Faculty Bibliography

It is well established that motor neurons depend for their survival on many trophic factors. In this study, we show that the precursor form of NGF (pro-NGF) can induce the death of motor neurons via engagement of the p75 neurotrophin receptor. The pro-apoptotic activity was dependent upon the presence of sortilin, a p75 co-receptor expressed on motor neurons. One potential source of pro-NGF is reactive astrocytes, which up-regulate the levels of pro-NGF in response to peroxynitrite, an oxidant and producer of free radicals. Indeed, motor neuron viability was sensitive to conditioned media from cultured astrocytes treated with peroxynitrite and this effect could be reversed using a specific antibody against the pro-domain of pro-NGF. These results are consistent with a role for activated astrocytes and pro-NGF in the induction of motor neuron death and suggest a possible therapeutic target for the treatment of motor neuron disease

Although processes leading up to the point of synapse formation are fairly well understood, the precise sequence of events in which the membranes of two separate cells "lock in" to form a mature synaptic junctional complex is poorly understood. A careful study of the molecules operating at the synapse indicates that their roles are more multifarious than once imagined. In this review we posit that the synapse is a functional organelle with poorly defined boundaries and a complex biochemistry. The role of adhesion molecules, including the integration of their signaling and adhesive properties in the context of synaptic activity is discussed.

A key event in the pathogenesis of asthma and allergies is the production of IgE antibodies. We show here that IgE(+) cells were exceptional because they were largely found outside germinal centers and expressed, from very early on, a genetic program of plasma cells. In spite of their extragerminal center localization, IgE(+) cells showed signs of somatic hypermutation and affinity maturation. We demonstrated that high-affinity IgE(+) cells could be generated through a unique differentiation program that involved two phases: a pre-IgE phase in which somatic hypermutation and affinity maturation take place in IgG1(+) cells, and a post-IgE-switching phase in which IgE cells differentiate swiftly into plasma cells. Our results have implications for the understanding of IgE memory responses in allergy

The use of the zebrafish as a model organism for the analysis of cardiac development is no longer proof-of-principle science. Over the last decade, the identification of a variety of zebrafish mutations and the subsequent cloning of mutated genes have revealed many critical regulators of cardiogenesis. More recently, increasingly sophisticated techniques for phenotypic characterization have facilitated analysis of the specific mechanisms by which key genes drive cardiac specification, morphogenesis, and function. Future enrichment of the arsenal of experimental strategies available for zebrafish should continue the yield of high returns from such a small source

A web-based survey was developed to evaluate joint arthroplasty surgeon's preferences for the return to sporting activities after total hip arthroplasty. This survey listed 30 groups of activities (37 specific sports) and was sent to all members of the Hip Society and American Association of Hip and Knee Surgeons. All surgeons were asked to grade each activity as follows: allow, allow with experience, not allowed, or undecided. Results were computed using a power analysis, Z test, and chi(2) test to determine statistical significance. There were a total of 549 responses giving an overall response rate of 72%, with 93% (92/99) of the Hip Society members and 72% (522/727) of American Association of Hip and Knee Surgeons members responding to the survey. Consensus guidelines and postoperative timing for the return to specific activities are presented

BACKGROUND: Acute lung injury is common during sepsis. Whereas gaseous exchange often can be supported adequately, death results frequently from cardio-circulatory depression, the mechanisms of which remain unclear. The aim of this study was to determine whether cardio-circulatory dysfunction during sepsis results from release of macrophage migration inhibitory factor (MIF) by the lung. METHODS: Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in adult Sprague-Dawley rats. Macrophage MIF was measured in the plasma sampled from the right ventricle (pre-lung) and left atrium (post-lung). RESULTS: The concentration of macrophage MIF in each of the post-lung samples was higher than in the corresponding pre-lung sample at 6 h (p = 0.015; paired t-test), 20 h (p = 0.008), and 30 h (p = 0.026) after the induction of sepsis. Next, rats that underwent CLP were treated with either saline (control) or our specific MIF inhibitor, (S, R )-3-(4-hydroxyphenyl)-4,5-dehydro-5-isoxazole acetic acid methyl ester (ISO-1). Echocardiography revealed that ISO-1 significantly improved the left ventricular end-diastolic volume index (p = 0.02), stroke volume index (p = 0.01), and cardiac index (p = 0.02) at 30 h after the induction of sepsis. CONCLUSIONS: The lung appears to release significant amounts of macrophage MIF into the systemic circulation during late sepsis. Inhibition of MIF in a clinically relevant time frame blocked polymicrobial peritonitis-induced cardio-circulatory dysfunction. Inhibition of MIF may be a useful strategy to prevent cardio-circulatory deterioration associated with late sepsis

