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1.  The Exocyst Complex Associates with Microtubules to Mediate Vesicle Targeting and Neurite Outgrowth 
During neuronal development, vesicles are targeted to the growth cone to promote neurite outgrowth and synaptogenesis. The Exocyst complex is an essential macromolecule in the secretory pathway that may play a role in vesicle targeting. Although it has been shown that this complex is enriched in rat brain, the molecular mechanism underlying its function is largely unknown. Here, we report that the Exocyst complex coimmunoprecipitates with microtubules from total rat brain lysate. Additionally, the Exocyst complex subcellular localization changes on neuronal differentiation. In undifferentiated pheochromocytoma (PC12) cells, this complex is associated with microtubules at the microtubule organizing center. However, in differentiated PC12 cells and cultured hippocampal neurons, the Exocyst complex and microtubules extend to the growing neurite and colocalize at the growth cone with synaptotagmin. Inhibition of the NGF-activated MAP kinase pathway blocks the Exocyst complex and microtubule redistribution, abolishing neurite outgrowth and promoting cytosolic accumulation of secretory vesicles. Consistently, the overexpression of Exocyst sec10 subunit mutant blocks neurite outgrowth. These results indicate that the Exocyst complex targets secretory vesicles to specific domains of the plasma membrane through its association with the microtubules, promoting neurite outgrowth.
PMCID: PMC3674029  PMID: 11356872
Exocyst complex; microtubules; exocytosis; vesicle targeting; neurite outgrowth; differentiation; MAP kinase pathway
2.  Exocyst Requirement for Endocytic Traffic Directed Toward the Apical and Basolateral Poles of Polarized MDCK Cells 
Molecular Biology of the Cell  2007;18(10):3978-3992.
The octameric exocyst complex is associated with the junctional complex and recycling endosomes and is proposed to selectively tether cargo vesicles directed toward the basolateral surface of polarized Madin-Darby canine kidney (MDCK) cells. We observed that the exocyst subunits Sec6, Sec8, and Exo70 were localized to early endosomes, transferrin-positive common recycling endosomes, and Rab11a-positive apical recycling endosomes of polarized MDCK cells. Consistent with its localization to multiple populations of endosomes, addition of function-blocking Sec8 antibodies to streptolysin-O–permeabilized cells revealed exocyst requirements for several endocytic pathways including basolateral recycling, apical recycling, and basolateral-to-apical transcytosis. The latter was selectively dependent on interactions between the small GTPase Rab11a and Sec15A and was inhibited by expression of the C-terminus of Sec15A or down-regulation of Sec15A expression using shRNA. These results indicate that the exocyst complex may be a multipurpose regulator of endocytic traffic directed toward both poles of polarized epithelial cells and that transcytotic traffic is likely to require Rab11a-dependent recruitment and modulation of exocyst function, likely through interactions with Sec15A.
doi:10.1091/mbc.E07-02-0097
PMCID: PMC1995710  PMID: 17686995
3.  Mammalian Septins Nomenclature 
Molecular Biology of the Cell  2002;13(12):4111-4113.
There are 10 known mammalian septin genes, some of which produce multiple splice variants. The current nomenclature for the genes and gene products is very confusing, with several different names having been given to the same gene product and distinct names given to splice variants of the same gene. Moreover, some names are based on those of yeast or Drosophila septins that are not the closest homologues. Therefore, we suggest that the mammalian septin field adopt a common nomenclature system, based on that adopted by the Mouse Genomic Nomenclature Committee and accepted by the Human Genome Organization Gene Nomenclature Committee. The human and mouse septin genes will be named SEPT1–SEPT10 and Sept1–Sept10, respectively. Splice variants will be designated by an underscore followed by a lowercase “v” and a number, e.g., SEPT4_v1.
doi:10.1091/mbc.E02-07-0438
PMCID: PMC138619  PMID: 12475938

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