p180 is involved in the interaction between the endoplasmic reticulum and microtubules through a novel microtubule-binding and bundling domain.
p180 was originally reported as a ribosome-binding protein on the rough endoplasmic reticulum membrane, although its precise role in animal cells has not yet been elucidated. Here, we characterized a new function of human p180 as a microtubule-binding and -modulating protein. Overexpression of p180 in mammalian cells induced an elongated morphology and enhanced acetylated microtubules. Consistently, electron microscopic analysis clearly revealed microtubule bundles in p180-overexpressing cells. Targeted depletion of endogenous p180 by small interfering RNAs led to aberrant patterns of microtubules and endoplasmic reticulum in mammalian cells, suggesting a specific interaction between p180 and microtubules. In vitro sedimentation assays using recombinant polypeptides revealed that p180 bound to microtubules directly and possessed a novel microtubule-binding domain (designated MTB-1). MTB-1 consists of a predicted coiled-coil region and repeat domain, and strongly promoted bundle formation both in vitro and in vivo when expressed alone. Overexpression of p180 induced acetylated microtubules in cultured cells in an MTB-1-dependent manner. Thus, our data suggest that p180 mediates interactions between the endoplasmic reticulum and microtubules mainly through the novel microtubule-binding and -bundling domain MTB-1.
Ogawa-Goto
Kiyoko
K
Department of Pathology, National Institute of Infectious Diseases, Shinjuku, Tokyo 162-8640, Japan. kgoto@nippi-inc.co.jp
Tanaka
Keiko
K
Ueno
Tomonori
T
Tanaka
Keisuke
K
Kurata
Takeshi
T
Sata
Tetsutaro
T
Irie
Shinkichi
S
D000107:Acetylation / Q000187:drug effects; D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D019281:Dimerization; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D050505:Mutant Proteins / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000172:deficiency / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014162:Transfection
D050505:Mutant Proteins; D010455:Peptides; D034741:RNA, Small Interfering; D018160:Receptors, Cytoplasmic and Nuclear; D017239:Paclitaxel