Molecular mechanism underlying the association of Coronin-7 with Golgi membranes.

Coronin-7 (Crn7) is a ubiquitous mammalian WD40-repeat protein that localizes to the Golgi complex, interacts with AP-1 adaptor complex via binding of a tyrosine-288-based sorting signal to the mu1-subunit of AP-1, and participates in the maintenance of the Golgi structure and function. Here, we define the requirements for the recruitment of Crn7 from the cytosol to the Golgi. We establish that Src activity is indispensable for the interaction of Crn7 with Golgi membranes. Crn7 binds Src in vivo and can be phosphorylated by recombinant Src in vitro. We demonstrate that tyrosine-758 is the major Src phosphorylation site. Further, to be targeted to membranes Crn7 requires the presence of cargo in the Golgi complex. Finally, downregulation of the mu1-subunit of AP-1 leads to the dispersal of Crn7 from the Golgi membranes. We propose a mechanism whereby sequential events of protein interaction and posttranslational modification result in the membrane targeting of Crn7.

[Morphogenesis and pattering in hydra. II. Molecular mechanisms]. / Morfogenez i formirovanie patterna u gidry. II. Molekuliarnye mekhanizmy.

Molecular mechanisms of morphogenesis and pattern formation have been extensively studied during the last decades. Recent data suggest that many of the signalling systems as well as transcription factors governing embryonic development in the higher animals have been already established in the lower Metazoa. This review summarizes the information on the roles of peptide systems, signal transduction cascades, transcriptional activators and the extracellular matrix-processing enzymes in the developmental processes in Hydra.

[Morphogenesis and formation of a pattern in hydra. I. Distribution of morphogenetic potential]. / Morfogenez i formirovanie patterna u gidry. I. Raspredelenie morfogeneticheskogo potentsiala.

True multicellularity is characterized by complex interactions between individual cells of the organism as well as by organization of cell masses into spatially and functionally determined structures promoting the exchange of information. Morphogenetic processes--genetically programmed generation of structures--always correlate with determination and maintenance of a pattern, i.e. a system of spatial relationships between them. Hydroid polyps provide a wide variety of approaches to study morphogenesis and patterning. Being comparatively simply organized, these animals have nevertheless certain developed mechanisms underlaying such processes as regeneration of missing structures, recovery of normal pattern after dissociation of polyps into single cells, tissue transdifferentiation in non-complementary chimaeras. An important feature of regeneration of hydroid polyps is its independence of the nerve net elements; the basis for regeneration is rather stored in epithelial cells and in their interactions. Phenomenological data, provided in the XVIII-XX centuries, allowed to propose several theoretical models of pattern regulation in hydra. The main goal of this paper is to review contemporary models of morphogenesis and patterning in the hydroid polyps.