• BMB Reports
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• v.51 no.9
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• pp.425-426
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• 2018

As highly conserved signaling cascades of multicellular organisms, Wnt and Hippo pathways control a wide range of cellular activities, including cell adhesion, fate determination, cell cycle, motility, polarity, and metabolism. Dysregulation of those pathways are implicated in many human diseases, including cancer. Similarly to ${\beta}-catenin$ in the Wnt pathway, the YAP transcription co-activator is a major player in Hippo. Although the intracellular dynamics of YAP are well-known to largely depend on phosphorylation by LATS and AMPK kinases, the molecular effector of YAP cytosolic translocation remains unidentified. Recently, we reported that the Dishevelled (DVL), a key scaffolding protein between canonical and non-canonical Wnt pathway, is responsible for nuclear export of phosphorylated YAP. The DVL is also required for YAP intracellular trafficking induced by E-cadherin, ${\alpha}-catenin$, or metabolic stress. Note that the p53/LATS2 and LKB1/AMPK tumor suppressor axes, commonly inactivated in human cancer, govern the reciprocal inhibition between DVL and YAP. Conversely, loss of the tumor suppressor allows co-activation of YAP and Wnt independent of epithelial polarity or contact inhibition in human cancer. These observations provide novel mechanistic insight into (1) a tight molecular connection merging the Wnt and Hippo pathways, and (2) the importance of tumor suppressor contexts with respect to controlled proliferation and epithelial polarity regulated by cell adhesion.

• Journal of Life Science
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• v.30 no.1
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• pp.106-112
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• 2020

Aminoacyl tRNA synthetase complex interacting multifunctional protein 2 (AIMP2) is a scaffolding protein required for the assembly of multi-tRNA synthetase, and it can exert pro-apoptotic activity in response to DNA damage. In the presence of DNA damage, AIMP2 binds to mouse double minute 2 homolog (MDM2) to protect p53 from MDM2 attack. TGF-β signaling results in the nuclear translocation of AIMP2, whereby AIMP2 interacts with FUSE-binding protein, and, thus, suppresses c-myc. TNF receptor-associated factor 2 (TRAF2) is an important mediator between TNF-receptors 1 and 2 which are involved in the signaling of c-Jun N-terminal kinase (JNK), nuclear factor κB (NF-κB), and p38 mitogen-activated protein kinases (MAPKs). TRAF2 is required for the activations of JNK and NF-κB via TNF-α and the mediation of anti-apoptosis signaling. AIMP2 can also enhance pro-apoptosis in the TNF-α signaling. During this signaling, AIMP2 assists the association of E3 ubiquitin ligase, the cellular inhibitor of apoptosis protein 1 (c-IAP1) which is well known and responsible for the degradation of TRAF2. The formation of a complex among AIMP2, TRAF2, and c-IAP1 results in proteasome-mediated TRAF2 degradation. AIMP2 can induce apoptosis via downregulation of TRAF2 to interact directly in TNF-α signaling. This review provides new insight into the molecular mechanism responsible for AIMP2 and TRAF2 complex formation and treatments for TNFα-associated diseases.

• Journal of Life Science
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• v.26 no.8
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• pp.963-969
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• 2016

Kinesin superfamily proteins (KIFs) are microtubule-dependent molecular motor proteins essential for the intracellular transport of organelles and protein complexes in cells. Kinesin 1 is a member of those KIFs that transport various cargoes, including organelles, synaptic vesicles, neurotransmitter receptors, cell signaling molecules, and mRNAs through interaction between its light chain subunit and the cargoes. Kinesin light chains (KLCs) are non-motor subunits that associate with the kinesin heavy chain (KHC) dimer. KLCs interact with many different binding proteins, but their particular binding proteins have not yet been fully identified. We used the yeast two-hybrid assay to identify proteins that interact with the tetratricopeptide repeat (TPR) domain of KLC1. We found an interaction between the TPR domain of KLC1 and Wiskott-Aldrich syndrome protein family member 1 (WAVE1), a member of the WASP/WAVE family involved in regulation of actin cytoskeleton. WAVE1 bound to the six TPR domain-containing regions of KLC1 and did not interact with KHCs (KIF5A, KIF5B, and KIF5C) in the yeast two-hybrid assay. The carboxyl (C)-terminal verprolin-cofilin-acidic (VCA) domain of WAVE1 is essential for interaction with KLC1. Also, other WAVE isoforms (WAVE2 and WAVE3) interacted with KLC1 in the yeast two-hybrid assay. When co-expressed in HEK-293T cells, WAVE1 co-localized with KLC1 and co-immunoprecipitated with KLC1 and KIF5B. These results suggest that kinesin 1 motor protein may transport WAVE complexes or WAVE-coated cargoes in cells.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1206-1212
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• 2023

