Eung-Gook Kim - Academia.edu (original) (raw)

Papers by Eung-Gook Kim

Research paper thumbnail of Basic Fibroblast Growth Factor Stimulates Activation of Rac1 through a p85 βPIX Phosphorylation-dependent Pathway

Journal of Biological Chemistry, 2003

we reported that phosphorylation of p85 ␤PIX, a guanine nucleotide exchange factor (GEF) for Rac1... more we reported that phosphorylation of p85 ␤PIX, a guanine nucleotide exchange factor (GEF) for Rac1/Cdc42, is a signal for translocation of the PIX complex to neuronal growth cones and is associated with basic fibroblast growth factor (bFGF)induced neurite outgrowth. However, the issue of whether p85 ␤PIX phosphorylation affects GEF activity on Rac1/Cdc42 is yet to be explored. Here we show that Rac1 activation occurs in a p85 ␤PIX phosphorylationdependent manner. A GST-PBD binding assay reveals that Rac1 is activated in a dose-and time-dependent manner in PC12 cells in response to bFGF. Inhibition of ERK or PAK2, the kinases upstream of p85 ␤PIX in the bFGF signaling, prevents Rac1 activation, suggesting that phosphorylation of p85 ␤PIX functions upstream of Rac1 activation. To directly address this issue, transfection studies with wild-type and mutant p85 ␤PIX (S525A/ T526A, a non-phosphorylatable form) were performed. Expression of mutant PIX markedly inhibits both bFGFand nerve growth factor (NGF)-induced activation of Rac1, indicating that phosphorylation of p85 ␤PIX is responsible for activation of this G protein. Both wildtype and mutant p85 ␤PIX displaying negative GEF activity (L238R/L239S) are similarly recruited to growth cones, suggesting that Rac1 activation is not essential for translocation of the PIX complex (PAK2-p85 ␤PIX-Rac1). However, expression of mutant p85 ␤PIX (L238R/ L239S) results in retraction of the pre-existing neurites. Our results provide evidence that bFGF-and NGF-induced phosphorylation of p85 ␤PIX mediates Rac1 activation, which in turn regulates cytoskeletal reorganization at growth cones, but not translocation of the PIX complex.

Research paper thumbnail of Defining regorafenib as a senomorphic drug: therapeutic potential in the age-related lung disease emphysema

Experimental & Molecular Medicine

Senescence, a hallmark of aging, is a factor in age-related diseases (ARDs). Therefore, targeting... more Senescence, a hallmark of aging, is a factor in age-related diseases (ARDs). Therefore, targeting senescence is widely regarded as a practicable method for modulating the effects of aging and ARDs. Here, we report the identification of regorafenib, an inhibitor of multiple receptor tyrosine kinases, as a senescence-attenuating drug. We identified regorafenib by screening an FDA-approved drug library. Treatment with regorafenib at a sublethal dose resulted in effective attenuation of the phenotypes of βPIX knockdown- and doxorubicin-induced senescence and replicative senescence in IMR-90 cells; cell cycle arrest, and increased SA-β-Gal staining and senescence-associated secretory phenotypes, particularly increasing the secretion of interleukin 6 (IL-6) and IL-8. Consistent with this result, slower progression of βPIX depletion-induced senescence was observed in the lungs of mice after treatment with regorafenib. Mechanistically, the results of proteomics analysis in diverse types of ...

Research paper thumbnail of Secular trends and determinants of influenza vaccination uptake among patients with cardiovascular disease in Korea: Analysis using a nationwide database

Frontiers in Cardiovascular Medicine

BackgroundInfluenza vaccination reduces cardiovascular events in patients with cardiovascular dis... more BackgroundInfluenza vaccination reduces cardiovascular events in patients with cardiovascular disease (CVD). Identifying the factors that affect influenza vaccination uptake can help improve the prognosis in patients with CVD. This study aimed to evaluate the secular trends of influenza vaccination uptake and factors associated with lack of vaccination in individuals with CVD.Materials and methodsWe analyzed the annual trends and factors associated with influenza vaccination among 3,264 patients with CVD, included from the Korea National Health and Nutrition Examination Survey which reflect the health and nutritional status of the nationwide population of Korea conducted between 2007/2008 and 2018/2019. We used a stratified, multistage sampling method.ResultsThe influenza vaccination rate was greater in patients with CVD (53–74%) than in those without CVD (28–40%). Multivariable logistic regression analysis showed that age <50 years [odds ratio (OR), 16.22; 95% confidence interva...

