Kristen L. Mueller

T-cell receptor signaling to integrins.

Summary:  Integrin adhesion receptors are critical for antigen recognition by T cells and for regulated recirculation and trafficking into and through various tissues in the body. T‐cell receptor (TCR) signaling induces rapid increases in integrin function that facilitate T‐cell activation by promoting stable contact with antigen‐presenting cells and extracellular proteins in the environment. In this review, we outline the molecular mechanisms by which the TCR signals to integrins and present a model that highlights four key events: (i) initiation of proximal TCR signals nucleated by the linker for activated T cells (LAT) adapter protein and involving Itk, phospholipase C‐γ1, Vav1, and Src homology 2 domain‐containing leukocyte‐specific phosphoprotein of 76 kDa; (ii) transmission of integrin activation signals from the LAT signalosome to integrins by protein kinase (PK) C and the adapter protein, adhesion and degranulation‐promoting adapter protein; (iii) assembly of integrin‐associated signaling complexes that include PKD, the guanosine triphosphatase Rap1 and its effectors, and talin; and (iv) reorganization of the actin cytoskeleton by WAVE2 and other actin‐remodeling proteins. These events coordinate changes in integrin conformation and clustering that result in enhanced integrin functional activity following TCR stimulation.

Synthesis and UV Studies of A Small Library of 6-Aryl-4-hydroxy-2-pyrones. A Relevant Structural Feature for the Inhibitory Property of Arisugacin Against Acetylcholinesterase

Abstract 4-Hydroxypyrones belong to an important class of compounds not only because of their medicinal significance, but also because they represent a common structural feature among natural products that are biologically relevant. We describe here preparations of a small library of 6-aryl-4-hydroxy-pyrones which represent structural analogs of the DE-ring of arisugacin, a potent and selective inhibitor against acetylcholinesterasc. Given the structural significance of the DE-ring in the inhibitory activity of arisugacin chemical shifts of relevant protons on the pyrone ring are compared and distinct features in UV absorptions of these 6-aryl-4-hydroxy-pyrones are described.

Adhesion and Degranulation-Promoting Adapter Protein (ADAP) Positively Regulates T Cell Sensitivity to Antigen and T Cell Survival

The hemopoietic specific adapter protein ADAP (adhesion and degranulation-promoting adapter protein) positively regulates TCR-dependent, integrin-mediated adhesion and participates in signaling pathways downstream of the TCR that result in T cell activation. The specific role of ADAP in regulating Ag-dependent T cell interactions with APCs and T cell activation following Ag stimulation is not known. We used ADAP−/− DO11.10 T cells to demonstrate that ADAP promotes T cell conjugation to Ag-laden APCs. Complementary in vitro and in vivo approaches reveal that ADAP controls optimal T cell proliferation, cytokine production, and expression of the prosurvival protein Bcl-xL in response to limiting Ag doses. Furthermore, ADAP is critical for clonal expansion in vivo independent of Ag concentration under conditions of low clonal abundance. These results suggest that ADAP regulates T cell activation by promoting Ag-dependent T cell-APC interactions, resulting in enhanced T cell sensitivity to Ag, and by participating in prosurvival signaling pathways initiated by Ag stimulation.

Cutting Edge: LFA-1 Integrin-Dependent T Cell Adhesion Is Regulated by Both Ag Specificity and Sensitivity

Ab stimulation of the TCR rapidly enhances the functional activity of the LFA-1 integrin. Although TCR-mediated changes in LFA-1 activity are thought to promote T cell-APC interactions, the Ag specificity and sensitivity of TCR-mediated triggering of LFA-1 is not clear. We demonstrate that peptide/MHC (pMHC) tetramers rapidly enhance LFA-1-dependent adhesion of OT-I TCR transgenic CD8+ T cells to purified ICAM-1. Inhibition of src family tyrosine kinase or PI3K activity blocked pMHC tetramer- and anti-CD3-stimulated adhesion. These effects are highly specific because partial agonist and antagonist pMHC tetramers are unable to stimulate OT-I T cell adhesion to ICAM-1. The Ag thresholds required for T cell adhesion to ICAM-1 resemble those of early T cell activation events, because optimal LFA-1 activation occurs at tetramer concentrations that fail to induce maximal T cell proliferation. Thus, TCR signaling to LFA-1 is highly Ag specific and sensitive to low concentrations of Ag.

