The Dictyostelium MAP kinase ERK2 regulates multiple, independent developmental pathways

Area of Science:

• Cellular and Molecular Biology
• Developmental Biology
• Biochemistry

Background:

• Mitogen-activated protein kinase ERK2 (Extracellular signal-regulated kinase 2) is known to be essential for cell aggregation in Dictyostelium.
• erk2 null cells cannot relay cAMP chemotactic signals due to a lack of adenylyl cyclase stimulation.

Purpose of the Study:

• To investigate the role of ERK2 in controlling gene expression and morphogenesis during the multicellular stages of Dictyostelium development.
• To elucidate the distinct functions of ERK2 in aggregation and later developmental processes.

Main Methods:

• Utilized a temperature-sensitive ERK2 mutant in Dictyostelium discoideum.
• Employed suspension assays to analyze gene expression.
• Constructed chimeric organisms to study spatial patterning.
• Performed temperature shift experiments to assess developmental requirements.

Main Results:

• ERK2 is not essential for aggregation-stage cAMP-induced gene expression or postaggregative gene expression.
• Prespore gene SP60 induction is abolished, and prestalk gene ecmA induction is reduced in erk2 mutants.
• ERK2 is essential for proper morphogenesis and the induction/maintenance of prespore gene expression during multicellular development.
• ERK2-dependent cell-type differentiation is independent of its role in adenylyl cyclase activation.

Conclusions:

• ERK2 plays distinct roles at independent stages of Dictyostelium development.
• During aggregation, ERK2 is required for adenylyl cyclase activation.
• During multicellular development, ERK2 is essential for morphogenesis and cell-type-specific gene expression.