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.

Keyword: Embryogenesis, gene expression, stathmin, zebrafish.