Disease relevance of DDAH2

• In a case-control study design single nucleotide polymorphisms (SNPs) were determined at eight sites in the DDAH1 gene and at one site (Pro231Pro) in the DDAH2 gene from 132 women with pre-eclampsia and 112 healthy controls [1].
• These findings were further supported by demonstrating a decrease in DDAH2 function in the experimental pulmonary hypertension model [2].
• Although Ad-catenin increased the percentage of cells in the S phase with enhanced expression of cyclin D1 and E2 in both cell types, the increase in cell number was only evident in cardiac fibroblasts, whereas hypertrophy and binuclear cells were more prominent in cardiomyocytes [3].
• The results presented here suggest that decreased DDAH levels as well as increased PRMT gene expression could cause the elevation of plasma ADMA levels, thereby eliciting hypertension in CKD [4].
• A DDAH from Pseudomonas aeruginosa was cloned, and asymmetrically methylated arginine analogues were shown to be the preferred substrates, with ADMA displaying a slightly higher k(cat)/K(M) value than NMMA [5].

Psychiatry related information on DDAH2

• The discovery of a functional polymorphism within the DDAH2 promoter suggests that there may be common, individual differences in the ability to metabolise ADMA in vivo, that in turn, might underlie susceptibility to cardiovascular disease [6].
• Motor neuron generation depends on two critical periods of SHH signaling: an early period during which naive neural plate cells are converted into ventralized progenitors and a late period that extends well into S phase of the final progenitor cell division, during which SHH drives the differentiation of ventralized progenitors into motor neurons [7].
• At the maximum sleep deprivation, increases were observed in counts of WBC, granulocytes, monocytes, NK activity, and the proportion of lymphocytes in the S phase of the cell cycle [8].
• These data suggest that, when planning and interpreting quantitative data and perturbation experiments, consideration must be given to the role of serine-threonine kinases and transcription factors during decision making in M phase as well as in G1-S phase [9].

High impact information on DDAH2

• Accumulating data suggest that mTOR functions in a previously unrecognized signal transduction pathway required for the progression of IL-2-stimulated T cells from G1 into the S phase of the cell cycle [10].
• Activation of E2F transcription factors is thought to drive the expression of genes essential for the transition of cells from G1 to S phase and for the initiation of DNA replication [11].
• Cohesin establishes sister-chromatid cohesion from S phase until mitosis or meiosis [12].
• Induction of p21 results in downregulation of cyclin A-Cdk activity and accordingly attenuation of S phase progression [13].
• This novel mechanism for regulating protein stability establishes a window of time prior to S phase when pre-RCs can assemble which we propose represents a critical function of cyclin E [14].

Chemical compound and disease context of DDAH2

• Here, we find that 2-chloroacetamidine irreversibly inhibits both DDAH from Pseudomonas aeruginosa and human PAD4 in a time- and concentration-dependent manner, despite the nonoverlapping substrate specificities and low levels of amino acid identity of their catalytic domains [15].
• With this in mind, we performed DNA flow-cytometric measurements of ploidy and the fraction of cells in the synthesis phase of the cell cycle (S-phase fraction) on 395 specimens of node-negative breast cancer from our bank of frozen tumors, using the aliquots of pulverized frozen tissue from steroid-receptor assays [16].
• Analysis of chromosome replication patterns of the HSR in human neuroblastoma and in drug-resistant Chinese hamster cells by tritiated thymidine radioautography indicated that the long, abnormally staining region replicated relatively rapidly and synchronously and terminated replication before the midpoint of the S phase [17].
• The HFF cells, spared S-phase drug toxicity by their unique response to histidinol and theophylline, showed total survival and viability [18].
• Synchronized hepatoma tissue culture (HTC) cells, accumulated at the G1/S boundary with aminopterin, were released into S phase with either thymidine or 5-bromodeoxyuridine (BUdR) [19].

Biological context of DDAH2

• Overexpression of DDAH2 gene was established by liposome-mediated gene transfection in ECV304 endothelial cell line [20].
• In this study we have identified a core promoter region of the DDAH2 gene, and transcription factor sites that play an important role in the regulation of DDAH2 expression [6].
• Common genetic variation in a basal promoter element alters DDAH2 expression in endothelial cells [6].
• Sp1 small interfering RNA blocked DDAH2-induced upregulation of VEGF [21].
• Phylogenetic analysis of DDAH sequences from diverse species suggests that DDAH gene duplication occurred prior to the emergence of bony fish some 400 million years ago [22].

Anatomical context of DDAH2

• Whereas DDAH2 is expressed at relatively high levels in all fetal tissues examined, DDAH1 expression varies little between fetal and adult tissues [22].
• In contrast, in pulmonary hypertensive tissue, the immunoreactivity of DDAH2 in pulmonary endothelium was significantly decreased compared with DDAH1 [2].
• In cultured human endothelial cells, DDAH-1 was uniformly distributed in the cytosol and nucleus, whereas DDAH-2 was found only in the cytosol [23].
• Immunohistochemistry in human and rat control tissue demonstrated both isoforms of DDAH in the endothelial layer and in the alveolar epithelium [2].
• In addition the DDAH inhibitor, S-2-amino-4(3-methylguanidino)butanoic acid (4124W 1mM), markedly reduced human umbilical vein endothelial cell tube formation in vitro [24].