Research paper thumbnail of Model for regulation of growth cone morphology and neurite branching by NM II through dynamic interactions with GEFs

<p>NM II forms a complex with GEFs of the Dbl family when it is active as an ATPase <a h... more <p>NM II forms a complex with GEFs of the Dbl family when it is active as an ATPase <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0095212#pone.0095212-Lee1&quot; target="_blank">[16]</a>. The scheme shows three different ways to disrupt this complex: two non-physiological ones (inhibition of NM II using BBS or DH domain overexpression) and a physiological one (stimulation with NGF). Non-physiological disruptions directly target NM II and its binding interface with GEFs, whereas physiological disruption by NGF stimulation operates through the GEF–Cdc42 (Rac1)–PAK1 pathway. BBS or DH domain overexpression induces persistent dissociation of the NM II–GEF complex, which results in strong Cdc42 activation. Activation of this Rho GTPase in turn promotes the release of GEFs from NM II, thereby forming a positive feedback loop. The resultant aberrant targeting of GEFs, concomitant with Rho GTPase activation, alters actin dynamics, which leads to morphological abnormalities in growth cones and on the distal axon, such as irregular filopodial structures, and even fragmentation of growth cones and multiple protrusions and branching on the distal axon. In contrast to these non-physiological disruptions, NGF stimulates transient Cdc42/Rac1 activation; thus, the dissociation of the NM II–GEF (for example βPIX) complex is also transient. We believe that this transient and regulated mode of Rho GTPase activation meets the requirement for physiological growth cone motility and neurite outgrowth associated with neuronal differentiation.</p

Research paper thumbnail of CIL:26555, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, NIH3T3 cells were treated with 50 µm blebbistatin (BBS) for 15 min. and stained for βPIX (green) and myosin IIA (red). βPIX staining is transformed into numerous small puncta along the membrane after BBS treatment, and that myosin staining is excluded from the leading edge. These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is the original data file from Fig. S4, "Potential involvement of βPIX in blebbistatin-induced morphological changes in MII-regulated cell protrusion and adhesion." J. Cell Biol. 2010. Vol. 190(4):663–674.

Research paper thumbnail of CIL:26549, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, Swiss3T3 cells were co-stained for βPIX (green) and myosin IIA (red). These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is the original data file from Fig. 2F "colocalization of MII with GEFs", J. Cell Biol. 2010. Vol. 190(4):663–674.

Research paper thumbnail of CIL:26525, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, NIH3T3 cells were co-stained for betaPIX (green) and myosin IIA (red). These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is original data file from Fig. S2 "Colocalization of MII and GEFs in NIH3T3 fibroblasts", in J. Cell Biol. 2010. Vol. 190(4):663–674

Research paper thumbnail of A Novel Neutralizing Antibody Targeting Receptor Binding Domain of SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the current COVID-19 glob... more Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the current COVID-19 global pandemic. Vaccines and therapeutics are urgently needed for this highly transmissible virus. In this study, we screened human monoclonal antibodies (mAbs) targeting the receptor binding domain (RBD) of the SARS-CoV-2 spike protein from an antibody library constructed from peripheral blood mononuclear cells of a COVID-19 convalescent patient. A potent neutralizing antibody, termed CT-P59, was identified and found to be effective against various SARS-CoV-2 isolates including the D614G spike protein variant without antibody-dependent enhancement effect. Complex crystal structure of CT-P59 Fab/SARS-CoV-2 RBD showed that CT-P59 blocks interaction regions of SARS-CoV-2 RBD for its cellular receptor, angiotensin converting enzyme 2 (ACE2). The binding orientation of CT-P59 is notably different from the previously reported neutralizing mAbs targeting SARS-CoV-2 RBD suggesting that CT-P59 can ...

Research paper thumbnail of Histologic Changes in Non–Small Cell Lung Cancer under Various Treatments: A Comparison of Histology and Mutation Status in Serial Samples

Cancer Research and Treatment, 2021

PurposeHistologic change is a resistant mechanism in lung cancer. The most common histological ch... more PurposeHistologic change is a resistant mechanism in lung cancer. The most common histological change is the switch from adenocarcinoma (AdenoCa) to small cell carcinoma (SCC) against to tyrosine kinase inhibitors (TKI). However, it is not clear whether other treatment modalities are involved in the histologic changes.Materials and MethodsWe investigated histological changes in eight cases, after various treatments, and compared the molecular profiles between primary tumors and changed tumors using exome sequencing where tissue was available.ResultsThree cases of AdenoCa that were changed into SCC retained the initial mutations after TKI and/or surgical treatment. After treatment with TKI and immunotherapy, an EGFR (epidermal growth factor receptor)-mutant AdenoCa changed to squamous cell carcinoma (SqCa). SqCa in a patient treated with surgery was changed into combined AdenoCa and SqCa. These two cases showed the same genetic variations between the two distinct non–small cell carci...

Research paper thumbnail of Evaluation of the immune responses to and cross-protective efficacy of Eurasian H7 avian influenza viruses

Journal of virology, Jun 22, 2017

Due to increasing concerns of human infection by various H7 viruses, including recent H7N9 viruse... more Due to increasing concerns of human infection by various H7 viruses, including recent H7N9 viruses, we evaluated the genetic relationships and the cross-protective efficacies of three different Eurasian H7 avian influenza viruses. Phylogenic and molecular analysis revealed that recent Eurasian H7 viruses can be separated into two different lineages with relatively high amino acid identity within groups (94.8 to 98.8%), and low amino acid identity (90.3 to 92.6 %) between the groups. In vivo immunization with representatives of each group revealed that while group-specific cross-reactivity was induced, cross-reactive HI titers were approximately fourfold lower against heterologous group viruses compared to homologous group viruses. Moreover, the group I (RgW109/06) vaccine could protect 100% of immunized mice from various group I viruses, while only 20 to 40% of immunized mice survived lethal challenge with heterologous group II viruses and exhibited high viral titers in the lung. Mo...

