The inherited neurodegenerative disorder glutaric aciduria type 1 (GA1) results from mutations in the gene for the mitochondrial matrix enzyme glutaryl-CoA dehydrogenase (GCDH), which leads to elevations of the dicarboxylates glutaric acid (GA) and 3-hydroxyglutaric acid (3OHGA) in brain and blood. The characteristic clinical presentation of GA1 is a sudden onset of dystonia during catabolic situations, resulting from acute striatal injury. The underlying mechanisms are poorly understood, but the high levels of GA and 3OHGA that accumulate during catabolic illnesses are believed to play a primary role. Both GA and 3OHGA are known to be substrates for Na
The metabolic disorder glutaric aciduria type 1 (GA1) is caused by deficiency of the mitochondrial glutaryl-CoA dehydrogenase (GCDH), leading to accumulation of the pathologic metabolites glutaric acid (GA) and 3-hydroxyglutaric acid (3OHGA) in blood, urine and tissues. Affected patients are prone to metabolic crises developing during catabolic conditions, with an irreversible destruction of striatal neurons and a subsequent dystonic-dyskinetic movement disorder. The pathogenetic mechanisms mediated by GA and 3OHGA have not been fully characterized. Recently, we have shown that GA and 3OHGA are translocated through membranes via sodium-dependent dicarboxylate cotransporter (NaC) 3, and organic anion transporters (OATs) 1 and 4. Here, we show that induced metabolic crises in Gcdh(-/-) mice lead to an altered renal expression pattern of NaC3 and OATs, and the subsequent intracellular GA and 3OHGA accumulation. Furthermore, OAT1 transporters are mislocalized to the apical membrane during metabolic crises accompanied by a pronounced thinning of proximal tubule brush border membranes. Moreover, mitochondrial swelling and increased excretion of low molecular weight proteins indicate functional tubulopathy. As the data clearly demonstrate renal proximal tubule alterations in this GA1 mouse model during induced metabolic crises, we propose careful evaluation of renal function in GA1 patients, particularly during acute crises. Further studies are needed to investigate if these findings can be confirmed in humans, especially in the long-term outcome of affected patients.
While mammary tumours are the main reasons of death in bitches, early detection of tumours and metastases is crucial for survival of affected dogs. Invasiveness and angiogenesis, which are important processes of tumour growth and spreading, require connective tissue remodelling. This process is dominantly mediated by matrix metalloproteinases (MMP), which are well known to be positively regulated by relaxin (RLX) in various tissues, including human breast cancer. So far, the presence of RLX and its receptor RXFP-1 as well as their linkage with MMP in canine mammary tumours (CMT) is completely unknown. In the first part of the present study, concentrations of RLX, oestradiol and progesterone from plasma samples of bitches with CMT were compared with clinical and survival data to investigate the predictive value of these hormones. In the second part, the expressions of RLX, RXFP-1 and MMP-2, -9 and -13 were examined by real-time reverse transcriptase polymerase chain reaction (RT-PCR) in 31 CMT samples. Finally, relationships of systemic plasma RLX or locally expressed RLX with expression of MMP in CMT were analyzed for the first time. Comparison of hormone concentrations in 93 bitches in terms of benign or malignant nature of the CMT, lung metastases, recidivation and 12-month survival discovered no significances. The expressions of RLX, RXFP-1 and MMP were independent from plasma RLX, but expressions of local RLX and RXFP-1 showed a strong correlation (p = 0.00004, r = 0.671) as well as RXFP-1 and MMP-2 (p = 0.009, r = 0.463), indicating a possible significant role of the locally produced RLX in CMT pathogenesis as an inducer of connective tissue remodelling.
We have identified, cloned and characterized a formerly unknown protein from Streptomyces lividans spores. The deduced protein belongs to a novel member of the metallophosphatase superfamily and contains a phosphatase domain and predicted binding sites for divalent ions. Very close relatives are encoded in the genomic DNA of many different Streptomyces species. As the deduced related homologues diverge from other known phosphatase types, we named the protein MptS (metallophosphatase type from Streptomyces). Comparative physiological and biochemical investigations and analyses by fluorescence microscopy of the progenitor strain, designed mutants carrying either a disruption of the mptS gene or the reintroduced gene as fusion with histidine codons or the egfp gene led to the following results: (i) the mptS gene is transcribed in the course of aerial mycelia formation. (ii) The MptS protein is produced during the late stages of growth, (iii) accumulates within spores, (iv) functions as an active enzyme that releases inorganic phosphate from an artificial model substrate, (v) is required for spore dormancy and (vi) MptS supports the interaction amongst Streptomyces lividans spores with conidia of the fungus Aspergillus proliferans. We discuss the possible role(s) of MptS-dependent enzymatic activity and the implications for spore biology.
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