A Point Mutation in the Ubiquitin Ligase RNF170 That Causes Autosomal Dominant Sensory Ataxia Destabilizes the Protein and Impairs Inositol 1,4,5-Trisphosphate Receptor-mediated Ca2+ Signaling

Wright, Forrest A.; Lu, Justine P; Sliter, Danielle A.; Dupré, Nicolas; Rouleau, Guy A.; Wojcikiewicz, Richard J.H.

doi:10.1074/jbc.m115.655043

Cited by 30 publications

(43 citation statements)

References 45 publications

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“…Oligonucleotides targeting exons 5 or 13 (GGT-GCGGAGTATCGATTCAT and GCACCTCCACGCAGAG-TCGT, respectively) were introduced into ␣T3 cells and clones were screened by immunoblotting with anti-IP 3 R1 (25). Of the cell lines screened, ϳ25% lacked IP 3 R1, and 2 lines for each targeted exon were characterized further with essentially identical results.…”

Section: Methodsmentioning

confidence: 99%

“…Antibodies raised in rabbits were: anti-IP 3 R1 (21), anti-erlin2 (22) Cell Lysis, Immunoprecipitation (IP), and SDS-PAGE-To prepare lysates, cells or brain tissues were harvested with icecold lysis buffer containing either 1% CHAPS or 1% Triton X-100 (14). CHAPS was used for all experiments involving IP, except when exogenous Bok ubiquitination was assessed, when cells were harvested with DTT-free Triton X-100 lysis buffer supplemented with 5 mM N-ethylmaleimide, followed by addition of 5 mM DTT 30 min later (25). Lysates were incubated on ice for 30 min and clarified by centrifugation at 16,000 ϫ g for 10 min at 4°C.…”

Section: Methodsmentioning

confidence: 99%

“…Generation and Analysis of IP 3 R1 Knock-out (KO) LinesThe CRISPR/hCas9 system (27) was used to target exons within the mouse IP 3 R1 gene and create ␣T3IP 3 R1KO cell lines as described (25). Oligonucleotides targeting exons 5 or 13 (GGT-GCGGAGTATCGATTCAT and GCACCTCCACGCAGAG-TCGT, respectively) were introduced into ␣T3 cells and clones were screened by immunoblotting with anti-IP 3 R1 (25).…”

Section: Methodsmentioning

confidence: 99%

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The Stability and Expression Level of Bok Are Governed by Binding to Inositol 1,4,5-Trisphosphate Receptors

Schulman

Wright

Han

et al. 2016

Journal of Biological Chemistry

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104

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Bok is a member of the Bcl-2 protein family that governs the intrinsic apoptosis pathway, although the role that Bok plays in this pathway is unclear. We have shown previously in cultured cell lines that Bok interacts strongly with inositol 1,4,5-trisphosphate receptors (IP 3 Rs), suggesting that it may contribute to the structural integrity or stability of IP 3 R tetramers. Here we report that Bok is similarly IP 3 R-assocated in mouse tissues, that essentially all cellular Bok is IP 3 R bound, that it is the helical nature of the Bok BH4 domain, rather than specific amino acids, that mediates binding to IP 3 Rs, that Bok is dramatically stabilized by binding to IP 3 Rs, that unbound Bok is ubiquitinated and degraded by the proteasome, and that binding to IP 3 Rs limits the pro-apoptotic effect of overexpressed Bok. Agents that stimulate IP 3 R activity, apoptosis, phosphorylation, and endoplasmic reticulum stress did not trigger the dissociation of mature Bok from IP 3 Rs or Bok degradation, indicating that the role of proteasome-mediated Bok degradation is to destroy newly synthesized Bok that is not IP 3 R associated. The existence of this unexpected proteolytic mechanism that is geared toward restricting Bok to that which is bound to IP 3 Rs, implies that unbound Bok is deleterious to cell viability and helps explain the current uncertainty regarding the cellular role of Bok.Bok is a member of the Bcl-2 protein family that controls the intrinsic apoptosis pathway (1-3). Bok contains four Bcl-2 homology domains (BH1-4) 2 and shares greatest sequence homology with the pro-apoptotic proteins Bak and Bax (1-4). However, unlike Bak and Bax, which have clearly defined roles in mediating mitochondrial outer membrane permeabilization (5, 6), the cellular role of Bok is unclear. Key observations that pertain to our current understanding of the function of Bok are (i) that the atypical C-terminal transmembrane (TM) domain of Bok localizes it to membranes of the endoplasmic reticulum (ER) and Golgi (7), (ii) that Bok over-expression leads to apoptosis (7-10) if Bak or Bax are present (7), indicating that Bok lies upstream of Bak and Bax, (iii) that Bok Ϫ/Ϫ mice are phenotypically normal (4, 11, 12), while Bax Ϫ/Ϫ Bak Ϫ/Ϫ mice exhibit multiple severe defects (1), indicating that Bok cannot substitute for Bak and Bax, and (iv) that ER stress-induced apoptosis (13) can be suppressed in Bok Ϫ/Ϫ mouse cells in vitro and in vivo (12), although this result has not been seen by all groups (7). Overall, these data suggest that Bok plays a very different role from Bax and Bak, and that it may participate in the pathway between ER stress and apoptosis.Another intriguing facet of Bok cell biology is that it binds very strongly to inositol 1,4,5-trisphosphate (IP 3 ) receptors (IP 3 Rs) (14), proteins that form tetrameric, IP 3 -, and Ca 2ϩ -gated Ca 2ϩ channels in ER membranes and play a key role in vertebrate cell signaling (15,16). Of the three mammalian IP 3 R types, Bok binding is strongest to IP 3 R1 and IP 3 R2 (14) and the...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

The Stability and Expression Level of Bok Are Governed by Binding to Inositol 1,4,5-Trisphosphate Receptors

Schulman

Wright

Han

et al. 2016

Journal of Biological Chemistry

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104

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“…For example, autosomal dominant sensory ataxia, a neurodegenerative disorder characterized by the destruction of the posterior columns of the spinal cord, is caused by a point mutation in the ER membrane ubiquitin ligase RNF170, which participates in the ubiquitination of activated IP 3 R. Recent studies have revealed that the disease-causing point mutation in RNF170 disrupts salt bridges between its TMD, which provokes RNF170 destabilization and leads to IICR inhibition [70].…”

Section: Mutations In the Ip3r1 Gene And Ataxiasmentioning

confidence: 99%

Inositol 1,4,5‐trisphosphate receptors and neurodegenerative disorders

Egorova

Bezprozvanny

2018

The FEBS Journal

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The inositol 1,4,5-trisphosphate receptor (IP 3 R) is an intracellular ion channel that mediates the release of calcium ions from the endoplasmic reticulum. It plays a role in basic biological functions, such as cell division, differentiation, fertilization and cell death, and is involved in developmental processes including learning, memory and behavior. Deregulation of neuronal calcium signaling results in disturbance of cell homeostasis, synaptic loss and dysfunction, eventually leading to cell death. Three IP 3 R subtypes have been identified in mammalian cells and the predominant isoform in neurons is IP 3 R type 1. Dysfunction of IP 3 R type 1 may play a role in the pathogenesis of certain neurodegenerative diseases as enhanced activity of the IP 3 R was observed in models of Huntington's disease, spinocerebellar ataxias and Alzheimer's disease. These results suggest that IP 3 R-mediated signaling is a potential target for treatment of these disorders. In this review we discuss the structure, functions and regulation of the IP 3 R in healthy neurons and in conditions of neurodegeneration. IntroductionInositol 1,4,5-trisphosphate receptors (IP 3 Rs) are a family of intracellular ion channels that mediate calcium (Ca 2+ ) release from the endoplasmic reticulum (ER) following stimulation by the second messenger inositol 1,4,5-trisphosphate (IP 3 ). Generation of IP 3 molecules is caused by the activation of phospholipase C in response to the activation of G proteincoupled receptors such as serotonergic receptors, adrenergic receptors, calcitonin receptors, histamine receptors, metabotropic glutamate receptors (mGluRs), Abbreviations AAV, adeno-associated virus; AD, Alzheimer's disease; ALG-2, apoptosis-linked gene 2; ARM, armadillo; Ab, beta amyloid; BH, Bcl-2 homology; CaBP1, calcium-binding protein 1; CTD, C-terminal domain; EM, electron microscopy; ER, endoplasmic reticulum; FAD, familial Alzheimer's disease; GRP78, 78-kDa glucose regulated protein; HAP1, huntingtin-associated protein 1; HD, Huntington's disease; HelD, helical domain; Htt, huntingtin; IBC, IP 3 -binding core; IICR, inositol 1,4,5-trisphosphate-induced calcium release; ILD, 'intervening lateral' domain; IP 3 , inositol 1,4,5-trisphosphate; IP 3 R1, IP 3 R type 1; IP 3 R, inositol 1,4,5-trisphosphate receptor; IRBIT, IP 3 R binding protein released with IP 3 ; KO, knock-out; LBD, ligand-binding domain; LNK, helical linker domain; MCI, mild cognitive impairment; mGluR, metabotropic glutamate receptor; mPTP, mitochondrial permeability transition pore; MSN, medium spiny neuron; NMDA, N-methyl-D-aspartate; NTR, Nterminal region; Opt, opisthotonos; PC, Purkinje cell; polyQ, polyglutamine; PS, presenilin; RyR, ryanodine receptor; SAD, sporadic Alzheimer's disease; SCA, spinocerebellar ataxia; SD, IP 3 -binding suppressor domain; SUMF1, sulfatase modifying factor 1; TG2, transglutaminase type 2; TMD, transmembrane domain; WT, wild-type; YAC, yeast artificial chromosome; b-TF, b-trefoil. 3547The (Fig. 1). Upon extracellular stimulation -by various ...

