Mcl-1 fragment induces apoptosis through direct interaction with Bax

Mcl-1 full-length (Mcl-1^1-350), a tightly regulated protein, plays an important role in protecting cells against apoptosis. Cleavage of Mcl-1 at Asp127 by caspase (Mcl-1^C1) contributes to the regulation of Mcl-1 expression, but its pro-apoptotic function remains controversial. Here, we reported that Mcl-1^128-350 expression induced caspase-dependent apoptosis. We demonstrated that Mcl-1^128-350 but not Mcl-1^1-350 interacts with Bax. This interaction required an intact BH3 Mcl-1^128-350 domain and leads to Bax activation and translocation to mitochondria. The silencing of Bax, but not of Bak, prevented Mcl-1^128-350 induced apoptosis. In conclusion, Mcl-1^128-350 exerts a pro-apoptotic function governed by its capacity to interact with Bax.

Structured summary

MINT-7306752: Mcl-1 (uniprotkb:Q07820) physically interacts (MI:0915) with BAK (uniprotkb:Q16611) by anti tag coimmunoprecipitation (MI:0007)MINT-7306728: Mcl-1 (uniprotkb:Q07820) physically interacts (MI:0914) with BAX (uniprotkb:Q07812) and BAK (uniprotkb:Q16611) by anti tag coimmunoprecipitation (MI:0007)MINT-7307171: F1 ATPase (uniprotkb:Q5TC12), Mcl-1 (uniprotkb:Q07820) and BAX (uniprotkb:Q07812) colocalize (MI:0403) by cosedimentation through density gradients (MI:0029)     

BS69 cooperates with TRAF3 in the regulation of Epstein-Barr virus-derived LMP1/CTAR1-induced NF-κB activation

Epstein-Barr virus latent membrane protein 1 (LMP1) activates NF-κB signaling pathways through two C-terminal regions, CTAR1 and CTAR2. Previous studies have demonstrated that BS69, a multidomain cellular protein, regulates LMP1/CTAR2-mediated NF-κB activation by interfering with the complex formation between TRADD and LMP1/CTAR2. Here, we found that BS69 directly interacted with the LMP1/CTAR1 domain and regulated LMP1/CTAR1-mediated NF-κB activation and subsequent IL-6 production. Regarding the mechanisms involved, we found that BS69 directly interacted with TRAF3, a negative regulator of NF-κB activation. Furthermore, small-interfering RNA-mediated knockdown experiments revealed that TRAF3 was involved in the BS69-mediated suppression of LMP1/CTAR1-induced NF-κB activation.

Structured summary

MINT-7556591: lmp1 (uniprotkb:P03230) physically interacts (MI:0915) with BS69 (uniprotkb:Q15326) by anti tag coimmunoprecipitation (MI:0007)MINT-7556646: TRAF6 (uniprotkb:Q9Y4K3) physically interacts (MI:0915) with BS69 (uniprotkb:Q15326) by anti tag coimmunoprecipitation (MI:0007)MINT-7556658, MINT-7556670: TRAF3 (uniprotkb:Q13114) physically interacts (MI:0915) with BS69 (uniprotkb:Q15326) by anti tag coimmunoprecipitation (MI:0007)MINT-7556607: TRAF1 (uniprotkb:Q13077) physically interacts (MI:0915) with BS69 (uniprotkb:Q15326) by anti tag coimmunoprecipitation (MI:0007)MINT-7556634: TRAF5 (uniprotkb:O00463) physically interacts (MI:0915) with BS69 (uniprotkb:Q15326) by anti tag coimmunoprecipitation (MI:0007)MINT-7556622: TRAF2 (uniprotkb:Q12933) physically interacts (MI:0915) with BS69 (uniprotkb:Q15326) by anti tag coimmunoprecipitation (MI:0007)     

β2-Chimaerin binds to EphA receptors and regulates cell migration

Ephrins and Eph receptors have key roles in regulation of cell migration during development. We found that the RacGAP β2-chimaerin (chimerin) bound to EphA2 and EphA4 and inactivated Rac1 in response to ephrinA1 stimulation. EphA4 bound to β2-chimaerin through its kinase domain and promoted binding of Rac1 to β2-chimaerin. In addition, knockdown of endogenous β2-chimaerin blocked ephrinA1-induced suppression of cell migration. These results suggest that β2-chimaerin is activated by EphA receptors and mediates the EphA receptor-dependent regulation of cell migration.

