Dexamethasone regulates expression of BRUCE/Apollon and the proliferation of neural progenitor cells

Glucocorticoid hormones (GHs) regulate cell proliferation of neural progenitor cells (NPCs) contributing to reduction of neurogenesis after stress. We show here that dexamethasone (Dex) decreases BRUCE/Apollon (BRUCE) in cultured NPCs in a GH-receptor-dependent manner. Downregulation of BRUCE by Dex or using silencing RNA reduced the number of proliferating NPCs, whilst overexpression of BRUCE counteracted the effect of Dex. Dex also elevated the deubiquitinating enzyme, Usp8/Ubpy, which via Nrdp1 decreases BRUCE. The results show that BRUCE is a target for GHs in the NPCs, and that BRUCE controls cell division of NPCs and possibly of other stem cells.

Structured summary

MINT-7148564: Nrdp1 (uniprotkb:Q8BH75) physically interacts (MI:0914) with BRUCE (uniprotkb:O88738) by anti bait co-immunoprecipitation (MI:0006)MINT-7148555: Nrdp1 (uniprotkb:Q8BH75) physically interacts (MI:0914) with Usp8 (uniprotkb:Q80U87) by anti bait co-immunoprecipitation (MI:0006)     

The β1 subunit of Na/K-ATPase interacts with BKCa channels and affects their steady-state expression on the cell surface

Large conductance Ca²⁺-activated K⁺ channels (BK_Ca) encoded by the Slo1 gene play a role in the physiological regulation of many cell types. Here, we show that the β1 subunit of Na⁺/K⁺-ATPase (NKβ1) interacts with the cytoplasmic COOH-terminal region of Slo1 proteins. Reduced expression of endogenous NKβ1 markedly inhibits evoked BK_Ca currents with no apparent effect on their gating. In addition, NKβ1 down-regulated cells show decreased density of Slo1 subunits on the cell surface.

Structured summary

MINT-7260438, MINT-7260555: Slo1 (uniprotkb:Q8AYS8) physically interacts (MI:0915) with NKbeta1 (uniprotkb:P08251) by anti bait coimmunoprecipitation (MI:0006)MINT-7260587, MINT-7260606, MINT-7260619, MINT-7260632: Slo1 (uniprotkb:Q08460) physically interacts (MI:0915) with NKbeta 1 (uniprotkb:P08251) by pull down (MI:0416)MINT-7260570: NKbeta1 (uniprotkb:P08251) and Slo1 (uniprotkb:Q8AYS8) colocalize (MI:0403) by fluorescence microscopy (MI:0416)MINT-7260414: Slo1 (uniprotkb:Q08460) physically interacts (MI:0915) with NKbeta1 (uniprotkb:P08251) by two hybrid (MI:0018)     

Bag-1M inhibits the transactivation of the glucocorticoid receptor via recruitment of corepressors

The Bcl-2 associated athanogene 1M (Bag-1M) is known to repress the transactivation of the glucocorticoid receptor (GR). We report here that Bag-1M inhibits the action of GR via recruitment of corepressors, including nuclear receptor corepressor (NcoR) and silencing mediator for retinoic acid and thyroid hormone receptor (SMRT), and histone deacetylase (HDAC)3 to the genomic response element of a glucocorticoid-regulated human metallothionein IIa (hMTIIa) gene. A mutant GR lacking the interaction with BAG-1M fails to recruit the corepressors NcoR and SMRT. RNAi-mediated knock down of corepressors and the use of HDAC inhibitor relieved Bag-1M-induced repression on the transactivation of the GR. In addition, Bag-1M is not involved in the degradation of the receptor. These findings indicate a novel mechanism by which Bag-1M acts as a corepressor and downregulates the activity of the GR.

Structured summary

MINT-7216164: HDAC3 (uniprotkb:O15379) physically interacts (MI:0914) with Bag1 (uniprotkb:Q99933) by anti bait coimmunoprecipitation (MI:0006)MINT-7216183: NCOR (uniprotkb:O75376) physically interacts (MI:0914) with Bag1 (uniprotkb:Q99933) by anti bait coimmunoprecipitation (MI:0006)MINT-7216175: SMRT (uniprotkb:Q9Y618) physically interacts (MI:0914) with Bag1 (uniprotkb:Q99933) by anti bait coimmunoprecipitation (MI:0006)     

FKBP25, a novel regulator of the p53 pathway, induces the degradation of MDM2 and activation of p53

The p53 tumour suppressor protein is tightly controlled by the E3 ubiquitin ligase, mouse double minute 2 (MDM2), but maintains MDM2 expression as part of a negative feedback loop. We have identified the immunophilin, 25 kDa FK506-binding protein (FKBP25), previously shown to be regulated by p53-mediated repression, as an MDM2-interacting partner. We show that FKBP25 stimulates auto-ubiquitylation and proteasomal degradation of MDM2, leading to the induction of p53. Depletion of FKBP25 by siRNA leads to increased levels of MDM2 and a corresponding reduction in p53 and p21 levels. These data are consistent with the idea that FKBP25 contributes to regulation of the p53-MDM2 negative feedback loop.

