Characterization and Expression Analysis of Stathmin Family Genes during Embryogenesis in Zebrafish, Danio rerio

Abstract

Stathmin family genes are known to mediate microtubule disassembly that makes them potential regulators for integrating diverse intracellular signaling pathways. To investigate the roles of stathmins in zebrafish (＂Danio rerio＂) development, we cloned and characterized four zebrafish stathmin genes, including ＂stathmin 1b＂ (＂stmn1b＂), ＂stathmin-like 2a＂ (＂stmn2a＂), ＂stathmin-like 3＂ (＂stmn3＂), and ＂stathmin-like 4＂ (＂stmn4＂). All four stathmins contains a conserved stathmin-like domain with consensus phosphorylation domains and share high homology with their vertebral counterparts. RT-PCR and whole-mount ＂in situ＂ hybridization analyses revealed that zebrafish ＂stathmins＂ are mainly expressed in the central nervous system with divergent temporal and spatial expressions. This suggests roles of stathmins in neuronal regulation during development in zebrafish. By knocking down ＂stmn2a＂ we observed smaller brain, enlarge brain ventricle, brain edema and narrowed midbrain and hindbrain boundary. We also confirmed the observed phenotypes by using whole-mount ISH against ＂islet1＂ and found that ＂islet1＂ expression was reduced in ＂stmn2a＂ MO-injected embryos. In addition, these brain defects were specifically due to the loss of ＂stmn2a＂ because they could not be induced by a mis-match ＂stmn2a＂ MO and could be rescued by co-injecting ＂stmn2a＂ mRNA. Collectively, these results suggest a pivotal role of ＂stmn2a＂ in zebrafish brain development.