Cox17 is the candidate copper metallochaperone for delivery of copper ions to the mitochondrion for assembly of cytochrome c oxidase. Cox17 purified as a recombinant molecule lacking any purification tag binds three Cu(I) ions per monomer in a polycopper cluster as shown by X-ray absorption spectroscopy. The CuCox17 complex exists in a dimer/tetramer equilibrium with a 20 microM k(d). The spectroscopic data do not discern whether the dimeric complex forms a single hexanuclear Cu(I) cluster or two separate trinuclear Cu(I) clusters. The Cu(I) cluster(s) exhibit(s) predominantly trigonal Cu(I) coordination. The cluster(s) in Cox17 resemble(s) the polycopper clusters in Ace1 and the Cup1 metallothionein in being pH-stable and luminescent. The physical properties of the CuCox17 complex purified as an untagged molecule differ from those reported previously for a GST-Cox17 fusion protein. The CuCox17 cluster is distinct from the polycopper cluster in Cup1 in being labile to ligand exchange. CuCox17 localized within the intermitochondrial membrane space appears to be predominantly tetrameric, whereas the cytosolic CuCox17 is primarily a dimeric species. Cys-->Ser substitutions at Cys23, Cys24, or Cys26 abolish the Cox17 function and prevent tetramerization, although Cu(I) binding is largely unaffected. Thus, the oligomeric state of Cox17 may be important to its physiological function.

Differentiation of fibroblasts into a-smooth muscle actin (SMA)-expressing myofibroblasts represents a critical step in the pathogenesis of fibrotic disorders, and is generally regarded as irreversible. Prostaglandin E 2 (PGE 2 ) has been shown to prevent multiple aspects of fibroblast activation, including the differentiation of fibroblasts to myofibroblasts. Here, we investigated its ability to reverse this differentiated phenotype. Fetal and adult lung fibroblasts were induced to differentiate into myofibroblasts by 24-hour culture with transforming growth factor (TGF)-b1 or endothelin-1. Cells were then treated without or with PGE 2 for various intervals and assessed for a-SMA expression. In the absence of PGE 2 treatment, a-SMA expression induced by TGF-b1 was persistent and stable for up to 8 days. By contrast, PGE 2 treatment effected a dose-dependent decrease in a-SMA and collagen I expression that was observed 2 days after PGE 2 addition, peaked at 3 days, and persisted through 8 days in culture. This effect was not explained by an increase in myofibroblast apoptosis, and indeed, reintroduction of TGF-b1 2 days after addition of PGE 2 prompted dedifferentiated fibroblasts to re-express a-SMA, indicating redifferentiation to myofibroblasts. This effect of PGE 2 was associated with inhibition of focal adhesion kinase signaling, and a focal adhesion kinase inhibitor was also capable of reversing myofibroblast phenotype. These data unambiguously demonstrate reversal of established myofibroblast differentiation. Because many patients have established or even advanced fibrosis by the time they seek medical attention, this capacity of PGE 2 has the potential to be harnessed for therapy of late-stage fibrotic disorders.Keywords: E prostanoid receptor; transforming growth factor-b1; endothelin-1; a-smooth muscle actin; focal adhesion kinase Pathologic scarring or fibrosis results in impaired organ function in diseases such as cirrhosis, diabetes, end-stage renal disease, scleroderma, and pulmonary fibrosis (1, 2). The accumulation of myofibroblasts within pathologic lesions is a pivotal feature of many fibrotic disorders (1, 2). Fibroblasts possess the potential to differentiate into myofibroblasts, which are distinguished from fibroblasts by their expression of contractile proteins, such as a-smooth muscle actin (a-SMA), and their exuberant production of extracellular matrix proteins, such as collagen I. This expression of a-SMA and increased extracellular matrix production endow myofibroblasts with the ability to participate in wound contraction (3). Because the differentiation of fibroblasts to myofibroblasts is generally considered irreversible (4), resolution of normal wound repair is thought to require apoptosis of myofibroblasts (5). By contrast, pathologic fibrosis occurs when myofibroblasts fail to apoptose and instead accumulate and persist within tissues, contributing to progressive scarring. Indeed, idiopathic pulmonary fibrosis (IPF)-the most common and fatal type of lung fibrosis-is characterized b...

There is mounting evidence that obesity is associated with asthma, both of which are seeing a dramatic increase in prevalence. Not only is obesity a risk factor for the development of asthma, it is also associated with poor asthma control. Asthma phenotypes associated with obesity include early-onset allergic asthma and late-onset non-allergic asthma. The pathogenesis of the linkage is complex; obesity causes a variety of mechanical, metabolic, and immunological changes that can affect the airways. The treatment of asthma in obesity can be challenging as obesity is associated with poor response to standard controller medications. A tailored approach that involves combining pharmacologic and non-pharmacologic therapies including weight loss, dietary interventions and exercise, along with identification and treatment of obstructive sleep apnea should therefore be considered in this population.