Evolutionary Analysis and Expression of Teleost Thy-1

Microdomain-forming proteins and the role of the reggies/flotillins during axon regeneration in zebrafish

The two proteins reggie-1 and reggie-2 (flotillins) were identified in axon-regenerating neurons in the central nervous system and shown to be essential for neurite growth and regeneration in fish and mammals. Reggies/flotillins are microdomain scaffolding proteins sharing biochemical properties with lipid raft molecules, form clusters at the cytoplasmic face of the plasma membrane and interact with signaling molecules in a cell type specific manner. In this review, reggie microdomains, lipid rafts, related scaffolding proteins and caveolin-which, however, are responsible for their own microdomains and functions-are introduced. Moreover, the function of the reggies in axon growth is demonstrated: neurons fail to extend axons after reggie knockdown. Furthermore, our current concept of the molecular mechanism underlying reggie function is presented: the association of glycosyl-phophatidyl inositol (GPJ)-anchored surface proteins with reggie microdomains elicits signals which activate src tyrosine and mitogen-activated protein kinases, as well as small guanosine 5'-triphosphate-hydrolyzing enzymes. This leads to the mobilization of intracellular vesicles and to the recruitment of bulk membrane and specific cargo proteins, such as cadherin, to specific sites of the plasma membrane such as the growth cone of elongating axons. Thus, reggies regulate the targeted delivery of cargo-a process which is required for process extension and growth. This article is part of a Special Issue entitled Zebrafish Models of Neurological Diseases.

Immunoglobulin superfamily is conserved but evolved rapidly and is active in the silkworm, Bombyx mori

Immunoglobulin superfamily (IgSF) proteins are known for their abilities to specifically recognize and adhere to cells. In this paper, we predicted the presence of 133 IgSF proteins in the silkworm (Bombyx mori) genome. Comparison with similar proteins in other model organisms (Caenorhabditis elegans, Drosophila melanogaster, Anopheles gambiae, Apis mellifera and Homo sapiens) indicated that IgSF proteins are conserved but have rapidly evolved from worms to human beings. However, these proteins are well conserved amongst insects. Silkworm microarray-based expression data showed tissue expression of 57 IgSF genes and microbe-induced differential expression of 37 genes. Based on the expression data, we can conclude that the silkworm IgSF is active.