Immigration Brings New Pathology with No Standardized Treatment Protocol Madura Foot Case Studies Phialemonium and Phaeoacremonium.

Madura foot is an uncommon invasive soft-tissue infection that foot and ankle specialists encounter. We present two rare cases of Phialemonium and Phaeoacremonium fungi infections of the foot diagnosed in northern California to inform physicians on the presentation and current treatment options for this unique pathology. The two cases presented outline the clinical presentations, diagnostic data, and surgical and antimicrobial interventions. There is a concentration on the antimicrobial options depending on which of the over 20 species is encountered. The pertinent literature and supporting data are reviewed to create an outline for discussion of treatment protocols when faced with these emerging opportunistic infections.

Angiomotin stabilization by tankyrase inhibitors antagonizes constitutive TEAD-dependent transcription and proliferation of human tumor cells with Hippo pathway core component mutations.

The evolutionarily conserved Hippo inhibitory pathway plays critical roles in tissue homeostasis and organ size control, while mutations affecting certain core components contribute to tumorigenesis. Here we demonstrate that proliferation of Hippo pathway mutant human tumor cells exhibiting high constitutive TEAD transcriptional activity was markedly inhibited by dominant negative TEAD4, which did not inhibit the growth of Hippo wild-type cells with low levels of regulatable TEAD-mediated transcription. The tankyrase inhibitor, XAV939, identified in a screen for inhibitors of TEAD transcriptional activity, phenocopied these effects independently of its other known functions by stabilizing angiomotin and sequestering YAP in the cytosol. We also identified one intrinsically XAV939 resistant Hippo mutant tumor line exhibiting lower and less durable angiomotin stabilization. Thus, angiomotin stabilization provides a new mechanism for targeting tumors with mutations in Hippo pathway core components as well as a biomarker for sensitivity to such therapy.

Stable heteroplasmy at the single-cell level is facilitated by intercellular exchange of mtDNA.

Eukaryotic cells carry two genomes, nuclear (nDNA) and mitochondrial (mtDNA), which are ostensibly decoupled in their replication, segregation and inheritance. It is increasingly appreciated that heteroplasmy, the occurrence of multiple mtDNA haplotypes in a cell, plays an important biological role, but its features are not well understood. Accurately determining the diversity of mtDNA has been difficult, due to the relatively small amount of mtDNA in each cell (<1% of the total DNA), the intercellular variability of mtDNA content and mtDNA pseudogenes (Numts) in nDNA. To understand the nature of heteroplasmy, we developed Mseek, a novel technique to purify and sequence mtDNA. Mseek yields high purity (>90%) mtDNA and its ability to detect rare variants is limited only by sequencing depth, providing unprecedented sensitivity and specificity. Using Mseek, we confirmed the ubiquity of heteroplasmy by analyzing mtDNA from a diverse set of cell lines and human samples. Applying Mseek to colonies derived from single cells, we find heteroplasmy is stably maintained in individual daughter cells over multiple cell divisions. We hypothesized that the stability of heteroplasmy could be facilitated by intercellular exchange of mtDNA. We explicitly demonstrate this exchange by co-culturing cell lines with distinct mtDNA haplotypes. Our results shed new light on the maintenance of heteroplasmy and provide a novel platform to investigate features of heteroplasmy in normal and diseased states.

Role of progerin-induced telomere dysfunction in HGPS premature cellular senescence.

Hutchinson-Gilford Progeria Syndrome (HGPS) is a premature-aging syndrome caused by a dominant mutation in the gene encoding lamin A, which leads to an aberrantly spliced and processed protein termed progerin. Previous studies have shown that progerin induces early senescence associated with increased DNA-damage signaling and that telomerase extends HGPS cellular lifespan. We demonstrate that telomerase extends HGPS cellular lifespan by decreasing progerin-induced DNA-damage signaling and activation of p53 and Rb pathways that otherwise mediate the onset of premature senescence. We show further that progerin-induced DNA-damage signaling is localized to telomeres and is associated with telomere aggregates and chromosomal aberrations. Telomerase amelioration of DNA-damage signaling is relatively rapid, requires both its catalytic and DNA-binding functions, and correlates in time with the acquisition by HGPS cells of the ability to proliferate. All of these findings establish that HGPS premature cellular senescence results from progerin-induced telomere dysfunction.

Effects of p21 deletion in mouse models of premature aging.

An approach to investigate the role of cellular senescence in organismal aging has been to abrogate signaling pathways known to induce cellular senescence and to assess the effects in mouse models of premature aging. Recently, we reported the effect of loss of function of p21, a gene implicated in p53-induced cellular senescence, in the background of the Ku80(-/-) premature aging mouse (Zhao et al., EMBO Rep 2009). Here, we provide an overview of the effects of p21 deletion in different models of premature aging.

Cellular senescence and organismal ageing in the absence of p21(CIP1/WAF1) in ku80(-/-) mice.

Ku80 is important in the repair of DNA double-strand breaks by its essential function in non-homologous end-joining. The absence of Ku80 causes the accumulation of DNA damage and leads to premature ageing in mice. We showed that mouse embryonic fibroblasts (MEFs) from ku80(-/-) mice senesced rapidly with elevated levels of p53 and p21. Deletion of p21 delayed the early senescence phenotype in ku80(-/-) MEFs, despite an otherwise intact response of p53. In contrast to ku80(-/-)p53(-/-) mice, which die rapidly primarily from lymphomas, there was no significant increase in tumorigenesis in ku80(-/-)p21(-/-) mice. However, ku80(-/-)p21(-/-) mice showed no improvement with respect to rough fur coat or osteopaenia, and even showed a shortened lifespan compared with ku80(-/-) mice. These results show that the increased lifespan of ku80(-/-) MEFs owing to the loss of p21 is not associated with an improvement of the premature ageing phenotypes of ku80(-/-) mice observed at the organismal level.