Structured summary

MINT-6823686:MDM2 (uniprotkb:Q00987) physically interacts (MI:0218) with FKBP25 (uniprotkb:Q00688) by anti bait coimmunoprecipitation (MI:0006)MINT-6823707, MINT-6823722:MDM2 (uniprotkb:Q00987) physically interacts (MI:0218) with FKBP25 (uniprotkb:Q62446) by pull down (MI:0096)MINT-6823775:P53 (uniprotkb:Q04637) physically interacts (MI:0218) with MDM2 (uniprotkb:Q00987) by anti bait coimmunoprecipitation (MI:0006)MINT-6823735, MINT-6823749:FKBP25 (uniprotkb:Q62446) binds (MI:0407) to MDM2 (uniprotkb:Q00987) by pull down (MI:0096)MINT-6823761:Ubiquitin (UNIPROTKB:62988)P physically interacts (MI:0218) with MDM2 (uniprotkb:Q00987) by pull down (MI:0096)MINT-6823669:MDM2 (uniprotkb:Q00987) physically interacts (MI:0218) with FKBP25 (uniprotkb:Q00688) by two hybrid (MI:0018)     

NMDA receptors interact with flotillin-1 and -2, lipid raft-associated proteins

N-methyl-d-aspartate receptors (NMDARs) mediate excitatory synaptic transmission in the brain. Here we demonstrate interactions between the NR2A and NR2B subunits of NMDARs with flotillin-1 (flot-1), a lipid raft-associated protein. When mapped, analogous regions in the far distal C-termini of NR2A and NR2B mediate binding to flot-1, and the prohibitin homology domain of flot-1 contains binding sites for NR2A and NR2B. Although NR2B can also directly bind to flot-2 via a separate region of its distal C-terminus, NMDARs were significantly more colocalized with flot-1 than flot-2 in cultured hippocampal neurons. Overall, this study defines a novel interaction between NMDARs and flotillins.

Structured summary

MINT-7013094: NR2A (uniprotkb:Q00959), NR2B (uniprotkb:Q00960) and Flot2 (uniprotkb:Q9Z2S9) colocalize (MI:0403) by fluorescence microscopy (MI:0416)MINT-7013147: Flot1 (uniprotkb:Q9Z1E1) physically interacts (MI:0218) with NR2A (uniprotkb:Q00959) by anti bait coimmunoprecipitation (MI:0006)MINT-7013189: Flot1 (uniprotkb:Q9Z1E1) physically interacts (MI:0218) with Flot2 (uniprotkb:Q9Z2S9) by anti bait coimmunoprecipitation (MI:0006)MINT-7013033: NR2A (uniprotkb:Q00959) physically interacts (MI:0218) with Flot1 (uniprotkb:Q9Z1E1) by two hybrid (MI:0018)MINT-7013178: NR1 (uniprotkb:P35439) physically interacts (MI:0218) with Flot2 (uniprotkb:Q9Z2S9) by anti bait coimmunoprecipitation (MI:0006)MINT-7013197, MINT-7013210: NR2B (uniprotkb:Q00960) and NR2A (uniprotkb:Q00959) physically interact (MI:0218) with Flot2 (uniprotkb:Q9Z2S9) by anti bait coimmunoprecipitation (MI:0006)MINT-7013002: NR2B (uniprotkb:Q00960) physically interacts (MI:0218) with Flot1 (uniprotkb:O08917) by two hybrid (MI:0018)MINT-7013117: Flot1 (uniprotkb:Q9Z1E1), NR2B (uniprotkb:Q00960) and NR2A (uniprotkb:Q00959) colocalize (MI:0403) by fluorescence microscopy (MI:0416)MINT-7013171: NR1 (uniprotkb:P35439) physically interacts (MI:0218) with Flot1 (uniprotkb:Q9Z1E1) by anti bait coimmunoprecipitation (MI:0006)MINT-7013017: NR2A (uniprotkb:Q00959) physically interacts (MI:0218) with Flot1 (uniprotkb:O08917) by two hybrid (MI:0018)MINT-7013054: NR2B (uniprotkb:Q00960) physically interacts (MI:0218) with Flot1 (uniprotkb:Q9Z1E1) by two hybrid (MI:0018)MINT-7013129: Flot1 (uniprotkb:Q9Z1E1) physically interacts (MI:0218) with NR2B (uniprotkb:Q00960) by anti bait coimmunoprecipitation (MI:0006)MINT-7013155: NR1 (uniprotkb:P35439) physically interacts (MI:0218) with NR2B (uniprotkb:Q00960) by anti bait coimmunoprecipitation (MI:0006)MINT-7013074: NR2B (uniprotkb:Q00960) physically interacts (MI:0218) with Flot2 (uniprotkb:Q9Z2S9) by two hybrid (MI:0018)MINT-7013162: NR1 (uniprotkb:P35439) physically interacts (MI:0218) with NR2A (uniprotkb:Q00959) by anti bait coimmunoprecipitation (MI:0006)     

