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Identification of an organelle-specific myosin V receptor

Class V myosins are widely distributed among diverse organisms and move cargo along actin filaments. Some myosin Vs move multiple types of cargo, where the timing of movement and the destinations of selected cargoes are unique. Here, we report the discovery of an organelle-specific myosin V receptor. Vac17p, a novel protein, is a component of the vacuole-specific receptor for Myo2p, a Saccharomyces cerevisiae myosin V. Vac17p interacts with the Myo2p cargo-binding domain, but not with vacuole inheritance-defective myo2 mutants that have single amino acid changes within this region. Moreover, a region of the Myo2p tail required specifically for secretory vesicle transport is neither required for vacuole inheritance nor for Vac17p–Myo2p interactions. Vac17p is localized on the vacuole membrane, and vacuole-associated Myo2p increases in proportion with an increase in Vac17p. Furthermore, Vac17p is not required for movement of other cargo moved by Myo2p. These findings demonstrate that Vac17p is a component of a vacuole-specific receptor for Myo2p. Organelle-specific receptors such as Vac17p provide a mechanism whereby a single type of myosin V can move diverse cargoes to distinct destinations at different times

Empyema necessitans caused by methicillin-resistant Staphylococcus aureus: a case report and literature review

Abstract Background Empyema necessitans (EN) is a rare condition characterized by pleural infection with pus spreading into adjacent soft tissues. Although Mycobacterium tuberculosis and Actinomyces israelii are common causative agents, methicillin-resistant Staphylococcus aureus (MRSA) is relatively rare, but it is associated with high mortality in empyema cases. We aimed to report a unique case of EN caused by MRSA and present a literature review to better understand this rare condition. Case presentation A 69-year-old man with a history of right ureteral stone presented with fever and left anterior thoracic pain. A physical examination revealed redness and swelling in the left thoracic region. Imaging studies confirmed EN with fluid accumulation around the sternocostal joint of the left first rib. MRSA was identified from blood and pleural fluid cultures. The patient received antimicrobial therapy, and a chest tube was inserted for drainage. Despite initial improvement, vertebral osteomyelitis was diagnosed on day 17. The antimicrobials were subsequently terminated after 6 weeks, but vertebral osteomyelitis recurred, and treatment was resumed and completed on day 215. Conclusion EN caused by MRSA is rare, and the literature review revealed 14 cases from human sources. Positive blood cultures were observed in 40% of cases, and metastatic infections were present in 30% of cases. Osteomyelitis was the most common type of metastatic lesion. All the patients underwent drainage. Patients with MRSA-associated EN frequently develop disseminated lesions and should therefore be carefully examined. Moreover, appropriate treatment with antibiotics and drainage is necessary for a good prognosis. Although the prognosis appeared to be favorable in our review, publication bias and treatment challenges for metastatic infections should be considered

Generation of corneal epithelial cells from induced pluripotent stem cells derived from human dermal fibroblast and corneal limbal epithelium.

Induced pluripotent stem (iPS) cells can be established from somatic cells. However, there is currently no established strategy to generate corneal epithelial cells from iPS cells. In this study, we investigated whether corneal epithelial cells could be differentiated from iPS cells. We tested 2 distinct sources: human adult dermal fibroblast (HDF)-derived iPS cells (253G1) and human adult corneal limbal epithelial cells (HLEC)-derived iPS cells (L1B41). We first established iPS cells from HLEC by introducing the Yamanaka 4 factors. Corneal epithelial cells were successfully induced from the iPS cells by the stromal cell-derived inducing activity (SDIA) differentiation method, as Pax6(+)/K12(+) corneal epithelial colonies were observed after prolonged differentiation culture (12 weeks or later) in both the L1B41 and 253G1 iPS cells following retinal pigment epithelial and lens cell induction. Interestingly, the corneal epithelial differentiation efficiency was higher in L1B41 than in 253G1. DNA methylation analysis revealed that a small proportion of differentially methylated regions still existed between L1B41 and 253G1 iPS cells even though no significant difference in methylation status was detected in the specific corneal epithelium-related genes such as K12, K3, and Pax6. The present study is the first to demonstrate a strategy for corneal epithelial cell differentiation from human iPS cells, and further suggests that the epigenomic status is associated with the propensity of iPS cells to differentiate into corneal epithelial cells

DNA methylation analysis of corneal epithelium-related genes.

<p>Methylation analysis of individual genes was performed. Methylation frequency in K12, K3, Pax6, p63, and K14 genes were not statistically different among L1B41, 253G1, and 201B7 (significance level; p<0.001 [ = diffscore >33 or <−33]).</p

The effect of BMP4 treatment on iPS cells during corneal epithelial differentiation by the SDIA method.

<p>(A, B) 0.5 µM BMP4 was added during the first 2 weeks of differentiation by the SDIA method. Triple immunostaining showed that BMP4 treatment inhibited corneal epithelial induction from both iPS cell lines (K12: red, Pax6: green, K14: blue). (C) Real-time RT-PCR showed that Pax6 and K12 expression was completely suppressed by BMP4 treatment in L1B41 iPS cells. In contrast, BMP4 showed no significant effect on delta-N p63 expression. The graph showed the mean ± S.E. of 3–7 independent samples, respectively. *p<0.05 (BMP4⁻ vs. BMP4⁺, Mann-Whitney rank-sum test), N.S. = not significant. Scale bar: 100 µm.</p