Structured summary

MINT-7013428: EphA1 (uniprotkb:Q60750) physically interacts (MI:0218) with Chimaerin beta 2 (uniprotkb:Q80XD1-2) and EphA4 (uniprotkb:O08542) by anti tag coimmunoprecipitation (MI:0007)MINT-7013515: Chimaerin beta 2 (uniprotkb:Q80XD1-2) physically interacts (MI:0218) with Rac1 (uniprotkb:P63001) by anti tag coimmunoprecipitation (MI:0007)MINT-7013410: EphA1 (uniprotkb:Q60750) physically interacts (MI:0218) with Chimaerin beta 1 (uniprotkb:Q80XD1-1) and EphA4 (uniprotkb:O08542) by anti tag coimmunoprecipitation (MI:0007)MINT-7013503: Chimaerin beta 1 (uniprotkb:Q80XD1-1) physically interacts (MI:0218) with EphA4 (uniprotkb:O08542) by anti tag coimmunoprecipitation (MI:0007)MINT-7013472: Chimaerin beta 2 (uniprotkb:Q80XD1-2) physically interacts (MI:0218) with EphA2 (uniprotkb:O43921) by anti tag coimmunoprecipitation (MI:0007)MINT-7013450: EphA1 (uniprotkb:Q60750) physically interacts (MI:0218) with EphA2 (uniprotkb:O43921) and Chimaerin beta 2 (uniprotkb:P52757-1) by anti tag coimmunoprecipitation (MI:0007)MINT-7013491: Chimaerin beta 2 (uniprotkb:Q80XD1-2) physically interacts (MI:0218) with EphA4 (uniprotkb:O08542) by anti tag coimmunoprecipitation (MI:0007)     

Identification of LRP1B-interacting proteins and inhibition of protein kinase Cα-phosphorylation of LRP1B by association with PICK1

Recent studies show LDL receptor-related protein 1B, LRP1B as a transducer of extracellular signals. Here, we identify six interacting partners of the LRP1B cytoplasmic region by yeast two-hybrid screen and confirmed their in vivo binding by immunoprecipitation. One of the partners, PICK1 recognizes the C-terminus of LRP1B and LRP1. The cytoplasmic domains of LRP1B are phosphorylated by PKCα about 100 times more efficiently than LRP1. Binding of PICK1 inhibits phosphorylation of LRP1B, but does not affect LRP1 phosphorylation.This study presents the possibility that LRP1B participates in signal transduction which PICK1 may regulate by inhibiting PKCα phosphorylation of LRP1B.

Structured summary

MINT-6801075: Lrp1b (uniprotkb:Q9JI18) physically interacts (MI:0218) with SNTG2 (uniprotkb:Q925E0) by two hybrid (MI:0018)MINT-6801030, MINT-6801468: Lrp1b (uniprotkb:Q9JI18) physically interacts (MI:0218) with Pick1 (uniprotkb:Q80VC8) by two hybrid (MI:0018)MINT-6801284: LRP1B4 (uniprotkb:Q9JI18) physically interacts (MI:0218) with RanBPM (uniprotkb:P69566) by anti tag coimmunoprecipitation (MI:0007)MINT-6801108: Lrp1b (uniprotkb:Q9JI18) physically interacts (MI:0218) with Grb7 (uniprotkb:Q03160) by two hybrid (MI:0018)MINT-6801090: Lrp1b (uniprotkb:Q9JI18) physically interacts (MI:0218) with RanBPM (uniprotkb:P69566) by two hybrid (MI:0018)MINT-6801008: Lrp1b (uniprotkb:Q9JI18) physically interacts (MI:0218) with Jip-1b (uniprotkb:Q9WVI9-1) by two hybrid (MI:0018)MINT-6801052: Lrp1b (uniprotkb:Q9JI18) physically interacts (MI:0218) with Jip-2 (uniprotkb:Q9ERE9) by two hybrid (MI:0018)MINT-6801258, MINT-6801271: LRP1B4 (uniprotkb:Q9JI18) physically interacts (MI:0218) with Pick1 (uniprotkb:Q80VC8) by anti tag coimmunoprecipitation (MI:0007)MINT-6801244: RanBPM (uniprotkb:P69566) physically interacts (MI:0218) with mLRP4 (uniprotkb:Q8VI56) by anti tag coimmunoprecipitation (MI:0007)MINT-6801131, MINT-6801158: LRP1B4 (uniprotkb:Q9JI18) physically interacts (MI:0218) with Jip-1b (uniprotkb:Q9WVI9-1) by anti tag coimmunoprecipitation (MI:0007)MINT-6801231: PICK1 (uniprotkb:Q80VC8) physically interacts (MI:0218) with mLRP4 (uniprotkb:Q8VI56) by anti tag coimmunoprecipitation (MI:0007)MINT-6801173: Jip-1b (uniprotkb:Q9WVI9-1) physically interacts (MI:0218) with mLRP4 (uniprotkb:Q8VI56) by anti tag coimmunoprecipitation (MI:0007)     