Research paper thumbnail of Overexpressed alpha3beta1 and constitutively activated extracellular signal-regulated kinase modulate the angiogenic properties of ECV304 cells

Molecules and cells, Jan 30, 1999

ECV304, a spontaneously transformed cell line derived from the human umbilical vein endothelial c... more ECV304, a spontaneously transformed cell line derived from the human umbilical vein endothelial cell (HUVEC) (Takahashi et al., 1990), has been developed as an in vitro angiogenesis model. In the present study, we further characterized the angiogenic properties of this cell line. Compared to HUVEC, ECV304 cells showed distinct features including a higher activity of cellular adhesion, slower but reproducible progression of angiogenesis on Matrigel, and resistance to apoptosis. Thus, the expression of integrin and activation of extracellular-signal regulated kinase 1/2 (Erk1/2), a downstream effector of the integrin pathway, were examined. Flow cytometry revealed that alpha3beta1 integrin was markedly upregulated in ECV304 cells, while alpha(v)beta1 and alpha5beta1 integrins were slightly downregulated. Consistent with this, the binding activity to collagen type IV and laminin, major extracellular matrices of Matrigel, was increased 1.4- and 1.9-fold in ECV304 cells, respectively. Th...

Research paper thumbnail of p21-Activated kinase 4 promotes prostate cancer progression through CREB

Oncogene, 2012

Prostate cancer is initially androgen-dependent but, over time, usually develops hormone-and chem... more Prostate cancer is initially androgen-dependent but, over time, usually develops hormone-and chemo-resistance. The present study investigated a role for p21-activated kinase 4 (PAK4) in prostate cancer progression. PAK4 activation was markedly inhibited by H89, a specific protein kinase A (PKA) inhibitor, and PAK4 was activated by the elevation of cAMP. The catalytic subunit of PKA interacted with the regulatory domain of PAK4, and directly phosphorylated PAK4 at serine 474 (S474). Catalytically active PAK4 enhanced the transcriptional activity of CREB independent of S133 phosphorylation. Stable knockdown of PAK4 in PC-3 and DU145 prostate cancer cells inhibited tumor formation in nude mice. Decreased tumorigenicity correlated with decreased expression of CREB and its targets, including Bcl-2 and cyclin A1. Additionally, in androgen-dependent LNCap-FGC cells, PAK4 regulated cAMPinduced neuroendocrine differentiation, which is known to promote tumor progression. Finally, PAK4 enhanced survival and decreased apoptosis following chemotherapy. These results suggested that PAK4 regulates progression toward hormone-and chemo-resistance in prostate cancer, and this study identified both a novel activation mechanism and potential downstream effector pathways. Therefore, PAK4 may be a promising therapeutic target in prostate cancer.

Research paper thumbnail of cAMP Response Element Binding-Protein- and Phosphorylation-Dependent Regulation of Tyrosine Hydroxylase by PAK4: Implications for Dopamine Replacement Therapy

Molecules and Cells

Parkinson's disease (PD) is characterized by a progressive loss of dopamine-producing neurons in ... more Parkinson's disease (PD) is characterized by a progressive loss of dopamine-producing neurons in the midbrain, which results in decreased dopamine levels accompanied by movement symptoms. Oral administration of l-3,4dihydroxyphenylalanine (L-dopa), the precursor of dopamine, provides initial symptomatic relief, but abnormal involuntary movements develop later. A deeper understanding of the regulatory mechanisms underlying dopamine homeostasis is thus critically needed for the development of a successful treatment. Here, we show that p21-activated kinase 4 (PAK4) controls dopamine levels. Constitutively active PAK4 (caPAK4) stimulated transcription of tyrosine hydroxylase (TH) via the cAMP response element-binding protein (CREB) transcription factor. Moreover, caPAK4 increased the catalytic activity of TH through its phosphorylation of S 40 , which is essential for TH activation. Consistent with this result, in human midbrain tissues, we observed a strong correlation between phosphorylated PAK4 S474 , which represents PAK4 activity, and phosphorylated TH S40 , which reflects their enzymatic activity. Our findings suggest that targeting the PAK4 signaling pathways to restore dopamine levels may provide a new therapeutic approach in PD.

Research paper thumbnail of p21-activated kinase 4 controls the aggregation of α-synuclein by reducing the monomeric and aggregated forms of α-synuclein: involvement of the E3 ubiquitin ligase NEDD4-1

Cell Death & Disease

Aggregation of misfolded alpha-synuclein (α-synuclein) is a central player in the pathogenesis of... more Aggregation of misfolded alpha-synuclein (α-synuclein) is a central player in the pathogenesis of neurodegenerative diseases. Therefore, the regulatory mechanism underlying α-synuclein aggregation has been intensively studied in Parkinson’s disease (PD) but remains poorly understood. Here, we report p21-activated kinase 4 (PAK4) as a key regulator of α-synuclein aggregation. Immunohistochemical analysis of human PD brain tissues revealed an inverse correlation between PAK4 activity and α-synuclein aggregation. To investigate their causal relationship, we performed loss-of-function and gain-of-function studies using conditional PAK4 depletion in nigral dopaminergic neurons and the introduction of lentivirus expressing a constitutively active form of PAK4 (caPAK4; PAK4S445N/S474E), respectively. For therapeutic relevance in the latter setup, we injected lentivirus into the striatum following the development of motor impairment and analyzed the effects 6 weeks later. In the loss-of-fun...

