The molecular machinery of germ line specification.
Germ cells occupy a unique position in animal reproduction, development, and evolution. In sexually reproducing animals, only they can produce gametes and contribute genetically to subsequent generations. Nonetheless, germ line specification during embryogenesis is conceptually the same as the specification of any somatic cell type: germ cells must activate a specific gene regulatory network in order to differentiate and go through gametogenesis. While many genes with critical roles in the germ line have been characterized with respect to expression pattern and genetic interactions, it is the molecular interactions of the relevant gene products that are ultimately responsible for germ cell differentiation. This review summarizes the current state of knowledge on the molecular functions and biochemical connections between germ line gene products. We find that homologous genes often interact physically with the same conserved molecular partners across the metazoans. We also point out cases of nonhomologous genes from different species whose gene products play analogous biological roles in the germ line. We suggest a preliminary molecular definition of an ancestral "pluripotency module" that could have been modified during metazoan evolution to become specific to the germ line.
Ewen-Campen
Ben
B
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA.
Schwager
Evelyn E
EE
Extavour
Cassandra G M
CG
D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D019070:Cell Lineage; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005854:Germ Cells / Q000502:physiology*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D000074462:Positive Regulatory Domain I-Binding Factor 1; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D019485:Bone Morphogenetic Proteins; D029742:Caenorhabditis elegans Proteins; D026901:Membrane Transport Proteins; D009687:Nuclear Proteins; C513258:Prdm1 protein, mouse; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C100950:pie-1 protein, C elegans; D000074462:Positive Regulatory Domain I-Binding Factor 1; D053487:DEAD-box RNA Helicases