la gestion (maîtres d’ouvrage, maîtres d’œuvre et gestionnaires) pour cerner la diversité des représentations portées sur les dispositifs techniques et sur les micropolluants. Une analyse d’un corpus, constitué de revues professionnelles spécialisées, invite à mieux comprendre les évolutions des discours tenus. Les résultats montrent que la gestion des eaux pluviales est avant tout envisagée de manière quantitative et partielle. La production de connaissances concrètes sur les performances des systèmes de gestion alternatives des eaux pluviales pourrait accompagner ces acteurs vers des démarches de gestion plus qualitatives

CX3CL1 homo-oligomerization drives cell-to-cell adherence

International audienceDuring inflammatory response, blood leukocytes adhere to the endothelium. This process involves numerous adhesion molecules, including a transmembrane chemokine, CX3CL1, which behaves as a molecular cluster. How this cluster assembles and whether this association has a functional role remain unknown. The analysis of CX3CL1 clusters using native electrophoresis and single molecule fluorescence kinetics shows that CX3CL1 is a homo-oligomer of 3 to 7 monomers. Fluorescence recovery after photobleaching assays reveal that the CX3CL1-transmembrane domain peptide self-associates in both cellular and acellular lipid environments, while its random counterpart (i.e. peptide with the same residues in a different order) does not. This strongly indicates that CX3CL1 oligomerization is driven by its intrinsic properties. According to the molecular modeling, CX3CL1 does not associate in compact bundles but rather with monomers linearly assembled side by side. Finally, the CX3CL1 transmembrane peptide inhibits both the CX3CL1 oligomerization and the adhesive function, while its random counterpart does not. This demonstrates that CX3CL1 oligomerization is mandatory for its adhesive potency. Our results provide a new direction to control CX3CL1-dependent cellular adherence in key immune processes. The migration of blood leukocytes to damaged tissues is the first step of the inflammation process and involves a sequence of coordinated interactions between leukocytes and endothelial cells 1-3. The chemotactic cytokines called chemokines that primarily attract leukocytes, are central to the physiological and pathological inflamma-tory processes 4-6. Chemokines trigger leukocyte activation and their firm adhesion to the inflamed endothelium, mainly through integrins 7-9. Two members of the chemokine family are exceptions: CXCL16 and CX3CL1. In addition to their chemokine domain (CD), these two chemokines possess three domains: a mucin-like stalk, a transmembrane (TM) domain, and a cytosolic tail 10,11. When interacting with their cognate receptors (CXCR6 and CX3CR1, respectively), these chemokines induce cell-cell adhesion 12. CXCL16 and CX3CL1 can also be cleaved by metalloproteinases, such as ADAM10 and ADAM17 13-15 , to produce a soluble form with chemotactic functions. The CX3CL1 chemokine, with its unique CX3CR1 receptor 16 , is involved in adherence to the endothelium of the inflammatory monocyte population (CD14 hi CD16-CX3CR1 + CCR2 + in humans, Ly6C hi CX3CR1 + CCR2 + in mice) 12,17-20 likely through interaction with platelets 21,22. This chemokine is also involved in the recruitment of NK lymphocytes 23,24 and in lymphocyte survival as in allergic diseases 25 , as well as in monocytic 26,27 and neuronal survival 28-31. An additional function of the CX3CR1-CX3CL1 pair is the regulation of the patrolling behavior and the margination of monocytes in blood vessels 32,33 or their adherence to the bone marrow 34. The CX3CL1 chemokine is also involved in cytoadhesion of red blood cells infected with the malaria parasite Plasmodiu

A conditional inducible JAK2V617F transgenic mouse model reveals myeloproliferative disease that is reversible upon switching off transgene expression

Aberrant activation of the JAK/STAT pathway is thought to be the critical event in the pathogenesis of the chronic myeloproliferative neoplasms (MPNs) polycythemia vera, essential thrombocythemia and primary myelofibrosis. The most frequent genetic alteration in these pathologies is the activating JAK2V617F mutation, and expression of the mutant gene in mouse models was shown to cause a phenotype resembling the human diseases. Given the body of genetic evidence, it has come as a sobering finding that JAK inhibitor therapy only modestly suppresses the JAK2V617F allele burden, despite showing clear benefits in terms of reducing splenomegaly and constitutional symptoms in patients. To gain a better understanding if JAK2V617F is required for maintenance of myeloproliferative disease once it has evolved, we generated a conditional inducible transgenic JAK2V617F mouse model using the SCL-tTA-2S tet-off system. Our model corroborates that expression of JAK2V617F in hematopoietic stem and progenitor cells recapitulates key hallmarks of human MPNs, and exhibits gender differences in disease manifestation. The disease was found to be transplantable, and importantly, reversible when transgenic JAK2V617F expression was switched off. Our results indicate that mutant JAK2V617F-specific inhibitors should result in profound disease modification by disabling the MPN clone bearing mutant JAK2