HECT ubiquitin ligase Smurf1 targets the tumor suppressor ING2 for ubiquitination and degradation

Inhibitor of growth 2 (ING2) gene encodes a candidate tumor suppressor and is frequently reduced in many tumors. However, the mechanisms underlying the regulation of ING2, in particular its protein stability, are still unclear. Here we show that the homologous to E6AP carboxyl terminus (HECT)-type ubiquitin ligase Smad ubiquitination regulatory factor 1 (Smurf1) interacts with and targets ING2 for poly-ubiquitination and proteasomal degradation. Intriguingly, the ING2 binding domain in Smurf1 was mapped to the catalytic HECT domain. Furthermore, the C-terminal PHD domain of ING2 was required for Smurf1-mediated degradation. This study provided the first evidence that the stability of ING2 could be regulated by ubiquitin-mediated degradation.

Structured summary

MINT-7894271: ING2 (uniprotkb:Q9H160) binds (MI:0407) to Smurf1 (uniprotkb:Q9HCE7) by pull-down (MI:0096)MINT-7894319, MINT-7894339: ING2 (uniprotkb:Q9H160) physically interacts (MI:0915) with Smurf1 (uniprotkb:Q9HCE7) by anti tag co-immunoprecipitation (MI:0007)MINT-7894301: Smurf1 (uniprotkb:Q9HCE7) physically interacts (MI:0915) with ING2 (uniprotkb:Q9H160) by anti bait co-immunoprecipitation (MI:0006)MINT-7894358: ING1b (uniprotkb:Q9UK53-2) physically interacts (MI:0915) with Smurf1 (uniprotkb:Q9HCE7) by anti tag co-immunoprecipitation (MI:0007)MINT-7894249: ING2 (uniprotkb:Q9H160) physically interacts (MI:0915) with ubiquitin (uniprotkb:P62988) by anti tag co-immunoprecipitation (MI:0007)     

Transcriptional activation of hypoxia-inducible factor-1α by HDAC4 and HDAC5 involves differential recruitment of p300 and FIH-1

The interplay between hypoxia-inducible factor-1α (HIF-1α) and histone deacetylase (HDACs) have been well studied; however, the mechanism of cross-talk is unclear. Here, we investigated the roles of HDAC4 and HDAC5 in the regulation of HIF-1α function and its associated mechanisms. HDAC4 and HDAC5 enhanced transactivation by HIF-1α without stabilizing HIF-1α. HDAC4 and HDAC5 physically associated with HIF-1α through the inhibitory domain (ID) that is the binding site for factor inhibiting HIF-1 (FIH-1). In the presence of these HDACs, binding of HIF-1α to FIH-1 decreased, whereas binding to p300 increased. These results indicate that HDAC4 and HDAC5 increase the transactivation function of HIF-1α by promoting dissociation of HIF-1α from FIH-1 and association with p300.

Structured summary:

MINT-6802187:HIF1 alpha (uniprotkb:Q16665) physically interacts (MI:0218) with FIH1 (uniprotkb:Q9NWT6) by anti bait coimmunoprecipitation (MI:0006)MINT-6802058:HIF1 alpha (uniprotkb:Q16665) physically interacts (MI:0218) with HDAC4 (uniprotkb:P56524) by pull down (MI:0096)MINT-6802021:HIF1 alpha (uniprotkb:Q61221) physically interacts (MI:0218) with HDAC4 (uniprotkb:P56524) by anti bait coimmunoprecipitation (MI:0006)MINT-6802036:HIF1 alpha (uniprotkb:Q61221) physically interacts (MI:0218) with HDAC5 (uniprotkb:Q9UQL6) by anti bait coimmunoprecipitation (MI:0006)MINT-6802102:HIF1 alpha (uniprotkb:Q16665) physically interacts (MI:0218) with HDAC5 (uniprotkb:Q9UQL6) by pull down (MI:0096)MINT-6802121, MINT-6802156:P300 (uniprotkb:Q09472) physically interacts (MI:0218) with HIF1 alpha (uniprotkb:Q16665) by anti bait coimmunoprecipitation (MI:0006)     

