1. A method of increasing the expression level of survival of motor neuron 1(SMN1) in a subject suffered from a spinal muscular atrophy (SMA), comprising administering to the subject an effective amount of ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) inhibitor and a pharmaceutically acceptable carrier; wherein the expression level of SMN1is up-regulated when the UCHL1 inhibitor decreases expression level of UCHL1.