In JoVE (1)

Other Publications (2)

Articles by Pavani Beesetty in JoVE

Other articles by Pavani Beesetty on PubMed

Transcriptional Responses of Uropathogenic Escherichia Coli to Increased Environmental Osmolality Caused by Salt or Urea

Infection and Immunity. Jan, 2013  |  Pubmed ID: 23090957

Uropathogenic Escherichia coli (UPEC) is the most common causative agent of urinary tract infections in humans. The majority of urinary infections develop via ascending route through the urethra, where bacterial cells come in contact with human urine prior to reaching the bladder or kidneys. Since urine contains significant amounts of inorganic ions and urea, it imposes osmotic and denaturing stresses on bacterial cells. In this study, we determined the transcriptional adaptive responses of UPEC strain CFT073 to the presence of 0.3 M NaCl or 0.6 M urea in the growth medium. The cell responses to these two osmolytes were drastically different. Although most of the genes of the osmotically inducible regulon were overexpressed in medium with salt, urea failed to stimulate osmotic stress response. At the same time, UPEC colonization genes encoding type 1 and F1C fimbriae and capsule biosynthesis were transcriptionally induced in the presence of urea but did not respond to increased salt concentration. We speculate that urea can potentially be sensed by uropathogenic bacteria to initiate infection program. In addition, several molecular chaperone genes were overexpressed in the presence of urea, whereas adding NaCl to the medium led to an upregulation of a number of anaerobic metabolism pathways.

Inactivation of TRPM7 Kinase Activity Does Not Impair Its Channel Function in Mice

Scientific Reports. Jul, 2014  |  Pubmed ID: 25030553

Transient receptor potential (TRP) family channels are involved in sensory pathways and respond to various environmental stimuli. Among the members of this family, TRPM7 is a unique fusion of an ion channel and a C-terminus kinase domain that is highly expressed in immune cells. TRPM7 serves as a key molecule governing cellular Mg(2+) homeostasis in mammals since its channel pore is permeable to Mg(2+) ions and can act as a Mg(2+) influx pathway. However, mechanistic links between its kinase activity and channel function have remained uncertain. In this study, we generated kinase inactive knock-in mutant mice by mutagenesis of a key lysine residue involved in Mg(2+)-ATP binding. These mutant mice were normal in development and general locomotor activity. In peritoneal macrophages isolated from adult animals the basal activity of TRPM7 channels prior to cytoplasmic Mg(2+) depletion was significantly potentiated, while maximal current densities measured after Mg(2+) depletion were unchanged in the absence of detectable kinase function. Serum total Ca(2+) and Mg(2+) levels were not significantly altered in kinase-inactive mutant mice. Our findings suggest that abolishing TRPM7 kinase activity does not impair its channel activity and kinase activity is not essential for regulation of mammalian Mg(2+) homeostasis.

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