Jean-Yves Daniel

Acute oxidative stress is associated with cell proliferation in the mouse liver.

Oxidative stress is known to produce tissue injury and to activate various signaling pathways. To investigate the molecular events linked to acute oxidative stress in mouse liver, we injected a toxic dose of paraquat. Liver necrosis was first observed, followed by histological marks of cell proliferation. Concomitantly, activation of the MAP kinase pathway and increased levels of the anti‐apoptotic protein Bcl‐XL were observed. Gene expression profiles revealed that the differentially expressed genes were potentially involved in cell proliferation. These data suggest that paraquat‐induced acute oxidative stress triggers the activation of regeneration‐related events in the liver.

Differential expression of nm23 genes in adult mouse dorsal root ganglia

Nm23 has been identified as a gene family encoding different isoforms of nucleoside diphosphate kinase (NDPK). This protein is a key enzyme in nucleotide metabolism and has been shown to play important roles in various cellular functions. In the present study, we have investigated the expression of three isotypes in mouse dorsal root ganglia. In situ hybridization and reverse transcriptase‐polymerase chain reaction analysis demonstrated high levels of nm23‐M1, ‐M2, and ‐M3 mRNA expression in peripheral nervous tissue. Moreover, in situ hybridization also displayed a specific nuclear localization for nm23‐M2 mRNA. Immunohistochemistry with light and electron microscopy on isoform‐specific antibodies revealed a differential subcellular distribution of NDPK isoforms. Isoform A was mainly cytosolic, showing only partial association with organelles. In contrast, isoform B was also found in the nucleus, which is in agreement with its proposed role as a transcription factor. The results also indicate a preferential association of isoform C with endoplasmic reticulum and plasma membranes in neuronal cells. Furthermore, isoform C appeared to combine with other NDPK isoforms as demonstrated by double‐labeling evidence by electron microscopy and might be responsible for binding NDPK oligomers to membranes. Thus, isoform C may be considered as a protein of importance for maintaining intracellular pools of GTP in the vicinity of membranes and, hence, for transmembrane signaling. The results indicate a high expression of NDPK isoforms, not only in the central but also in the peripheral nervous system. Their different subcellular compartmentalization suggests that they have isoform‐specific roles in neuronal cell physiology. J. Comp. Neurol. 444:306–323, 2002.

Infrared spectroscopy: a reagent-free method to distinguish Alzheimer's disease patients from normal-aging subjects.

The physiopathogenesis of Alzheimers disease (AD) is related to various biochemical mechanisms that may be reflected by changes in plasma components. In the current study, Fourier transform-infrared (FT-IR) spectroscopy was used to identify these biochemical variations by monitoring spectral differences in the plasma of 40 AD patients compared with those of 112 control subjects. A hierarchical classification in the whole mid-infrared region allowed a clear separation between AD and controls (C) that was optimized by using a restricted spectral range (1480-1428 cm(-1)). Spectral changes confirmed vibration differences between AD and C mostly related to modified lipid and nucleic acid structures involved in oxidative stress-dependent processes of AD. Moreover, the analysis of samples in the 1480-910-cm(-1) region allowed the distinction between C and AD with an accuracy of 98.4% and showed 2 subgroups C(1) and C(2) within the C group. Interestingly, the C(1) subgroup was located closer to the AD group than the C(2) subgroup, which suggests biochemical differences within the nondemented subjects. Biochemical studies revealed a significant increase in a specific marker of oxidative stress, F8-isoprostanes (8-epi-PGF2alpha) levels, in the plasma of AD patients as compared with total controls and subgroup C(2) but not subgroup C(1). Thus, these results suggest that use of FT-IR spectroscopy could be valuable to distinguish AD patients from normal-aging subjects.

Expression patterns of nm23 genes during mouse organogenesis

Nucleoside di-phosphate kinase enzyme (NDPK) isoforms, encoded by the nm23 family of genes, may be involved in various cellular differentiation and proliferation processes. We have therefore analyzed the expression of nm23-M1, -M2, -M3, and -M4 during embryonic mouse development. In situ hybridization data has revealed the differential expression of nm23 mRNA during organogenesis. Whereas nm23-M1 and -M3 are preferentially expressed in the nervous and sensory systems, nm23-M2 mRNA is found ubiquitously. Irrespective of the developmental state studied, nm23-M4 mRNA is only expressed at low levels in a few embryonic organs. In the cerebellum and cerebral cortex, nm23-M1, -M2, and -M3 are present in the neuronal differentiation layer, whereas nm23-M4 mRNA is distributed in the proliferating layer. Thus, nm23 mRNA is differentially expressed, and the diverse NDPK isoforms are sequentially involved in various developmental processes.

Characterization of the nm23-M2, nm23-M3 and nm23-M4 mouse genes: comparison with their human orthologs

The nm23 gene family is thought to be involved in physiopathological processes such as growth, differentiation and cancer promotion, progression or metastasis. We report here the mouse nm23-M3 and nm23-M4 complementary DNA sequences and the genomic cloning, characterization and tissue expression pattern of the nm23-M2, nm23-M3 and nm23-M4 genes, in comparison with their human and rat orthologs and with the human nm23-H1 and mouse nm23-M1 genes. The organization and structure of the members of this gene family are remarkably similar in human and rodents. Accordingly, the striking similarities between the human and mouse nm23 genes enable the use of mouse transgenic and knock-out models for studying the role of nucleoside diphosphate kinase isoforms in human physiopathology.

