Platelet-derived growth factor-stimulated pulmonary artery smooth muscle cells regulate pulmonary artery endothelial cell dysfunction through extracellular vesicle miR-409-5p.

Platelet-derived growth factor (PDGF)-induced changes in vascular smooth muscle cells (VSMCs) stimulate vascular remodeling, resulting in vascular diseases such as pulmonary arterial hypertension. VSMCs communicate with endothelial cells through extracellular vesicles (EVs) carrying cargos, including microRNAs. To understand the molecular mechanisms through which PDGF-stimulated pulmonary artery smooth muscle cells (PASMCs) interact with pulmonary artery endothelial cells (PAECs) under pathological conditions, we investigated the crosstalk between PASMCs and PAECs via extracellular vesicle miR-409-5p under PDGF stimulation. miR-409-5p expression was upregulated in PASMCs upon PDGF signaling, and it was released into EVs. The elevated expression of miR-409-5p was transported to PAECs and led to their impaired function, including reduced NO release, which consequentially resulted in enhanced PASMC proliferation. We propose that the positive regulatory loop of PASMC-extracellular vesicle miR-409-5p-PAEC is a potential mechanism underlying the proliferation of PASMCs under PDGF stimulation. Therefore, miR-409-5p may be a novel therapeutic target for the treatment of vascular diseases, including pulmonary arterial hypertension.

Small interfering RNA (siRNA)-based therapeutic applications against viruses: principles, potential, and challenges.

RNA has emerged as a revolutionary and important tool in the battle against emerging infectious diseases, with roles extending beyond its applications in vaccines, in which it is used in the response to the COVID-19 pandemic. Since their development in the 1990s, RNA interference (RNAi) therapeutics have demonstrated potential in reducing the expression of disease-associated genes. Nucleic acid-based therapeutics, including RNAi therapies, that degrade viral genomes and rapidly adapt to viral mutations, have emerged as alternative treatments. RNAi is a robust technique frequently employed to selectively suppress gene expression in a sequence-specific manner. The swift adaptability of nucleic acid-based therapeutics such as RNAi therapies endows them with a significant advantage over other antiviral medications. For example, small interfering RNAs (siRNAs) are produced on the basis of sequence complementarity to target and degrade viral RNA, a novel approach to combat viral infections. The precision of siRNAs in targeting and degrading viral RNA has led to the development of siRNA-based treatments for diverse diseases. However, despite the promising therapeutic benefits of siRNAs, several problems, including impaired long-term protein expression, siRNA instability, off-target effects, immunological responses, and drug resistance, have been considerable obstacles to the use of siRNA-based antiviral therapies. This review provides an encompassing summary of the siRNA-based therapeutic approaches against viruses while also addressing the obstacles that need to be overcome for their effective application. Furthermore, we present potential solutions to mitigate major challenges.

Nucleolin Regulates Pulmonary Artery Smooth Muscle Cell Proliferation under Hypoxia by Modulating miRNA Expression.

Hypoxia induces the abnormal proliferation of vascular smooth muscle cells (VSMCs), resulting in the pathogenesis of various vascular diseases. RNA-binding proteins (RBPs) are involved in a wide range of biological processes, including cell proliferation and responses to hypoxia. In this study, we observed that the RBP nucleolin (NCL) was downregulated by histone deacetylation in response to hypoxia. We evaluated its regulatory effects on miRNA expression under hypoxic conditions in pulmonary artery smooth muscle cells (PASMCs). miRNAs associated with NCL were assessed using RNA immunoprecipitation in PASMCs and small RNA sequencing. The expression of a set of miRNAs was increased by NCL but reduced by hypoxia-induced downregulation of NCL. The downregulation of miR-24-3p and miR-409-3p promoted PASMC proliferation under hypoxic conditions. These results clearly demonstrate the significance of NCL-miRNA interactions in the regulation of hypoxia-induced PASMC proliferation and provide insight into the therapeutic value of RBPs for vascular diseases.

Role of MicroRNAs and Long Non-Coding RNAs in Sarcopenia.

Sarcopenia is an age-related pathological process characterized by loss of muscle mass and function, which consequently affects the quality of life of the elderly. There is growing evidence that non-coding RNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), play a key role in skeletal muscle physiology. Alterations in the expression levels of miRNAs and lncRNAs contribute to muscle atrophy and sarcopenia by regulating various signaling pathways. This review summarizes the recent findings regarding non-coding RNAs associated with sarcopenia and provides an overview of sarcopenia pathogenesis promoted by multiple non-coding RNA-mediated signaling pathways. In addition, we discuss the impact of exercise on the expression patterns of non-coding RNAs involved in sarcopenia. Identifying non-coding RNAs associated with sarcopenia and understanding the molecular mechanisms that regulate skeletal muscle dysfunction during aging will provide new insights to develop potential treatment strategies.

