title: RNA processing bodies, peroxisomes, Golgi bodies, mitochondria, and endoplasmic reticulum tubule junctions frequently pause at cortical microtubules.
abstract: Organelle motility, essential for cellular function, is driven by the cytoskeleton. In plants, actin filaments sustain the long-distance transport of many types of organelles, and microtubules typically fine-tune the motile behavior. In shoot epidermal cells of Arabidopsis thaliana seedlings, we show here that a type of RNA granule, the RNA processing body (P-body), is transported by actin filaments and pauses at cortical microtubules. Interestingly, removal of microtubules does not change the frequency of P-body pausing. Similarly, we show that Golgi bodies, peroxisomes, and mitochondria all pause at microtubules, and again the frequency of pauses is not appreciably changed after microtubules are depolymerized. To understand the basis for pausing, we examined the endoplasmic reticulum (ER), whose overall architecture depends on actin filaments. By the dual observation of ER and microtubules, we find that stable junctions of tubular ER occur mainly at microtubules. Removal of microtubules reduces the number of stable ER tubule junctions, but those remaining are maintained without microtubules. The results indicate that pausing on microtubules is a common attribute of motile organelles but that microtubules are not required for pausing. We suggest that pausing on microtubules facilitates interactions between the ER and otherwise translocating organelles in the cell cortex.
authors.affiliation: Biology Department, University of Massachusetts Amherst, Amherst, MA 01003, USA. hama.micro@gmail.com
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hamada
authors.forename: Motoki
authors.initials: M
authors.lastname: Tominaga
authors.forename: Takashi
authors.initials: T
authors.lastname: Fukaya
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Nakamura
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nakano
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Takashi
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Tobias I
authors.initials: TI
authors.lastname: Baskin
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D020675:Peroxisomes / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics
chemical_list: D018749:RNA, Plant