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)     

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)     

Regulation of HOXA2 gene expression by the ATP-dependent chromatin remodeling enzyme CHD8

Chromodomain, helicase, DNA-binding protein 8 (CHD8) is an ATP-dependent chromatin remodeling enzyme that has been demonstrated to exist within a large protein complex which includes WDR5, Ash2L, and RbBP5, members of the Mixed Lineage Leukemia (MLL) histone modifying complexes. Here we show that CHD8 relocalizes to the promoter of the MLL regulated gene HOXA2 upon gene activation. Depletion of CHD8 enhances HOXA2 expression under activating conditions. Furthermore, depletion of CHD8 results in a loss of the WDR5/Ash2L/RbBP5 subcomplex, and consequently H3K4 trimethylation, at the HOXA2 promoter. These studies suggest that CHD8 alters HOXA2 gene expression and regulates the recruitment of chromatin modifying enzymes.

Structured summary

MINT-7542810: CHD8 (uniprotkb:Q9HCK8) physically interacts (MI:0915) with RbBP5 (uniprotkb:Q15291) by anti tag coimmunoprecipitation (MI:0007)MINT-7542794: CHD8 (uniprotkb:Q9HCK8) physically interacts (MI:0915) with WDR5 (uniprotkb:P61964) by anti tag coimmunoprecipitation (MI:0007)MINT-7542820: CHD8 (uniprotkb:Q9HCK8) physically interacts (MI:0915) with ASH2L (uniprotkb:Q9UBL3) by anti tag coimmunoprecipitation (MI:0007)MINT-7542769: CHD8 (uniprotkb:Q9HCK8) physically interacts (MI:0914) with RbBP5 (uniprotkb:Q15291), ASH2L (uniprotkb:Q9UBL3) and WDR5 (uniprotkb:P61964) by anti tag coimmunoprecipitation (MI:0007)     

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)     

Programmed cell death-2 isoform1 is ubiquitinated by parkin and increased in the substantia nigra of patients with autosomal recessive Parkinson’s disease

Mutations in parkin gene are responsible for autosomal recessive Parkinson’s disease (ARPD) and its loss-of-function is assumed to affect parkin ubiquitin ligase activity. Accumulation of its substrate may induce dopaminergic neurodegeneration in the substantia nigra (SN) of ARPD. Here, we show that parkin interacts with programmed cell death-2 isoform 1 (PDCD2-1) and promotes its ubiquitination. Furthermore, accumulation of PDCD2-1 was found in the SN of ARPD as well as in sporadic PD, suggesting that common failure of the ubiquitin-proteasome system is associated with neuronal death in both ARPD and sporadic PD.Structured summary:MINT-6805975, MINT-6806032, MINT-6806051, MINT-6806070:PDCD2 (uniprotkb:Q16342) physically interacts (MI:0218) with Parkin (uniprotkb:O60260) by anti tag coimmunoprecipitation (MI:0007)MINT-6805947:Parkin (uniprotkb:O60260) physically interacts (MI:0218) with PDCD2 (uniprotkb:Q16342) by two hybrid (MI:0018)MINT-6806000: PDCD2 (uniprotkb:Q16342) physically interacts (MI:0218) with ubiquitin (uniprotkb:P62988) by anti tag coimmunoprecipitation (MI:0007).     

