Faculty Bibliography

BACKGROUND:cells within the mouse heart have been widely recognized as a stem cell population with multipotency that can give rise to cardiomyocytes, endothelial cells, and smooth muscle cells in vitro and after cardiac grafting. However, the developmental origin and authentic nature of these cells remain elusive. METHODS:cells. RESULTS:cells are in fact a pure endothelial cell population. They retain endothelial properties and exhibit minimal cardiomyogenic potential during development, normal aging and upon ischemic injury. CONCLUSIONS:cells in heart repair need to be reassessed.

Tinea incognito (TI) describes a common dermatophytosis with often atypical clinical features attributed to inappropriate use of topical immunomodulatory agents, usually corticosteroids. Given the high prevalence of TI and limited literature detailing this condition, we conducted a retrospective review of cases of pediatric dermatophytosis presenting to the Faculty Group Practice of the Ronald O. Perelman Department of Dermatology, New York University School of Medicine (New York, New York), between 2005 and 2016. Among microbiologically confirmed dermatophytosis cases, we found that even with prior treatment, TI often presented with classic features of tinea such as annularity and scale. The majority of cases were treated with oral antifungals, though some were treated with topical antifungals alone. This case series underscores the need to maintain a high clinical suspicion for TI.

Membrane proteins function in native cell membranes, but extraction into isolated particles is needed for many biochemical and structural analyses. Commonly used detergent-extraction methods destroy naturally associated lipid bilayers. Here, we devised a detergent-free method for preparing cell-membrane nanoparticles to study the multidrug exporter AcrB, by cryo-EM at 3.2-Ã… resolution. We discovered a remarkably well-organized lipid-bilayer structure associated with transmembrane domains of the AcrB trimer. This bilayer patch comprises 24 lipid molecules; inner leaflet chains are packed in a hexagonal array, whereas the outer leaflet has highly irregular but ordered packing. Protein side chains interact with both leaflets and participate in the hexagonal pattern. We suggest that the lipid bilayer supports and harmonizes peristaltic motions through AcrB trimers. In AcrB D407A, a putative proton-relay mutant, lipid bilayer buttresses protein interactions lost in crystal structures after detergent-solubilization. Our detergent-free system preserves lipid-protein interactions for visualization and should be broadly applicable.

There is a considerable need to identify those individuals with prostate cancer who have indolent disease. We propose that genes that control adult stem cell homeostasis in organs with slow turnover, such as the prostate, control cancer fate. One such gene, KLF4, overexpressed in murine prostate stem cells, regulates their homeostasis, blocks malignant transformation, and controls the self-renewal of tumor-initiating cells. KLF4 loss induces the molecular features of aggressive cancer and converts PIN lesions to invasive sarcomatoid carcinomas; its re-expression in vivo reverses this process. Bioinformatic analysis links these changes to human cancer. KLF4 and its downstream targets make up a gene signature that identifies indolent tumors and predicts recurrence-free survival. This approach may improve prognosis and identify therapeutic targets for advanced cancer.