Project description:Adult zebrafish have the ability to recover from spinal cord injury and exhibit re-growth of descending axons from the brainstem to the spinal cord. We performed gene expression analysis using microarray to find damage-induced genes after spinal cord injury, which shows that Sox11b mRNA is up-regulated at 11 days after injury. However, the functional relevance of Sox11b for regeneration is not known. Here, we report that the up-regulation of Sox11b mRNA after spinal cord injury is mainly localized in ependymal cells lining the central canal and in newly differentiating neuronal precursors or immature neurons. Using an in vivo morpholino-based gene knockout approach, we demonstrate that Sox11b is essential for locomotor recovery after spinal cord injury. In the injured spinal cord, expression of the neural stem cell associated gene, Nestin, and the proneural gene Ascl1a (Mash1a), which are involved in the self-renewal and cell fate specification of endogenous neural stem cells, respectively, is regulated by Sox11b. Our data indicate that Sox11b promotes neuronal determination of endogenous stem cells and regenerative neurogenesis after spinal cord injury in the adult zebrafish. Enhancing Sox11b expression to promote proliferation and neurogenic determination of endogenous neural stem cells after injury may be a promising strategy in restorative therapy after spinal cord injury in mammals. Spinal cord injury or control sham injury was performed on adult zebrafish. After 4, 12, or 264 hrs, a 5 mm segment of spinal cord was dissected and processed (as a pool from 5 animals) in three replicate groups for each time point and treatment.
Project description:Adult zebrafish have the ability to recover from spinal cord injury and exhibit re-growth of descending axons from the brainstem to the spinal cord. We performed gene expression analysis using microarray to find damage-induced genes after spinal cord injury, which shows that Sox11b mRNA is up-regulated at 11 days after injury. However, the functional relevance of Sox11b for regeneration is not known. Here, we report that the up-regulation of Sox11b mRNA after spinal cord injury is mainly localized in ependymal cells lining the central canal and in newly differentiating neuronal precursors or immature neurons. Using an in vivo morpholino-based gene knockout approach, we demonstrate that Sox11b is essential for locomotor recovery after spinal cord injury. In the injured spinal cord, expression of the neural stem cell associated gene, Nestin, and the proneural gene Ascl1a (Mash1a), which are involved in the self-renewal and cell fate specification of endogenous neural stem cells, respectively, is regulated by Sox11b. Our data indicate that Sox11b promotes neuronal determination of endogenous stem cells and regenerative neurogenesis after spinal cord injury in the adult zebrafish. Enhancing Sox11b expression to promote proliferation and neurogenic determination of endogenous neural stem cells after injury may be a promising strategy in restorative therapy after spinal cord injury in mammals.
Project description:Among the vertebrates, teleost and urodele amphibians are capable of regenerating their central nervous system. We have used crush injury method on zebrafish spinal cord, which is a common mammalian mode of injury in spinal cord. To identify the molecular mechanisms of the underlying cellular events during regeneration of zebrafish spinal cord, we have employed high density oligonucleotide microarrays and profiled the temporal transcriptome dynamics during the entire phenomenon. A total of 3842 genes expressed differentially with significant fold changes during spinal cord regeneration. Cluster analysis revealed event specific dynamic expression of genes related to inflammation, cell death, cell migration, cell proliferation, neurogenesis, neural patterning and axonal regrowth. We have also validated the expression pattern of 14 genes (which include inflammatory regulators, cell cycle regulators, pattern forming genes and signaling molecules) by different methodologies. Spatio-temporal analysis of STAT3 expression suggested its possible function in controlling inflammation and cell proliferation. Genes involved in the proliferating neural progenitors and their dorso-ventral patterning (sox2 and dbx2) are differentially expressed. Injury induced cell proliferation is controlled by many cell cycle regulators and some of them also show their common expression in other regenerating systems like fin, heart and retina. We also reported unusual expression pattern of certain pathway genes like one carbon folate metabolism and N-glycan biosynthesis which have not been reported during regeneration of spinal cord. Genes like stat3, socs3, atf3, mmp9 and sox11, which are known to control peripheral nervous system (PNS) regeneration in mammals, are also upregulated in zebrafish spinal cord injury (SCI) thus creating PNS like environment after injury. Our study provides a comprehensive genetic blue print of diverse cellular response(s) during regeneration of zebrafish spinal cord that could be used to induce successful regeneration in mammals. The spinal cord has been injured by crushing dorso-ventrally for 1 sec with a number 5 Dumont forceps at the level of 15th/16th vertebrae. Later the wound were sealed by placing a suture. Both spinal cord injured and sham operated fish were allowed to regenerate and the progress of regeneration was observed after 1, 3, 7, 10 and 15 days of injury. Zebrafishes were anesthetized deeply for 5 minutes in 0.1% tricaine (MS222; Sigma, USA) and approximately 1mm length of spinal cord both rostrally and caudally from injury epicenter were dissected out from 50-60 fishes in each batch and pooled for RNA extraction.
Project description:The study was designed to identify genes regulated after spinal transection that might contribute to regenerative growth of neurons projecting from the NMLF in Zebrafish. Zebrafish were injured by surgical transection of the spinal cord at 1 mm caudal to the brainstem-spinal cord junction (Injured). Animals receiving sham surgery (identical surgical procedures without transection) served as control (Control). The nucleus of the medial longitudinal fascicle (NMLF) was laser capture microdissected from approximately 30 frozen sections. RNA was prepared, amplified, and run on Affymetrix Zebrafish arrays. Zebrafish were used because they recover swimming function after spinal transection in about 6 weeks. The NMLF has been identified as a prominent group of neurons that descend through the site of injury in the spinal cord and that regenerate after injury. Times were selected to distinguish early events from those in the timeframe of regenerative growth.