Wnt3a Ectopic Expression Interferes Axonal Projection and Motor Neuron Positioning During the Chicken Spinal Cord Development

Abstract

The formation of dorsal-ventral axis of the spinal cord is controlled largely by dorsal signals such as Wnts (which are members of the wingless + MMTV integrants, Int family), besides ventral signals such as sonic hedgehog (Shh). Wnt3a, one of the Wnt family members, is involved in multiple cellular functions, including self-renewal, proliferation, differentiation, and motility. Here, we aim to study the mechanism of the regulation of chicken spinal cord patterning by Wnt3a. In this study, Wnt3a was ectopically expressed in the spinal cord of developing chicken embryos by in ovo electroporation. The results of immunofluorescent staining revealed that Wnt3a ectopic expression caused the abnormality of commissural axonal projection and the formation of nerve fibers was interrupted. It is worth noting that neurons in the ventricular zone, especially motor neurons, could not migrate laterally after the Wnt3a overexpression, which led to the malformation of motor column. In addition, we found that neurons could not protrude axons outwardly after overexpression of Wnt3a in the spinal cord. It was also found that Wnt3a overexpression inhibited the outgrowth of processes in culturing SH-SY5Y cells. In conclusion, we proposed that Wnt3a regulates neuronal morphology, which subsequently disrupts axonal projection and motor neuron positioning during spinal cord development.

Electrospun decellularized extracellular matrix scaffolds promote the regeneration of injured neurons

“…This human immortalized cell line could be differentiated into mature functional neurons as described before. Due to their neuronal morphology and functionality, differentiated SH-SY5Y cells have been used as an in vitro model for spinal cord development and in neurite outgrowth studies [ 38 , 40 , [60] , [61] , [62] ]. The alignment of differentiated neurons on the dECM scaffolds was successfully achieved indicating that the fiber diameter and fiber density in the engineered scaffolds represented topographical cues suitable for alignment as reported in literature [ 54 , 63 ].…”

Origins of Neural Progenitor Cell-Derived Axons Projecting Caudally after Spinal Cord Injury

“…Lacking more specific directional guidance, the neurons most likely to extend axons caudally into the host spinal cord from the graft would be located at the most caudal levels of the graft, where they are most likely to randomly encounter the caudal host spinal cord. It is also possible that molecules diffusing from host to graft could preferentially stimulate axonal outgrowth from more caudally located neurons in the graft (Li et al., 2018, Naoki, 2017), although evidence to support this possibility after SCI in the adult is lacking at present.…”