C-mip interacts with the p85 subunit of PI3 kinase and exerts a dual effect on ERK signaling via the recruitment of Dip1 and DAP kinase

In naive T cells, Lck exerts a negative control on the ERK/MAPK pathway. We show that c-mip (c-maf inducing protein) interacts with the p85 subunit of PI3 kinase and inactivates Lck, which results in Erk1/2 and p38 MAPK activation. This effect is not enough to activate AP1 given the inability of ERK to migrate into the nucleus and to transactivate its target genes. We demonstrate that c-mip interacts with Dip1 and upregulates DAPK, which blocks the nuclear translocation of ERK1/2. This dual effect of c-mip is unique and might represent a potential mechanism to prevent the development of an immune response.

Structured summary

MINT-7383650: p85 (uniprotkb:P27986) physically interacts (MI:0915) with c-Mip (uniprotkb:Q8IY22) by anti bait coimmunoprecipitation (MI:0006)MINT-7383661: c-Mip (uniprotkb:Q8IY22) physically interacts (MI:0915) with p85 (uniprotkb:P27986) by anti tag coimmunoprecipitation (MI:0007)MINT-7383676: p85 (uniprotkb:P27986) physically interacts (MI:0915) with p110 (uniprotkb:P42336) by anti bait coimmunoprecipitation (MI:0006)MINT-7383689, MINT-7383711: Dip-1 (uniprotkb:Q80SY4) physically interacts (MI:0915) with c-Mip (uniprotkb:Q8IY22) by anti tag coimmunoprecipitation (MI:0007)     

Serine 62 is a phosphorylation site in folliculin, the Birt-Hogg-Dubé gene product

Recently, it was reported that the product of Birt-Hogg-Dubé syndrome gene (folliculin, FLCN) is directly phosphorylated by 5′-AMP-activated protein kinase (AMPK). In this study, we identified serine 62 (Ser62) as a phosphorylation site in FLCN and generated an anti-phospho-Ser62-FLCN antibody. Our analysis suggests that Ser62 phosphorylation is indirectly up-regulated by AMPK and that another residue is directly phosphorylated by AMPK. By binding with FLCN-interacting proteins (FNIP1 and FNIP2/FNIPL), Ser62 phosphorylation is increased. A phospho-mimic mutation at Ser62 enhanced the formation of the FLCN-AMPK complex. These results suggest that function(s) of FLCN-AMPK-FNIP complex is regulated by Ser62 phosphorylation.

Structured summary

MINT-7298145, MINT-7298166: Flcn (uniprotkb:Q76JQ2) physically interacts (MI:0915) with AMPK alpha 1 (uniprotkb:P54645) by anti tag coimmunoprecipitation (MI:0007)MINT-7298267: AMPK alpha 1 (uniprotkb:Q13131) phosphorylates (MI:0217) tsc2 (uniprotkb:P49816) by protein kinase assay (MI:0424)MINT-7298182: FNIP1 (uniprotkb:Q8TF40) physically interacts (MI:0915) with Flcn (uniprotkb:Q76JQ2) by anti tag coimmunoprecipitation (MI:0007)MINT-7298132: AMPK alpha 1 (uniprotkb:Q13131) phosphorylates (MI:0217) Flcn (uniprotkb:Q76JQ2) by protein kinase assay (MI:0424)MINT-7298229: FNIPL (uniprotkb:Q9P278) physically interacts (MI:0915) with Flcn (uniprotkb:Q76JQ2) by anti tag coimmunoprecipitation (MI:0007)     

Nuclear import of Pin1 is mediated by a novel sequence in the PPIase domain

Pin1 actively regulates diverse biological/pathological processes, but little is known about the regulatory mechanisms of its cellular localization. In this study, we report that the endogenous Pin1 is distributed in both nucleus and cytoplasm. We found that point mutations of several basic amino acids in the PPIase domain of Pin1 significantly compromise its nuclear localization. Such inhibition is independent of Pin1 enzymatic activity, and is mainly due to the defects in the nuclear import. A novel sequence harboring these residues was identified as a putative nuclear localization signal (NLS) of Pin1. Importin α5 of the nuclear import machinery was found to interact with Pin1.

