A Study About The Regulatory Role Of IGF-1 On The Expression Of Muscle-specific Histone Methyltransferase SMYD1

IGF-1, insulin-like growth factor 1, plays an essential role in heart and skeletal muscle development. SMYD1, a heart and muscle-specific expressed gene, has been demonstrated to be a regulator of cardiomyocyte differentiation. However, it is not fully understood that how upstream signaling regulates SMYD1 expression. The research about the relation of IGF-1 and SMYDl will helpful to the study of the function of SMYD1 in muscle development and the study of related diseases. In this article, we try to demonstrate how IGF-1 regulates the expression of SMYD1. With RT-PCR analysis, the mRNA expression level of Smydl gene was upregulated in C2C12 cells during myogenic differentiation. The protein level of SMYD1 was upregulated as well as SRF, when C2C12 cells were treated with IGF-1 at different time point. In order to determine the IGF-1 response elements in SMYD1 promoter, we constructed a serial of different length of SMYD1 gene promoter luciferase reporter vector. By luciferase experiment, we discovered that the response element of IGF-1 in SMYD1 gene promoter were located at-620--110 bp. Next, using EMSA experiment, we found that SRF could bind to CArG site in SMYD1 promoter, while IGF-1 could regulate SRF binding in Smydl promoter. Then, using of luciferase experiments, we showed that the CArG element involved the regulation of IGF-1 on Smydl in transcriptional level partly. These findings suggested that IGF-1 could increase SMYD1 expression in transcription level in C2C12 cells.