Calcium, ATP and nuclear pore channel gating

Bustamante, J. O.; Michelette, E.R.F.; Geibel, J.P.; Dean, D.A.; McDonnell, T.J.; Hanover, J.A.

doi:10.1007/s004240050960

Cited by 23 publications

(16 citation statements)

References 24 publications

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“…The most variable structural moiety of the NPC is a rather tenuous central plug (discussed below), partially obstructing the central pore and being mobile. Its mobile character was previously documented by SFM (Stoffler et al 1999b(Stoffler et al , 2003Bustamante et al 2000).…”

Section: The Current Consensus Model Of the Nuclear Pore Complexmentioning

confidence: 90%

From the trap to the basket: getting to the bottom of the nuclear pore complex

2006

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Nuclear pore complexes (NPCs) are large supramolecular assemblies that perforate the doublemembraned nuclear envelope and serve as the sole gateways of molecular exchange between the cytoplasm and the nucleus in interphase cells. Combining novel specimen preparation regimes with innovative use of highresolution scanning electron microscopy, Hans Ris produced in the late eighties stereo images of the NPC with unparalleled clarity and structural detail, thereby setting new standards in the field. Since that time, efforts undertaken to resolve the molecular structure and architecture, and the numerous interactions that occur between NPC proteins (nucleoporins), soluble transport receptors, and the small GTPase Ran, have led to a deeper understanding of the functional role of NPCs in nucleocytoplasmic transport. In spite of these breakthroughs, getting to the bottom of the actual cargo translocation mechanism through the NPC remains elusive and controversial. Here, we review recent insights into NPC function by correlating structural findings with biochemical data. By introducing new experimental and computational results, we reexamine how NPCs can discriminate between receptor-mediated and passive cargo to promote vectorial translocation in a highly regulated manner. Moreover, we comment on the importance and potential benefits of identifying and experimenting with individual key components implicated in the translocation mechanism. We conclude by dwelling on questions that we feel are pertinent to a more rational understanding of the physical aspects governing NPC mechanics. Last but not least, we substantiate these uncertainties by boldly suggesting a new direction in NPC research as a means to verify such novel concepts, for example, a de novo designed 'minimalist' NPC.

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Section: The Current Consensus Model Of the Nuclear Pore Complexmentioning

confidence: 90%

From the trap to the basket: getting to the bottom of the nuclear pore complex

2006

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“…Using patchclamp techniques, it is possible to form giga-ohm seals on the outer NE for periods of many minutes without any evident ion flux (Bustamante et al, 2000). This is a striking finding, as even a conservative estimate of NPC density suggests that a typical patchclamp experiment should encompass 10-100 NPCs.…”

Section: Can Npcs Inhibit Ca 2+ Diffusion?mentioning

confidence: 97%

“…As the pores have a conductance of ~1 nanosiemen each, there should be a considerable current whenever a patch electrode is attached (Danker et al, 1997). However, electrophysiological recordings often detect only a few (about six per patch) operative channels (Bustamante et al, 2000). These observations have led to the suggestion that NPCs mainly exist in a closed conformation in which they are not ion conductive.…”

Section: Can Npcs Inhibit Ca 2+ Diffusion?mentioning

confidence: 99%

An update on nuclear calcium signalling

Bootman

Fearnley

Smyrnias

et al. 2009

Journal of Cell Science

189

194

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Over the past 15 years or so, numerous studies have sought to characterise how nuclear calcium (Ca 2+ ) signals are generated and reversed, and to understand how events that occur in the nucleoplasm influence cellular Ca 2+ activity, and vice versa. In this Commentary, we describe mechanisms of nuclear Ca 2+ signalling and discuss what is known about the origin and physiological significance of nuclear Ca 2+ transients. In particular, we focus on the idea that the nucleus has an autonomous Ca 2+ signalling system that can generate its own Ca 2+ transients that modulate processes such as gene transcription. We also discuss the role of nuclear pores and the nuclear envelope in controlling ion flux into the nucleoplasm. Journal of Cell Science 2338(which would cause its nuclear export) and through a physical interaction that occludes a nuclear-export sequence (NES) in the NFAT protein.An example of a nuclear-localised transcription factor that is regulated by both nuclear and cytosolic Ca 2+ signals is cyclic AMP response element-binding protein (CREB). The signalling mechanisms that underlie CREB activation have been worked out particularly well in neurons, in which it has been established that depolarisation leads to the rapid phosphorylation of CREB on Ser133 by Ca 2+ -calmodulin-dependent kinase IV, which provides a necessary, but not sufficient, signal for CREB-mediated gene transcription (Dolmetsch et al., 2001). The triggering event is an increase in cytosolic Ca 2+ levels in the immediate vicinity of L-type Ca 2+ channels or N-methyl-D-aspartate receptors that are found in the synapse, at a site that is distal to the nucleus (Shaywitz and Greenberg, 1999). As CREB is only found in the nucleus, the phosphorylation of Ser133 is mediated by one of several Ca 2+ -sensitive signal transduction cascades that convey information from the remote synapses into the nucleus. In the nucleus, phosphorylated CREB binds additional proteins to form a transcriptionally active complex (Shaywitz and Greenberg, 1999). Although the synaptic Ca 2+ signal does not need to propagate to the nucleus to induce phosphorylation of Ser133 on CREB, an increase in the level of nuclear Ca 2+ is required for CREB-mediated gene transcription to occur. This is because additional Ca 2+ -dependent phosphorylation of CREB and its co-activators is required (Chawla et al., 1998;Kornhauser et al., 2002). Indeed, nuclear injection of an artificial Ca 2+ buffer prevents CREB-mediated gene transcription, but not transcription induced by the serum-response element, which is sensitive to cytosolic Ca 2+ buffering (Hardingham et al., 1997).Another well-known target of nuclear Ca 2+ signalling is the transcriptional regulator downstream regulatory element antagonist modulator (DREAM). It is well established that DREAM represses the expression of prodynorphin, an opiate-receptor precursor, and that mice that lack DREAM have a constitutive analgesic condition (Cheng et al., 2002). DREAM contains four Ca 2+ -binding EF hands (a widely expressed structural mo...

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“…Furthermore, calcium depletion from the nuclear envelope cisterna inhibits passive diffusion and NLS-mediated transport through the NPC, probably by inducing conformational changes. 25,26 The broad variety of import substrates led the cell to develop a wide range of specific nuclear import pathways with corresponding regulation mechanisms, from which the importin ␤-pathway is one of the best characterized. [27][28][29] Import substrates bind either directly to importin ␤ or through the adapter protein importin ␣.…”

Section: Nuclear Import Of Proteinsmentioning

confidence: 99%