Faculty Bibliography

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

Although ras is a potent mitogenic oncogene, its tumorigenicity depends on cellular context and cooperative events. Here we show that low-level expression of a constitutively active Ha-ras in mouse urothelium induces simple urothelial hyperplasia that is resistant to progression to full-fledged bladder tumors even in the absence of Ink4a/Arf. In stark contrast, doubling of the gene dosage of the activated Ha-ras triggered early-onset, rapidly growing, and 100% penetrant tumors throughout the urinary tract. Tumor initiation required superseding a rate-limiting step between simple and nodular hyperplasia, the latter of which is marked by the emergence of mesenchymal components and the coactivation of AKT and STAT pathways as well as PTEN inactivation. These results indicate that overactivation of Ha-ras is both necessary and sufficient to induce bladder tumors along a low-grade, noninvasive papillary pathway, and they shed light on the recent findings that ras activation, via point mutation, overexpression, or intensified signaling from FGF receptor 3, occurs in 70%-90% of these tumors in humans. Our results highlight the critical importance of the dosage/strength of Ha-ras activation in dictating its tumorigenicity - a mechanism of oncogene activation not fully appreciated to date. Finally, our results have clinical implications, as inhibiting ras and/or its downstream effectors, such as AKT and STAT3/5, could provide alternative means to treat low-grade, superficial papillary bladder tumors, the most common tumor in the urinary system

Retinoic acid (RA) signaling is important for multiple aspects of embryonic development and tissue homeostasis. Heterodimers of retinoic acid receptors (RARs) and retinoid X receptors (RXRs) transduce RA signaling. It is not yet clear how the diversity of receptor combinations relates to the diversity of functions for RA. The expression patterns of three zebrafish RARs and four RXRs were reported recently. Here, we identify an additional RAR, a zebrafish RARgamma paralog, and two additional RXRs, duplicates of the previously identified RXRalpha and RXRgamma. Thus, the zebrafish genome contains duplicates of each RAR and RXR gene. All zebrafish RAR and RXR paralogs have overlapping and distinct areas of expression, as might be expected for duplicate genes in the process of diverging in function. By representing what is potentially the complete set of zebrafish RARs and RXRs, this study provides a valuable reference for future functional studies of the individual zebrafish RARs and RXRs

Epithelia can adjust the permeability of their paracellular permeation route to physiological requirements, pathological conditions, and pharmacological challenges. This is reflected by a transepithelial electrical resistance (TER) ranging from a few tenth to several thousands Omega.cm(2), depending on the degree of sealing of the tight junction (TJ). The present work is part of an effort to understand the causes and mechanisms underlying these adaptations. We observed that an extract of human urine (hDLU) increases TER in a concentration- and time-dependent manner and is more effective when added from the basolateral side of cultured monolayers of Madin-Darby canine kidney cells than from the apical one. We found that its main TER-increasing component is epidermal growth factor (hEGF), as depletion of this peptide with specific antibodies, or inhibition of its receptor with PD153035, abolishes its effect. Since the permeability of the TJ depends on the expression of several species of membrane proteins, chiefly claudins, we explored whether hDLU can affect five members of the claudin family, the three known members of the ZO family, and occludin. EGF present in hDLU decreases the content of claudins-1 and -2 as well as delocalizes them from the TJ and increases the content of claudin-4. As expected from the fact that the degree of sealing of the TJ must be a physiologically regulated parameter, besides of hEGF, we also found that hDLU appears to contain also other components that decrease TER, claudin-4 and -7, and that seem to act with different kinetics than the TER-increasing ones.

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

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.

FKBP52 is a member of the FK506-binding family of immunophilins and serves as a co-chaperone for steroid hormone nuclear receptors to govern appropriate hormone action in target tissues. Male mice missing Fkbp52 are infertile, and this infertility has been ascribed to compromised sensitivity of the anterior prostate, external genitalia, and other accessory sex organs to androgen. Here, we show additional defects contributing to infertility. We found that epididymal Fkbp52(-/-) sperm are sparse often with aberrant morphology, and they have reduced fertilizing capacity. This phenotype, initially observed in null males on a C57BL/6/129 background, is also maintained on a CD1 background. Expression studies show that while FKBP52 and androgen receptor are co-expressed in similar cell types in the epididymis, FKBP52 is also present in epididymal sperm flagella. Collectively, our results suggest that reduced number and abnormal morphology contribute to compromised fertilizing capacity of Fkbp52(-/-) sperm. This study is clinically relevant because unraveling the role of immunophilin signaling in male fertility will help identify new targets for male contraceptives and/or alleviate male infertility.

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

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