The Pseudomonas aeruginosa genome contains several different multidrug resistance (MDR) efflux pumps. Overproduction of these pumps reduces susceptibility to a variety of antibiotics. Some recently published works have analyzed the effect of the overproduction of MDR efflux pumps on bacterial virulence. Here we have studied the effect of overproduction of the efflux pumps MexAB-OprM, MexCD-OprJ, MexEF-OprN, and MexXY on type III secretion (T3S) in P. aeruginosa. The type III secretion system (T3SS) is used by P. aeruginosa to deliver toxins directly into the cytoplasm of the host cell. Our data indicate that overexpression of either MexCD-OprJ or MexEF-OprN is associated with the impairment of T3S in P. aeruginosa. No effect on overexpression of either MexAB-OprM or MexXY was detected. The observed defect in T3S was due to a lack of expression of genes belonging to the T3SS regulon. Transcription of this regulon is activated by ExsA in response to environmental signals. Overexpression of this transcriptional regulator complemented the defect in T3S observed in the MexCD-OprJ-and MexEF-OprN-overproducing strains. Taken together, these results suggest that overproduction of either MexCD-OprJ or MexEF-OprN is associated with a reduction in the transcription of the T3SS regulon due to the lack of expression of the exsA gene, encoding the master regulator of the system. The relevance of potential metabolic and quorum-sensing imbalances due to overexpression of MDR pumps associated with this phenotype is also discussed.

No abstract

Proteomic analysis of omental fat reveals differential expression of several proteins in PCOS patients and non-hyperandrogenic women presenting with morbid obesity. The application of this novel methodology adds further evidence to support the role of visceral adiposity in the pathogenesis of PCOS.

Obesity is increasing exponentially in developed countries and constitutes a public health problem by enhancing the risk for metabolic disorder and cardiovascular disease. Differences in gene expression profiles and in metabolic and biochemical properties have been well-described between omental and subcutaneous adipose tissue in humans. Because omental adipose tissue has been strongly associated with the development of insulin resistance, type 2 diabetes and cardiovascular disease, we searched for proteins differentially expressed in these two fat depots using two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) and mass spectrometry (MS). In this analysis, we found 43 proteins, several of which were validated by immunoblotting and immunostaining analyses. Results demonstrated tissue-specific molecular differences in the protein makeup of the two analyzed fat depots mainly related to metabolic processes such as glucose and lipid metabolism, lipid transport, protein synthesis, protein folding, response to stress and inflammation. This suggests higher metabolic activity as well as increased cell stress in the omental compared to the subcutaneous fat. These findings provide some insights into the role of omental fat in abdominal obesity-associated co-morbidities.