Gene_locus Report for: mouse-dpp4

Dipeptidyl peptidase IV (DP-IV), a member of the prolyl oligopeptidase family of peptidases, is involved in the metabolic inactivation of a glucose-dependent insulinotropic hormone, glucagon-like peptide 1 (GLP-1), and other incretin hormones. Here, we investigated the impact of DP-IV deficiency on body weight control and insulin sensitivity in mice. Whereas WT mice displayed accelerated weight gain and hyperinsulinemia when fed a high-fat diet (HFD), mice lacking the gene encoding DP-IV (DP-IV-/-) are refractory to the development of obesity and hyperinsulinemia. Pair-feeding and indirect calorimetry studies indicate that reduced food intake and increased energy expenditure accounted for the resistance to HFD-induced obesity in the DP-IV-/- mice. Ablation of DP-IV also is associated with elevated GLP-1 levels and improved metabolic control in these animals, resulting in improved insulin sensitivity, reduced pancreatic islet hypertrophy, and protection against streptozotocin-induced loss of beta cell mass and hyperglycemia. Together, these observations suggest that chronic deletion of DP-IV gene has significant impact on body weight control and energy homeostasis, providing validation of DP-IV inhibition as a viable therapeutic option for the treatment of metabolic disorders related to diabetes and obesity.

Dipeptidyl peptidase IV (DPP IV, EC 3.4.14.5) is an ectopeptidase whose expression is modulated during thymocyte differentiation and T cell activation. We describe here the organization of the mouse DPP IV gene. This gene, which encompasses more than 90 kb, is composed of 26 exons separated by introns, the lengths of which vary from 100 bp to more than 20 kb. Reverse PCR performed on RNA from different tissues indicated that DPP IV transcripts do not contain alternatively spliced CDS sequences and, therefore, are supposed to yield a single polypeptide. However, two types of specific mRNA have been detected that differ in their 3'UTR sequences. They derive from alternative polyadenylation of the DPP IV primary transcript, since the different 3'UTR sequences are contiguous in the mouse DPP IV gene. Sequence analysis of the gene 5'-flanking region revealed several structural features found in the TATAA-box-less promoters, including a G+C-rich segment, a high frequency of dinucleotide CpG, and an imperfect symmetrical dyad. The DPP IV gene was assigned by in situ hybridization to the mouse [2C2-2D] region, which is syntenic with human chromosome 2. These data indicate that the human Dpp4 locus is located within this synteny region (i.e., 2q14-q37). The genomic organization of the mouse DPP IV gene is compared to that of classical serine proteases and serine hydrolases. As structural and mechanistic conservation in the absence of sequence similarity is the most remarkable feature among alpha/beta hydrolases [Ollis, D. L., et al. (1992) Protein Eng. 5, 197-211], we report the possible evolutionary link between the DPP IV related family and alpha/beta hydrolases.

Thymocyte-activating molecule (THAM) was initially characterized as a developmentally regulated, dimeric cell-surface molecule capable of activating mouse thymocytes and T lymphocytes upon monoclonal antibody (mAb)-mediated cross-linking. We recently obtained structural evidence indicating that this molecule is the mouse homologue of the human T cell-activating ectoenzyme CD26 (dipeptidyl peptidase IV, DPP IV). We describe here the cloning and the characterization of THAM cDNA. Two clones (3.3 and 2.8 kilobases) were isolated. THAM-3.3 cDNA contains an open reading frame of 2,280 nucleotides that encodes a protein of 760 amino acids having a calculated size of 87,500 Da. Complete N-glycosylation at each of the nine potential sites would result in a mature 110,000-Da molecule. Protein sequence comparisons revealed a significant homology (in particular in the COOH-terminal domain) between THAM and the rat or human DPP IV or the yeast dipeptidyl aminopeptidase B molecules (92, 85, and 30% sequence identity, respectively). Structural comparison of serine proteases (i.e. acyl-amino acid hydrolase or prolyl endopeptidase) with the most conserved domain of THAM identified a stretch of 200 amino acids containing a putative catalytic triad arranged in a novel topological order (Ser-624, Asp-702, and His-734) thereby defining a subfamily of nonclassical serine proteases. Expression of THAM during thymus ontogeny was found to be mainly regulated at the transcriptional level as determined by RNase protection assay. To investigate directly some of the functions which have been ascribed to DPP IV, we transfected an ovalbumin/Aq-reactive, THAM- T hybridoma cell line with THAM-3.3 cDNA. The resultant transfectants acquired (i) DPP IV enzymatic activity that precisely paralleled the density of surface-expressed THAM; (ii) an Mr = 115,000 (reduced) and 110,000/128,000 (nonreduced) molecule that could be immunoprecipitated by the THAM-specific mAb H194-112; and (iii) the capacity of being triggered by this mAb to release interleukin-2. These data indicate that a single cDNA species can encode a multifunctional molecule (e.g. activation signal-transducing structure and ectopeptidase), the heterodimeric state of which very likely results from a differential post-translational modification of the same protein core.

