Submucosal glands of the tracheobronchial airways provide the important functions of secreting mucins, antimicrobial substances, and fluid. This review focuses on the ionic mechanism and regulation of gland fluid secretion and examines the possible role of gland dysfunction in the lethal disease cystic fibrosis (CF). The fluid component of gland secretion is driven by the active transepithelial secretion of both Cl(-) and HCO(3)(-) by serous cells. Gland fluid secretion is neurally regulated with acetylcholine, substance P, and vasoactive intestinal peptide (VIP) playing prominent roles. The cystic fibrosis transmembrane conductance regulator (CFTR) is present in the apical membrane of gland serous cells and mediates the VIP-induced component of liquid secretion whereas the muscarinic component of liquid secretion appears to be at least partially CFTR-independent. Loss of CFTR function, which occurs in CF disease, reduces the capacity of glands to secrete fluid but not mucins. The possible links between the loss of fluid secretion capability and the complex airway pathology of CF are discussed.

Here, we document that persistent mitochondria DNA (mtDNA) damage due to mitochondrial overexpression of the Y147A mutant uracil-N-glycosylase as well as mitochondrial overexpression of bacterial Exonuclease III or Herpes Simplex Virus protein UL12.5M185 can induce a complete loss of mtDNA (ρ0 phenotype) without compromising the viability of cells cultured in media supplemented with uridine and pyruvate. Furthermore, we use these observations to develop rapid, sequence-independent methods for the elimination of mtDNA, and demonstrate utility of these methods for generating ρ0 cells of human, mouse and rat origin. We also demonstrate that ρ0 cells generated by each of these three methods can serve as recipients of mtDNA in fusions with enucleated cells.

The gastric human pathogen Helicobacter pylori faces formidable challenges in the stomach including reactive oxygen and nitrogen intermediates. Here we demonstrate that arginase activity, which inhibits host nitric oxide production, is post-translationally stimulated by H. pylori thioredoxin (Trx) 1 but not the homologous Trx2. Trx1 has chaperone activity that renatures urea-or heat-denatured arginase back to the catalytically active state. Most reactive oxygen and nitrogen intermediates inhibit arginase activity; this damage is reversed by Trx1, but not Trx2. Trx1 and arginase equip H. pylori with a "renox guardian" to overcome abundant nitrosative and oxidative stresses encountered during the persistence of the bacterium in the hostile gastric environment.The gastric human pathogen Helicobacter pylori causes chronic gastritis and ulcers and has a strong link with gastric cancer. Despite enormous knowledge gleaned from two completely sequenced strains (1, 2), little is known about how this organism escapes the host innate and adaptive immune systems. The extensive inflammatory response observed in H. pylori-infected patients contributes to gastric damage; some of this damage is mediated by ROI/RNIs 3 such as NO and hydrogen peroxide. Arginase (RocF), which hydrolyzes L-arginine to urea and L-ornithine, inhibits macrophage NO production by directly competing with host nitric-oxide synthase for arginine availability (3). The urea can then be hydrolyzed by the copious H. pylori urease to yield carbon dioxide and ammonium, the latter of which neutralizes gastric acid. Indeed, acid treatment (pH 2) of H. pylori in the presence of arginine protects H. pylori in an arginase-dependent fashion (4). The arginase of H. pylori exhibits several unusual features, including optimal catalytic activity with cobalt, rather than manganese, and an acidic pH optimum (5). Furthermore, H. pylori arginase inhibits human T cell proliferation and T cell CD3 expression by siphoning arginine away from the host cell (6), potentially contributing to the inability of T cells to clear H. pylori infections. These findings point to a critical role for arginase in disarming two innate host defenses (acid and NO) and adaptive immunity (T cells), thereby disabling the two arms of the immune system. The critical questions remaining are: how is arginase modulated, and is arginase itself sensitive to ROI/RNIs? Here, we provide compelling evidence that H. pylori arginase is modulated at the post-translational level by thioredoxin 1 (Trx1) and that Trx1 protects arginase from ROI/RNIs and is an arginase chaperone.

The unavailability of tractable reverse genetic analysis approaches represents an obstacle to a better understanding of mitochondrial DNA replication. Here, we used CRISPR-Cas9 mediated gene editing to establish the conditional viability of knockouts in the key proteins involved in mtDNA replication. This observation prompted us to develop a set of tools for reverse genetic analysis in situ, which we called the GeneSwap approach. The technique was validated by identifying 730 amino acid (aa) substitutions in the mature human TFAM that are conditionally permissive for mtDNA replication. We established that HMG domains of TFAM are functionally independent, which opens opportunities for engineering chimeric TFAMs with customized properties for studies on mtDNA replication, mitochondrial transcription, and respiratory chain function. Finally, we present evidence that the HMG2 domain plays the leading role in TFAM species-specificity, thus indicating a potential pathway for TFAM-mtDNA evolutionary co-adaptations.

As a subunit of both the P-L polymerase complex and the P-N assembly complex, the vesicular stomatitis virus (VSV) P protein plays a pivotal role in transcription and replication of the viral genome. Constitutive phosphorylation of this protein is currently thought to be essential for formation of the P-L complex. We recently identified the three relevant phosphate acceptor sites in the VSV Indiana serotype P protein (R. L.