Research paper thumbnail of Cerebral Cavernous Malformation 1 Determines YAP/TAZ Signaling-Dependent Metastatic Hallmarks of Prostate Cancer Cells

Cancers

Enhanced Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) s... more Enhanced Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) signaling is correlated with the extraprostatic extension of prostate cancer. However, the mechanism by which YAP/TAZ signaling becomes hyperactive and drives prostate cancer progression is currently unclear. In this study, we revealed that higher expression of CCM1, which is uniquely found in advanced prostate cancer, is inversely correlated with metastasis-free and overall survival in patients with prostate cancer. We also demonstrated that CCM1 induces the metastasis of multiple types of prostate cancer cells by regulating YAP/TAZ signaling. Mechanistically, CCM1, a gene mutated in cerebral cavernous malformation, suppresses DDX5, which regulates the suppression of YAP/TAZ signaling, indicating that CCM1 and DDX5 are novel upstream regulators of YAP/TAZ signaling. Our findings highlight the importance of CCM1-DDX5-YAP/TAZ signaling in the metastasis of prostate cancer cells.

Research paper thumbnail of Association between Smoking Status and Incident Non-Cystic Fibrosis Bronchiectasis in Young Adults: A Nationwide Population-Based Study

Journal of Personalized Medicine

Smoking traditionally has not been considered as a cause of bronchiectasis. However, few studies ... more Smoking traditionally has not been considered as a cause of bronchiectasis. However, few studies have evaluated the association between smoking and bronchiectasis. This study aimed to investigate the association between smoking status and bronchiectasis development in young adults. This study included 6,861,282 adults aged 20–39 years from the Korean National Health Insurance Service database 2009–2012 who were followed-up until the date of development of bronchiectasis, death, or 31 December 2018. We evaluated the incidence of bronchiectasis according to smoking status. During a mean of 7.4 years of follow-up, 23,609 (0.3%) participants developed bronchiectasis. In multivariable Cox regression analysis, ex-smokers (adjusted hazard ratio (aHR) = 1.07, 95% confidence interval (CI) = 1.03–1.13) and current-smokers (aHR = 1.06, 95% CI = 1.02–1.10) were associated with incident bronchiectasis, with the highest HR in ≥ 10 pack-years current smokers (aHR = 1.12, 95% CI = 1.06–1.16). The a...

Research paper thumbnail of Altered endocytosis in cellular senescence

Ageing Research Reviews

Cellular senescence occurs in response to diverse stresses (e.g., telomere shortening, DNA damage... more Cellular senescence occurs in response to diverse stresses (e.g., telomere shortening, DNA damage, oxidative stress, oncogene activation). A growing body of evidence indicates that alterations in multiple components of endocytic pathways contribute to cellular senescence. Clathrin-mediated endocytosis (CME) and caveolaemediated endocytosis (CavME) represent major types of endocytosis that are implicated in senescence. More recent research has also identified a chromatin modifier and tumor suppressor that contributes to the induction of senescence via altered endocytosis. Here, molecular regulators of aberrant endocytosis-induced senescence are reviewed and discussed in the context of their capacity to serve as senescence-inducing stressors or modifiers.

Research paper thumbnail of CIL:26558, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, NIH3T3 cells were treated with 50 µm blebbistatin (BBS) for 15 min. and stained for βPIX (green) and myosin IIB (red). βPIX staining is transformed into numerous small puncta along the membrane after BBS treatment, and that myosin staining is excluded from the leading edge. These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is the original data file from Fig. S4, "Potential involvement of βPIX in blebbistatin-induced morphological changes in MII-regulated cell protrusion and adhesion." J. Cell Biol. 2010. Vol. 190(4):663–674.

Research paper thumbnail of CIL:26530, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, NIH3T3 cells were transfected with myc-tagged phosphomimetic constitutively active MLC mutants (MLCaa, green). After 20' exposure to PDGF, which induces myosin-inactivation, stress fiber disassembly, and stimulates fibroblast motility, the cells were fixed and co-stained for TRIO (a multifunctional, multidomain Rho guanine nucleotide exchange factor, red) and filamentous actin (blue). These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is original data from Fig. S5 "Expression of active MLC mutants inhibits the dissociation of MII–Trio complex," in J. Cell Biol. 2010. Vol. 190(4):663–674

Research paper thumbnail of CIL:26542, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, NIH3T3 cells were treated with scrambled siRNA (Scr) for 2 days, treated with blebbistatin (BBS) for 30 min., and stained for βPIX (green) and vinculin (red). BBS treatment caused a dramatic shift from large adhesions to numerous small focal complexes at the cell margin. These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is the original data file from Fig. 6A, "Requirement for βPIX in MII-regulated cell protrusion and adhesion." J. Cell Biol. 2010. Vol. 190(4):663–674.