Feedback regulation of Ras2 guanine nucleotide exchange factor (Ras2-GEF) activity of Cdc25p by Cdc25p phosphorylation in the yeast Saccharomyces cerevisiae

Ras-GEF Cdc25p has been found to be hyperphosphorylated upon glucose addition. This work provides evidence indicating that PKA activity positively regulates the degree of Cdc25p phosphorylation, and that the intracellular association of Cdc25p and Ras2p is independent of PKA activity. In vitro experiments revealed that the Ras2-GEF activity of Cdc25p is inhibited by Cdc25p phosphorylation. These data suggest a negative feedback mechanism by which intracellular cAMP synthesis is inhibited by PKA through Cdc25p phosphorylation.

Structured summary

MINT-8053016: CDC25p (uniprotkb:P04821) physically interacts (MI:0915) with ras2p (uniprotkb:P01120) by anti tag co-immunoprecipitation (MI:0007)MINT-8053030: ras2p (uniprotkb:P01120) physically interacts (MI:0915) with CDC25p (uniprotkb:P04821) by anti bait co-immunoprecipitation (MI:0006)     

S100 proteins regulate the interaction of Hsp90 with Cyclophilin 40 and FKBP52 through their tetratricopeptide repeats

S100 proteins are a subfamily of the EF-hand type calcium sensing proteins, the exact biological functions of which have not been clarified yet. In this work, we have identified Cyclophilin 40 (CyP40) and FKBP52 (called immunophilins) as novel targets of S100 proteins. These immunophilins contain a tetratricopeptide repeat (TPR) domain for Hsp90 binding. Using glutathione-S transferase pull-down assays and immunoprecipitation, we have demonstrated that S100A1 and S100A2 specifically interact with the TPR domains of FKBP52 and CyP40 in a Ca²⁺-dependent manner, and lead to inhibition of the CyP40-Hsp90 and FKBP52-Hsp90 interactions. These findings have suggested that the Ca²⁺/S100 proteins are TPR-targeting regulators of the immunophilins-Hsp90 complex formations.

Structured summary

MINT-7710442: FKBP52 (uniprotkb:Q02790) physically interacts (MI:0915) with S100A6 (uniprotkb:P06703) by competition binding (MI:0405)MINT-7710192: Cyp40 (uniprotkb:P26882) binds (MI:0407) to S100A1 (uniprotkb:P35467) by pull down (MI:0096)MINT-7710412: Cyp40 (uniprotkb:P26882) physically interacts (MI:0915) with S100A2 (uniprotkb:P29034) by competition binding (MI:0405)MINT-7710374: FKBP52 (uniprotkb:Q02790) binds (MI:0407) to S100A2 (uniprotkb:P29034) by pull down (MI:0096)MINT-7710452: Cyp40 (uniprotkb:P26882) physically interacts (MI:0914) with S100A2 (uniprotkb:P29034) and Hsp90 (uniprotkb:P07900) by anti tag coimmunoprecipitation (MI:0007)MINT-7710387: FKBP52 (uniprotkb:Q02790) binds (MI:0407) to S100A6 (uniprotkb:P06703) by pull down (MI:0096)MINT-7710279: FKBP52 (uniprotkb:Q02790) physically interacts (MI:0915) with S100A1 (uniprotkb:P35467) by competition binding (MI:0405)MINT-7710224: FKBP52 (uniprotkb:Q02790) binds (MI:0407) to Hsp90 (uniprotkb:P07900) by pull down (MI:0096)MINT-7710464: Cyp40 (uniprotkb:P26882) physically interacts (MI:0914) with S100A6 (uniprotkb:P06703) and Hsp90 (uniprotkb:P07900) by anti tag coimmunoprecipitation (MI:0007)MINT-7710249: Cyp40 (uniprotkb:P26882) binds (MI:0407) to Hsp90 (uniprotkb:P07900) by pull down (MI:0096)MINT-7710422: Cyp40 (uniprotkb:P26882) physically interacts (MI:0915) with S100A6 (uniprotkb:P06703) by competition binding (MI:0405)MINT-7710348: Cyp40 (uniprotkb:P26882) binds (MI:0407) to S100A2 (uniprotkb:P29034) by pull down (MI:0096)MINT-7710208: FKBP52 (uniprotkb:Q02790) binds (MI:0407) to S100A1 (uniprotkb:P35467) by pull down (MI:0096)MINT-7710265: Cyp40 (uniprotkb:P26882) physically interacts (MI:0915) with S100A1 (uniprotkb:P35467) by competition binding (MI:0405)MINT-7710361: Cyp40 (uniprotkb:P26882) binds (MI:0407) to S100A6 (uniprotkb:P06703) by pull down (MI:0096)MINT-7710476: FKBP52 (uniprotkb:Q02790) physically interacts (MI:0914) with S100A2 (uniprotkb:P29034) and Hsp90 (uniprotkb:P07900) by anti tag coimmunoprecipitation (MI:0007)MINT-7710316: FKBP52 (uniprotkb:Q02790) physically interacts (MI:0914) with S100A1 (uniprotkb:P35467) and Hsp90 (uniprotkb:P07900) by anti tag coimmunoprecipitation (MI:0007)MINT-7710432: FKBP52 (uniprotkb:Q02790) physically interacts (MI:0915) with S100A2 (uniprotkb:P29034) by competition binding (MI:0405)MINT-7710488: FKBP52 (uniprotkb:Q02790) physically interacts (MI:0914) with S100A6 (uniprotkb:P06703) and Hsp90 (uniprotkb:P07900) by anti tag coimmunoprecipitation (MI:0007)MINT-7710329: S100A6 (uniprotkb:P14069) physically interacts (MI:0914) with FKBP52 (uniprotkb:P30416) and Cyp40 (uniprotkb:Q08752) by anti bait coimmunoprecipitation (MI:0006)MINT-7710295: Cyp40 (uniprotkb:P26882) physically interacts (MI:0914) with Hsp90 (uniprotkb:P07900) and S100A1 (uniprotkb:P35467) by anti tag coimmunoprecipitation (MI:0007)     