Exosome-Based Treatment for Atherosclerosis.

Atherosclerosis is an inflammatory disease in which lipids accumulate on the walls of blood vessels, thickening and clogging these vessels. It is well known that cell-to-cell communication is involved in the pathogenesis of atherosclerosis. Exosomes are extracellular vesicles that deliver various substances (e.g., RNA, DNA, and proteins) from the donor cell to the recipient cell and that play an important role in intercellular communication. Atherosclerosis can be either induced or inhibited through cell-to-cell communication using exosomes. An understanding of the function of exosomes as therapeutic tools and in the pathogenesis of atherosclerosis is necessary to develop new atherosclerosis therapies. In this review, we summarize the studies on the regulation of atherosclerosis through exosomes derived from multiple cells as well as research on exosome-based atherosclerosis treatment.

Deficiency of Tristetraprolin Triggers Hyperthermia through Enhancing Hypothalamic Inflammation.

Tristetraprolin (TTP), an RNA-binding protein, controls the stability of RNA by capturing AU-rich elements on their target genes. It has recently been identified that TTP serves as an anti-inflammatory protein by guiding the unstable mRNAs of pro-inflammatory proteins in multiple cells. However, it has not yet been investigated whether TTP affects the inflammatory responses in the hypothalamus. Since hypothalamic inflammation is tightly coupled to the disturbance of energy homeostasis, we designed the current study to investigate whether TTP regulates hypothalamic inflammation and thereby affects energy metabolism by utilizing TTP-deficient mice. We observed that deficiency of TTP led to enhanced hypothalamic inflammation via stimulation of a variety of pro-inflammatory genes. In addition, microglial activation occurred in the hypothalamus, which was accompanied by an enhanced inflammatory response. In line with these molecular and cellular observations, we finally confirmed that deficiency of TTP results in elevated core body temperature and energy expenditure. Taken together, our findings unmask novel roles of hypothalamic TTP on energy metabolism, which is linked to inflammatory responses in hypothalamic microglial cells.

Effectiveness and safety of electrical moxibustion for knee osteoarthritis: A multicenter, randomized, assessor-blinded, parallel-group clinical trial.

BACKGROUND: The prevalence of knee osteoarthritis (KOA) is increasing, and it has emerged as a major health issue. Studies have been reported that moxibustion is effective for treating KOA, but conventional moxibustion is difficult to control the intensity of stimulation and causes smoke, harmful gases, or odors. An electrical moxibustion (EM) device was developed to solve these problems, so we conducted this study to evaluate the effectiveness and safety of EM as a treatment for KOA. METHODS: This is a multicenter, randomized, assessor-blinded, parallel-group clinical trial. Participants with KOA were randomly allocated into EM, traditional indirect moxibustion (TIM), or usual care groups. The moxibustion groups were received 12 sessions of moxibustion treatment at six acupuncture points (ST36, ST35, ST34, SP9, EX-LE4, SP10) over a period of 6 weeks. The usual care group was received usual treatment and self-care. The primary outcome was the degree of pain measured by numerical rating scale (NRS). The second outcomes were measured using visual analog scale, Korean version of the Western Ontario and McMaster Universities osteoarthritis index, patient global assessment, European quality of life five dimension five level scale, and warm sense threshold and heat pain threshold. For safety assessment, laboratory test and adverse events (AEs) were recorded. RESULTS: A total of 138 participants were assigned. While there was no significant NRS change in the usual care, EM and TIM showed significant decrease after treatment. Compared to the usual care, the mean change of NRS in the EM and TIM was significantly different, but there was no significance between two groups. Regarding secondary outcomes, EM and TIM also showed significant difference compared to the usual care, but there was no significance between two groups. Regarding safety assessment, while usual care showed significant safety among three groups, EM showed seven treatment-related AEs by four participants compared TIM's 10 events by 10 participants. In addition, there was no blister caused by burns in the EM, which occurred four cases in the TIM. CONCLUSION: This study shows that EM is effective to improve the pain and function by KOA with a certain level of safety.

BMP-Induced MicroRNA-101 Expression Regulates Vascular Smooth Muscle Cell Migration.