Research paper thumbnail of Basic Fibroblast Growth Factor Stimulates Activation of Rac1 through a p85 βPIX Phosphorylation-dependent Pathway

Journal of Biological Chemistry, 2003

we reported that phosphorylation of p85 ␤PIX, a guanine nucleotide exchange factor (GEF) for Rac1... more we reported that phosphorylation of p85 ␤PIX, a guanine nucleotide exchange factor (GEF) for Rac1/Cdc42, is a signal for translocation of the PIX complex to neuronal growth cones and is associated with basic fibroblast growth factor (bFGF)induced neurite outgrowth. However, the issue of whether p85 ␤PIX phosphorylation affects GEF activity on Rac1/Cdc42 is yet to be explored. Here we show that Rac1 activation occurs in a p85 ␤PIX phosphorylationdependent manner. A GST-PBD binding assay reveals that Rac1 is activated in a dose-and time-dependent manner in PC12 cells in response to bFGF. Inhibition of ERK or PAK2, the kinases upstream of p85 ␤PIX in the bFGF signaling, prevents Rac1 activation, suggesting that phosphorylation of p85 ␤PIX functions upstream of Rac1 activation. To directly address this issue, transfection studies with wild-type and mutant p85 ␤PIX (S525A/ T526A, a non-phosphorylatable form) were performed. Expression of mutant PIX markedly inhibits both bFGFand nerve growth factor (NGF)-induced activation of Rac1, indicating that phosphorylation of p85 ␤PIX is responsible for activation of this G protein. Both wildtype and mutant p85 ␤PIX displaying negative GEF activity (L238R/L239S) are similarly recruited to growth cones, suggesting that Rac1 activation is not essential for translocation of the PIX complex (PAK2-p85 ␤PIX-Rac1). However, expression of mutant p85 ␤PIX (L238R/ L239S) results in retraction of the pre-existing neurites. Our results provide evidence that bFGF-and NGF-induced phosphorylation of p85 ␤PIX mediates Rac1 activation, which in turn regulates cytoskeletal reorganization at growth cones, but not translocation of the PIX complex.

Research paper thumbnail of Defining regorafenib as a senomorphic drug: therapeutic potential in the age-related lung disease emphysema

Experimental & Molecular Medicine

Senescence, a hallmark of aging, is a factor in age-related diseases (ARDs). Therefore, targeting... more Senescence, a hallmark of aging, is a factor in age-related diseases (ARDs). Therefore, targeting senescence is widely regarded as a practicable method for modulating the effects of aging and ARDs. Here, we report the identification of regorafenib, an inhibitor of multiple receptor tyrosine kinases, as a senescence-attenuating drug. We identified regorafenib by screening an FDA-approved drug library. Treatment with regorafenib at a sublethal dose resulted in effective attenuation of the phenotypes of βPIX knockdown- and doxorubicin-induced senescence and replicative senescence in IMR-90 cells; cell cycle arrest, and increased SA-β-Gal staining and senescence-associated secretory phenotypes, particularly increasing the secretion of interleukin 6 (IL-6) and IL-8. Consistent with this result, slower progression of βPIX depletion-induced senescence was observed in the lungs of mice after treatment with regorafenib. Mechanistically, the results of proteomics analysis in diverse types of ...

Research paper thumbnail of Secular trends and determinants of influenza vaccination uptake among patients with cardiovascular disease in Korea: Analysis using a nationwide database

Frontiers in Cardiovascular Medicine

BackgroundInfluenza vaccination reduces cardiovascular events in patients with cardiovascular dis... more BackgroundInfluenza vaccination reduces cardiovascular events in patients with cardiovascular disease (CVD). Identifying the factors that affect influenza vaccination uptake can help improve the prognosis in patients with CVD. This study aimed to evaluate the secular trends of influenza vaccination uptake and factors associated with lack of vaccination in individuals with CVD.Materials and methodsWe analyzed the annual trends and factors associated with influenza vaccination among 3,264 patients with CVD, included from the Korea National Health and Nutrition Examination Survey which reflect the health and nutritional status of the nationwide population of Korea conducted between 2007/2008 and 2018/2019. We used a stratified, multistage sampling method.ResultsThe influenza vaccination rate was greater in patients with CVD (53–74%) than in those without CVD (28–40%). Multivariable logistic regression analysis showed that age <50 years [odds ratio (OR), 16.22; 95% confidence interva...

Research paper thumbnail of Model for regulation of growth cone morphology and neurite branching by NM II through dynamic interactions with GEFs

<p>NM II forms a complex with GEFs of the Dbl family when it is active as an ATPase <a h... more <p>NM II forms a complex with GEFs of the Dbl family when it is active as an ATPase <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0095212#pone.0095212-Lee1&quot; target="_blank">[16]</a>. The scheme shows three different ways to disrupt this complex: two non-physiological ones (inhibition of NM II using BBS or DH domain overexpression) and a physiological one (stimulation with NGF). Non-physiological disruptions directly target NM II and its binding interface with GEFs, whereas physiological disruption by NGF stimulation operates through the GEF–Cdc42 (Rac1)–PAK1 pathway. BBS or DH domain overexpression induces persistent dissociation of the NM II–GEF complex, which results in strong Cdc42 activation. Activation of this Rho GTPase in turn promotes the release of GEFs from NM II, thereby forming a positive feedback loop. The resultant aberrant targeting of GEFs, concomitant with Rho GTPase activation, alters actin dynamics, which leads to morphological abnormalities in growth cones and on the distal axon, such as irregular filopodial structures, and even fragmentation of growth cones and multiple protrusions and branching on the distal axon. In contrast to these non-physiological disruptions, NGF stimulates transient Cdc42/Rac1 activation; thus, the dissociation of the NM II–GEF (for example βPIX) complex is also transient. We believe that this transient and regulated mode of Rho GTPase activation meets the requirement for physiological growth cone motility and neurite outgrowth associated with neuronal differentiation.</p