ARF-dependent regulation of ATM and p53 associated KZNF (Apak) protein activity in response to oncogenic stress

The KRAB-type zinc-finger protein Apak (ATM and p53 associated KZNF protein) specifically suppresses p53-mediated apoptosis. Upon DNA damage, Apak is phosphorylated and inhibited by ATM kinase, resulting in p53 activation. However, how Apak is regulated in response to oncogenic stress remains unknown. Here we show that upon oncogene activation, Apak is inhibited in the tumor suppressor ARF-dependent but ATM-independent manner. Oncogene-induced ARF protein directly interacts with Apak and competes with p53 to bind to Apak, resulting in Apak dissociation from p53. Thus, Apak is differentially regulated in the ARF and ATM-dependent manner in response to oncogenic stress and DNA damage, respectively.

Structured summary

MINT-7989670: p53 (uniprotkb:P04637) binds (MI:0407) to APAK (uniprotkb:Q8TAQ5) by pull down (MI:0096)MINT-7989812: HDM2 (uniprotkb:Q00987) physically interacts (MI:0915) with ARF (uniprotkb:Q8N726-1) by anti bait coimmunoprecipitation (MI:0006)MINT-7989603, MINT-7989626: APAK (uniprotkb:Q8TAQ5) physically interacts (MI:0915) with ARF (uniprotkb:Q8N726-1) by anti bait coimmunoprecipitation (MI:0006)MINT-7989653: ARF (uniprotkb:Q8N726-1) binds (MI:0407) to APAK (uniprotkb:Q8TAQ5) by pull down (MI:0096)MINT-7989686, MINT-7989705, MINT-7989747:APAK (uniprotkb:Q8TAQ5) physically interacts (MI:0915) with ARF (uniprotkb:Q8N726-1) by anti tag coimmunoprecipitation (MI:0007)MINT-7989724: APAK (uniprotkb:Q8TAQ5) physically interacts (MI:0914) with ARF (uniprotkb:Q8N726-1) and p53 (uniprotkb:P04637) by anti tag coimmunoprecipitation (MI:0007)MINT-7989635: ARF (uniprotkb:Q8N726-1) and APAK (uniprotkb:Q8TAQ5) colocalize (MI:0403) by fluorescence microscopy (MI:0416)MINT-7989584, MINT-7989773: APAK (uniprotkb:Q8TAQ5) physically interacts (MI:0915) with p53 (uniprotkb:P04637) by anti tag coimmunoprecipitation (MI:0007)     

Phosphorylation of the eukaryotic initiation factor 3f by cyclin-dependent kinase 11 during apoptosis

eIF3f is a subunit of eukaryotic initiation factor 3 (eIF3). We previously showed that eIF3f is phosphorylated by cyclin dependent kinase 11 (CDK11^p46) which is an important effector in apoptosis. Here, we identified a second eIF3f phosphorylation site (Thr119) by CDK11^p46 during apoptosis. We demonstrated that eIF3f is directly phosphorylated by CDK11^p46 in vivo. Phosphorylation of eIF3f plays an important role in regulating its function in translation and apoptosis. Phosphorylation of eIF3f enhances the association of eIF3f with the core eIF3 subunits during apoptosis. Our data suggested that eIF3f may inhibit translation by increasing the binding to the eIF3 complex during apoptosis.

