Spinal cord injury and regeneration related gene No 10 (SCIRR10) was first identified as an EST in our efforts of seeking genes responsive to spinal cord neuron injuries.High levels of SCIRR10 mRNA expression were detected in adult CNS and several other organs.In injured spinal cord, the level of SCIRR10 expression was temporally elevated.A His-tagged-SCIRR10 affinity column was able to capture thyrotropin releasing hormone receptor 2 (TRHR2) from spinal cord lysates, suggesting that SCIRR10 interacted with TRHR2.The interaction between SCIRR10 and TRHR2 was further confirmed by the co-localization of a GFP-SCIRR10 fusion protein with RFP-TRHR2 fusion protein expressed on COS7 cells.In PC12 cells, recombinant SCIRR10 and conditional medium containing SCIRR10 induced activation of the phospholipase C and MAPK pathways, the major signal transduction pathways shared by TRHR2.Recombinant SCIRR10 protein and conditional medium containing SCIRR10 also enhanced the sprouting and growth of neurites from cultured embryonic rat cortex tissues.This biological function to promote neurite growth could be interdicted with pertussis toxin.Our data demonstrated that SCIRR10 is a novel neurotrophic factor that may play an important role in the regeneration of CNS injury.