Research paper thumbnail of CIL:26555, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, NIH3T3 cells were treated with 50 µm blebbistatin (BBS) for 15 min. and stained for βPIX (green) and myosin IIA (red). βPIX staining is transformed into numerous small puncta along the membrane after BBS treatment, and that myosin staining is excluded from the leading edge. These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is the original data file from Fig. S4, "Potential involvement of βPIX in blebbistatin-induced morphological changes in MII-regulated cell protrusion and adhesion." J. Cell Biol. 2010. Vol. 190(4):663–674.

Research paper thumbnail of CIL:26549, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, Swiss3T3 cells were co-stained for βPIX (green) and myosin IIA (red). These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is the original data file from Fig. 2F "colocalization of MII with GEFs", J. Cell Biol. 2010. Vol. 190(4):663–674.

Research paper thumbnail of CIL:26525, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, NIH3T3 cells were co-stained for betaPIX (green) and myosin IIA (red). These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is original data file from Fig. S2 "Colocalization of MII and GEFs in NIH3T3 fibroblasts", in J. Cell Biol. 2010. Vol. 190(4):663–674

Research paper thumbnail of A Novel Neutralizing Antibody Targeting Receptor Binding Domain of SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the current COVID-19 glob... more Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the current COVID-19 global pandemic. Vaccines and therapeutics are urgently needed for this highly transmissible virus. In this study, we screened human monoclonal antibodies (mAbs) targeting the receptor binding domain (RBD) of the SARS-CoV-2 spike protein from an antibody library constructed from peripheral blood mononuclear cells of a COVID-19 convalescent patient. A potent neutralizing antibody, termed CT-P59, was identified and found to be effective against various SARS-CoV-2 isolates including the D614G spike protein variant without antibody-dependent enhancement effect. Complex crystal structure of CT-P59 Fab/SARS-CoV-2 RBD showed that CT-P59 blocks interaction regions of SARS-CoV-2 RBD for its cellular receptor, angiotensin converting enzyme 2 (ACE2). The binding orientation of CT-P59 is notably different from the previously reported neutralizing mAbs targeting SARS-CoV-2 RBD suggesting that CT-P59 can ...

Research paper thumbnail of Histologic Changes in Non–Small Cell Lung Cancer under Various Treatments: A Comparison of Histology and Mutation Status in Serial Samples

Cancer Research and Treatment, 2021

PurposeHistologic change is a resistant mechanism in lung cancer. The most common histological ch... more PurposeHistologic change is a resistant mechanism in lung cancer. The most common histological change is the switch from adenocarcinoma (AdenoCa) to small cell carcinoma (SCC) against to tyrosine kinase inhibitors (TKI). However, it is not clear whether other treatment modalities are involved in the histologic changes.Materials and MethodsWe investigated histological changes in eight cases, after various treatments, and compared the molecular profiles between primary tumors and changed tumors using exome sequencing where tissue was available.ResultsThree cases of AdenoCa that were changed into SCC retained the initial mutations after TKI and/or surgical treatment. After treatment with TKI and immunotherapy, an EGFR (epidermal growth factor receptor)-mutant AdenoCa changed to squamous cell carcinoma (SqCa). SqCa in a patient treated with surgery was changed into combined AdenoCa and SqCa. These two cases showed the same genetic variations between the two distinct non–small cell carci...

Research paper thumbnail of Evaluation of the immune responses to and cross-protective efficacy of Eurasian H7 avian influenza viruses

Journal of virology, Jun 22, 2017

Due to increasing concerns of human infection by various H7 viruses, including recent H7N9 viruse... more Due to increasing concerns of human infection by various H7 viruses, including recent H7N9 viruses, we evaluated the genetic relationships and the cross-protective efficacies of three different Eurasian H7 avian influenza viruses. Phylogenic and molecular analysis revealed that recent Eurasian H7 viruses can be separated into two different lineages with relatively high amino acid identity within groups (94.8 to 98.8%), and low amino acid identity (90.3 to 92.6 %) between the groups. In vivo immunization with representatives of each group revealed that while group-specific cross-reactivity was induced, cross-reactive HI titers were approximately fourfold lower against heterologous group viruses compared to homologous group viruses. Moreover, the group I (RgW109/06) vaccine could protect 100% of immunized mice from various group I viruses, while only 20 to 40% of immunized mice survived lethal challenge with heterologous group II viruses and exhibited high viral titers in the lung. Mo...