Inflammation's Yin-Yang

IN THEIR PERSPECTIVE “A GOLDEN ERA OF NOBEL LAUREATES” (23 November 2012, p. 1033), J. L. Goldstein and M. S. Brown call attention to nine physicians who trained at the National Institutes of Health (NIH) in fundamental research from 1964 to 1972 and were subsequently awarded Nobel Prizes. They speculated on factors responsible for this remarkable confl uence, contrasting current research and medical education to their experiences. As dean of a research-intensive medical school who also trained at NIH, I offer some alternative perspectives. The NIH was a magical environment for biomedical research during the 1960s and 1970s. Many young physicians seeking academic careers—and some also wishing to avoid the military draft—spent time in NIH laboratories, some in combination with specialty training. The scientifi c environment was intoxicating, research resources seemed virtually unlimited, and scientifi c excellence was the highest value. Many experienced research success and now populate the leadership of biomedical research and academic medicine. Goldstein and Brown also raised important concerns. The fi rst relates to the tension between basic and translational research. The authors point out that whereas many of their later discoveries had clinical impact, they were not conducting “translational research” while at NIH. Few would contest that important biological research need not be translational. Fundamental inquiry into molecular, cellular, and physiologic pathways is foundational to translational and clinical research. Nevertheless, many who launched research careers at NIH did research aimed at understanding disease. The NIH Clinical Center was a hotbed of bedside-to-bench research. Patients with rare and complex disorders stimulated basic investigations of molecular pathways with mentors in labs only a hallway away. We spend too much time today unproductively parsing the defi nitions and relative value of basic and translational research. All research should be assessed by one criterion: the novelty, importance, and impact of the insights generated. Less important are the motivation of the scientist (e.g., understanding molecules and cells versus understanding disease), whether research links to health, the model system used (e.g., single molecules, mice, or humans), and the department in which it is conducted. A second issue involves the status of research in medical education today. The authors state that while basic science was core to medical education in the 1960s, science is presented in an abbreviated manner today. I do not recognize this as an accurate description of science education in today’s medical curricula, at least at research-intensive medical schools. Since the 1960s, the knowledge base within biomedical science has exploded, while important new areas such as health policy, global health, and biomedical ethics have emerged, requiring curricular choices. MD-Ph.D. programs train physician-scientists, and many schools now require scholarly projects of all students. The authors state that in the 1960s, the “best and the brightest” graduates were expected to pursue research careers. We delight when students pursue research, as many do today. We are also delighted when the “best and brightest” pursue clinical care and innovation, education, global health, and policy. Biomedical science is critical to the development of new treatments, but is one of several core missions of medical schools, as refl ected in the diverse choices that medical students make. Goldstein and Brown are concerned that NIH has shifted focus from basic science and “curiosity-driven” research to translational research and “big science.” I have considerable sympathy for this view. Research into fundamental mechanisms is critical, and selectively diminished support for such research threatens the scientific enterprise and human health. The development of consortia and “big data” approaches arose from the hypothesis that they enabled discoveries otherwise impossible. Some, such as the human genome project, have fulfi lled much if not all of their promise. With others, the jury is still out. The balance between individual curiosity-driven research into basic mechanisms and disease pathogenesis versus big science consortia will evolve, though it’s virtually certain that both will be necessary. The nine Nobelists are products of an NIH program in which physician trainees were instilled with passion for fundamental research, and the opportunity for medical students and physicians to be exposed to and inspired by great science is as important now as it was then. But the many opportunities and challenges facing medicine and research Letters to the Editor

Synthesis of dihydroxanthone derivatives and evaluation of their inhibitory activity against acetylcholinesterase: unique structural analogs of tacrine based on the BCD-ring of arisugacin.

A general approach to synthesis of dihydroxanthone derivatives is described here. In vitro evaluation of these dihydroxanthones demonstrated that some derivatives possess moderate anti-cholinesterase activities and better selectivities than tacrine for acetylcholinesterase over butyrylcholinesterase. Structural effects on anti-cholinesterase activities were also examined, and docking experiments were carried out to provide preliminary understandings of these experimental observations.

