2013 — 2018 |
Philippidou, Polyxeni |
K99Activity Code Description: To support the initial phase of a Career/Research Transition award program that provides 1-2 years of mentored support for highly motivated, advanced postdoctoral research scientists. R00Activity Code Description: To support the second phase of a Career/Research Transition award program that provides 1 -3 years of independent research support (R00) contingent on securing an independent research position. Award recipients will be expected to compete successfully for independent R01 support from the NIH during the R00 research transition award period. |
Hox Genes in the Development of Respiratory Circuits @ New York University School of Medicine
7. Project summary/ Abstract Breathing is a vital motor behavior that relies on diaphragm muscle contractions in mammals. The frequency and amplitude of breathing movements is controlled by neural networks residing in the brainstem and spinal cord. Degeneration of these networks leads to respiratory disorders, such as central sleep apneas, and, eventually, respiratory failure. My long term goal is to uncover the basic principles underlying respiratory circuit assembly so that we can begin to consider alternative treatment methods for respiratory dysfunction. A conundrum in the study of respiratory neural networks is that while significant progress has been made in defining the rhythmogenic circuits in the brain stem, the developmental origins, molecular identity and connectivity of spinal cord respiratory neurons remain unknown. Overall, the proposed research aims to define the genetic and molecular pathways that underlie spinal respiratory network assembly. We have recently demonstrated that the development of phrenic motor column (PMC) neurons in the cervical spinal cord, which innervate the diaphragm, requires the sustained activity of Hox5 genes. Mice lacking Hox5 genes in motor neurons (MNs) die of respiratory failure at birth and exhibit defects in multiple aspects of PMC identity, including clustering, axon guidance and diaphragm innervation. During the mentored part of this award, the role of Hox5 genes in PMC MNs will be further explored. Differential gene expression analysis will be carried out in order to identify genes acting downstream of Hox5 proteins to regulate distinct aspects of PMC development (Aim 1). Additionally, transsynaptic virus-based tracing approaches will be implored to examine how Hox5 removal from MNs affects the establishment of premotor inputs to the PMC (Aim 2). During the independent phase of the award, the role of Hox genes and their downstream targets in spinal cord respiratory interneuron development and connectivity will be examined (Aim 3). Addressing this question will rely heavily on genetic approaches, transsynaptic circuit labeling techniques and physiological respiratory assays, in which expertise will be acquired during the K99 phase. The mentored part of the research will be performed at the Dasen and Fishell labs at NYU Medical Center, an outstanding research environment that will provide all the equipment and facilities required for the proposed experiments. In addition, Dr. Kinkead at Laval University will act as a consultant and will provide training in the technique of plethysmography. I have assembled a committee who will oversee my progress and provide technical and intellectual input during the mentored part of the award. My previous experience in molecular neuroscience, in combination with a rigorous training plan, will ensure the successful completion of the proposed research aims, while the career development activities during the K99 phase of the award will facilitate a smooth transition to an independent position.
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0.943 |
2020 — 2021 |
Philippidou, Polyxeni |
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. |
'Genetic Control of Phrenic Motor Neuron Development and Maintece' @ Case Western Reserve University
Breathing is the most fundamental motor behavior for terrestrial vertebrates. The frequency and amplitude of breathing movements are controlled by neural networks residing in the brainstem and spinal cord. In mammals, contraction of the diaphragm muscle is essential for driving airflow into the lungs during inspiration. Despite the complexity of the neural networks that regulate respiratory rhythms, diaphragm contraction is controlled by a single motor input, the activity of motor neurons (MNs) within the Phrenic Motor Column (PMC) in the cervical spinal cord. Loss of PMC neurons is the primary cause of death in degenerative MN diseases such as amyotrophic lateral sclerosis (ALS) and spinal cord injuries. Despite their essential role, the molecular determinants of PMC neuron identity are largely unknown. We have found that the development of PMC neurons requires the sustained activity of Hox5 transcription factors. Mice lacking Hox5 genes in MNs die of respiratory failure at birth and exhibit defects in multiple aspects of PMC identity, including cell body position, axon guidance and diaphragm innervation. In this proposal we will investigate the function of Hox5 genes in determining and maintaining phrenic MN identity. In Aim 1 we will determine temporally distinct functions of Hox5 proteins in phrenic MNs and how phrenic MN identity is maintained throughout lifetime. In Aim 2 we will define how Hox5 genes control phrenic MN specification at the transcriptional level. In Aim 3 we will identify direct Hox5 effectors and dissect their regulatory mechanisms. We have developed an integrative methodology encompassing genetic models, high-throughput sequencing, electrophysiology and behavioral assays, such as plethysmography, to address these questions in vivo. The overarching goal of this proposal is to uncover the basic principles underlying phrenic MN specification and maintenance so that we can begin to consider alternative treatment methods for respiratory dysfunction.
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0.945 |