Proliferation and migration of vascular smooth muscle cells (VSMCs) are implicated in blood vessel development, maintenance of vascular homeostasis, and pathogenesis of vascular disorders. MicroRNAs (miRNAs) mediate the regulation of VSMC functions in response to microenvironmental signals. Because a previous study reported that miR-101, a tumor-suppressive miRNA, is a critical regulator of cell proliferation in vascular disease, we hypothesized that miR-101 controls important cellular processes in VSMCs. The present study aimed to elucidate the effects of miR-101 on VSMC function and its molecular mechanisms. We revealed that miR-101 regulates VSMC proliferation and migration. We showed that miR-101 expression is induced by bone morphogenetic protein (BMP) signaling, and we identified dedicator of cytokinesis 4 (DOCK4) as a novel target of miR-101. Our results suggest that the BMP-miR-101-DOCK4 axis mediates the regulation of VSMC function. Our findings help further the understanding of vascular physiology and pathology.

Vascular Smooth Muscle Cell-Derived Exosomal MicroRNAs Regulate Endothelial Cell Migration Under PDGF Stimulation.

Intercellular communication between vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) is essential for the maintenance of vascular homeostasis. The presence of exosomes, a recently discovered player in vascular cell communication, has been associated with vascular disease progression. However, the detailed mechanism of how the signal mediated by exosomes affects the function of vascular cells during vascular pathogenesis is yet to be further understood. In this study, we investigated the expression of exosomal microRNAs (miRNAs) secreted by VSMCs and their functional relevance to ECs in pathogenesis, including their role in processes such as platelet-derived growth factor (PDGF) stimulation. We observed that PDGF stimulation contributes to a change in exosomal miRNA release from VSMCs; specifically, miR-1246, miR-182, and miR-486 were deficient in exosomes derived from PDGF-stimulated VSMCs. The reduced miRNA expression in these exosomes is associated with an increase in EC migration. These findings increase our understanding of exosome-mediated crosstalk between vascular cells under a pathological condition.

Efficacy of Korean red ginseng (Panax ginseng) for middle-aged and moderate level of chronic fatigue patients: A randomized, double-blind, placebo-controlled trial.

OBJECTIVES: Chronic fatigue (CF) is unexplained fatigue lasting more than 6 months. Korean red ginseng (KRG) is known to have higher anti-fatigue substance than white ginseng. However, its efficacy and safety for CF is unknown. The purpose of this study was to investigate the effect of KRG on CF by various measurements and objective indicators. DESIGN: A randomized, double-blind, clinical trial was conducted on 50 patients with CF. INTERVENTION: Participants were allocated to KRG or placebo group (1:1 ratio) and visited hospital every 2 weeks during taking 3 g KRG or placebo for 6 weeks and followed up 4 weeks after the treatment. MAIN OUTCOME MEASURES: The primary outcome measurement was fatigue VAS. Secondary outcome measurements included FSS, CFSQ, SRI, scales of various fields (Depression: BDI; Sleep: ISI; Quality of life: EQ-5D 5 L), biochemical test (Antioxidants: d-ROMs, TBARS, BAP, and SOD; Cortisol concentration: salivary cortisol), blinding assessment, and adverse events. RESULTS: The fatigue VAS declined significantly in each group, but there were no significant differences between the groups. The 2 groups also had no significant differences in the secondary outcome measurements and there were no adverse events. Sub-group analysis indicated that patients with initial fatigue VAS below 80 mm and older than 50 years had significantly greater reductions in the fatigue VAS if they used KRG rather than placebo. CONCLUSIONS: By our study, KRG did not show absolute anti-fatigue effect but provided the objective evidence of fatigue-related measurement and the therapeutic potential for middle-aged individuals with moderate fatigue.

Hypoxia-induced miR-1260b regulates vascular smooth muscle cell proliferation by targeting GDF11.

Vascular smooth muscle cells (VSMCs) are a unique cell type that has unusual plasticity controlled by environmental stimuli. As an abnormal increase of VSMC proliferation is associated with various vascular diseases, tight regulation of VSMC phenotypes is essential for maintaining vascular homeostasis. Hypoxia is one environmental stress that stimulates VSMC proliferation. Emerging evidence has indicated that microRNAs (miRNAs) are critical regulators in the hypoxic responses of VSMCs. Therefore, we previously investigated miRNAs modulated by hypoxia in VSMCs and found that miR-1260b is one of the most upregulated miRNAs under hypoxia. However, the mechanism that underlies the regulation of VSMCs via miR-1260b in response to hypoxia has not been explored. Here we demonstrated that hypoxia-induced miR-1260b promotes VSMC proliferation. We also identified growth differentiation factor 11 (GDF11), a member of the TGF-ß superfamily, as a novel target of miR-1260b. miR-1260b directly targets the 3'UTR of GDF11. Downregulation of GDF11 inhibited Smad signaling and consequently enhanced the proliferation of VSMCs. Our findings suggest that miR-1260b-mediated GDF11-Smad-dependent signaling is an essential regulatory mechanism in the proliferation of VSMCs, and this axis is modulated by hypoxia to promote abnormal VSMC proliferation. Therefore, our study unveils a novel function of miR-1260b in the pathological proliferation of VSMCs under hypoxia. [BMB Reports 2020; 53(4): 206-211].