Understanding the molecular basis of the interaction between NDPK-A and AMPK α1

ABSTRACT Nucleoside diphosphate kinase (NDPK) (nm23/awd) belongs to a multifunctional family of highly conserved proteins (∼16 to 20 kDa) including two well-characterized isoforms (NDPK-A and -B). NDPK catalyzes the conversion of nucleoside diphosphates to nucleoside triphosphates, regulates a diverse array of cellular events, and can act as a protein histidine kinase. AMP-activated protein kinase (AMPK) is a heterotrimeric protein complex that responds to the cellular energy status by switching off ATP-consuming pathways and switching on ATP-generating pathways when ATP is limiting. AMPK was first discovered as an activity that inhibited preparations of acetyl coenzyme A carboxylase 1 (ACC1), a regulator of cellular fatty acid synthesis. We recently reported that NDPK-A (but not NDPK-B) selectively regulates the α1 isoform of AMPK independently of the AMP concentration such that the manipulation of NDPK-A nucleotide trans-phosphorylation activity to generate ATP enhanced the activity of AMPK. This regulation occurred irrespective of the surrounding ATP concentration, suggesting that “substrate channeling” was occurring with the shielding of NDPK-generated ATP from the surrounding medium. We speculated that AMPK α1 phosphorylated NDPK-A during their interaction, and here, we identify two residues on NDPK-A targeted by AMPK α1 in vivo. We find that NDPK-A S122 and S144 are phosphorylated by AMPK α1 and that the phosphorylation status of S122, but not S144, determines whether substrate channeling can occur. We report the cellular effects of the S122 mutation on ACC1 phosphorylation and demonstrate that the presence of E124 (absent in NDPK-B) is necessary and sufficient to permit both AMPK α1 binding and substrate channeling.

Organization and expression of mouse nm23-M1 gene. Comparison with nm23-M2 expression.

Nm23 is a gene family encoding different isoforms of the nucleotide diphosphate kinase (NDPK), an enzyme involved in the synthesis of nucleoside triphosphates. In the present study, the organization and expression of the nm23-M1 gene encoding the mouse NDPKA isoform are described. This gene is about 10kb long and composed of five exons. The organization and the exon-intron boundaries are strictly conserved as compared to the human and rat related genes. The gene promoter region did not exhibit any consensus TATA box, SP1 binding element or Inr sequence. By contrast, TCF-1/LEF-1 binding elements and Pit-1 consensus sequence were present. Northern blotting and in situ hybridization methods were carried out in adult and 18.5 days post-coitum (dpc) mouse embryo, respectively. They showed tissue-specific expression of nm23-M1 transcripts, despite housekeeping gene promoter features. The strongest signals were detected in the nervous system, sensory organs and embryonic thymus. In contrast nm23-M2 mRNA was shown to be more widely expressed.The relationship between nm23-M1 gene tissue-specific expression and the putative binding element of the promoter region is discussed.

Protein kinase CK2 acts as a signal molecule switching between the NDPK-A/AMPK alpha1 complex and NDPK-B.

The above article, published online on 7 February 2005, in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editor-in-Chief, Prof. Peter Lichter, the Union for International Cancer Control and John Wiley & Sons, Ltd. The retraction has been agreed due to reuse of several figure panels in the paper. Due to the time elapsed since the publication of the article, the original data for these figures are no longer available for re-analysis. The authors are therefore not able to confirm the accuracy of the reported results or provide updated figures to replace the duplicated panels.

Abstract 1445: The metastasis suppressor NM23-H1 promotes genomic stability through its 3’-5’ exonuclease and nucleoside diphosphate kinase activities following UV irradiation

NM23-H1 is a metastasis suppressor whose reduced expression is associated with aggressive forms of melanoma, hepatoma, and carcinomas of the breast, stomach and colon. The current study has identified NM23-H1 (termed H1 isoform in human, M1 in mouse) and two of its attendant enzymatic activities, the 3’-5’ exonuclease and nucleoside diphosphate kinase (NDPK), as novel participants in the response to UV-induced DNA damage. Kinetics of repair for total DNA polymerase-blocking lesions and nucleotide excision pathway-mediated repair of 6-4 photoproducts were significantly compromised in different cellular settings of NM23-H1-deficiency. These included the human melanoma cell line WM793 and embryo fibroblasts (MEFs) derived from mouse strains rendered deficient in either NM23-M1 alone or both the M1 and M2 isoforms in tandem. The NDPK activity of NM23-H1 was critical for early repair of both polychromatic UVB/UVA (275-400 nm)- and UVC (254 nm)-induced DNA damage. Elevated rates of spontaneous and UV-induced mutations were observed in WM793 cells and NM23-deficient MEFs. The mutational spectra reflected aberrant repair of 6-4 photoproducts and oxidatively-induced DNA damage, with the 3’-5’ exonuclease being the principal enzymatic activity required to reduce UV-induced mutagenesis. This study has provided the first evidence for an essential role of mammalian NM23 isoforms in maintaining genomic stability. This novel anti-mutator function appears relevant not only to the metastasis suppressor activity of NM23-H1, but also possibly resistance to UV-induced carcinogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1445. doi:10.1158/1538-7445.AM2011-1445

Human interleukin for DA cells or leukemia inhibitory factor is released by Vero cells in human embryo coculture**Supported by Association pour la Recherche contre le Cancer, grant number 6639 (France) and Ligue Départementale de lutte contre le Cancer de la Gironde (France).

In the light of the newly discovered implications of human interleukin for DA cells and leukemia inhibitory factor in embryology, we searched for the presence of this soluble cytokine in the supernatant of Vero cell coculture systems. Using a bioassay as well as a specific ELISA, we demonstrated that Vero cells are able to release large quantities of human interleukin for DA cells and leukemia inhibitory factor in the embryo-growing medium of such cocultures.