Cross-presentation of exogenous proteins on MHC class I complexes contributes to the priming CD8(+) T-cell responses. However, the mechanisms by which antigen-presenting cells transfer internalized proteins to the MHC class I loading pathway are not well understood. Endocytosed proteins often appear to require proteasomal processing and transport into the endoplasmic reticulum, but the intracellular routes involved in cross-presentation remain unclear. Understanding the molecular and cellular basis of cross-presentation will illuminate novel aspects of cell physiology and might lead to improved vaccine design

In response to ER stress, the pancreatic endoplasmic reticulum kinase (PERK) coordinates an adaptive program known as the integrated stress response (ISR) by phosphorylating the alpha subunit of eukaryotic translation initiation factor 2 (eIF2alpha). IFN-gamma, which activates the ER stress response in oligodendrocytes, is believed to play a critical role in the immune-mediated CNS disorder multiple sclerosis (MS) and its mouse model, experimental autoimmune encephalomyelitis (EAE). Here we report that CNS delivery of IFN-gamma before EAE onset ameliorated the disease course and prevented demyelination, axonal damage, and oligodendrocyte loss. The beneficial effects of IFN-gamma were accompanied by PERK activation in oligodendrocytes and were abrogated in PERK-deficient animals. Our results indicate that IFN-gamma activation of PERK in mature oligodendrocytes attenuates EAE severity and suggest that therapeutic approaches to activate the ISR could prove beneficial in MS

With a lack of distinct stem cell markers, isolation of tissue-specific stem cells for tissue engineering and gene therapy is a great challenge. Beta (beta)(1) integrin expression has been used as a way of enriching for putative epithelial stem cells through rapid adhesion to collagen IV or flow cytometry. This is a first report of enrichment of putative urothelial stem cells using rapid adhesion and flow cytometric methods. We assessed our success by determining the clonogenic and proliferative potential of the isolated cells. We demonstrated that enrichment based on beta(1) integrin expression with flow cytometry yields highly clonogenic and proliferative urothelial cells, whereas the rapid adhesion method is not as efficient, possibly because of the unique nature of urothelium, a transitional epithelium, compared to results reported in stratified and columnar epithelia

The epithelial-specific adaptor AP1B sorts basolateral proteins, but the trafficking routes where it performs its sorting role remain controversial. Here, we used an RNAi approach to knock down the medium subunit of AP1B (mu1B) in the prototype epithelial cell line Madin-Darby canine kidney (MDCK). Mu1B-knocked down MDCK cells displayed loss of polarity of several endogenous and exogenous basolateral markers transduced via adenovirus vectors, but exhibited normal polarity of apical markers. We chose two well characterized basolateral protein markers, the transferrin receptor (TfR) and the vesicular stomatitis virus G protein, to study the sorting role of AP1B. A surface-capture assay introduced here showed that mu1B-knocked down MDCK cells plated on filters at confluency and cultured for 4.5 d, sorted TfR correctly in the biosynthetic route but incorrectly in the recycling route. In contrast, these same cells missorted vesicular stomatitis virus G apically in the biosynthetic route. Strikingly, recently confluent MDCK cells (1-3 d) displayed AP1B-dependence in the biosynthetic route of TfR, which decreased with additional days in culture. Sucrose density gradient analysis detected AP1B predominantly in TfR-rich endosomal fractions in MDCK cells confluent for 1 and 4 d. Our results are consistent with the following model: AP1B sorts basolateral proteins in both biosynthetic and recycling routes of MDCK cells, as a result of its predominant functional localization in recycling endosomes, which constitute a post-Golgi station in the biosynthetic route of some plasma membrane proteins. TfR utilizes a direct route from Golgi to basolateral membrane that is established as the epithelial monolayer matures.