Activation of PRMT1 and PRMT5 mediates hypoxia- and ischemia-induced apoptosis in human lung epithelial cells and the lung of miniature pigs: the role of p38 and JNK mitogen-activated protein kinases.

Severe hypoxic and ischemic injury leads to primary graft dysfunction after lung transplantation. Arginine methylation, which is responsible for the regulation of a variety of biological functions, is mediated by protein arginine methylation transferases (PRMTs). This study examined the role of hypoxia in PRMT activation in A549 human lung epithelial cells, as well as the role of ischemia in PRMT activation in the lung of miniature pigs. In A459 cells, hypoxia increased the expression of PRMT1 and PRMT5, and overexpression of PRMT1 and PRMT5 induced apoptosis. The transfection of PRMT1 and PRMT5 small interfering RNA (siRNA) prevented hypoxia-inducible factor (HIF)-1α expression and apoptosis in A549 cells. Hypoxia-induced expression of PRMT1 and PRMT5 was blocked by p38 and JNK mitogen-activated protein kinase (MAPK) inhibitors, but not by an inhibitor of extracellular signal-regulated kinases (ERK) 1/2. In the lungs of miniature pigs, ischemia stimulated PRMT1 and PRMT5 expression and induced phosphorylation of p38 MAPK (p-p38), phosphorylation of JNK (p-JNK), and apoptotic molecules. These results demonstrate that PRMT1 and PRMT5 are involved in hypoxia and ischemia-induced apoptosis via p-p38 MAPK and p-JNK in in vitro and in vivo models.

Pathotyping avian pathogenic Escherichia coli strains in Korea.

To examine the genetic background of avian pathogenic Escherichia coli (APEC) that affects virulence of this microorganism, we characterized the virulence genes of 101 APEC strains isolated from infected chickens between 1985 ˜ 2005. Serotypes were determined with available anti-sera and median lethal doses were determined in subcutaneously inoculated chicks. The virulence genes we tested included ones encoding type 1 fimbriae (fimC), iron uptake-related (iroN, irp2, iucD, and fyuA), toxins (lt, st, stx1, stx2, and vat), and other factors (tsh, hlyF, ompT, and iss). Twenty-eight strains were found to be O1 (2.0%), O18 (3.0%), O20 (1.0%), O78 (19.8%), and O115 (2.0%) serotypes. The iroN (100%) gene was observed most frequently followed by ompT (94.1%), fimC (90.1%), hlyF (87.1%), iss (78.2%), iucD (73.3%), tsh (61.4%), fyuA (44.6%), and irp2 (43.6%). The strains were negative for all toxin genes except for vat (10.9%). All the strains were classified into 27 molecular pathotypes (MPs). The MP25, MP19, and MP10 pathotypes possessing iroN-fimC-ompT-hlyF-iucD-tsh-iss-irp2-fyuA (22.8%), iroN-fimC-ompT-hlyF-iucD-tsh-iss (21.8%), and iroN-fimC-ompT-hlyF-iss (11.9%) genotypes, respectively, were predominant. Redundancy of iron uptake-related genes was clearly observed and some strains were associated with higher mortality than others. Therefore, strains with the predominant genotypes can be used for diagnosis and vaccine.

Chronological study of antibiotic resistances and their relevant genes in Korean avian pathogenic Escherichia coli isolates.

Antibiograms and relevant genotypes of Korean avian pathogenic Escherichia coli (APEC) isolates (n = 101) recovered between 1985 and 2005 were assessed via disc diffusion test, PCR, restriction enzyme analysis, and sequencing. These isolates were highly resistant to tetracycline (84.2%), streptomycin (84.2%), enrofloxacin (71.3%), and ampicillin (67.3%), and most of the tetracycline, streptomycin, enrofloxacin, and ampicillin resistances were associated with tetA and/or tetB, aadA and/or strA-strB, mutations in gyrA and/or parC, and TEM, respectively. Class 1 integrons were detected in 40 isolates (39.6%), and a variety of gene cassettes conferring streptomycin (aadA), gentamicin (aadB), and trimethoprim (dfr) resistances were identified: aadA1a (27.5%), dfrV-orfD (2.5%), aadB-aadA1a (2.5%), dfrI-aadA1a (47.5%), dfrXVII-aadA5 (12.5%), and dfrXII-orfF-aadA2 (7.5%). In addition, several types of common promoters (P(ant)) of the gene cassettes (hybrid P1, weak P1, or weak P1 plus P2) and single-nucleotide polymorphisms in aadA1a were identified. The results of a chronological analysis demonstrated significant and continuous increases in the frequencies of resistances to several antibiotics (tetracycline, streptomycin, enrofloxacin, ampicillin, and trimethoprim-sulfamethoxazole) and of the relevant resistance genes (tetA, strA-strB, and TEM), mutations in gyrA and parC, and multidrug-resistant APEC strains during the period 2000 to 2005.