Characterization of stmn1a and genetic effects of a 22-bp Indel in its promoter region of bighead carp Hypophthalmichthys nobilis

Abstract

Stathmin 1 (stmn1) gene, which is involved in the control of cell cycle progression, cell proliferation, differentiation and motility, is a crucial relay in the signal transduction of multiple signaling pathways. Reports on the function of stmn1 in fish are scarce. In this study, the characterization and function of stmn1a gene were explored in an important food fish, namely bighead carp (Hypophthalmichthys nobilis). The bighead carp stmn1a (Hynstmn1a) genomic sequence, which has 2995 bp with an ORF of 447 bp, is evolutionarily conserved in teleost fish. The highest level of expression of Hynstmn1a is in the un-fertilized eggs and spleen of adult bighead carp. The overexpression of Hynstmn1a facilitates cell cycle progression and suppresses apoptosis in EPC cells. In an siRNA assay, disruption of stmn1a in EPC cells resulted in the inhibition of cell cycle progression and promotion of apoptosis. Analysis of promoter activity indicated that an upstream transcription factor (foxo4) regulates Hynstmn1a. Zebrafish mutants with stmn1a knockout by CRISPR/Cas9 exhibited a significant retardation of body length (p ​< ​0.05). There was no significant difference in body weight between stmn1a-mutant zebrafish and wild-type (p ​= ​0.053). A 22-bp Indel in the promoter region of Hynstmn1a with an observed heterozygosity (Ho) of 0.136 in a bighead carp population (n ​= ​191). The polymorphism of this 22-bp Indel genotype is significantly associated with body length (BL), head length (HL) (p ​< ​0.05), body weight (BW), head height (HH), and head width (HW) (p ​< ​0.01), showing its genetic effects on growth promotion. This study sheds light on the function of stmn1a in fish and demonstrates the potential of the 22-bp Indel of Hynstmn1a as a gene marker when selecting breeding individuals for faster growth and a bigger head of bighead carp in aquaculture.