Effect of Oxygen Content on Current Stress-Induced Instability in Bottom-Gate Amorphous InGaZnO Thin-Film Transistors.

The effect of oxygen content on current-stress-induced instability was investigated in bottom-gate amorphous InGaZnO (a-IGZO) thin-film transistors. The observed positive threshold voltage shift (ΔVT) was dominated by electron trapping in the gate insulator (GI), whereas it was compensated by donor creation in a-IGZO active regions when both current flows and a high lateral electric field were present. Stress-induced ΔVT increased with increasing oxygen content irrespective of the type of stress because oxygen content influenced GI quality, i.e., higher density of GI electron traps, as well as typical direct current (DC) performance like threshold voltage, mobility, and subthreshold swing. It was also found that self-heating became another important mechanism, especially when the vertical electric field and channel current were the same, independent of the oxygen content. The increased ΔVT with oxygen content under positive gate bias stress, positive gate and drain bias stress, and target current stress was consistently explained by considering a combination of the density of GI electron traps, electric field relaxation, and self-heating-assisted electron trapping.

Hypoxia Promotes Vascular Smooth Muscle Cell Proliferation through microRNA-Mediated Suppression of Cyclin-Dependent Kinase Inhibitors.

Regulation of vascular smooth muscle cell (VSMC) proliferation is essential to maintain vascular homeostasis. Hypoxia induces abnormal proliferation of VSMCs and causes vascular proliferative disorders, such as pulmonary hypertension and atherosclerosis. As several cyclin/cyclin-dependent kinase (CDK) complexes and CDK inhibitors (CKIs) control cell proliferation, in this study, we investigated CKIs involved in the hypoxia-induced proliferation process of human primary pulmonary artery smooth muscle cells to understand the underlying molecular mechanism. We demonstrated that p15, p16, and p21 are downregulated in pulmonary artery smooth muscle cells when exposed to hypoxia. In addition, we identified novel hypoxia-induced microRNAs (hypoxamiRs) including miR-497, miR-1268a, and miR-665 that are upregulated under hypoxia and post-transcriptionally regulate p15, p16, and p21 genes, respectively, by directly targeting their 3'UTRs. These miRNAs promoted the proliferation of VSMCs, and their inhibition decreased VSMC proliferation even in hypoxic conditions. Overall, this study revealed that miRNA-mediated regulatory mechanism of CKIs is essential for hypoxia-induced proliferation of VSMCs. These findings provide insights for a better understanding of the pathogenesis of vascular proliferative disorders.

Efficacy and safety of electric heating moxibustion for perennial allergic rhinitis: protocol for a randomized controlled trial.

BACKGROUND: Allergic rhinitis (AR) is an IgE-mediated disease that adversely affects quality of life. Many studies report that moxibustion is an effective treatment for perennial allergic rhinitis (PAR). However, it is difficult to perform moxibustion on the face because of possible burning of the skin and the noxious effects of smoke. Electric heating moxibustion does not have these limitations. The purpose of this clinical trial is to assess the possibility of treating PAR with electric heating moxibustion and to assess the feasibility of conducting a clinical test on a larger scale. METHODS: This is a randomized, open-label, assessor-blind, parallel-design pilot clinical study. We will recruit 40 eligible participants and randomly allocate them into an electric heating moxibustion group or an acupuncture group at a 1:1 ratio. Patients in both groups will receive eight treatments over 4 weeks, and the final follow-up will be 4 weeks after the last treatment. Eleven acupuncture points will be used for patients in both groups (EX-HN3 and bilateral EX-HN-8, LI20, LI4, GB20, and ST36). The primary outcome measure is change in the Total Nasal Symptom Score, and the secondary outcome measures are changes in the Rhinoconjunctivitis Quality of Life Questionnaire, nasal endoscopy index for pattern identification, pattern identification questionnaire for AR, total IgE, eosinophil count, and adverse effects. DISCUSSION: This clinical trial will examine the effect of electric heating moxibustion on PAR. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03342105 . Registered on 14 November 2017.

MicroRNA-Mediated Health-Promoting Effects of Phytochemicals.

Phytochemicals are known to benefit human health by modulating various cellular processes, including cell proliferation, apoptosis, and inflammation. Due to the potential use of phytochemicals as therapeutic agents against human diseases such as cancer, studies are ongoing to elucidate the molecular mechanisms by which phytochemicals affect cellular functions. It has recently been shown that phytochemicals may regulate the expression of microRNAs (miRNAs). MiRNAs are responsible for the fine-tuning of gene expression by controlling the expression of their target mRNAs in both normal and pathological cells. This review summarizes the recent findings regarding phytochemicals that modulate miRNA expression and promote human health by exerting anticancer, photoprotective, and anti-hepatosteatosis effects. Identifying miRNAs modulated by phytochemicals and understanding the regulatory mechanisms mediated by their target mRNAs will facilitate the efforts to maximize the therapeutic benefits of phytochemicals.

Hypoxia-induced regulation of mTOR signaling by miR-7 targeting REDD1.

Oxygen is an important factor mediating cell growth and survival under physiological and pathological conditions. Therefore, cells have well-regulated response mechanisms in the face of changes in oxygen levels in their environment. A subset of microRNAs (miRNAs) termed the hypoxamir has been suggested to be a critical mediator of the cellular response to hypoxia. Regulated in development and DNA damage response 1 (REDD1) is a negative regulator of mammalian target of rapamycin (mTOR) signaling in the response to cellular stress, and is elevated in many cell types under hypoxia, with consequent inhibition of mTOR signaling. However, the underlying posttranscriptional regulatory mechanism by miRNAs that contribute to this hypoxia-induced reduction in REDD1 expression remain unknown. Therefore, the aim of the current study was to identify the miRNAs participating in the hypoxic cellular response by scanning the 3'-untranslated region (3'-UTR) of REDD1 for potential miRNA-binding sites using a computer algorithm, TargetScan. miR-7 emerged as a novel hypoxamir that regulates REDD1 expression and is involved in mTOR signaling. miR-7 could repress REDD1 expression posttranscriptionally by directly binding with the 3'-UTR. Upon hypoxia, miR-7 expression was downregulated in HeLa cells to consequently derepress REDD1, resulting in inhibition of mTOR signaling. Moreover, overexpression of miR-7 was sufficient to reverse the hypoxia-induced inhibition of mTOR signaling. Therefore, our findings suggest miR-7 as a key regulator of hypoxia-mediated mTOR signaling through modulation of REDD1 expression. These findings contribute new insight into the miRNA-mediated molecular mechanism of the hypoxic response through mTOR signaling, highlighting potential targets for tumor suppression.

miR-92b-3p-TSC1 axis is critical for mTOR signaling-mediated vascular smooth muscle cell proliferation induced by hypoxia.

Pulmonary artery smooth muscle cells (PASMCs) undergo proliferation by the mammalian target of rapamycin (mTOR) signaling pathway under hypoxia. Hypoxia induces expression of a specific set of microRNAs (miRNAs) in a variety of cell types. We integrated genomic analyses of both small non-coding RNA and coding transcripts using next-generation sequencing (NGS)-based RNA sequencing with the molecular mechanism of the mTOR signaling pathway in hypoxic PASMCs. These analyses revealed hypoxia-induced miR-92b-3p as a potent regulator of the mTOR signaling pathway. We demonstrated that miR-92b-3p directly targets the 3'-UTR of a negative regulator in the mTOR signaling pathway, TSC1. mTOR signaling and consequent cell proliferation were promoted by enforced expression of miR-92b-3p but inhibited by knocking down endogenous miR-92b-3p. Furthermore, inhibition of miR-92b-3p attenuated hypoxia-induced proliferation of vascular smooth muscle cells (VSMCs). Therefore, this study elucidates a novel role of miR-92b-3p as a hypoxamir in the regulation of the mTOR signaling pathway and the pathological VSMC proliferative response under hypoxia. These findings will help us better understand the miRNA-mediated molecular mechanism of the proliferative response of hypoxic VSMCs through the mTOR signaling pathway.

Molecular basis of maintaining an oxidizing environment under anaerobiosis by soluble fumarate reductase.

Osm1 and Frd1 are soluble fumarate reductases from yeast that are critical for allowing survival under anaerobic conditions. