Biochemical and structural analyses reveal that the tumor suppressor neurofibromin (NF1) forms a high-affinity dimer

Sherekar, Mukul; Han, Sae‐Won; Ghirlando, Rodolfo; Messing, Simon; Drew, Matthew; Rabara, Dana; Waybright, Timothy J.; Juneja, Puneet; O’Neill, Hugh; Stanley, Christopher B.; Bhowmik, Debsindhu; Ramanathan, Arvind; Subramaniam, Sriram; Nissley, Dwight V.; Gillette, William; McCormick, Frank; Esposito, Dominic

doi:10.1016/s0021-9258(17)49919-4

Cited by 38 publications

(20 citation statements)

References 44 publications

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“…Nf1 5,6 is a multifunctional tumour suppressor protein forming an obligate high-affinity dimer 7 of about 640-kDa molecular weight. As a GTPase-activating protein (GAP), its primary function is suppression of the Ras signalling cascade by accelerating the GTP hydrolysis rate of Ras, which returns Ras to its inactive GDP bound form 4,8 .…”

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confidence: 99%

The structure of neurofibromin isoform 2 reveals different functional states

Naschberger

Baradaran

Rupp

et al. 2021

Nature

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The autosomal dominant monogenetic disease neurofibromatosis type 1 (NF1) affects approximately one in 3,000 individuals and is caused by mutations in the NF1 tumour suppressor gene, leading to dysfunction in the protein neurofibromin (Nf1)1,2. As a GTPase-activating protein, a key function of Nf1 is repression of the Ras oncogene signalling cascade. We determined the human Nf1 dimer structure at an overall resolution of 3.3 Å. The cryo-electron microscopy structure reveals domain organization and structural details of the Nf1 exon 23a splicing3 isoform 2 in a closed, self-inhibited, Zn-stabilized state and an open state. In the closed conformation, HEAT/ARM core domains shield the GTPase-activating protein-related domain (GRD) so that Ras binding is sterically inhibited. In a distinctly different, open conformation of one protomer, a large-scale movement of the GRD occurs, which is necessary to access Ras, whereas Sec14-PH reorients to allow interaction with the cellular membrane4. Zn incubation of Nf1 leads to reduced Ras-GAP activity with both protomers in the self-inhibited, closed conformation stabilized by a Zn binding site between the N-HEAT/ARM domain and the GRD–Sec14-PH linker. The transition between closed, self-inhibited states of Nf1 and open states provides guidance for targeted studies deciphering the complex molecular mechanism behind the widespread neurofibromatosis syndrome and Nf1 dysfunction in carcinogenesis.

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confidence: 99%

The structure of neurofibromin isoform 2 reveals different functional states

Naschberger

Baradaran

Rupp

et al. 2021

Nature

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“…In an earlier study with primary neurons, we found that neurofibromin, in addition to its colocalization with cytosolic MTs, localizes also in the nucleus and identified a bipartite NLS in the CTD (Figure 1B) as the probable mediator of nuclear entry [37]. Previously thought as an artifact in the skin epithelium, nuclear neurofibromin is detected with a variety of techniques, i.e., immunocytochemistry (e.g., white arrows in Figure 3), subcellular fractionations, or proteomics [28,29,[37][38][39][51][52][53] in all cells of an ectodermal origin.…”

Section: Neurofibromins As Maps and Their Role In Mitosismentioning

confidence: 82%

“…Our results show that the direction of the ΔNLS or NLS knockdown effects is most often opposite and suggest that the two functionally interact when both present. Whether this occurs through the formation of a dimer, if neurofibromins form dimers [28,68] in eukaryotic cells at normal neurofibromin concentrations, is an intriguing question. Indeed, how the NLS and ΔNLS conformations may affect dimer formation is an interesting experimental goal.…”

Section: Chromosome Segregation Fidelitymentioning

confidence: 99%

“…Along several such scientific efforts, the importance of other domains (Figure 1B) in the allosteric regulation of GRD has been established. Indeed, collective experimental evidence has postulated that neurofibromin domains may bind each other to form dimers [28], as well as, multiple proteins to coordinate Ras signalling ( [25-27, 29, 30], reviewed in [31]). For example, in glioma cells overexpression of CSRD plus GRD -after phosphorylations by PKCε or αbinding to cortical F-actin increases and imposes a positive allosteric regulation on GRD and thus intense Ras deactivation, which is sufficient to switch the effect of EGF signalling from proliferation to differentiation [30].…”

Section: Introductionmentioning

confidence: 99%

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Two Tails for Neurofibromin: A Tale of Two Microtubule-Associated Proteins

Peta¹,

Tsirimonaki²,

Fedonidis³

et al. 2022

Clinical and Basic Aspects of Neurofibromatosis Type 1

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Neurofibromatosis type 1, NF-1, is a common monogenic (NF1) disease, characterized by highly variable clinical presentation and high predisposition for tumors, especially those of astrocytic origin (low- to high-grade gliomas). Unfortunately, very few genotype–phenotype correlations have been possible, and the numerous identified mutations do not offer help for prognosis and patient counselling. Whole gene deletion in animals does not successfully model the disease, as NF-1 cases caused by point mutations could be differentially affected by cell type-specific alternative splice variants of NF1. In this chapter, we will discuss the differential Microtubule-Associated-Protein (MAP) properties of NLS or ΔNLS neurofibromins, produced by the alternatively splicing of exon 51, which also contains a Nuclear Localization Sequence (NLS), in the assembly of the mitotic spindle and in faithful genome transmission. We will also commend on the major theme that emerges about NLS-containing tumor suppressors that function as mitotic MAPs.

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“…Second, we demonstrated differential effects of NF1 germline mutations on neuronal differentiation. These differential effects could reflect the fact that neurofibromin functions as a high-affinity dimer, where different mutations could change the overall architecture of the dimer interface (Sherekar et al, 2020). Because neurons from individuals with NF1 harbor only a single NF1 germline mutation, different NF1 mutations likely cause unique neuron-related pathologies.…”

Section: Discussionmentioning

confidence: 99%

Human iPSC-Derived Neurons and Cerebral Organoids Establish Differential Effects of Germline NF1 Gene Mutations

et al. 2020

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Neurofibromatosis type 1 (NF1) is a common neurodevelopmental disorder caused by a spectrum of distinct germline NF1 gene mutations, traditionally viewed as equivalent loss-of-function alleles. To specifically address the issue of mutational equivalency in a disease with considerable clinical heterogeneity, we engineered seven isogenic human induced pluripotent stem cell lines, each with a different NF1 patient NF1 mutation, to identify potential differential effects of NF1 mutations on human central nervous system cells and tissues. Although all mutations increased proliferation and RAS activity in 2D neural progenitor cells (NPCs) and astrocytes, we observed striking differences between NF1 mutations on 2D NPC dopamine levels, and 3D NPC proliferation, apoptosis, and neuronal differentiation in developing cerebral organoids. Together, these findings demonstrate differential effects of NF1 gene mutations at the cellular and tissue levels, suggesting that the germline NF1 gene mutation is one factor that underlies clinical variability.

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Biochemical and structural analyses reveal that the tumor suppressor neurofibromin (NF1) forms a high-affinity dimer

Cited by 38 publications

References 44 publications

The structure of neurofibromin isoform 2 reveals different functional states

The structure of neurofibromin isoform 2 reveals different functional states

Two Tails for Neurofibromin: A Tale of Two Microtubule-Associated Proteins

Human iPSC-Derived Neurons and Cerebral Organoids Establish Differential Effects of Germline NF1 Gene Mutations

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