title: The receptor guanylyl cyclase Npr2 is essential for sensory axon bifurcation within the spinal cord.
abstract: Sensory axonal projections into the spinal cord display a highly stereotyped pattern of T- or Y-shaped axon bifurcation at the dorsal root entry zone (DREZ). Here, we provide evidence that embryonic mice with an inactive receptor guanylyl cyclase Npr2 or deficient for cyclic guanosine monophosphate-dependent protein kinase I (cGKI) lack the bifurcation of sensory axons at the DREZ, i.e., the ingrowing axon either turns rostrally or caudally. This bifurcation error is maintained to mature stages. In contrast, interstitial branching of collaterals from primary stem axons remains unaffected, indicating that bifurcation and interstitial branching are processes regulated by a distinct molecular mechanism. At a functional level, the distorted axonal branching at the DREZ is accompanied by reduced synaptic input, as revealed by patch clamp recordings of neurons in the superficial layers of the spinal cord. Hence, our data demonstrate that Npr2 and cGKI are essential constituents of the signaling pathway underlying axonal bifurcation at the DREZ and neuronal connectivity in the dorsal spinal cord.
authors.affiliation: Max Delbrück Centrum für Molekulare Medizin, Berlin D-13092, Germany.
authors.forename: Hannes
authors.initials: H
authors.lastname: Schmidt
authors.forename: Agne
authors.initials: A
authors.lastname: Stonkute
authors.forename: René
authors.initials: R
authors.lastname: Jüttner
authors.forename: Susanne
authors.initials: S
authors.lastname: Schäffer
authors.forename: Jens
authors.initials: J
authors.lastname: Buttgereit
authors.forename: Robert
authors.initials: R
authors.lastname: Feil
authors.forename: Franz
authors.initials: F
authors.lastname: Hofmann
authors.forename: Fritz G
authors.initials: FG
authors.lastname: Rathjen
mesh_terms: D000818:Animals; D001369:Axons / Q000201:enzymology*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000172:deficiency / Q000378:metabolism; D004594:Electrophysiology; D004789:Enzyme Activation; D005727:Ganglia, Spinal / Q000166:cytology / Q000196:embryology / Q000201:enzymology; D006162:Guanylate Cyclase / Q000378:metabolism*; D051379:Mice; D008817:Mice, Mutant Strains; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009619:Nociceptors / Q000378:metabolism; D011434:Proprioception; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology / Q000201:enzymology*; D013126:Spinal Nerve Roots / Q000166:cytology / Q000201:enzymology; D000099242:Atrial Natriuretic Factor Receptor B
chemical_list: D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; D000099242:Atrial Natriuretic Factor Receptor B