Structured summary

MINT-6948874: EIF3b (uniprotkb:P55884) physically interacts (MI:0218) with EIF3f (uniprotkb:O00303) by anti bait coimmunoprecipitation (MI:0006)MINT-6948891: EIF3b (uniprotkb:P55884) physically interacts (MI:0218) with EIF3c (uniprotkb:Q99613), EIF3a (uniprotkb:Q14152) and EIF3f (uniprotkb:O00303) by anti bait coimmunoprecipitation (MI:0006)MINT-6948836, MINT-6948849, MINT-6948862: CDK11p46 (uniprotkb:P21127) phosphorylates (MI:0217) EIF3f (uniprotkb:O00303) by protein kinase assay (MI:0424)     

MCC, a new interacting protein for Scrib, is required for cell migration in epithelial cells

To further characterize the molecular events supporting the tumor suppressor activity of Scrib in mammals, we aim to identify new binding partners. We isolated MCC, a recently identified binding partner for β-catenin, as a new interacting protein for Scrib. MCC interacts with both Scrib and the NHERF1/NHERF2/Ezrin complex in a PDZ-dependent manner. In T47D cells, MCC and Scrib proteins colocalize at the cell membrane and reduced expression of MCC results in impaired cell migration. By contrast to Scrib, MCC inhibits cell directed migration independently of Rac1, Cdc42 and PAK activation. Altogether, these results identify MCC as a potential scaffold protein regulating cell movement and able to bind Scrib, β-catenin and NHERF1/2.

Structured summary

MINT-7211022: SCRIB (uniprotkb:Q14160) and MCC (uniprotkb:P23508) colocalize (MI:0403) by fluorescence microscopy (MI:0416)MINT-7210609: SCRIB (uniprotkb:Q14160) physically interacts (MI:0915) with MCC (uniprotkb:P23508) by two hybrid (MI:0018)MINT-7210759, MINT-7210792: SCRIB (uniprotkb:Q14160) physically interacts (MI:0914) with PIX beta (uniprotkb:Q14155) by pull down (MI:0096)MINT-7210883, MINT-7210820: SCRIB (uniprotkb:Q14160) physically interacts (MI:0914) with MCC (uniprotkb:P23508) by anti bait coimmunoprecipitation (MI:0006)MINT-7210634, MINT-7210690, MINT-7210731: SCRIB (uniprotkb:Q14160) physically interacts (MI:0914) with MCC (uniprotkb:P23508) by pull down (MI:0096)MINT-7211267: E6 (uniprotkb:P06463) physically interacts (MI:0915) with SCRIB (uniprotkb:Q14160), SNX27 (uniprotkb:Q96L92), UTRN (uniprotkb:P46939), CASK (uniprotkb:O14936), DMD (uniprotkb:P11532) and Dlg (uniprotkb:Q12959) by pull down (MI:0096)MINT-7211237: MCC (uniprotkb:P23508) physically interacts (MI:0915) with SCRIB (uniprotkb:Q14160), EZR (uniprotkb:P15311), SNX27 (uniprotkb:Q96L92), NHERF1 (uniprotkb:O14745) and NHERF2 (uniprotkb:Q15599) by pull down (MI:0096)     

The fast-mobility isoform of mouse Mcl-1 is a mitochondrial matrix-localized protein with attenuated anti-apoptotic activity

The full-length pro-survival protein Mcl-1 predominantly resides on the outer membrane of mitochondria. Here, we identified a mitochondrial matrix-localized isoform of Mcl-1 that lacks 33 amino acid residues at the N-terminus which serve both as a mitochondrial targeting and processing signal. Ectopically-expressed Mcl-1 without the N-terminal 33 residues failed to enter the mitochondrial matrix but retained wt-like activities both for interaction with BH3-only proteins and anti-apoptosis. In contrast, the mitochondrial matrix-localized isoform failed to interact with BH3-only proteins and manifested an attenuated anti-apoptotic activity. This study reveals that import of Mcl-1 into the mitochondrial matrix results in the attenuation of Mcl-1’s anti-apoptotic function.