Research paper thumbnail of Overexpressed alpha3beta1 and constitutively activated extracellular signal-regulated kinase modulate the angiogenic properties of ECV304 cells

Molecules and cells, Jan 30, 1999

ECV304, a spontaneously transformed cell line derived from the human umbilical vein endothelial c... more ECV304, a spontaneously transformed cell line derived from the human umbilical vein endothelial cell (HUVEC) (Takahashi et al., 1990), has been developed as an in vitro angiogenesis model. In the present study, we further characterized the angiogenic properties of this cell line. Compared to HUVEC, ECV304 cells showed distinct features including a higher activity of cellular adhesion, slower but reproducible progression of angiogenesis on Matrigel, and resistance to apoptosis. Thus, the expression of integrin and activation of extracellular-signal regulated kinase 1/2 (Erk1/2), a downstream effector of the integrin pathway, were examined. Flow cytometry revealed that alpha3beta1 integrin was markedly upregulated in ECV304 cells, while alpha(v)beta1 and alpha5beta1 integrins were slightly downregulated. Consistent with this, the binding activity to collagen type IV and laminin, major extracellular matrices of Matrigel, was increased 1.4- and 1.9-fold in ECV304 cells, respectively. Th...

Research paper thumbnail of p21-Activated kinase 4 promotes prostate cancer progression through CREB

Oncogene, 2012

Prostate cancer is initially androgen-dependent but, over time, usually develops hormone-and chem... more Prostate cancer is initially androgen-dependent but, over time, usually develops hormone-and chemo-resistance. The present study investigated a role for p21-activated kinase 4 (PAK4) in prostate cancer progression. PAK4 activation was markedly inhibited by H89, a specific protein kinase A (PKA) inhibitor, and PAK4 was activated by the elevation of cAMP. The catalytic subunit of PKA interacted with the regulatory domain of PAK4, and directly phosphorylated PAK4 at serine 474 (S474). Catalytically active PAK4 enhanced the transcriptional activity of CREB independent of S133 phosphorylation. Stable knockdown of PAK4 in PC-3 and DU145 prostate cancer cells inhibited tumor formation in nude mice. Decreased tumorigenicity correlated with decreased expression of CREB and its targets, including Bcl-2 and cyclin A1. Additionally, in androgen-dependent LNCap-FGC cells, PAK4 regulated cAMPinduced neuroendocrine differentiation, which is known to promote tumor progression. Finally, PAK4 enhanced survival and decreased apoptosis following chemotherapy. These results suggested that PAK4 regulates progression toward hormone-and chemo-resistance in prostate cancer, and this study identified both a novel activation mechanism and potential downstream effector pathways. Therefore, PAK4 may be a promising therapeutic target in prostate cancer.

Research paper thumbnail of cAMP Response Element Binding-Protein- and Phosphorylation-Dependent Regulation of Tyrosine Hydroxylase by PAK4: Implications for Dopamine Replacement Therapy

Molecules and Cells

Parkinson's disease (PD) is characterized by a progressive loss of dopamine-producing neurons in ... more Parkinson's disease (PD) is characterized by a progressive loss of dopamine-producing neurons in the midbrain, which results in decreased dopamine levels accompanied by movement symptoms. Oral administration of l-3,4dihydroxyphenylalanine (L-dopa), the precursor of dopamine, provides initial symptomatic relief, but abnormal involuntary movements develop later. A deeper understanding of the regulatory mechanisms underlying dopamine homeostasis is thus critically needed for the development of a successful treatment. Here, we show that p21-activated kinase 4 (PAK4) controls dopamine levels. Constitutively active PAK4 (caPAK4) stimulated transcription of tyrosine hydroxylase (TH) via the cAMP response element-binding protein (CREB) transcription factor. Moreover, caPAK4 increased the catalytic activity of TH through its phosphorylation of S 40 , which is essential for TH activation. Consistent with this result, in human midbrain tissues, we observed a strong correlation between phosphorylated PAK4 S474 , which represents PAK4 activity, and phosphorylated TH S40 , which reflects their enzymatic activity. Our findings suggest that targeting the PAK4 signaling pathways to restore dopamine levels may provide a new therapeutic approach in PD.

Research paper thumbnail of p21-activated kinase 4 controls the aggregation of α-synuclein by reducing the monomeric and aggregated forms of α-synuclein: involvement of the E3 ubiquitin ligase NEDD4-1

Cell Death & Disease

Aggregation of misfolded alpha-synuclein (α-synuclein) is a central player in the pathogenesis of... more Aggregation of misfolded alpha-synuclein (α-synuclein) is a central player in the pathogenesis of neurodegenerative diseases. Therefore, the regulatory mechanism underlying α-synuclein aggregation has been intensively studied in Parkinson’s disease (PD) but remains poorly understood. Here, we report p21-activated kinase 4 (PAK4) as a key regulator of α-synuclein aggregation. Immunohistochemical analysis of human PD brain tissues revealed an inverse correlation between PAK4 activity and α-synuclein aggregation. To investigate their causal relationship, we performed loss-of-function and gain-of-function studies using conditional PAK4 depletion in nigral dopaminergic neurons and the introduction of lentivirus expressing a constitutively active form of PAK4 (caPAK4; PAK4S445N/S474E), respectively. For therapeutic relevance in the latter setup, we injected lentivirus into the striatum following the development of motor impairment and analyzed the effects 6 weeks later. In the loss-of-fun...

