Complexity in signaling networks is often derived from co-opting one set of molecules for multiple operations. Understanding how cells achieve such sophisticated processing using a finite set of molecules within a confined space--what we call the ""signaling paradox""--is critical to biology and engineering as well as the emerging field of synthetic biology. In the Inoue Lab, we have recently developed a series of chemical-molecular tools that allow for inducible, quick-onset and specific perturbation of various signaling molecules. Using this novel technique in conjunction with fluorescence imaging, microfabricated devices, quantitative analysis and computational modeling, we are dissecting intricate signaling networks. In particular, we investigate positive-feedback mechanisms underlying the initiation of neutrophil chemotaxis (known as symmetry breaking), as well as spatio-temporally compartmentalized signaling of Ras and membrane lipids such as phosphoinositides. In parallel, we also try to understand how cell morphology affects biochemical pathways inside cells. Ultimately, we will generate completely orthogonal machinery in cells to achieve existing, as well as novel, cellular functions. Our synthetic, multidisciplinary approach will elucidate the signaling paradox created by nature.

Intestinal chloride secretion is stimulated during diarrhea. Cholera toxin is secreted by bacterium Vibrio cholera and is responsible for the watery diarrhea after cholera infection. Mechanistically, cholera toxin increases intracellular cyclic AMP, which subsequently activates protein kinase A and the cystic fibrosis transmembrane regulator chloride channel (CFTR). However, we recently identified an intestinal cAMP-Ca cross-talk signaling pathway that is initiated by elevation of intracellular cAMP and subsequently elevates intracellular Ca concentrations through the exchange protein activated by cAMP (Epac). This observation suggests that both CFTR and calcium-activated chloride channels are targets of elevated intracellular cAMP signaling molecule. Therefore, we are studying the role of calcium-activated Cl channels in intestinal chloride secretion under physiological conditions and during diarrhea. We are also determining whether the recently identified transmembrane protein 16 family of proteins, which are calcium-activated chloride channels, is also involved in intestinal chloride secretion in addition to the well characterized CFTR channel. Increased understanding of regulation of intestinal Cl secretion provides the necessary background information for the development of therapeutic drugs for the treatment of diarrhea, constipation and cystic fibrosis. The discovery that calcium-activated chloride channels are involved in intestinal chloride secretion provides additional targets for anti-diarrhea drug development.

Secretory diarrhea is a leading cause of childhood morbidity and mortality in developing countries. While diarrhea can be treated with oral rehydration solution (ORS), inclusion of zinc with oral ORS has been shown to reduce the duration of diarrhea. However, how zinc improves diarrhea is not known. It has been shown that zinc acts as an intestinal epithelial cell basolateral potassium channel blocker of cyclic AMP-mediated chloride secretion. We discovered that zinc also stimulates intestinal sodium and water absorption via the epithelial Na/H exchanger, NHE3. Zinc reverses the effect of cyclic AMP inhibition of NHE3 activity. The effect of zinc on NHE3 cannot be duplicated with other divalent metal ions. It has been well established that Na/H exchanger regulatory proteins are involved in NHE3 regulation. Whether these regulatory proteins are involved in zinc stimulation of NHE3 is a focus of our study. Our goal is to reveal mechanisms to explain how zinc improves diarrhea and to understand the role of zinc in salt and water homeostasis in the gut. Our study will provide a scientific basis to justify the inclusion of zinc in ORS for the treatment of secretory diarrhea.

The Hoffmann Lab is focused on reducing TB and HIV morbidity and mortality in the low and middle income settings through behavioral and implementation science approaches. Work has focused on understanding individual-level behavior towards linkage to care and continued care engagement for HIV and TB and using this knowledge to develop approaches to increase HIV testing, linkage to care, HIV viral load suppression, and retention in care. Other work has focused on health system strategies to improve service delivery and improve adherence to best practice to guidelines-based care. The group's research includes work on the general population, corrections inmates and ex-inmates, men at risk for HIV, and recently hospitalized individuals. Most of the research has been in South Africa and elsewhere in sub-Saharan Africa.

The Hey-Kyoung Lee Lab is interested in exploring the cellular and molecular changes that happen at synapses to allow memory storage. We use various techniques, including electrophysiological recording, biochemical and molecular analysis, and imaging, to understand the cellular and molecular changes that happen during synaptic plasticity. Currently, we are examining the molecular and cellular mechanisms of global homeostatic synaptic plasticity using sensory cortices as model systems. In particular, we found that loss of vision elicits global changes in excitatory synaptic transmission in the primary visual cortex. Vision loss also triggers specific synaptic changes in other primary sensory cortices, which we postulate underlies sensory compensation in the blind. One of our main research goals is to understand the mechanisms underlying such cross-modal synaptic plasticity. We are also interested in elucidating the events that occur in diseased brains. In collaboration with other researchers, we are analyzing various mouse models of Alzheimer's disease, especially focusing on the possible alterations in synaptic plasticity mechanisms.

The Brain Health Program is a multidisciplinary team of faculty from the departments of neurology, psychiatry, epidemiology, and radiology lead by Leah Rubin and Jennifer Coughlin. In the hope of revealing new directions for therapies, the group studies molecular biomarkers identified from tissue and brain imaging that are associated with memory problems related to HIV infection, aging, dementia, mental illness and traumatic brain injury. The team seeks to advance policies and practices to optimize brain health in vulnerable populations while destigmatizing these brain disorders. Current and future projects include research on: the roles of the stress response, glucocorticoids, and inflammation in conditions that affect memory and the related factors that make people protected or or vulnerable to memory decline; new mobile apps that use iPads to improve our detection of memory deficits; clinical trials looking at short-term effects of low dose hydrocortisone and randomized to 28 days of treatment; imaging brain injury and repair in NFL players to guide players and the game; and the role of inflammation in memory deterioration in healthy aging, patients with HIV, and other neurodegenerative conditions.

Researchers in the Harold Lehmann Lab study evidence-based medicine. We are currently examining the informatics infrastructure of research and the secondary use of electronic health record data for research. The team is also evaluating the value of classic evidence reports versus social media versus links to community services for community health workers.

Research in the Hanan Aboumatar Lab focuses on advancing patient-centered outcomes through improved patient and family involvement. We also focus on multilevel methods to increase the patient-centered focus of care delivery. Recent research examined the impact of a quality-improvement intervention on patient involvement in primary care and treatment with respect and dignity in intensive care.

Work in the Hsin-Chieh Yeh Lab focuses on clinical trials and cohort studies of diabetes, obesity and behavioral intervention, cancer and hypertension. Recent investigations have focused on novel risk factors and complications related to obesity and type 2 diabetes, particularly lung function, smoking and cancer. We recently co-led a randomized clinical trial of tailored dietary advice for consumption of dietary supplements to lower blood pressure and improve cardiovascular disease risk factors in hypertensive urban African Americans.

Research in the Henry Fessler Lab is focused on pulmonary medicine. We are interested in heart-lung interaction, mechanical ventilation and lung mechanics. We’re also interested in medical education and recently examined contemporary strategies for effective lecturing.