Manipulating the Microbiota

![Figure][1] Capsules being prepared for fecal transplantation therapy, which is used, often successfully, to treat intractable gut disorders such as Clostridium difficile infection. PHOTO: KEN RICHARDSON In John Donnes famous words, no man is an island. Rather, all organisms, including

HIV/AIDS: Eastern Europe

![Figure][1] CREDIT: MALCOLM LINTON “Why is AIDS almost nonexistent in the Soviet Union?” asked a 1991 news story in Science , headlined the “Russian AIDS Puzzle.” The story (13 September 1991, p. 1214) offered no good explanation for why the epidemic, then a decade old, had spared Eastern Europe and Central Asia but speculated that the dissolution of the Soviet Union might pave the way for HIV. It did. Today, the region is home to an estimated 1.5 million HIV-infected people, and the rate of spread remains dauntingly high. From 18 to 23 July 2010, more than 20,000 HIV/AIDS researchers will gather in Vienna, Austria—the “gateway” to Eastern Europe—for the 18th International AIDS Conference to try to bridge the gap between scientists and policymakers in East and West. In this issue, Science looks closely at the factors that in the mid-1990s led to the rapid spread of HIV in Russia and Ukraine, which account for more than 90% of the infections in the region. With a travel grant from the Open Society Institutes Public Health Program, correspondent Jon Cohen and photographer Malcolm Linton visited researchers, clinicians, advocates, and affected communities in both countries. The package of stories that begins on p. [160][2] examines how public health officials, health-care workers, researchers, and members of civil society in different regions have responded to the epidemic, as well as the criticisms that the governments have done too little to slow the spread of the virus. The central dilemma is that HIV in the region has been mainly transmitted by injecting drug users sharing needles, and the “harm reduction” strategies successfully used in Western Europe and elsewhere, such as needle exchange or opiate-substitution treatment, have not taken root in the more conservative climate of the East. Critics charge that stigma and discrimination against drug users by government officials, law enforcement, and the medical community have fueled the problem. A slideshow published online further captures some of the challenges in the region and how they are being addressed. Building a strong response to HIV/AIDS takes several years in almost every country. But Russia, Ukraine, and their neighbors have an advantage: They can learn from the many other countries that began confronting the virus more than a decade before it hit Eastern Europe. The News package is followed by Policy Forums and original research about the fields most pressing topics, which will take center stage at the upcoming conference. Girard and colleagues (p. [147][3]) advocate for the importance of a renewed commitment to universal access to prevention, treatment, and care. Jewkes (p. [145][4]) discusses the continuing contribution of gender inequities to the prevalence of HIV/AIDS in women, especially in South Africa. A Review by Trono et al. (p. [174][5]) focuses on the latent viral reservoir that persists in HIV-infected people, describing the underlying biology and potential interventions that may lead to a cure. A report by Wu et al. ( Science Express) describes a trio of new broadly neutralizing antibodies isolated from an HIV-infected person that attach to the CD4 binding site of the virus and can potently neutralize a broad range of viral strains. [1]: pending:yes [2]: /lookup/doi/10.1126/science.329.5988.160 [3]: /lookup/doi/10.1126/science.1193294 [4]: /lookup/doi/10.1126/science.1193794 [5]: /lookup/doi/10.1126/science.1191047

Local macrophage clean-up

Tissue Repair Infection, especially by helminths or bacteria, can cause tissue damage (see the Perspective by Bouchery and Harris). Minutti et al. studied mouse models of helminth infection and fibrosis. They expressed surfactant protein A (a member of the complement component C1q family) in the lung, which enhanced interleukin-4 (IL-4)–mediated proliferation and activation of alveolar macrophages. This activation accelerated helminth clearance and reduced lung injury. In the peritoneum, C1q boosted macrophage activation for liver repair after bacterial infection. By a different approach, Bosurgi et al. discovered that after wounding caused by migrating helminths in the lung or during inflammation in the gut of mice, IL-4 and IL-13 act only in the presence of apoptotic cells to promote tissue repair by local macrophages. Science , this issue p. [1076][1], p. [1072][2]; see also p. [1014][3] [1]: /lookup/doi/10.1126/science.aaj2067 [2]: /lookup/doi/10.1126/science.aai8132 [3]: /lookup/doi/10.1126/science.aan6782

High-resolution insights into the intasome

Structural Biology An essential step in the life cycle of lentiviruses such as HIV-1 is when viral DNA integrates into the host genome, establishing a permanent infection of the host cell. The viral integrase enzyme catalyzes this process and is a major drug target. During viral integration,