Day 1 :
University of South Carolina, Columbia, SC
Keynote: Allosteric modulatory effects on HIV-1 Tat protein-induced inhibition of human dopamine transporter function
Time : 09:35-10:15
Dr. Zhu’s research aims toward finding solutions to a newly recognized challenge in treatment for HIV-associated neurocognitive disorders (HANDs). About one-half of HIV-1-positive individuals suffer from HAND, which dramatically affects memory, learning, decision-making, planning and overall quality of life. Cocaine has been shown to exacerbate the severity of HAND. HAND is associated with HIV-1 viral proteins, which are present in the brain of HIV-1-infected patients. HIV-1 transactivator of transcription (Tat) protein--an HIV regulatory protein--is thought to inhibit neuronal communication by acting directly on the human dopamine transporter, a membrane protein in the brain responsible for pumping the dopamine back into the cytosol and terminating dopamine signaling during neurotransmission. Dr. Zhu’s project is to investigate how cocaine and Tat work to create binders that derail neuronal communication in the brain. The ultimate goal is to develop neuroprotective drugs and help HIV patients recover their neurological function.
The inducible HIV-1 Tat transgenic (iTat) mouse model recapitulates many aspects of neurocognitive impairments observed in HIV infected individuals. Tat and cocaine synergistically increase synaptic dopamine (DA) levels by directly inhibiting DA transporter (DAT) activity, ultimately leading to dopaminergic neuron damage. This study determined allosteric modulatory effects of SRI-30827 on HIV-1 Tat protein-mediated regulation of human DAT and cocaine condition place preference (CPP) in iTat mice. Results show that SRI-30827 attenuated Tat-induced inhibition of [3H]DA uptake and [3H]WIN35,428 binding in PC12 cells expressing human DAT. After a 7-d doxycycline (Dox) treatment, HPLC analysis revealed that DA content in the prefrontal cortex (PFC) and nucleus accumbens (NAc) of iTat-Tg mice were increased by 92% and 37%, respectively, compared to control mice. Consistently, DA/DOPAC in the PFC and NAc of iTat-Tg mice was increased by 44% and 26%, respectively. We performed the patch clamp recording to measure medium spine neurons (MSN) firing in brain NAc slices of iTat mice in the presence of DA and cocaine. Results show that that action potential frequency of NAc shell MSN was significantly increased in iTat mice compared to control mice. Further, action potential frequency of NAc shell neurons was decreased in response to 5 μM cocaine, and further decreased when cocaine and 5 μM were applied together, which were completely attenuated in iTat mice. Finally, we found that ICV infusion of SRI-30827, a novel allosteric modulator, partially attenuated the potentiated cocaine-CPP in iTat mice. These findings suggest the hypothesis that Tat potentiates cocaine rewarding effect and allostericmodulator has potential for treatment of Tat-induced drug reward.
Taipei Veterans General Hospital, Taipei, Taiwan
Keynote: Leptin is essential for spinal microglia activation and the development of neuropathic pain after preganglionic cervical root avulsion
Time : 10:15-10:55
Ming-Chao Huang was born in 1958, in Taipei, Taiwan. He obtained MD degree from Taipei Medical University, Taiwan, in 1984. He got his PhD degree from Tokyo Women’s Medical University, Japan, in 1996. He is a neurosurgeon and is currently the division Chief of Department of Neurosurgery, Taipei Veterans General Hospital, Taipei, Taiwan. He is also the Associate Professor of Taipei Medical University and Central Taiwan Technological University. His clinical specialty includes spinal surgery (including degeneration and trauma), peripheral nerve surgery (including tumor surgery and nerve repair), and brain tumor surgery. His research interests are nerve root injury (including basic mechanism and surgical repair), neuropathic pain (including basic study and treatment), and brain tumor (including medical and surgical treatment).
Preganglionic cervical root avulsion (PCRA) affects both the peripheral and central nervous systems and is often associated with neuropathic pain. Unlike peripheral nerve injuries (PNI), central lesions caused by disruption of cervical roots from the spinal cord following PCRA contribute to the generation of neuropathic pain. Leptin is involved in the development of neuropathic pain after PNI by affecting neurons. However, whether leptin is involved in microglial activation leading to neuropathic pain after PCRA is unknown. In this studies, the preganglionic avulsion of the left 6th-8th cervical roots was performed in C57B/6J mice and leptin-deficient mice. A leptin antagonist or leptin was administered to C57B/6J mice and leptin-deficient mice after injury, respectively. The expression pattern of spinal microglia was examined by immunofluorescent staining. Von Frey filaments were used to test pain sensitivity. Our data showed that leptin is essential for the development of neuropathic pain after PCRA. Allodynia was absent in the leptin-deficient mice and the mice administered the leptin antagonist. We also found that leptin deficiency or the administration of its antagonist inhibited the development of microgliosis, the expression of CD86 and iNOS, and Wallerian degeneration in the spinal cord. Moreover, the administration of exogenous leptin to leptin-deficient mice reversed these effects. We concluded that leptin is involved in the proliferation and activation of microglia, which in turn enhances the development of neuropathic pain. Blocking the effects of leptin might be a target for the treatment of neuropathic pain after PCRA.
Neuropsychiatric Research, National Health Research Institutes, Taiwan
Time : 11:15-11:55
Dr. Wen-Hai Chou received his PhD from Department of Molecular Medicine, University of Texas Health Science Center, San Antonio, and post-doctoral studies from University of California, San Francisco. He is an Assistant Investigator of National Health Research Institutes, Taiwan. He has published more than 22 papers in reputed journals including Neuron, Journal of Clinical Investigation, Journal of Neuroscience, and Journal of Biological Chemistry. He was elected as a Fellow of the American Heart Association (F.A.H.A.) for making major and productive contributions in cardiovascular basic sciences in 2011
Cardiac arrest continues to be the leading cause of death worldwide. Global cerebral ischemia that accompanies cardiac arrest is one of the major causes of morbidity and mortality. Out of many therapeutic approaches investigated, one of them is ischemic preconditioning, which is sufficient to protect brain tissues from subsequent lethal ischemic insult. PKCε peptide activator administered before, but not after, ischemia mediates preconditioning and confers neuroprotection. However, the use of preconditioning as a therapeutic approach has not become standard clinical practice because the occurrence of cardiac arrest and cerebral ischemia is sudden and unpredictable. Thus, post-ischemic therapeutic targets have to be unraveled. The beneficial effects of PKCε peptide activators in ischemic preconditioning stimulate interests in understanding the molecular and cellular actions of PKCε after global cerebral ischemia. A detailed understanding of PKCε signaling pathways requires identification of its downstream targets. This study is to determine the downstream mediators of PKCε, so that novel therapeutic targets can be developed. We found that PKCε mediated the phosphorylation of Activating transcription factor 2 (ATF2) at Threonine 52 in the hippocampus. ATF2 is a member of the activator protein 1 (AP1) transcription factor superfamily regulating normal growth and development as well as response to cellular stress. In response to global cerebral ischemia, PKCε expression was gradually decreased. This resulted in leakage of nuclear ATF2 to the mitochondria, and subsequent ischemia-induced neurodegeneration (Fig. 1). This study not only provides the first insight into the neuronal cell death regulated by PKCε and ATF2, but also establishes a strong base to develop new classes of therapeutic molecules to inhibit the leakage of ATF2 and reduce brain injury after cardiac arrest.