Structured summary

MINT-7965637: NOXA (uniprotkb:Q9JM54) physically interacts (MI:0915) with Mcl-1 (uniprotkb:P97287) by anti tag coimmunoprecipitation (MI:0007)MINT-7965699: Mcl-1 (uniprotkb:P97287) physically interacts (MI:0915) with Bim (uniprotkb:O43521) by anti bait coimmunoprecipitation (MI:0006)MINT-7965655: Mcl-1 (uniprotkb:P97287) physically interacts (MI:0915) with NOXA (uniprotkb:Q9JM54) by anti bait coimmunoprecipitation (MI:0006)MINT-7965711: Bim (uniprotkb:O43521) physically interacts (MI:0915) with Mcl-1 (uniprotkb:P97287) by anti tag coimmunoprecipitation (MI:0007)MINT-7965673: PUMA (uniprotkb:Q9BXH1) physically interacts (MI:0915) with Mcl-1 (uniprotkb:P97287) by anti tag coimmunoprecipitation (MI:0007)MINT-7965685: Mcl-1 (uniprotkb:P97287) physically interacts (MI:0915) with PUMA (uniprotkb:Q9BXH1) by anti bait coimmunoprecipitation (MI:0006)     

Evidence for leptin receptor isoforms heteromerization at the cell surface

Leptin mediates its metabolic effects through several leptin receptor (LEP-R) isoforms. In humans, long (LEPRb) and short (LEPRa,c,d) isoforms are generated by alternative splicing. Most of leptin’s effects are believed to be mediated by the OB-Rb isoform. However, the role of short LEPR isoforms and the possible existence of heteromers between different isoforms are poorly understood. Using BRET1 and optimized co-immunoprecipitation, we observed LEPRa/b and LEPRb/c heteromers located at the plasma membrane and stabilized by leptin. Given the widespread coexpression of LEPRa and LEPRb, our results suggest that LEPRa/b heteromers may represent a major receptor species in most tissues.

Structured summary

MINT-7714817: LEPRb (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRb (uniprotkb:P48357-1) by anti tag co-immunoprecipitation (MI:0007)MINT-7714785: LEPRc (uniprotkb:P48357-2) physically interacts (MI:0915) with LEPRc (uniprotkb:P48357-2) by bioluminescence resonance energy transfer (MI:0012)MINT-7714951, MINT-7714744: LEPRa (uniprotkb:P48357-3) physically interacts (MI:0915) with LEPRa (uniprotkb:P48357-3) by bioluminescence resonance energy transfer (MI:0012)MINT-7714859: LEPRb (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRa (uniprotkb:P48357-3) by anti tag co-immunoprecipitation (MI:0007)MINT-7714885, MINT-7714672: LEPRb (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRb (uniprotkb:P48357-1) by bioluminescence resonance energy transfer (MI:0012)MINT-7714835: LEPRa (uniprotkb:P48357-3) physically interacts (MI:0915) with LEPRa (uniprotkb:P48357-3) by anti tag co-immunoprecipitation (MI:0007)MINT-7714914, MINT-7714723, MINT-7714759: LeprB (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRa (uniprotkb:P48357-3) by bioluminescence resonance energy transfer (MI:0012)MINT-7714703, MINT-7714936, MINT-7714772: LEPRb (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRc (uniprotkb:P48357-2) by bioluminescence resonance energy transfer (MI:0012)MINT-7714872: LEPRb (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRc (uniprotkb:P48357-2) by anti tag co-immunoprecipitation (MI:0007)     

Interaction specificity of Arabidopsis 14-3-3 proteins with phototropin receptor kinases

Phototropin receptor kinases play an important role in optimising plant growth in response to blue light. Much is known regarding their photochemical reactivity, yet little progress has been made to identify downstream signalling components. Here, we isolated several interacting proteins for Arabidopsis phototropin 1 (phot1) by yeast two-hybrid screening. These include members of the NPH3/RPT2 (NRL) protein family, proteins associated with vesicle trafficking, and the 14-3-3 lambda (λ) isoform from Arabidopsis. 14-3-3λ and phot1 were found to colocalise and interact in vivo. Moreover, 14-3-3 binding to phot1 was limited to non-epsilon 14-3-3 isoforms and was dependent on key sites of receptor autophosphorylation. No 14-3-3 binding was detected for Arabidopsis phot2, suggesting that 14-3-3 proteins are specific to phot1 signalling.

Structured summary

MINT-7146953: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with ARF7 (uniprotkb:Q9LFJ7) by two hybrid (MI:0018)MINT-7147335: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 phi (uniprotkb:P46077) by far Western blotting (MI:0047)MINT-7146854: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with RPT2 (uniprotkb:Q682S0) by two hybrid (MI:0018)MINT-7147215: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 lambda (uniprotkb:P48349) by anti tag coimmunoprecipitation (MI:0007)MINT-7147044, MINT-7147185, MINT-7147200, MINT-7147413: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 lambda (uniprotkb:P48349) by far Western blotting (MI:0047)MINT-7146983: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with 14-3-3 lambda (uniprotkb:P48349) by two hybrid (MI:0018)MINT-7146871: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with NPH3-like (uniprotkb:Q9S9Q9) by two hybrid (MI:0018)MINT-7146905: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with ARF2 (uniprotkb:Q9M1P5) by two hybrid (MI:0018)MINT-7147364: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 upsilon (uniprotkb:P42645) by far Western blotting (MI:0047)MINT-7147234: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 kappa (uniprotkb:P48348) by far Western blotting (MI:0047)     