The Wnt/β-catenin pathway plays essential roles in regulating various cellular behaviors, including proliferation, survival, and differentiation [1-3]. The intracellular β-catenin level, which is regulated by a proteasomal degradation pathway, is critical to Wnt/β-catenin pathway control [4]. Normally, casein kinase 1 (CK1) and glycogen synthase kinase-3β (GSK-3β), which form a complex with the scaffolding protein Axin and the tumor suppressor protein adenomatous polyposis coli (APC), phosphorylate β-catenin at Ser45, Thr41, Ser37, and Ser33 [5, 6]. Phosphorylated β-catenin is ubiquitinated by the β-transducin repeat-containing protein (β-TrCP), an F-box E3 ubiquitin ligase complex, and ubiquitinated β-catenin is degraded via a proteasome pathway [7, 8]. Colorectal cancer is a significant cause of cancer-related deaths worldwide. Abnormal up-regulation of the Wnt/β-catenin pathway is a major pathological event in intestinal epithelial cells during human colorectal cancer oncogenesis [9]. Genetic mutations in the APC gene are observed in familial adenomatous polyposis coli (FAP) and sporadic colorectal cancers [10]. In addition, mutations in the N-terminal phosphorylation motif of the β-catenin gene were found in patients with colorectal cancer [11]. These mutations cause β-catenin to accumulate in the nucleus, where it forms complexes with transcription factors of the T-cell factor/lymphocyte enhancer factor (TCF/LEF) family to stimulate the expression of β-catenin responsive genes, such as c-Myc and cyclin D1, which leads to colorectal tumorigenesis [12-14]. Therefore, downregulating β-catenin response transcription (CRT) is a potential strategy for preventing and treating colorectal cancer. Plant cytokinins are N⁶-substituted purine derivatives; they promote cell division in plants and regulate developmental pathways. Natural cytokinins are classified as isoprenoid (isopentenyladenine, zeatin, and dihydrozeatin), aromatic (benzyladenine, topolin, and methoxytopolin), or furfural (kinetin and kinetin riboside), depending on their structure [15, 16]. Kinetin riboside was identified in coconut water and is a naturally produced cytokinin that induces apoptosis and exhibits antiproliferative activity in several human cancer cell lines [17]. However, little attention has been paid to kinetin riboside's mode of action. In this study, we show that kinetin riboside exerts its cytotoxic activity against colon cancer cells by suppressing the Wnt/β-catenin pathway and promoting intracellular β-catenin degradation.

• Journal of Life Science
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• v.25 no.5
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• pp.594-600
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• 2015

Protein-protein interactions have a critical role in the regulation of many cellular functions. Postsynaptic density-95/disks large/zonula occludens-1 (PDZ) domain is one of domains that mediate protein-protein interactions. PDZ domains typically bind to the specific motif at the carboxyl (C)-terminal end of partner proteins. Multi-PDZ domain protein 1 (MUPP1), which has 13 PDZ domains, serves a scaffolding function for structure proteins and signaling proteins, but the cellular function of MUPP1 has not been fully elucidated. We used the yeast two-hybrid system to identify proteins that interact with PDZ domains of MUPP1. We found an interaction between MUPP1 and muskelin. Muskelin was recently identified as a GABA_A receptor (GABA_AR) α1 subunit binding protein and known to have a role in receptor endocytosis and degradation. Muskelin bound to the 3^rd PDZ domain, but not to other PDZ domains of MUPP1. The C-terminal end of muskelin was essential for the interaction with MUPP1 in the yeast two-hybrid assay. When co-expressed in HEK-293T cells, muskelin but not the C-terminal deleted muskelin was co-immunoprecipitated with MUPP1. In addition, MUPP1 co-localized with muskelin at the same subcellular region in cells. These findings collectively suggest that MUPP1 or its interacting proteins could modulate GABA_AR trafficking and turnover through the interaction with muskelin.

