Minisymposium 20: Organelle Development
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M2003: The family of Arabidopsis peroxin 11 isoforms promotes replication and/or proliferation of peroxisomes in suspension-culture cells
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Presenter: |
Lingard, Matthew J Contact Presenter |
Authors | Lingard, Matthew J (A) Trelease, Richard N (A) | | Affiliations: |
(A): Arizona State University
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Peroxin 11 (Pex11) homologs in mammals and fungi participate in peroxisome division (cell-cycle-dependent duplication) and proliferation (cell-cycle-independent multiplication). In these organisms, peroxisome division and proliferation typically involve two consecutive phases: elongation and fission. Arabidopsis possesses five Pex11 isoforms (AtPex11a-e). Previously, Lingard and Trelease (2006, J Cell Sci 119: 1961-1972) showed that overexpression of AtPex11c or -d in Arabidopsis suspension cells resulted in peroxisome elongation without fission, whereas AtPex11e promoted peroxisome doubling without elongation. To further explore possible role(s) of AtPex11 isoform(s) in peroxisome duplication, Arabidopsis suspension cell protoplasts were PEG transformed with double-stranded RNAs (dsRNAs) to induce post-transcriptional gene silencing. In protoplasts transformed with AtPex11c, -d, or -e specific dsRNAs, real-time PCR revealed significant decreases in the levels of individual AtPex11c, -d, or -e mRNA. On the other hand, protoplasts transformed with dsRNAs common to all three isoforms exhibited a decrease in the levels of all three mRNAs. Four days after transformation, protoplasts that divided once and exhibited reduced levels of all three mRNAs possessed half the number of peroxisomes per daughter cell compared to once-divided daughter protoplasts transformed with nonspecific dsRNAs. Interestingly, those daughter cells with reduced levels of individual AtPex11c, -d, or -e mRNAs did not exhibit a reduction in peroxisome number. We conclude that AtPex11c, -d, and -e cooperatively participate in the peroxisome division process wherein the elongation and fission phases are partitioned between AtPex11c and/or -d (elongation) and AtPex11e (fission). NSF Grant MCB-0091826.