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“…Insights are now available on IP 3 R degradation by ERassisted and 26S proteasomal turnover after cell stimulation and IP 3 R activation [26]. In such conditions, IP 3 Rs become ubiquitinated due to recruitment of the erlin1/2 complex and RNF170, an E3 ubiquitin ligase [27][28][29]. …”

mentioning

confidence: 99%

Tumor suppressive Ca2+ signaling is driven by IP3 receptor fitness

Bultynck¹,

Campanella²

2017

CST

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Intracellular Ca2+ signals critically control a plethora of cellular functions, of which many impact cellular death and/or survival, processes often dysregulated in cancer [1]. In healthy cells, Ca 2+ signaling is employed for normal cell physiology and survival functions [2]. Yet, when a cell is exposed to toxic stimuli or suffering from enduring cell stress, like irreparable DNA damage, the Ca 2+ -signaling toolbox can be rapidly switched from a "pro-survival" modus into a "pro-death" modus, thereby initiating demise pathways [3]. The highly dynamic nature of Ca 2+ signaling allows cells to swiftly response to stress and damage, preventing the survival of damaged cells and malignant transformation that eventually results in tumor formation. Alterations in the expression, activity and regulation of Ca 2+ -transport systems both at the plasma membrane and at organelles like the endoplasmic reticulum (ER) and mitochondria have been implicated in oncogenesis and neoplasia [1,4]. These changes result in aberrant Ca 2+ -signaling events that could favor resistance to cell death, migration or senescence escape [5].Over the last decade, we learnt that tight contacts and functional connections involving Ca 2+ exchanges between the ER, the main intracellular Ca 2+ -storage organelle, and the mitochondria are pivotal for cell-fate decisions [3,[6][7][8].These contact sites contain chaperone-coupled Ca 2+ -flux systems: the IP 3 receptors (IP 3 Rs) at the ER side and the voltage-dependent anion channels (VDACs) at the mitochondrial outer membrane side [9]. These are controlled/exploited by several cellular factors and regulatory proteins, including oncogenes and tumor suppressors [10][11][12]. Basal Ca 2+ fluxes between ER and mitochondria sustain anabolic pathways for mitochondrial metabolism, ensuring proper cell cycle progression [13]. Yet, continued elevated ER-mitochondrial Ca 2+ transfers result in loss of mitochondrial membrane integrity and release of apoptogenic factors [14]. Tuned ER-mitochondrial Ca 2+ transfer is therefore key to cells' response to pro-apoptotic stimuli: the failure of which results in cell death resistance, as often observed in cancer cells [15,16]. In fact, the efficacy of chemotherapeutic agents and photodynamic therapy depends on the ability of these agents to elicit ER-mitochondrial Ca 2+ exchanges [15]. In the context of apoptosis, previous work proposed unique roles for the type 3 IP 3 R isoform (IP 3 R3) [17] and type 1 VDAC isoform (VDAC1) [18] even though other IP 3 R isoforms can contribute to the initiation of cell death programs [19,20]. Received: 12.10.2017, Accepted 20.10.2017, Published 01.11.2017. Keywords: cancer, oncogenesis, tumor suppression, IP3R3, calcium signaling, PTEN, FBXL2, BAP1. G. Bultynck and M. Campanella (2017 . Several tumor suppressors and oncogenes have been identified as direct regulators of the IP 3 R, whereby tumor suppressors (like BRCA1, PTEN, PML) and oncogenes (like Bcl-2, PKB/Akt) that respectively promote and suppress the activity of IP 3 R cha...

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A Point Mutation in the Ubiquitin Ligase RNF170 That Causes Autosomal Dominant Sensory Ataxia Destabilizes the Protein and Impairs Inositol 1,4,5-Trisphosphate Receptor-mediated Ca2+ Signaling

Cited by 30 publications

References 45 publications

The Stability and Expression Level of Bok Are Governed by Binding to Inositol 1,4,5-Trisphosphate Receptors

The Stability and Expression Level of Bok Are Governed by Binding to Inositol 1,4,5-Trisphosphate Receptors

Inositol 1,4,5‐trisphosphate receptors and neurodegenerative disorders

Tumor suppressive Ca2+ signaling is driven by IP3 receptor fitness

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