title: Making the connection - shared molecular machinery and evolutionary links underlie the formation and plasticity of occluding junctions and synapses.
abstract: The pleated septate junction (pSJ), an ancient structure for cell-cell contact in invertebrate epithelia, has protein components that are found in three more-recent junctional structures, the neuronal synapse, the paranodal region of the myelinated axon and the vertebrate epithelial tight junction. These more-recent structures appear to have evolved through alterations of the ancestral septate junction. During its formation in the developing animal, the pSJ exhibits plasticity, although the final structure is extremely robust. Similar to the immature pSJ, the synapse and tight junctions both exhibit plasticity, and we consider evidence that this plasticity comes at least in part from the interaction of members of the immunoglobulin cell adhesion molecule superfamily with highly regulated membrane-associated guanylate kinases. This plasticity regulation probably arose in order to modulate the ancestral pSJ and is maintained in the derived structures; we suggest that it would be beneficial when studying plasticity of one of these structures to consider the literature on the others. Finally, looking beyond the junctions, we highlight parallels between epithelial and synaptic membranes, which both show a polarized distribution of many of the same proteins - evidence that determinants of apicobasal polarity in epithelia also participate in patterning of the synapse.
authors.affiliation: Simon Fraser University, Department of Molecular Biology and Biochemistry, Burnaby, British Columbia V5A 1S6, Canada nharden@sfu.ca.
authors.forename: Nicholas
authors.identifier: 0000-0003-1319-7247
authors.initials: N
authors.lastname: Harden
authors.affiliation: Simon Fraser University, Department of Molecular Biology and Biochemistry, Burnaby, British Columbia V5A 1S6, Canada Simon Fraser University, Department of Biomedical Physiology and Kinesiology, Burnaby, British Columbia V5A 1S6, Canada.
authors.forename: Simon Ji Hau
authors.initials: SJ
authors.lastname: Wang
authors.affiliation: Simon Fraser University, Department of Biomedical Physiology and Kinesiology, Burnaby, British Columbia V5A 1S6, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Krieger
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism*; D008566:Membranes / Q000378:metabolism; D008954:Models, Biological; D013569:Synapses / Q000378:metabolism*
keywords: Epithelial plasticity; Paranodal junction; Septate junction; Synapse; Synaptic plasticity; Tight junction