Major Depressive Disorder (MDD) is a recurrent mental illness that afflicts approximately 1 in 6 Americans at least once during their lifetime. While the causes are likely to be multi-factoral, the onset of MDD correlates with structural defects in the hippocampus, including alterations in dendritic morphology. The levels of neurotrophic factors like Brain Derived Neurotrophic Factor (BDNF), which stimulates dendritic growth, are decreased in both humans suffering from MDD and in animal models of MDD. However, while the decrease in BDNF levels is known to correlate with alterations in dendritic morphology, the underlying signaling mechanisms by which BDNF stimulates dendritic growth are unknown. Identifying these pathways is critical to understand how dendritic development and synaptogenesis occurs normally and how it is altered during bouts of MDD. Our long-range goal is to identify the intracellular signals by which neurotrophic factors control dendritic development and to determine how these signals are regulated in both normal and depressed brains. The objective of this application is to determine the signaling pathways by which one critical neurotrophic factor, BDNF, controls dendritic morphogenesis, synaptogenesis and the maintenance of synaptic structures. Our central hypothesis is that BDNF stimulates dendritic development via a coordinated response comprised of genomic regulation of both critical protein-coding genes and non-coding microRNAs whose expression are altered during depression. We have formulated this hypothesis on the basis of our published and unpublished data, which shows that an increase CREB dependent regulation of both protein coding genes and non-coding microRNAs are essential for BDNF dependent dendritic growth and synaptogenesis. The combination of these events not only activates pathways that promote dendritic growth but also inhibits pathways that suppress dendritic growth. We will test our central hypothesis with the following Specific Aims: 1. Determine the requirement of CREB regulated protein coding genes in BDNF-stimulated dendritic growth and synaptogenesis. 2. Determine the requirement for CREB regulated micro-RNAs in BDNF dependent dendritic growth and synaptogenesis. Determine the role of protein coding genes and micro-RNAs in vivo during normal development and during periods of altered BDNF expression. We will use biochemical, genetic, cell biological, behavioral and imaging approaches to address these specific aims. The rationale that underlies the proposed research is that once the critical signaling molecules linking BDNF to dendritic and spine remodeling become known they can be targeted for the treatment and prevention of MDD. These studies are innovative because they apply the expertise of the PI in signal transduction to a critical and under examined problem: to identify the molecular mechanisms underlying structural changes occurring during depression. We have enlisted the help of our consultant Jaak Panksepp, who has extensive experience in studying models of depression. Additionally, these results are expected to have a broad impact on the field as abnormalities in dendritic arborization and spinogenesis are common to numerous forms of mental retardation including Fragile X, Down's, and Rett syndromes.
The proposed research is relevant to public health because Major Depressive Disorder (MDD) is a debilitating mental illness that affects 1 in 6 Americans at some point in their lives. Unfortunately the currently available antidepressants only help a subset (50-70%) of patients with MDD. Onset of MDD is associated with a decrease in the levels of Brain Derived Neurotrophic Factor (BDNF). However, while the decrease in BDNF levels is known to correlate with alterations in dendritic morphology, the underlying signaling mechanisms by which BDNF stimulates dendritic growth are unknown. By understanding these processes, we are laying the foundation for the development of new therapies, such as genetic screens, gene therapies, and targeted drug design, to treat MDD.
|Gray, Kevin T; Suchowerska, Alexandra K; Bland, Tyler et al. (2016) Tropomodulin isoforms utilize specific binding functions to modulate dendrite development. Cytoskeleton (Hoboken) 73:316-28|
|Monreal, I Abrrey; Liu, Qian; Tyson, Katherine et al. (2015) Branched dimerization of Tat peptide improves permeability to HeLa and hippocampal neuronal cells. Chem Commun (Camb) 51:5463-6|
|Hayashi, Lauren; Sheth, Meghal; Young, Alexander et al. (2015) The effect of the aquatic contaminants bisphenol-A and PCB-95 on the zebrafish lateral line. Neurotoxicology 46:125-36|
|Benoist, Caroline C; Kawas, Leen H; Zhu, Mingyan et al. (2014) The procognitive and synaptogenic effects of angiotensin IV-derived peptides are dependent on activation of the hepatocyte growth factor/c-met system. J Pharmacol Exp Ther 351:390-402|
|Dhar, Matasha; Wayman, Gary A; Zhu, Mingyan et al. (2014) Leptin-induced spine formation requires TrpC channels and the CaM kinase cascade in the hippocampus. J Neurosci 34:10022-33|
|Lesiak, Adam; Zhu, Mingyan; Chen, Hao et al. (2014) The environmental neurotoxicant PCB 95 promotes synaptogenesis via ryanodine receptor-dependent miR132 upregulation. J Neurosci 34:717-25|
|Dhar, Matasha; Zhu, Mingyan; Impey, Soren et al. (2014) Leptin induces hippocampal synaptogenesis via CREB-regulated microRNA-132 suppression of p250GAP. Mol Endocrinol 28:1073-87|
|Hansen, Katelin F; Karelina, Kate; Sakamoto, Kensuke et al. (2013) miRNA-132: a dynamic regulator of cognitive capacity. Brain Struct Funct 218:817-31|
|McCoy, Alene T; Benoist, Caroline C; Wright, John W et al. (2013) Evaluation of metabolically stabilized angiotensin IV analogs as procognitive/antidementia agents. J Pharmacol Exp Ther 344:141-54|
|Kawas, Leen H; Benoist, Caroline C; Harding, Joseph W et al. (2013) Nanoscale mapping of the Met receptor on hippocampal neurons by AFM and confocal microscopy. Nanomedicine 9:428-38|
Showing the most recent 10 out of 19 publications