ABSTRACT
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.
Subject(s)
Monomeric GTP-Binding Proteins/genetics , Nucleoside-Diphosphate Kinase/genetics , Transcription Factors/genetics , Amino Acid Sequence , Animals , Blotting, Northern , Cloning, Molecular , DNA/chemistry , DNA/genetics , DNA, Complementary/chemistry , DNA, Complementary/genetics , Embryo, Mammalian/enzymology , Embryo, Mammalian/metabolism , Exons , Gene Expression Regulation, Developmental , Gene Expression Regulation, Enzymologic , Genes/genetics , Humans , In Situ Hybridization , Introns , Isoenzymes/genetics , Mice , Molecular Sequence Data , NM23 Nucleoside Diphosphate Kinases , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sequence Alignment , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Transcription Initiation SiteABSTRACT
Erythropoietic protoporphyria (EPP) is characterized clinically by cutaneous photosensitivity and biochemically by the accumulation of excessive amounts of protoporphyrin in erythrocytes, plasma, feces, and other tissues, such as the liver. The condition is inherited as an autosomal dominant or recessive trait, with a deficiency of ferrochelatase activity. A major concern in EPP patients is the development of cholestasis with accumulation of protoporphyrin in hepatobiliary structures and progressive cellular damage, which can rapidly lead to fatal hepatic failure. The availability of a mouse model for the disease, the Fech(m1Pas)/Fech(m1Pas) mutant mouse, allowed us to test a cellular therapy protocol to correct the porphyric phenotype. When Fech/Fech mice received bone marrow cells from normal animals, the accumulation of protoporphyrin in red blood cells and plasma was reduced 10-fold but still remained 2.5 times above normal levels. Interestingly, in very young animals, bone marrow transplantation can prevent hepatobiliary complications as well as hepatocyte alterations and partially reverse protoporphyrin accumulation in the liver. Bone marrow transplantation may be an option for EPP patients who are at risk of developing hepatic complications.
Subject(s)
Bone Marrow Transplantation , Liver/pathology , Porphyria, Erythropoietic/therapy , Animals , Female , Liver/metabolism , Male , Mice , Mice, Inbred BALB C , Porphyria, Erythropoietic/metabolism , Porphyria, Erythropoietic/pathology , Protoporphyrins/biosynthesisABSTRACT
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.
Subject(s)
Monomeric GTP-Binding Proteins , Transcription Factors/genetics , Transcription Factors/metabolism , Animals , Chromosome Mapping , Exons , Genomic Library , In Situ Hybridization , Intestinal Mucosa/embryology , Mice , Mice, Inbred C57BL , Models, Genetic , NM23 Nucleoside Diphosphate Kinases , Nucleoside-Diphosphate Kinase/genetics , Polymerase Chain Reaction , Promoter Regions, Genetic , Sequence Homology, Amino Acid , Thymus Gland/embryology , Tissue Distribution , Transcription Factors/analysis , Transcription, GeneticABSTRACT
Nm23 has been identified as a gene family encoding different isoforms of the nucleoside diphosphate kinase. This protein is a key enzyme in the control of cellular concentrations of nucleoside triphosphates. Moreover, it has been shown to play important roles in various cellular functions such as differentiation and metastasis. In the present study, a second cDNA for nucleoside diphosphate kinase A (Nm23-M1) was isolated from a cDNA library of mouse embryonic stem cells. This clone encodes the same putative 152 aminoacids long protein as an already published cDNA but is longer in both its 5' and 3' untranslated regions. Tissue and cellular distribution of nm23-M1 mRNA was investigated by using Northern blot analysis and in situ hybridization. Nm23-M1 transcripts were found to be widely distributed throughout the mouse central nervous system with prominent expression in several restricted areas. No differences were noticed between the distribution of long and short transcripts. Furthermore, a similar pattern of expression was described in the central nervous system for nm23-M2 mRNA, encoding a second isoform of the nucleoside diphosphate kinase. However, the transcript of this isoform displayed a wider distribution and was expressed in all organs analysed by northern blotting. The possible involvement of nm23-M1 in differentiation of mouse nervous system is further discussed.