• Journal of Ginseng Research
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• v.47 no.6
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• pp.755-765
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• 2023

Background: Caveolin-1, the scaffolding protein of cholesterol-rich invaginations, plays an important role in store-operated Ca²⁺ influx and its phosphorylation at Tyr14 (p-caveolin-1) is vital to mobilize protection against myocardial ischemia (MI) injury. SOCE, comprising STIM1, ORAI1 and TRPC1, contributes to intracellular Ca²⁺ ([Ca²⁺]_i) accumulation in cardiomyocytes. The purified extract of steamed Panax ginseng (EPG) attenuated [Ca²⁺]_i overload against MI injury. Thus, the aim of this study was to investigate the possibility of EPG affecting p-caveolin-1 to further mediate SOCE/[Ca²⁺]_i against MI injury in neonatal rat cardiomyocytes and a rat model. Methods: PP2, an inhibitor of p-caveolin-1, was used. Cell viability, [Ca²⁺]_i concentration were analyzed in cardiomyocytes. In rats, myocardial infarct size, pathological damages, apoptosis and cardiac fibrosis were evaluated, p-caveolin-1 and STIM1 were detected by immunofluorescence, and the levels of caveolin-1, STIM1, ORAI1 and TRPC1 were determined by RT-PCR and Western blot. And, release of LDH, cTnI and BNP was measured. Results: EPG, ginsenosides accounting for 57.96%, suppressed release of LDH, cTnI and BNP, and protected cardiomyocytes by inhibiting Ca²⁺ influx. And, EPG significantly relieved myocardial infarct size, cardiac apoptosis, fibrosis, and ultrastructure abnormality. Moreover, EPG negatively regulated SOCE via increasing p-caveolin-1 protein, decreasing ORAI1 mRNA and protein levels of ORAI1, TRPC1 and STIM1. More importantly, inhibition of the p-caveolin-1 significantly suppressed all of the above cardioprotection of EPG. Conclusions: Caveolin-1 phosphorylation is involved in the protective effects of EPG against MI injury via increasing p-caveolin-1 to negatively regulate SOCE/[Ca²⁺]_i.

• Journal of Life Science
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• v.30 no.1
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• pp.10-17
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• 2020

Kinesin-1 is microtubule-dependent plus-end direct molecular motor protein essential for intracellular transport. It is a member of the kinesin superfamily proteins (KIFs) which transport cargo, including organelles, vesicles, neurotransmitter receptors, cell-signaling molecules, and protein complexes through interaction between its light chain subunit and the cargo. Kinesin light chain 1 (KLC1) is a non-motor subunit that associates with the kinesin heavy chain (KHC). Although KLC1 interacts with many different adaptor proteins and scaffolding proteins, its binding proteins have not yet been fully identified. We used the yeast two-hybrid assay to identify proteins that interact with the tetratricopeptide repeat (TPR) domain of KLC1, and found an interaction between KLC1 and EH domain-binding protein 1 like 1 (EHBP1L1). EHBP1L1 bound to the region containing all six TPR repeats of KLC1 and did not interact with KIF5B (a motor protein of kinesin 1) or KIF3A (a motor protein of kinesin 2) in the yeast two-hybrid assay. The carboxyl-terminus of the coiled-coil domain of EHBP1L1 is essential for interaction with KLC1. However, another EHBP1L1 isoform, EHBP1, did not interact with KLC1 in the yeast two-hybrid assay. KLC1 interacted with GST-EHBP1L1 and its coiled-coil domain but not with GST only. When co-expressed in HEK-293T cells, EHBP1L1 co-localized with KLC1 and co-immunoprecipitated with KLC1 and KIF5B but not KIF3A. These results suggest that kinesin 1 motor protein may transport EHBP1L1-associated cargo in cells.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2525-2528
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• 2013