Excitatory amino acid transporter 2 associates with phosphorylated tau and is localized in neurofibrillary tangles of tauopathic brains

Phosphorylated tau (p-tau) is the principal component of neurofibrillary tangles, a pathological hallmark, and likely plays a neurotoxic role in tauopathies including Alzheimer’s disease (AD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). We subjected brains from autopsy cases of AD, PSP, and CBD to a variety of immunohistochemical, immunoblotting, and pull-down assays. In this study, we show that excitatory amino acid transporter 2 (EAAT2) preferentially interacted with phosphorylated tau and was localized in neurofibrillary tangles in the brains of such patients. These results strongly indicate that EAAT2 acts in tauopathy-related neurodegeneration, and abnormalities in glutamate transport play an important role in the pathogenesis of tauopathies.

Structured summary

MINT-7148349, MINT-7148361:TAU (uniprotkb:P10636) physically interacts (MI:0914) with EAAT2 (uniprotkb:P43004) by pull-down (MI:0096)MINT-7148372, MINT-7148384:TAU (uniprotkb:P10636) physically interacts (MI:0914) with EAAT2 (uniprotkb:P43004) by anti bait coimmunoprecipitation (MI:0006)     

BS69 negatively regulates the canonical NF-κB activation induced by Epstein-Barr virus-derived LMP1

Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) activates NF-κB signaling pathways through the two C-terminal regions, CTAR1 and CTAR2. BS69 has previously been shown to be involved in LMP1-induced c-Jun N-terminal kinase activation through CTAR2 by interacting with tumor necrosis factor (TNFR) receptor-associated factor 6. In the present study, our manipulation of BS69 expression clearly indicates that BS69 negatively regulates LMP1-mediated NF-κB activation and up-regulates IL-6 mRNA expression and IκB degradation. Our immunoprecipitation experiments suggest that BS69 decreases complex formation between LMP1 and TNFR-associated death domain protein (TRADD).

Structured summary

MINT-7032462: LMP1 (uniprotkb:P03230) physically interacts (MI:0218) with TRADD (uniprotkb:Q15628) by anti bait coimmunoprecipitation (MI:0006)MINT-7032451: BS69 (uniprotkb:Q15326) and LMP1 (uniprotkb:P03230) colocalize (MI:0403) by fluorescence microscopy (MI:0416)MINT-7032478: LMP1 (uniprotkb:P03230) physically interacts (MI:0218) with BRAM1 (uniprotkb:Q15326) by anti bait coimmunoprecipitation (MI:0006)     

Polo-like kinase-1 phosphorylates MDM2 at Ser260 and stimulates MDM2-mediated p53 turnover

The E3 ubiqutin ligase, murne double-minute clone 2 (MDM2), promotes the degradation of p53 under normal homeostatic conditions. Several serine residues within the acidic domain of MDM2 are phosphorylated to maintain its activity but become hypo-phosphorylated following DNA damage, leading to inactivation of MDM2 and induction of p53. However, the signalling pathways that mediate these phosphorylation events are not fully understood. Here we show that the oncogenic and cell cycle-regulatory protein kinase, polo-like kinase-1 (PLK1), phosphorylates MDM2 at one of these residues, Ser260, and stimulates MDM2-mediated turnover of p53. These data are consistent with the idea that deregulation of PLK1 during tumourigenesis may help suppress p53 function.

Structured summary

MINT-7266353: MDM2 (uniprotkb:Q00987) physically interacts (MI:0915) with PLK1 (uniprotkb:P53350) by pull down (MI:0096)MINT-7266344, MINT-7266329: MDM2 (uniprotkb:Q00987) physically interacts (MI:0915) with PLK1 (uniprotkb:P53350) by anti bait coimmunoprecipitation (MI:0006)MINT-7266250: PLK1 (uniprotkb:P53350) phosphorylates (MI:0217) p53 (uniprotkb:P04637) by protein kinase assay (MI:0424)MINT-7266241, MINT-7266318: PLK1 (uniprotkb:P53350) phosphorylates (MI:0217) MDM2 (uniprotkb:P23804) by protein kinase assay (MI:0424)MINT-7266231, MINT-7266805, MINT-7266264, MINT-7266299: PLK1 (uniprotkb:P53350) phosphorylates (MI:0217) MDM2 (uniprotkb:Q00987) by protein kinase assay (MI:0424)