Role of importin-β in the control of nuclear envelope assembly by Ran

TY - JOUR

T1 - Role of importin-β in the control of nuclear envelope assembly by Ran

AU - Zhang, Chuanmao

AU - Hutchins, James R A

AU - Mühlhäusser, Petra

AU - Kutay, Ulrike

AU - Clarke, Paul R.

PY - 2002/3/19

Y1 - 2002/3/19

N2 - Compartmentalization of the genetic material into a nucleus bounded by a nuclear envelope (NE) is the hallmark of a eukaryotic cell. The control of NE assembly is poorly understood, but in a cell-free system made from Xenopus eggs, NE assembly involves the small GTPase Ran [1, 2]. In this system, Sepharose beads coated with Ran induce the formation of functional NEs in the absence of chromatin [2]. Here, we show that importin-β, an effector of Ran involved in nucleocytoplasmic transport and mitotic spindle assembly, is required for NE assembly induced by Ran. Concentration of importin-β on beads is sufficient to induce NE assembly in Xenopus egg extracts. The function of importin-β in NE assembly is disrupted by a mutation that decreases affinity for nucleoporins containing FxFG repeats. By contrast, a truncated protein that cannot interact with importin-α is functional. Thus, importin-β functions in NE assembly by recruiting FxFG nucleoporins rather than by interaction through importin-α with karyophilic proteins carrying classical nuclear localization signals. Importin-β links NE assembly, mitotic spindle assembly, and nucleocytoplasmic transport to regulation by Ran and may coordinate these processes during cell division.

AB - Compartmentalization of the genetic material into a nucleus bounded by a nuclear envelope (NE) is the hallmark of a eukaryotic cell. The control of NE assembly is poorly understood, but in a cell-free system made from Xenopus eggs, NE assembly involves the small GTPase Ran [1, 2]. In this system, Sepharose beads coated with Ran induce the formation of functional NEs in the absence of chromatin [2]. Here, we show that importin-β, an effector of Ran involved in nucleocytoplasmic transport and mitotic spindle assembly, is required for NE assembly induced by Ran. Concentration of importin-β on beads is sufficient to induce NE assembly in Xenopus egg extracts. The function of importin-β in NE assembly is disrupted by a mutation that decreases affinity for nucleoporins containing FxFG repeats. By contrast, a truncated protein that cannot interact with importin-α is functional. Thus, importin-β functions in NE assembly by recruiting FxFG nucleoporins rather than by interaction through importin-α with karyophilic proteins carrying classical nuclear localization signals. Importin-β links NE assembly, mitotic spindle assembly, and nucleocytoplasmic transport to regulation by Ran and may coordinate these processes during cell division.

UR - https://www.scopus.com/pages/publications/0036006299

U2 - 10.1016/S0960-9822(02)00714-5

DO - 10.1016/S0960-9822(02)00714-5

M3 - Article

C2 - 11909537

AN - SCOPUS:0036006299

SN - 0960-9822

VL - 12

SP - 498

EP - 502

JO - Current Biology

JF - Current Biology

IS - 6

ER -