Structured summary:

MINT-6803320: PIN1 (uniprotkb:Q13255) and importin alpha 5 (uniprotkb:P52294) physically interact (MI:0218) by anti tag coimmunoprecipitation (MI:0007)MINT-6803333: importin alpha 3 (uniprotkb:O00505) and PIN1 (uniprotkb:Q13255) physically interact (MI:0218) by anti tag coimmunoprecipitation (MI:0007)MINT-6803357: PIN1 (uniprotkb:Q13255) physically interacts (MI:0218) with importin alpha 5 (uniprotkb:P52294) by anti bait coimmunoprecipitation (MI:0006)MINT-6803345: St3 (uniprotkb:P40763) and importin alpha 5 (uniprotkb:P52294) physically interact (MI:0218) by anti tag coimmunoprecipitation (MI:0007)     

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)     

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)     

p53 inhibits tumor cell invasion via the degradation of snail protein in hepatocellular carcinoma

The tumor suppressor protein p53 is a key regulator of cell cycle arrest and apoptosis. Snail protein regulates cancer-associated malignancies. However, the relationship between p53 and Snail proteins in hepatocellular carcinoma (HCC) has not been completely understood. To determine whether Snail and p53 contribute to hepatocarcinogenesis, we analyzed the expression of Snail proteins in p53-overexpressing HCC cells. We found that p53 wild-type (WT) induced the degradation of Snail protein via murine double minute 2-mediated ubiquitination, whereas p53 mutant did not induce Snail degradation. As we expected, only p53WT induced endogenous Snail protein degradation and inhibited tumor cell invasion. These findings contribute to a better understanding of the role of p53 mutation and Snail overexpression as a late event in hepatocarcinogenesis.

Structured summary

MINT-7718917: p53 (uniprotkb:P04637) physically interacts (MI:0915) with Snai1 (uniprotkb:O95863) by anti bait coimmunoprecipitation (MI:0006)MINT-7719877: Snai1 (uniprotkb:O95863) physically interacts (MI:0915) with ubiquitin (uniprotkb:P62988) by anti tag coimmunoprecipitation (MI:0007)MINT-7718928: Snai1 (uniprotkb:O95863) physically interacts (MI:0915) with p53 (uniprotkb:P04637) by anti tag coimmunoprecipitation (MI:0007)MINT-7718939: Snai1 (uniprotkb:O95863) physically interacts (MI:0915) with MDM2 (uniprotkb:Q00987) by anti tag coimmunoprecipitation (MI:0007)     

The scaffold protein JIP3 functions as a downstream effector of the small GTPase ARF6 to regulate neurite morphogenesis of cortical neurons

The small GTPase ADP-ribosylation factor 6 (ARF6) plays crucial roles in a wide variety of cell functions. To better understand the molecular mechanisms of ARF6-mediated signaling and cellular functions, we sought new ARF6-binding proteins in the mouse brain. We identified the signaling scaffold protein JNK-interacting protein 3 (JIP3), which is exclusively expressed in neurons, as a downstream effector of ARF6. Overexpression of a unique dominant negative mutant of ARF6, which was unable to interact with JIP3, and knockdown of JIP3 in mouse cortical neurons stimulated the elongation and branching of neurites. These results provide evidence that ARF6/JIP3 signaling regulates neurite morphogenesis.

Structured summary

MINT-7892698: PIP5K gamma 661 (uniprotkb:O70161) physically interacts (MI:0915) with Arf6 (uniprotkb:P62331) by anti tag coimmunoprecipitation (MI:0007)MINT-7892333, MINT-7892573, MINT-7892594, MINT-7892629, MINT-7892644, MINT-7892522, MINT-7892716: Arf6 (uniprotkb:P62331) physically interacts (MI:0915) with JLP (uniprotkb:Q58A65) by anti tag coimmunoprecipitation (MI:0007)MINT-7892509: Arf6 (uniprotkb:P62331) physically interacts (MI:0915) with JIP3 (uniprotkb:Q9ESN9) by pull down (MI:0096)MINT-7892770: Arf6 (uniprotkb:P62331) binds (MI:0407) to JIP3 (uniprotkb:Q9ESN9) by pull down (MI:0096)MINT-7892755: Arf6 (uniprotkb:P62331) binds (MI:0407) to JLP (uniprotkb:Q58A65) by pull down (MI:0096)MINT-7892289, MINT-7892314: Arf6 (uniprotkb:P62331) physically interacts (MI:0915) with JLP (uniprotkb:Q58A65) by pull down (MI:0096)MINT-7892353, MINT-7892615, MINT-7892657, MINT-7892672, MINT-7892549, MINT-7892738: Arf6 (uniprotkb:P62331) physically interacts (MI:0915) with JIP3 (uniprotkb:Q9ESN9) by anti tag coimmunoprecipitation (MI:0007)