TY - JOUR
T1 - A delayed role for nitric oxide-sensitive guanylate cyclases in a migratory population of embryonic neurons
AU - Wright, Jay
AU - Schwinof, Kristine M.
AU - Snyder, Mark A.
AU - Copenhaver, Philip F.
N1 - Funding Information:
We thank Dr. James Truman, who originally observed NO-sensitive sGC activity within the EP cells and led us to perform this study. We also thank Drs. David Morton, Alan Nighorn, and Sharon Hesterlee for providing us with cDNA clones of Manduca sGCα1 and sGCβ1, and for their numerous helpful suggestions. Drs. H. W. M. Steinbusch and J. De Vente kindly provided us with the anti-cGMP antiserum, and Dr. Hugo Bellen generously supplied the anti-synaptotagmin antiserum used in this report. We are grateful for the expertise of Drs. Angela M. Horgan and Anda Cornea who performed the confocal microscopy shown in Fig. 9. We thank Drs. Gary Ciment, David Morton, and William Wolfgang for critical readings of the manuscript. This work was supported by NIH Grants NS35369 and NS34439.
PY - 1998/12/1
Y1 - 1998/12/1
N2 - Neuronal differentiation requires a coordinated intracellular response to diverse extracellular stimuli, but the role of specific signaling mechanisms in regulating this process is still poorly understood. Soluble guanylate cyclases (sGCs), which can be stimulated by diffusible free radical gasses such as nitric oxide (NO) and carbon monoxide (CO) to produce the intracellular messenger cGMP, have recently been found to be expressed within a variety of embryonic neurons and implicated in the control of both neuronal motility and differentiation. Using the enteric nervous system (ENS) of the moth, Manduca sexta, we examined the role of NO and NO-sensitive sGCs during the migration and differentiation of an identified set of migratory neurons (the EP cells). Shortly after the onset of their migration, a subset of EP cells began to express NO-sensitive sGC activity (visualized with an anti- cGMP antiserum). Unlike many neurons in the central nervous system, the expression of sGC activity in the EP cells was not transient but persisted throughout subsequent periods of axon elongation and terminal branch formation on the gut musculature. In contrast, nitric oxide synthase activity (visualized using NADPH-diaphorase histochemistry) was undetectable in the vicinity of the EP cells until the period of synapse formation. Manipulations designed to alter sGC and NOS activity in an in vivo embryonic culture preparation had no discernible effect on either the migration or axonal outgrowth of the EP cells. In contrast, inhibition of both of these enzymes resulted in a significant reduction in terminal synaptic branch formation within the postmigratory neurons. These results indicate that while NO- sensitive sGC activity is expressed precociously within the EP cells during their initial migratory dispersal, a role for this signaling pathway can only be demonstrated well after migration is complete, coincident with the formation of mature synaptic connections.
AB - Neuronal differentiation requires a coordinated intracellular response to diverse extracellular stimuli, but the role of specific signaling mechanisms in regulating this process is still poorly understood. Soluble guanylate cyclases (sGCs), which can be stimulated by diffusible free radical gasses such as nitric oxide (NO) and carbon monoxide (CO) to produce the intracellular messenger cGMP, have recently been found to be expressed within a variety of embryonic neurons and implicated in the control of both neuronal motility and differentiation. Using the enteric nervous system (ENS) of the moth, Manduca sexta, we examined the role of NO and NO-sensitive sGCs during the migration and differentiation of an identified set of migratory neurons (the EP cells). Shortly after the onset of their migration, a subset of EP cells began to express NO-sensitive sGC activity (visualized with an anti- cGMP antiserum). Unlike many neurons in the central nervous system, the expression of sGC activity in the EP cells was not transient but persisted throughout subsequent periods of axon elongation and terminal branch formation on the gut musculature. In contrast, nitric oxide synthase activity (visualized using NADPH-diaphorase histochemistry) was undetectable in the vicinity of the EP cells until the period of synapse formation. Manipulations designed to alter sGC and NOS activity in an in vivo embryonic culture preparation had no discernible effect on either the migration or axonal outgrowth of the EP cells. In contrast, inhibition of both of these enzymes resulted in a significant reduction in terminal synaptic branch formation within the postmigratory neurons. These results indicate that while NO- sensitive sGC activity is expressed precociously within the EP cells during their initial migratory dispersal, a role for this signaling pathway can only be demonstrated well after migration is complete, coincident with the formation of mature synaptic connections.
KW - Guanylate cyclase
KW - Manduca sexta
KW - Neuronal migration
KW - Nitric oxide
KW - Synaptogenesis
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U2 - 10.1006/dbio.1998.9066
DO - 10.1006/dbio.1998.9066
M3 - Article
C2 - 9851840
AN - SCOPUS:0032373229
SN - 0012-1606
VL - 204
SP - 15
EP - 33
JO - Developmental Biology
JF - Developmental Biology
IS - 1
ER -