Associations of DDAH2 with chemical compounds

• The enzyme dimethylarginine dimethylaminohydrolase (DDAH) specifically hydrolyzes these asymmetrically methylated arginine residues to citrulline and methylamines [22].
• Nitric oxide (NO) synthesis is modulated by dimethylarginine dimethylaminohydrolase (DDAH) via metabolizing asymmetric dimethylarginine (ADMA), an endogenous NO synthase (NOS) inhibitor [20].
• The presence of a reactive cysteine residue (Cys-249) in the active site of DDAH raised the possibility that DDAH activity might be directly regulated by S-nitrosylation of this residue by NO [25].
• In addition, the metabolism of ADMA, but not SDMA, occurs via hydrolytic degradation to citrulline and dimethylamine by the enzyme dimethylarginine dimethylaminohydrolase (DDAH) [26].
• The levels of ADMA, allantoin, nitrate, and nitrite in conditioned media and the activity of dimethylarginine dimethylaminohydrolase (DDAH), the content of thiols and reactive oxygen species in endothelial cells, were determined [27].

Physical interactions of DDAH2

• Exposure to CD437 results in enhanced E2F-1 binding to its DNA consensus sequences and transcriptional activity during S phase [28].
• We demonstrated that PARP-1 and PCNA co-immunoprecipitated both from the soluble and the DNA-bound fraction isolated from S-phase-synchronized HeLa cells [29].
• An active cyclin D-CDK4/6 complex is required for pRb phosphorylation to allow the cell cycle to progress from G1 to S phase [30].
• Namely, in the nucleoplasm pRb2/p130-E2F4 complexes are more numerous during G0/G1 while in the nucleolus they increase in S phase [31].
• We show that MDM2 protein is stabilized at S phase [32].

Enzymatic interactions of DDAH2

• It has been shown previously that RPA32 is phosphorylated both during the S-phase of a normal cell cycle and in response to DNA damage [33].
• Cdc25 A regulates entry into S-phase by dephosphorylating Cdk2, it cooperates with activated oncogenes in inducing transformation and is overexpressed in several human tumors [34].
• Considering recent in vitro studies, these data are consistent with a proposed model in which Cdc6 is serine-54 phosphorylated during S phase and functions as a chromatin-bound signal that prevents reformation of prereplication complexes [35].
• This is the first demonstration that Skp2 is induced and phosphorylated in the late G1 and S phase of hepatocytes in vivo in regenerating liver as well as in vitro in mitogen-stimulated hepatocytes [36].
• These results, together with the functions of Cdc7p in yeast, suggest that HsCdc7 may phosphorylate critical substrate(s) that regulate the G1/S phase transition and/or DNA replication in mammalian cells [37].

Co-localisations of DDAH2

• However, several hours after treatment with methyl methanesulfonate (MMS) Triton-insoluble form of GFP-hRad18 accumulates in S-phase nuclei where it colocalizes with PCNA [38].

Regulatory relationships of DDAH2

• Finally, we show that immunodepletion of E2F3 activity inhibits the induction of S phase in proliferating cells [39].
• The tumour suppressor gene product APC blocks cell cycle progression from G0/G1 to S phase [40].
• Here, we present evidence to show that the full-length human or mouse MDM2 expressed from their respective cDNA can inhibit the G0/G1-S phase transition of NIH 3T3 and normal human diploid cells [41].
• Microinjection of the WT1 cDNA into quiescent cells or cells in early to mid G1 phase blocked serum-induced cell cycle progression into S phase [42].
• Deregulated expression of E2F family members induces S-phase entry and overcomes p16INK4A-mediated growth suppression [43].

Other interactions of DDAH2

• Chromosomal localization, gene structure, and expression pattern of DDAH1: comparison with DDAH2 and implications for evolutionary origins [22].
• Knocking down the DDAH2 gene reduced VEGF production, and DDAH2 overexpression enhanced both proliferation and migration of endothelial cells [21].
• Decreased DDAH activity and DDAH-2 protein expression may cause accumulation of endogenous inhibitors of endothelial NOS, thereby contributing to endothelial dysfunction in the failing heart [23].
• The G6 gene encodes a regulatory nuclear chloride ion channel protein, while the G6A gene encodes a putative homologue of the enzyme N omega,N omega-dimethylarginine dimethylaminohydrolase, which is thought to be involved in regulating nitric oxide synthesis [44].
• Experiments with phospho-amino acid-specific antibodies indicate that the S phase-specific mobility shift is due to the phosphorylation at specific N-terminal (S/T)(S/T)P residues of the MCM4 protein [45].

Analytical, diagnostic and therapeutic context of DDAH2

• Expression levels of PRMT genes and DDAH proteins were analyzed by semiquantitative reverse transcription-PCR and Western blotting, respectively [4].
• ADMA concentration and DDAH activity were determined by HPLC [46].
• We hypothesized that lowering ADMA concentrations by dimethylarginine dimethylaminohydrolase (DDAH) overexpression in the recipient might suppress GCAD and long-term immune responses in murine cardiac allografts [47].
• DDAH is present in RBCs as supported by hydrolysis of both ADMA and L-NMMA, but not symmetric dimethylarginine, and by immunoprecipitation/Westem blot using a specific monoclonal antibody to human DDAH [48].
• In a pilot study of end-stage renal disease (ESRD) patients, RBC DDAH activity with ADMA as substrate correlated inversely with age (p = 0.005) and enzyme activities were higher in patients with greater diastolic blood pressure drops during hemodialysis (p = 0.02) [48].

References