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Original Article |
Correspondence to: Victoria J. Allan, School of Biological Sciences, University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT, UK. Tel:(44) 161-275-5646 Fax:(44) 161-275-5082 E-mail:viki.allan{at}man.ac.uk.
Cytoplasmic dynein is the major minus enddirected microtubule motor in animal cells, and associates with many of its cargoes in conjunction with the dynactin complex. Interaction between cytoplasmic dynein and dynactin is mediated by the binding of cytoplasmic dynein intermediate chains (CD-IC) to the dynactin subunit, p150Glued. We have found that both CD-IC and p150Glued are cleaved by caspases during apoptosis in cultured mammalian cells and in Xenopus egg extracts. Xenopus CD-IC is rapidly cleaved at a conserved aspartic acid residue adjacent to its NH2-terminal p150Glued binding domain, resulting in loss of the otherwise intact cytoplasmic dynein complex from membranes. Cleavage of CD-IC and p150Glued in apoptotic Xenopus egg extracts causes the cessation of cytoplasmic dyneindriven endoplasmic reticulum movement. Motility of apoptotic membranes is restored by recruitment of intact cytoplasmic dynein and dynactin from control cytosol, or from apoptotic cytosol supplemented with purified cytoplasmic dyneindynactin, demonstrating the dynamic nature of the association of cytoplasmic dynein and dynactin with their membrane cargo.
Key Words: microtubule, motor, apoptosis, trafficking, caspase
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