Resistance mechanisms to TP53-MDM2 inhibition identified by in vivo piggyBac transposon mutagenesis screen in an Arf-/-mouse model

Inhibitors of double minute 2 protein (MDM2)-tumor protein 53 (TP53) interaction are predicted to be effective in tumors in which the TP53 gene is wild type, by preventing TP53 protein degradation. One such setting is represented by the frequent CDKN2A deletion in human cancer that, through inactivation of p14ARF, activates MDM2 protein, which in turn degrades TP53 tumor suppressor. Here we used piggyBac (PB) transposon insertional mutagenesis to anticipate resistance mechanisms occurring during treatment with the MDM2- TP53 inhibitor HDM201. Constitutive PB mutagenesis in Arf-/- mice provided a collection of spontaneous tumors with characterized insertional genetic landscapes. Tumors were allografted in large cohorts of mice to assess the pharmacologic effects of HDM201. Sixteen out of 21 allograft models were sensitive to HDM201 but ultimately relapsed under treatment. A comparison of tumors with acquired resistance to HDM201 and untreated tumors identified 87 genes that were differentially and significantly targeted by the PB transposon. Resistant tumors displayed a complex clonality pattern suggesting the emergence of several resistant subclones. Among the most frequent alterations conferring resistance, we observed somatic and insertional loss-of-function mutations in transformation- related protein 53 (Trp53) in 54% of tumors and transposonmediated gain-of-function alterations in B-cell lymphoma-extra large (Bcl-xL), Mdm4, and two TP53 family members, resulting in expression of the TP53 dominant negative truncations δNTrp63 and δNTrp73. Enhanced BCL-xL and MDM4 protein expression was confirmed in resistant tumors, as well as in HDM201-resistant patient-derived tumor xenografts. Interestingly, concomitant inhibition of MDM2 and BCL-xL demonstrated significant synergy in p53 wild-type cell lines invitro. Collectively, our findings identify several potential mechanisms by which TP53 wild-type tumors may escape MDM2-targeted therapy

NVP-CHZ868, a Type II JAK2 Inhibitor, Reverses Type I JAK Inhibitor Persistence and Demonstrates Efficacy in Myeloproliferative Neoplasms

Summary Although clinically tested JAK inhibitors offer significant benefit to myeloproliferative neoplasm (MPN) patients, they do not induce molecular remissions. We previously demonstrated that MPN cells become persistent to type I JAK inhibitors which bind the active conformation of JAK2 and enable JAK2 transactivation. We investigated if NVP-CHZ868, a novel type II JAK inhibitor, would demonstrate activity in JAK inhibitor persistent cells and in murine MPN models. JAK2/MPL-mutant cell lines were sensitive to NVP-CHZ868, including type I JAK inhibitor-persistent cells. CHZ868 showed significant activity in murine MPN models and induced reductions in mutant allele burden not observed with type I JAK inhibitors. These data demonstrate that type II JAK inhibition should be pursued as a therapeutic approach for MPN patients. Significance Although clinically tested JAK inhibitors reduce splenomegaly and systemic symptoms, they cannot significantly reduce the MPN clone. We previously demonstrated that MPN cells can acquire persistence to type I JAK inhibitors, which bind the active conformation of JAK2 and enable activation of JAK2 in trans by other JAK family members. We show that engaging JAK2 in the inactive conformation with the novel type II inhibitor CHZ868 retains efficacy in type I JAK inhibitor persistent cells, and shows increased efficacy in murine models of polycythemia vera and myelofibrosis, including significant reductions in disease burden not observed with first-generation JAK inhibitors. These data demonstrate that type II JAK inhibitors improve the targeting of aberrant JAK2 signaling, offering increased therapeutic efficacy

Type II JAK2 inhibition in B-cell acute lymphoblastic leukemia

A variety of cancers depend on JAK2 signaling, including the high-risk subset of B-cell acute lymphoblastic leukemias (B-ALLs) with CRLF2 rearrangements. Type I JAK2 inhibitors induce JAK2 hyperphosphorylation in these leukemias and have limited activity. To overcome this, we developed the type II inhibitor NVP-CHZ868, which stabilizes JAK2 in an inactive conformation. CHZ868 potently suppressed the growth of CRLF2-rearranged human B-ALL cells, abrogated JAK2 signaling, and improved survival in mice with primary human or murine B-ALL. CHZ868 and dexamethasone synergistically induced apoptosis of CRLF2-rearranged human B-ALL cells and improved survival compared to CHZ868 alone. Together, these data provide the foundation for trials of type II JAK2 inhibition in patients with CRLF2-rearranged B-ALL and other JAK2-dependent disorders