Cell Migration - Mutants

Mutants

Insight into how complex biological processes work can often be gleaned from a study of mutations. In the case of the intracellular mechanisms underlying cell movement, this has been largely unsuccessful. Thus, although many mutants are known in Drosophila, which affect migratory processes, these tend to fall into two groups: transcription factors (such as slow border cells (slbo), which affects the migration of the border cells) or key regulator proteins (such as C-Jun N-terminal kinases (JNK), which controls dorsal closure). These, however, tell us little about how cells actually move.

Another major source of mutants is the haploid amoeba Dictyostelium. Many single-copy genes associated with cytoskeletal function have been deleted: These mutants usually have only a weak phenotype, suggesting either that these genes are not required for locomotion, or that there are multiple mechanisms by which cells can move. However, temperature-sensitive mutants in the genes for N-ethylmaleimide sensitive fusion protein (NSF) and Sec1 rapidly block cell migration indicating that the NSF protein and Sec1p are both required for some aspects of cell movement. NSF is known to function in intracellular membrane fusion; Sec1p in yeast is required for polarised exocytosis.