Research paper thumbnail of Cerebral Cavernous Malformation 1 Determines YAP/TAZ Signaling-Dependent Metastatic Hallmarks of Prostate Cancer Cells

Cancers

Enhanced Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) s... more Enhanced Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) signaling is correlated with the extraprostatic extension of prostate cancer. However, the mechanism by which YAP/TAZ signaling becomes hyperactive and drives prostate cancer progression is currently unclear. In this study, we revealed that higher expression of CCM1, which is uniquely found in advanced prostate cancer, is inversely correlated with metastasis-free and overall survival in patients with prostate cancer. We also demonstrated that CCM1 induces the metastasis of multiple types of prostate cancer cells by regulating YAP/TAZ signaling. Mechanistically, CCM1, a gene mutated in cerebral cavernous malformation, suppresses DDX5, which regulates the suppression of YAP/TAZ signaling, indicating that CCM1 and DDX5 are novel upstream regulators of YAP/TAZ signaling. Our findings highlight the importance of CCM1-DDX5-YAP/TAZ signaling in the metastasis of prostate cancer cells.

Research paper thumbnail of Association between Smoking Status and Incident Non-Cystic Fibrosis Bronchiectasis in Young Adults: A Nationwide Population-Based Study

Journal of Personalized Medicine

Smoking traditionally has not been considered as a cause of bronchiectasis. However, few studies ... more Smoking traditionally has not been considered as a cause of bronchiectasis. However, few studies have evaluated the association between smoking and bronchiectasis. This study aimed to investigate the association between smoking status and bronchiectasis development in young adults. This study included 6,861,282 adults aged 20–39 years from the Korean National Health Insurance Service database 2009–2012 who were followed-up until the date of development of bronchiectasis, death, or 31 December 2018. We evaluated the incidence of bronchiectasis according to smoking status. During a mean of 7.4 years of follow-up, 23,609 (0.3%) participants developed bronchiectasis. In multivariable Cox regression analysis, ex-smokers (adjusted hazard ratio (aHR) = 1.07, 95% confidence interval (CI) = 1.03–1.13) and current-smokers (aHR = 1.06, 95% CI = 1.02–1.10) were associated with incident bronchiectasis, with the highest HR in ≥ 10 pack-years current smokers (aHR = 1.12, 95% CI = 1.06–1.16). The a...

Research paper thumbnail of Altered endocytosis in cellular senescence

Ageing Research Reviews

Cellular senescence occurs in response to diverse stresses (e.g., telomere shortening, DNA damage... more Cellular senescence occurs in response to diverse stresses (e.g., telomere shortening, DNA damage, oxidative stress, oncogene activation). A growing body of evidence indicates that alterations in multiple components of endocytic pathways contribute to cellular senescence. Clathrin-mediated endocytosis (CME) and caveolaemediated endocytosis (CavME) represent major types of endocytosis that are implicated in senescence. More recent research has also identified a chromatin modifier and tumor suppressor that contributes to the induction of senescence via altered endocytosis. Here, molecular regulators of aberrant endocytosis-induced senescence are reviewed and discussed in the context of their capacity to serve as senescence-inducing stressors or modifiers.

Research paper thumbnail of CIL:26558, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, NIH3T3 cells were treated with 50 µm blebbistatin (BBS) for 15 min. and stained for βPIX (green) and myosin IIB (red). βPIX staining is transformed into numerous small puncta along the membrane after BBS treatment, and that myosin staining is excluded from the leading edge. These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is the original data file from Fig. S4, "Potential involvement of βPIX in blebbistatin-induced morphological changes in MII-regulated cell protrusion and adhesion." J. Cell Biol. 2010. Vol. 190(4):663–674.

Research paper thumbnail of CIL:26530, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, NIH3T3 cells were transfected with myc-tagged phosphomimetic constitutively active MLC mutants (MLCaa, green). After 20' exposure to PDGF, which induces myosin-inactivation, stress fiber disassembly, and stimulates fibroblast motility, the cells were fixed and co-stained for TRIO (a multifunctional, multidomain Rho guanine nucleotide exchange factor, red) and filamentous actin (blue). These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is original data from Fig. S5 "Expression of active MLC mutants inhibits the dissociation of MII–Trio complex," in J. Cell Biol. 2010. Vol. 190(4):663–674

Research paper thumbnail of CIL:26542, Mus musculus, fibroblast. In Cell Image Library

To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhe... more To study the molecular mechanism by which nonmuscle myosin II (MII) regulates protrusion and adhesion dynamics in migrating cells, NIH3T3 cells were treated with scrambled siRNA (Scr) for 2 days, treated with blebbistatin (BBS) for 30 min., and stained for βPIX (green) and vinculin (red). BBS treatment caused a dramatic shift from large adhesions to numerous small focal complexes at the cell margin. These findings help elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells. This image is the original data file from Fig. 6A, "Requirement for βPIX in MII-regulated cell protrusion and adhesion." J. Cell Biol. 2010. Vol. 190(4):663–674.