The Homer protein family, also known as the family of cytoplasmic scaffolding proteins, which include three subtypes (Homer1, Homer2, Homer3). Homer3 can regulate transcription and play a very important role in the differentiation and development for some tissues (e.g. muscle and nervous systems). The current studies showed that Homer3 abnormal expression changes in acute myeloid leukemia (AML). Forced expression of Homer3 in transfected K562 cells inhibited proliferation, influenced the cell cycle profile, affected apoptosis induced by $As_2O_3$ through inhibition of Bcl2 expression, and also promoted cell differentiation induced by 12-O-tetra decanoylphorbol-acetate (TPA). These results showed that Homer3 is a novel gene which plays a certain role in the occurrence and development of AML.

• Journal of Microbiology and Biotechnology
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• v.17 no.11
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• pp.1782-1788
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• 2007

Cellulosomes in Clostridium cellulovorans are assembled by the interaction between the repeated cohesin domains of a scaffolding protein (CbpA) and the dockerin domain of enzyme components. In this study, we determined the synergistic effects on cellulosic and hemicellulosic substrates by three different recombinant mini-cellulosomes containing either endoglucanase EngB or endoxylanase XynA bound to mini-CbpA with one cohesin domain (mini-CbpAl), two cohesins (mini-CbpA12), or four cohesins (mini-CbpAl234). The assembly of EngB or XynA with mini-CbpA increased the activity against carboxymethyl cellulose, acid-swollen cellulose, Avicel, xylan, and com fiber 1.1-1.8-fold compared with that for the corresponding enzyme alone. A most distinct improvement was shown with com fiber, a natural substrate containing xylan, arabinan, and cellulose. However, there was little difference in activity between the three different mini-cellulosomes when the cellulosomal enzyme concentration was held constant regardless of the copy number of cohesins in the cellulosome. A synergistic effect was observed when the enzyme concentration was increased to be proportional to the number of cohesins in the mini-cellulosome. The highest degree of synergy was observed with mini-CbpAl234 (1.8-fold) and then mini-CbpAl2 (1.3-fold), and the lowest synergy was observed with mini-CbpAl (1.2-fold) when Avicel was used as the substrate. As the copy number of cohesin was increased, there was more synergy. These results indicate that the clustering effect (physical enzyme proximity) of the enzyme within the mini-cellulosome is one of the important factors for efficient degradation of plant cell walls.

• Journal of Microbiology and Biotechnology
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• v.30 no.11
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• pp.1626-1639
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• 2020

In Caenorhabditis elegans, SHN-1 is the homologue of SHANK, a scaffolding protein. In this study, we determined the molecular basis for SHN-1/SHANK in the regulation of innate immune response to fungal infection. Mutation of shn-1 increased the susceptibility to Candida albicans infection and suppressed the innate immune response. After C. albicans infection for 6, 12, or 24 h, both transcriptional expression of shn-1 and SHN-1::GFP expression were increased, implying that the activated SHN-1 may mediate a protection mechanism for C. elegans against the adverse effects from fungal infection. SHN-1 acted in both the neurons and the intestine to regulate the innate immune response to fungal infection. In the neurons, GLR-1, an AMPA ionotropic glutamate receptor, was identified as the downstream target in the regulation of innate immune response to fungal infection. GLR-1 further positively affected the function of SER-7-mediated serotonin signaling and antagonized the function of DAT-1-mediated dopamine signaling in the regulation of innate immune response to fungal infection. Our study suggests the novel function of SHN-1/SHANK in the regulation of innate immune response to fungal infection. Moreover, our results also denote the crucial role of neurotransmitter signals in mediating the function of SHN-1/SHANK in regulating innate immune response to fungal infection.