In JoVE (1)
Other Publications (8)
- Developmental Dynamics : an Official Publication of the American Association of Anatomists
- Nature Neuroscience
- Neuron Glia Biology
- Purinergic Signalling
- The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
- Brain Research
- The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
Articles by Sarah Kucenas in JoVE
Motor Nerve Transection and Time-lapse Imaging of Glial Cell Behaviors in Live Zebrafish Gwendolyn M. Lewis, Sarah Kucenas 1Department of Biology, University of Virginia Although the peripheral nervous system (PNS) is capable of significant repair after injury, little is known about the cellular and molecular mechanisms that govern this phenomenon. Using live, transgenic zebrafish and a reproducible nerve transection assay, we can study dynamic glial cell behaviors during nerve degeneration and regeneration.
Other articles by Sarah Kucenas on PubMed
Molecular Characterization and Embryonic Expression of the Family of N-methyl-D-aspartate Receptor Subunit Genes in the Zebrafish Developmental Dynamics : an Official Publication of the American Association of Anatomists. Nov, 2005 | Pubmed ID: 16123982 We present the cloning of 10 N-methyl-D-aspartate (NMDA) receptor subunits from the zebrafish. These subunits fall into five subtypes, each containing two paralogous genes. Thus, we report two NMDAR1 genes (NR1.1 and NR1.2), and eight NMDAR2 genes, designated NR2A.1 and NR2A.2, NR2B.1 and NR2B.2, NR2C.1 and NR2C.2, and NR2D.1 and NR2D.2. The predicted sequences of the NR1 paralogs display 90% identity to the human protein. The NR2 subunits show less identity, differing most at the N- and C-termini. The NR1 genes are both expressed embryonically, although in a nonidentical manner. NR1.1 is found in brain, retina, and spinal cord at 24 hours postfertilization (hpf). NR1.2 is expressed in the brain at 48 hpf but not in the spinal cord. NR2 developmental gene expression varies: both paralogs of the NR2A are expressed at 48 hpf in the retina, only one paralog of the NR2B is expressed at low levels in the heart at 48 hpf. Neither of the NR2C is expressed embryonically. Both paralogs of the NR2D are expressed: 2D.1 is in the forebrain, retina, and spinal cord at 24 hpf, whereas the 2D.2 is only found in the retina. Our findings demonstrate that the zebrafish can serve as a useful model system for investigating the role of NMDA receptors in the development of the nervous system.
CNS-derived Glia Ensheath Peripheral Nerves and Mediate Motor Root Development Nature Neuroscience. Feb, 2008 | Pubmed ID: 18176560 Motor function requires that motor axons extend from the spinal cord at regular intervals and that they are myelinated by Schwann cells. Little attention has been given to another cellular structure, the perineurium, which ensheaths the motor nerve, forming a flexible, protective barrier. Consequently, the origin of perineurial cells and their roles in motor nerve formation are poorly understood. Using time-lapse imaging in zebrafish, we show that perineurial cells are born in the CNS, arising as ventral spinal-cord glia before migrating into the periphery. In embryos lacking perineurial glia, motor neurons inappropriately migrated outside of the spinal cord and had aberrant axonal projections, indicating that perineurial glia carry out barrier and guidance functions at motor axon exit points. Additionally, reciprocal signaling between perineurial glia and Schwann cells was necessary for motor nerve ensheathment by both cell types. These insights reveal a new class of CNS-born glia that critically contributes to motor nerve development.
Nkx2.2a Promotes Specification and Differentiation of a Myelinating Subset of Oligodendrocyte Lineage Cells in Zebrafish Neuron Glia Biology. May, 2008 | Pubmed ID: 19737431 During development, multipotent neural precursors give rise to oligodendrocyte progenitor cells (OPCs), which migrate and divide to produce additional OPCs. Near the end of embryogenesis and during postnatal stages, many OPCs stop dividing and differentiate as myelinating oligodendrocytes, whereas others persist as nonmyelinating cells. Investigations of oligodendrocyte development in mice indicated that the Nkx2.2 transcription factor both limits the number of OPCs that are formed and subsequently promotes their differentiation, raising the possibility that Nkx2.2 plays a key role in determining myelinating versus nonmyelinating fate. We used in vivo time-lapse imaging and loss-of-function experiments in zebrafish to further explore formation and differentiation of oligodendrocyte lineage cells. Our data show that newly specified OPCs are heterogeneous with respect to gene expression and fate. Whereas some OPCs express the nkx2.2a gene and differentiate as oligodendrocytes, others that do not express nkx2.2a mostly remain as nonmyelinating OPCs. Similarly to mouse, loss of nkx2.2a function results in excess OPCs and delayed oligodendrocyte differentiation. Notably, excess OPCs are formed as a consequence of prolonged OPC production from neural precursor cells. We conclude that Nkx2.2 promotes timely specification and differentiation of myelinating oligodendrocyte lineage cells from species representing different vertebrate taxa.
Ectodermal P2X Receptor Function Plays a Pivotal Role in Craniofacial Development of the Zebrafish Purinergic Signalling. Sep, 2009 | Pubmed ID: 19529983 P2X receptors are non-selective cation channels operated by extracellular ATP. Currently, little is known concerning the functions of these receptors during development. Previous work from our lab has shown that zebrafish have two paralogs of the mammalian P2X3 receptor subunit. One paralog, p2rx3.1, is expressed in subpopulations of neural and ectodermal cells in the embryonic head. To investigate the role of this subunit in early cranial development, we utilized morpholino oligonucleotides to disrupt its translation. Loss of this subunit resulted in craniofacial defects that included malformation of the pharyngeal skeleton. During formation of these structures, there was a marked increase in cell death within the branchial arches. In addition, the epibranchial (facial, glossopharyngeal, and vagal) cranial sensory ganglia and their circuits were perturbed. These data suggest that p2rx3.1 function in ectodermal cells is involved in purinergic signaling essential for proper craniofacial development and sensory circuit formation in the embryonic and larval zebrafish.
