Faculty Bibliography

The yellow fever vaccine YF-17D is one of the most successful vaccines ever developed in humans. Despite its efficacy and widespread use in more than 600 million people, the mechanisms by which it stimulates protective immunity remain poorly understood. Recent studies using systems biology approaches in humans have revealed that YF-17D-induced early expression of general control nonderepressible 2 kinase (GCN2) in the blood strongly correlates with the magnitude of the later CD8(+) T cell response. We demonstrate a key role for virus-induced GCN2 activation in programming dendritic cells to initiate autophagy and enhanced antigen presentation to both CD4(+) and CD8(+) T cells. These results reveal an unappreciated link between virus-induced integrated stress response in dendritic cells and the adaptive immune response.

Unlike many viruses that suppress cellular protein synthesis, host mRNA translation and polyribosome formation are stimulated by human cytomegalovirus (HCMV). How HCMV impacts the translationally regulated cellular mRNA repertoire and its contribution to virus biology remains unknown. Using polysome profiling, we show that HCMV presides over the cellular translational landscape, selectively accessing the host genome to extend its own coding capacity and regulate virus replication. Expression of the HCMV UL38 mTORC1-activator partially recapitulates these translational alterations in uninfected cells. The signature of cellular mRNAs translationally stimulated by HCMV resembles pathophysiological states (such as cancer) where translation initiation factor levels or activity increase. In contrast, cellular mRNAs repressed by HCMV include those involved in differentiation and the immune response. Surprisingly, interfering with the virus-induced activation of cellular mRNA translation can either limit or enhance HCMV growth. The unanticipated extent to which HCMV specifically manipulates host mRNA translation may aid in understanding its association with complex inflammatory disorders and cancer.

We report the presence of a membranous tubulovesicular network in the planctomycete bacterium Gemmata obscuriglobus. This endomembrane system interacts with membrane coat proteins and is capable of protein internalization and degradation. Taken together, this suggests that the planctomycetal bacterium could illuminate the emergence of complex endomembrane systems.

Although antipsychotic drugs can reduce psychotic behavior within a few hours, full efficacy is not achieved for several weeks, implying that there may be rapid, short-term changes in neuronal function, which are consolidated into long-lasting changes. We showed that the antipsychotic drug haloperidol, a dopamine receptor type 2 (D2R) antagonist, stimulated the kinase Akt to activate the mRNA translation pathway mediated by the mammalian target of rapamycin complex 1 (mTORC1). In primary striatal D2R-positive neurons, haloperidol-mediated activation of mTORC1 resulted in increased phosphorylation of ribosomal protein S6 (S6) and eukaryotic translation initiation factor 4E-binding protein (4E-BP). Proteomic mass spectrometry revealed marked changes in the pattern of protein synthesis after acute exposure of cultured striatal neurons to haloperidol, including increased abundance of cytoskeletal proteins and proteins associated with translation machinery. These proteomic changes coincided with increased morphological complexity of neurons that was diminished by inhibition of downstream effectors of mTORC1, suggesting that mTORC1-dependent translation enhances neuronal complexity in response to haloperidol. In vivo, we observed rapid morphological changes with a concomitant increase in the abundance of cytoskeletal proteins in cortical neurons of haloperidol-injected mice. These results suggest a mechanism for both the acute and long-term actions of antipsychotics.

The discovery and characterization of broadly neutralizing antibodies (bnAbs) against influenza viruses have raised hopes for the development of monoclonal antibody (mAb)-based immunotherapy and the design of universal influenza vaccines. Only one human bnAb (CR8020) specifically recognizing group 2 influenza A viruses has been previously characterized that binds to a highly conserved epitope at the base of the hemagglutinin (HA) stem and has neutralizing activity against H3, H7, and H10 viruses. Here, we report a second group 2 bnAb, CR8043, which was derived from a different germ-line gene encoding a highly divergent amino acid sequence. CR8043 has in vitro neutralizing activity against H3 and H10 viruses and protects mice against challenge with a lethal dose of H3N2 and H7N7 viruses. The crystal structure and EM reconstructions of the CR8043-H3 HA complex revealed that CR8043 binds to a site similar to the CR8020 epitope but uses an alternative angle of approach and a distinct set of interactions. The identification of another antibody against the group 2 stem epitope suggests that this conserved site of vulnerability has great potential for design of therapeutics and vaccines.