Dipeptidyl peptidase IV (DP-IV), a member of the prolyl oligopeptidase family of peptidases, is involved in the metabolic inactivation of a glucose-dependent insulinotropic hormone, glucagon-like peptide 1 (GLP-1), and other incretin hormones. Here, we investigated the impact of DP-IV deficiency on body weight control and insulin sensitivity in mice. Whereas WT mice displayed accelerated weight gain and hyperinsulinemia when fed a high-fat diet (HFD), mice lacking the gene encoding DP-IV (DP-IV-/-) are refractory to the development of obesity and hyperinsulinemia. Pair-feeding and indirect calorimetry studies indicate that reduced food intake and increased energy expenditure accounted for the resistance to HFD-induced obesity in the DP-IV-/- mice. Ablation of DP-IV also is associated with elevated GLP-1 levels and improved metabolic control in these animals, resulting in improved insulin sensitivity, reduced pancreatic islet hypertrophy, and protection against streptozotocin-induced loss of beta cell mass and hyperglycemia. Together, these observations suggest that chronic deletion of DP-IV gene has significant impact on body weight control and energy homeostasis, providing validation of DP-IV inhibition as a viable therapeutic option for the treatment of metabolic disorders related to diabetes and obesity.

The high degree of similarity between the mouse and human genomes is demonstrated through analysis of the sequence of mouse chromosome 16 (Mmu 16), which was obtained as part of a whole-genome shotgun assembly of the mouse genome. The mouse genome is about 10% smaller than the human genome, owing to a lower repetitive DNA content. Comparison of the structure and protein-coding potential of Mmu 16 with that of the homologous segments of the human genome identifies regions of conserved synteny with human chromosomes (Hsa) 3, 8, 12, 16, 21, and 22. Gene content and order are highly conserved between Mmu 16 and the syntenic blocks of the human genome. Of the 731 predicted genes on Mmu 16, 509 align with orthologs on the corresponding portions of the human genome, 44 are likely paralogous to these genes, and 164 genes have homologs elsewhere in the human genome; there are 14 genes for which we could find no human counterpart.

Dipeptidyl peptidase IV (DPP IV, EC 3.4.14.5) is an ectopeptidase whose expression is modulated during thymocyte differentiation and T cell activation. We describe here the organization of the mouse DPP IV gene. This gene, which encompasses more than 90 kb, is composed of 26 exons separated by introns, the lengths of which vary from 100 bp to more than 20 kb. Reverse PCR performed on RNA from different tissues indicated that DPP IV transcripts do not contain alternatively spliced CDS sequences and, therefore, are supposed to yield a single polypeptide. However, two types of specific mRNA have been detected that differ in their 3'UTR sequences. They derive from alternative polyadenylation of the DPP IV primary transcript, since the different 3'UTR sequences are contiguous in the mouse DPP IV gene. Sequence analysis of the gene 5'-flanking region revealed several structural features found in the TATAA-box-less promoters, including a G+C-rich segment, a high frequency of dinucleotide CpG, and an imperfect symmetrical dyad. The DPP IV gene was assigned by in situ hybridization to the mouse [2C2-2D] region, which is syntenic with human chromosome 2. These data indicate that the human Dpp4 locus is located within this synteny region (i.e., 2q14-q37). The genomic organization of the mouse DPP IV gene is compared to that of classical serine proteases and serine hydrolases. As structural and mechanistic conservation in the absence of sequence similarity is the most remarkable feature among alpha/beta hydrolases [Ollis, D. L., et al. (1992) Protein Eng. 5, 197-211], we report the possible evolutionary link between the DPP IV related family and alpha/beta hydrolases.

Thymocyte-activating molecule (THAM) was initially characterized as a developmentally regulated, dimeric cell-surface molecule capable of activating mouse thymocytes and T lymphocytes upon monoclonal antibody (mAb)-mediated cross-linking. We recently obtained structural evidence indicating that this molecule is the mouse homologue of the human T cell-activating ectoenzyme CD26 (dipeptidyl peptidase IV, DPP IV). We describe here the cloning and the characterization of THAM cDNA. Two clones (3.3 and 2.8 kilobases) were isolated. THAM-3.3 cDNA contains an open reading frame of 2,280 nucleotides that encodes a protein of 760 amino acids having a calculated size of 87,500 Da. Complete N-glycosylation at each of the nine potential sites would result in a mature 110,000-Da molecule. Protein sequence comparisons revealed a significant homology (in particular in the COOH-terminal domain) between THAM and the rat or human DPP IV or the yeast dipeptidyl aminopeptidase B molecules (92, 85, and 30% sequence identity, respectively). Structural comparison of serine proteases (i.e. acyl-amino acid hydrolase or prolyl endopeptidase) with the most conserved domain of THAM identified a stretch of 200 amino acids containing a putative catalytic triad arranged in a novel topological order (Ser-624, Asp-702, and His-734) thereby defining a subfamily of nonclassical serine proteases. Expression of THAM during thymus ontogeny was found to be mainly regulated at the transcriptional level as determined by RNase protection assay. To investigate directly some of the functions which have been ascribed to DPP IV, we transfected an ovalbumin/Aq-reactive, THAM- T hybridoma cell line with THAM-3.3 cDNA. The resultant transfectants acquired (i) DPP IV enzymatic activity that precisely paralleled the density of surface-expressed THAM; (ii) an Mr = 115,000 (reduced) and 110,000/128,000 (nonreduced) molecule that could be immunoprecipitated by the THAM-specific mAb H194-112; and (iii) the capacity of being triggered by this mAb to release interleukin-2. These data indicate that a single cDNA species can encode a multifunctional molecule (e.g. activation signal-transducing structure and ectopeptidase), the heterodimeric state of which very likely results from a differential post-translational modification of the same protein core.