2014 — 2020 |
Shelly, Maya |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. R56Activity Code Description: To provide limited interim research support based on the merit of a pending R01 application while applicant gathers additional data to revise a new or competing renewal application. This grant will underwrite highly meritorious applications that if given the opportunity to revise their application could meet IC recommended standards and would be missed opportunities if not funded. Interim funded ends when the applicant succeeds in obtaining an R01 or other competing award built on the R56 grant. These awards are not renewable. |
Molecular Mechanisms of Dendrite Formation During Embryonic Neuronal Development @ State University New York Stony Brook
Molecular Mechanisms of Dendrite Initiation During Embryonic Neuronal Development The formation and directed growth of axon and dendrite, migration to a desired location in the developing brain, maturation of axonal and dendritic arbors, and establishment of proper synaptic connections are essential processes during embryonic neuronal development. With these overlapping and well coordinated developmental processes, the development of a neuronal cell begins with a process in which the neuron establishes axon and dendrite identities, an architecture that is critical for the input/output functions of the neuron. In the last decade, much effort has been made towards the elucidation of the molecular and cellular mechanisms that control axon initiation and outgrowth1-23. The morphological and functional differentiation of dendrites persists throughout life and underlies experience-dependent plasticity. Moreover, aberrations affecting dendrite development and maturation play key role in severe disorders such as mental retardation and autism spectrum disorders. The identification of the signaling pathways that determine the early events in dendrite development is of great importance for efforts to translate these mechanisms into clinical application. Despite this, the molecular mechanisms that establish the dendritic identity during embryonic development remain largely unexplored. The current mechanistic paradigm for neuronal development is that axon differentiation of one neurite is accompanied by dendrite formation in other neurites, suggesting that dendrite development may represent a default pathway. This proposal offers an alternative hypothesis to dendrites by default and proposes a 'three-step' model of axon/dendrite establishment that is driven by opposite changes in the activity of the second messengers cAMP and cGMP. First, local elevation of cAMP-activity in a single undifferentiated neurite determines its axon fate17,19. Second, a negative signal propagating from the forming axon results in inhibition of axon formation in all other neurites of the same cell3,18-20. Last, localized cGMP-specific signaling events19,25,26 determine the dendrite fate of these neurites. In this proposal we identify cGMP-specific dendrite promoting events. We propose three specific aims to test our hypothesis both in vitro and in vivo. First, we directly determine cGMP-induced dendrite formation in cultured rodent sympathetic neurons44,45 in which dendrite differentiation is an inducible process. Next, we examine possible dendrite-specific determinants downstream and upstream of cGMP signaling. Last, we examine cGMP-dependent promotion of dendrite development in cortical progenitors in the developing embryonic brain in vivo. In these studies we employ a wide range of approaches that combine embryonic genetic manipulation using in utero electroporation, mouse genetics, biochemistry, material engineering, time-lapse microscopy and fluorescence resonance energy transfer (FRET) imaging. The cGMP- specific events that determine the dendritic fate, as identified in this study, are directly implicated in the neuropathology of autism spectrum disorders.