High-density lipoprotein (HDL) particles transport (among other molecules) cholesterol (HDL-C). In epidemiological studies, plasma HDL-C levels have an inverse relationship to the risk of atherosclerotic cardiovascular disease. It has been assumed that this reflects the protective functions of HDL, which include their ability to promote cholesterol efflux. Yet, several recent pharmacological and genetic studies have failed to demonstrate that increased plasma levels of HDL-C resulted in decreased cardiovascular disease risk, giving rise to a controversy regarding whether plasma levels of HDL-C reflect HDL function, or that HDL is even as protective as assumed. The evidence from preclinical and (limited) clinical studies shows that HDL can promote the regression of atherosclerosis when the levels of functional particles are increased from endogenous or exogenous sources. The data show that regression results from a combination of reduced plaque lipid and macrophage contents, as well as from a reduction in its inflammatory state. Although more research will be needed regarding basic mechanisms and to establish that these changes translate clinically to reduced cardiovascular disease events, that HDL can regress plaques suggests that the recent trial failures do not eliminate HDL from consideration as an atheroprotective agent but rather emphasizes the important distinction between HDL function and plasma levels of HDL-C.

Recent discoveries of microRNAs (miRNAs) that control high-density lipoprotein abundance and function have expanded our knowledge of the mechanisms regulating this important lipoprotein subclass. miRNAs have been shown to regulate gene networks that control high-density lipoprotein biogenesis and uptake, as well as discrete steps in the reverse cholesterol transport pathway. Furthermore, high-density lipoprotein itself has been shown to transport miRNAs selectively in health and disease, offering new possibilities of how this lipoprotein may alter gene expression in distal target cells and tissues. Collectively, these discoveries offer new insights into the mechanisms governing high-density lipoprotein metabolism and function and open new avenues for the development of therapeutics for the treatment of cardiovascular disease.

Progranulin (PGRN) is a growth factor that has been implicated in wound healing, inflammation, infection, tumorigenesis, and is most known for its neuroprotective and proliferative properties in neurodegenerative disease. This pleiotropic growth factor has been found to be a key player and regulator of a diverse spectrum of multi-systemic functions. Its critical anti-inflammatory role in rheumatoid arthritis and other inflammatory disease models has allowed for the propulsion of research to establish its significance in musculoskeletal diseases, including inflammatory conditions involving bone and cartilage pathology. In this review, we aim to elaborate on the emerging role of PGRN in the musculoskeletal system, reviewing its particular mechanisms described in various musculoskeletal diseases, with special focus on osteoarthritis and inflammatory joint disease patho-mechanisms and potential therapeutic applications of PGRN and its derivatives in these and other musculoskeletal diseases.

The canonical Sonic Hedgehog (Shh)/Gli pathway plays multiples roles during central nervous system (CNS) development. To elucidate the molecular repertoire of Shh mediators, we have recently described novel transcriptional targets in response to Shh pathway modulation. Among them, we were able to identify Neogenin1 (Neo1), a death dependence receptor, as a new direct Shh downstream regulator in neural precursor proliferation. As appropriate Shh signaling is required for cerebellar growth and alterations cause Shh-driven medulloblastoma (MB), here we have addressed the role of the Shh/Neogenin1 interaction in the context of cerebellar development and cancer. We demonstrate that the Shh pathway regulates Neogenin1 expression in mouse models that recapitulate the Shh MB subtype. We show that the canonical Shh pathway directly regulates the Neo1 gene acting through an upstream sequence in its promoter both in vitro and in vivo in granule neuron precursor cells. We also identified and characterized a functional Gli-binding site in the first intron of the human NEO1 gene. Gene expression profiling of more than 300 MB shows that NEO1 is indeed upregulated in SHH tumors compared to the other MB subgroups. Finally, we provide evidence that NEO1 is necessary for cell cycle progression in a human MB cell line, because a loss of function of NEO1 arrests cells in the G2/M phase. Taken together, these results highlight Neogenin1 as a novel downstream effector of the Shh pathway in MB and a possible therapeutic target.