FIGURE 1.

The interplay and interactions between membrane-bound organelles and the cytoskeleton. (A) MT-dependent transport of membrane-bound organelles such as mitochondria (i), lysosomes (ii) and the ER (iii) and (iv) in mammalian cells. ER tubules and microtubules can elongate together at the tip of a growing MT (TAC; iii) or ER tubules can be pulled out by microtubules via motor-dependent sliding (iv). (B) MT dynamics is mediated by membrane-bound organelles. MT nucleation can be induced by Golgi outposts (i). MT growth can be regulated by mitochondria (ii) and Rab5 + early endosomes (iii). MTs and the ER colocalize and co-stabilize each other in axons via an interplay between MTs and the ER (iv). (C) ER remodeling is regulated by interactions between the ER and lysosomes in conjunction with the cytoskeleton. ER tubules wrap around lysosomes (i). ER tubules are pulled out by hitchhiking on moving lysosomes (ii). Fission of ER tubules is induced by lysosome collisions (iii). (D) Lysosome fission is regulated by an interaction between the ER and lysosomes in association with the cytoskeleton (i, ii, iii). ER tubules induce lysosome fission (i), ER-MT interactions promote kinesin-1 loading onto lysosomes (ii) and lysosome transport is driven by kinesin-1 along MTs. Mitochondrial fission is mediated by ER tubules (iv, v, vi). ER-mitochondria contacts mark the pre-constriction site (iv), Drp1 is recruited to this pre-constriction site (v) and promotes mitochondrial fission (vi).