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2021 |
Shelly, Maya |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Controlling Spatially Restricted Intracellular Protein-Activity During Embryonic Neuronal Development Using Biomagnetic Otechnologies @ State University New York Stony Brook
Controlling spatially restricted intracellular protein-activity during embryonic neuronal development using biomagnetic nanotechnologies During mammalian embryonic development, neuronal cells polarize to create distinct cellular compartments of the axon and dendrite that inherently differ in the molecular composition of their cytoplasm, cytoskeleton, and plasma membrane. These differences underlie the unique morphology and function of these compartments and are responsible for directed information flow in the brain. Whereas axons transmit the chemical and electrical neuronal signals, the dendrites receive and integrate them. This polarized architecture arises from precisely regulated spatial segregation of specific intracellular proteins? activities to discrete subcellular regions of a single neuronal cell that respectively dictate the axonal vs. dendritic fate. Aberrations in the localization of these proteins? activity lead to defective neuron polarization and underlie severe human neurodevelopmental pathologies including intellectual and motor disabilities, epilepsy, and autism spectrum disorders. The ability to exert precise spatio-temporal control on intracellular protein-activity would permit directed regulation of neuronal polarization and may provide new approaches for the repair of the underlying neurodevelopmental pathologies. To date, no existing technologies, including leading molecular-genetics, light-controlled protein activation, or their combination using optogenetics, can allow sustained spatial restriction of intracellular protein-activity in the developing neuron. The main objective of this study is to address this fundamental challenge in neurobiology by developing biomagnetic-based nanotechnologies that will enable the spatial and temporal control of intracellular protein function in developing embryonic neurons. Specifically, we will develop biomagnetic-nanotechnologies to deliver and retain localized activity of the kinase LKB1, to dictate the process of axon formation in embryonic neurons in culture. Such a proposal demands a multi-disciplinary approach that integrates neurobiology, material engineering, and bioelectronics, for the development of protein based neuro-therapeutics. Many cellular events that dictate cell morphogenesis, metabolic state, or its unique physiological functions, in all cell types across evolutionarily distant species, are determined by highly localized and timed activity of specific intracellular proteins. The causative role of a critical intracellular protein in a particular cellular event or the ability to control that event can only be achieved by directed subcellular localization and retention of the protein or its activity. As current methodologies for spatio-temporal manipulation of protein function are inherently incapable of allowing the long-term spatial confinement of protein function, our studies will be applicable to many fundamental cellular events, as polarization and migration, and to the many intracellular proteins that control these cellular processes.
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2021 |
Shelly, Maya |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Molecular Mechanisms That Initiate Apical Dendrite Development During Embryonic Neuronal Development @ State University New York Stony Brook
Molecular mechanisms that initiate leading process and apical dendrite polarization during embryonic neuronal development An early and essential event in mammalian embryonic brain development is neuronal polarization, in which distinct axonal and dendritic compartments are formed. Axons and dendrites inherently differ in the molecular composition of their cytoplasm, cytoskeleton, and plasma membrane. These differences underlie the unique morphology and function of these compartments, and are responsible for directed information flow in the brain. Aberrations in neuron polarization lead to developmental neuropathologies, intellectual disability, epilepsy, autism spectrum disorders, and neuropsychiatric pathologies. Bipolar polarity establishment in postmitotic neocortical and hippocampal CA1 pyramidal neuron progenitors marks polarization of the axon and the apical dendrite. The apical dendrite will develop from the leading process of the bipolar neuron whereas the trailing process will become the axon. Specification of the axon has dominated studies on neuron polarization, yielding an understanding of the mechanisms underlying axonal identity, its specification and growth. Much effort has also been directed towards elucidation of the mechanisms that control later events in dendrite morphogenesis - growth, branching, and structural plasticity. However, the events leading to bipolar polarity and the subsequent development of the apical dendrite, have remained elusive. We propose that distinctly higher cyclic GMP (cGMP) generated via localized assembly of a cGMP production machinery at the leading edge of developing pyramidal neurons, promotes bipolar polarity, leading process formation, and apical dendrite development. Using state of the art lifetime decay FLIM-FRET cGMP measurements in mouse developing pyramidal neurons in acute slice, combined with cutting edge genetic manipulations, and localized, directed optogenetic manipulations of cGMP production, this study is designed to determine the spatio-temporal regulation of cGMP during polarity establishment and apical dendrite development, and to identify its mechanistic basis in developing pyramidal neurons in vivo. Our studies will provide important advance in the understanding of the early molecular events that take place during axon and apical dendrite establishment in principal excitatory neurons in the rodent brain, and will contribute to the identification of molecular targets and development of therapeutics for developmental neuropathologies resulting from abnormal axon and dendrite development.
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