A Selective Glial Barrier at Motor Axon Exit Points Prevents Oligodendrocyte Migration from the Spinal Cord The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Dec, 2009 | Pubmed ID: 19955371 Nerve roots have specialized transition zones that permit axon extension but limit cell movement between the CNS and PNS. Boundary cap cells prevent motor neuron soma from following their axons into the periphery, thereby contributing to a selective barrier. Transition zones also restrict movement of glial cells. Consequently, axons that cross the CNS-PNS interface are insulated by central and peripheral myelin. The mechanisms that prevent the migratory progenitors of oligodendrocytes and Schwann cells, the myelinating cells of the CNS and PNS, respectively, from crossing transition zones are not known. Here, we show that interactions between myelinating glial cells prevent their movements across the interface. Using in vivo time-lapse imaging in zebrafish we found that, in the absence of Schwann cells, oligodendrocyte progenitors cross ventral root transition zones and myelinate motor axons. These studies reveal that distinct mechanisms regulate the movement of axons, neurons, and glial cells across the CNS-PNS interface.
Angiotensin II and CRF Receptors in the Central Nucleus of the Amygdala Mediate Hemodynamic Response Variability to Cocaine in Conscious Rats Brain Research. Jan, 2010 | Pubmed ID: 19879859 Stress or cocaine evokes either a large increase in systemic vascular resistance (SVR) or a smaller increase in SVR accompanied by an increase in cardiac output (designated vascular and mixed responders, respectively) in Sprague-Dawley rats. We hypothesized that the central nucleus of the amygdala (CeA) mediates this variability. Conscious, freely-moving rats, instrumented for measurement of arterial pressure and cardiac output and for drug delivery into the CeA, were given cocaine (5 mg/kg, iv, 4-6 times) and characterized as vascular (n=15) or mixed responders (n=10). Subsequently, we administered cocaine after bilateral microinjections (100 nl) of saline or selective agents in the CeA. Muscimol (80 pmol), a GABA(A) agonist, or losartan (43.4 pmol), an AT(1) receptor antagonist, attenuated the cocaine-induced increase in SVR in vascular responders, selectively, such that vascular responders were no longer different from mixed responders. The corticotropin releasing factor (CRF) antagonist, alpha-helical CRF(9-41) (15.7 pmol), abolished the difference between cardiac output and SVR in mixed and vascular responders. We conclude that greater increases in SVR observed in vascular responders are dependent on AT(1) receptor activation and, to a lesser extent on CRF receptors. Therefore, AT(1) and CRF receptors in the CeA contribute to hemodynamic response variability to intravenous cocaine.
Sox10 is Necessary for Oligodendrocyte Survival Following Axon Wrapping Glia. Jun, 2010 | Pubmed ID: 20229602 Cells of the oligodendrocyte lineage, which form the myelinating glia of the vertebrate central nervous system, undergo a stepwise developmental progression entailing specification from neuroepithelial precursors, proliferation, migration to expand and distribute the population, and differentiation to ensheath axons with myelin. Understanding the genetic mechanisms that regulate each of these steps during development is important, because this might lead to therapies to promote remyelination following neural injury or disease. Genetic studies in mice indicated that the Sox10 transcription factor is required during the differentiation stage to promote myelin gene expression. However, whether Sox10 also promotes other features of oligodendroctye differentiation remained unknown. In this study, we used time-lapse imaging to investigate the behavior and fates of oligodendrocyte lineage cells in zebrafish embryos and larvae that lacked Sox10 function. This revealed that the myelinating subset of oligodendrocyte progenitor cells (OPCs) migrates, divides, and wraps axons normally, but then dies. Nonmyelinating oligodendrocyte progenitors divided more frequently, maintaining a normal population size. New oligodendrocytes produced by these progenitors wrapped axons and survived, but did not express myelin genes at high levels. We conclude that, in addition to promoting myelin gene expression, Sox10 function is necessary for the survival of myelinating oligodedrocytes subsequent to axon wrapping but is not required for the survival of nonmyelinating OPCs.
Perineurial Glia Require Notch Signaling During Motor Nerve Development but Not Regeneration The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Mar, 2013 | Pubmed ID: 23467342 Motor nerves play the critical role of shunting information out of the CNS to targets in the periphery. Their formation requires the coordinated development of distinct cellular components, including motor axons and the Schwann cells and perineurial glia that ensheath them. During nervous system assembly, these glial cells must migrate long distances and terminally differentiate, ensuring the efficient propagation of action potentials. Although we know quite a bit about the mechanisms that control Schwann cell development during this process, nothing is known about the mechanisms that mediate the migration and differentiation of perineurial glia. Using in vivo imaging in zebrafish, we demonstrate that Notch signaling is required for both perineurial migration and differentiation during nerve formation, but not regeneration. Interestingly, loss of Notch signaling in perineurial cells also causes a failure of Schwann cell differentiation, demonstrating that Schwann cells require perineurial glia for aspects of their own development. These studies describe a novel mechanism that mediates multiple aspects of perineurial development and reveal the critical importance of perineurial glia for Schwann cell maturation and nerve formation.