Dataset Information

Complementary expression of EphA7 and SCO-spondin during posterior commissure development.

ABSTRACT: Bilaterally symmetric organisms need to exchange information between the two sides of their bodies in order to integrate sensory inputs and coordinate motor control. This exchange occurs through commissures formed by neurons that project axons across the midline to the contralateral side of the central nervous system. The posterior commissure is the first transversal axonal tract of the embryonic vertebrate brain. It is located in the dorsal portion of the prosomere 1, at the caudal diencephalon. The axons of the posterior commissure principally come from neurons of ventrolateral and dorsolateral pretectal nuclei (parvocellular and magnocellular nucleus of the posterior commissure, respectively) that extend their axons toward the dorsal region. The trajectory of these axons can be divided into the following three stages: (1) dorsal axon extension towards the lateral roof plate; (2) fasciculation in the lateral roof plate; and (3) midline decision of turning to the ipsilateral side or continuing to the opposite side. The mechanisms and molecules that guide the axons during these steps are unknown. In the present work, immunohistochemical and in situ hybridization analyses were performed, with results suggesting the participation of EphA7 in guiding axons from the ventral to the dorsal region of the prosomere 1 through the generation of an axonal corridor limited by repulsive EphA7 walls. At the lateral roof plate, the axons became fasciculated in presence of SCO-spondin until reaching the midline. Finally, EphA7 expression was observed in the diencephalic midline roof plate, specifically in the region where some axons turn to the ipsilateral side, suggesting its participation in this decision. In summary, the present work proposes a mechanism of posterior commissure formation orchestrated by the complementary expression of the axon guidance cues SCO-spondin and EphA7.

SUBMITTER: Stanic K

PROVIDER: S-EPMC4068196 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Complementary expression of EphA7 and SCO-spondin during posterior commissure development.

Stanic Karen K Vera América A González Melissa M Recabal Antonia A Astuya Allison A Torrejón Marcela M Montecinos Hernán H Caprile Teresa T

Frontiers in neuroanatomy 20140624

Bilaterally symmetric organisms need to exchange information between the two sides of their bodies in order to integrate sensory inputs and coordinate motor control. This exchange occurs through commissures formed by neurons that project axons across the midline to the contralateral side of the central nervous system. The posterior commissure is the first transversal axonal tract of the embryonic vertebrate brain. It is located in the dorsal portion of the prosomere 1, at the caudal diencephalon ...[more]

PMID: 25009468

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Project description:Cerebrospinal fluid is a clear fluid that occupies the ventricular and subarachnoid spaces within and around the brain and spinal cord. Cerebrospinal fluid is a dynamic signaling milieu that transports nutrients, waste materials and neuroactive substances that are crucial for the development, homeostasis and functionality of the central nervous system. The mechanisms that enable cerebrospinal fluid to simultaneously exert these homeostatic/dynamic functions are not fully understood. SCO-spondin is a large glycoprotein secreted since the early stages of development into the cerebrospinal fluid. Its domain architecture resembles a combination of a matricellular protein and the ligand-binding region of LDL receptor family. The matricellular proteins are a group of extracellular proteins with the capacity to interact with different molecules, such as growth factors, cytokines and cellular receptors; enabling the integration of information to modulate various physiological and pathological processes. In the same way, the LDL receptor family interacts with many ligands, including β-amyloid peptide and different growth factors. The domains similarity suggests that SCO-spondin is a matricellular protein enabled to bind, modulate, and transport different cerebrospinal fluid molecules. SCO-spondin can be found soluble or polymerized into a dynamic threadlike structure called the Reissner fiber, which extends from the diencephalon to the caudal tip of the spinal cord. Reissner fiber continuously moves caudally as new SCO-spondin molecules are added at the cephalic end and are disaggregated at the caudal end. This movement, like a conveyor belt, allows the transport of the bound molecules, thereby increasing their lifespan and action radius. The binding of SCO-spondin to some relevant molecules has already been reported; however, in this review we suggest more than 30 possible binding partners, including peptide β-amyloid and several growth factors. This new perspective characterizes SCO-spondin as a regulator of cerebrospinal fluid activity, explaining its high evolutionary conservation, its apparent multifunctionality, and the lethality or severe malformations, such as hydrocephalus and curved body axis, of knockout embryos. Understanding the regulation and identifying binding partners of SCO-spondin are crucial for better comprehension of cerebrospinal fluid physiology.

Dataset Information

Complementary expression of EphA7 and SCO-spondin during posterior commissure development.

Publications

Complementary expression of EphA7 and SCO-spondin during posterior commissure development.

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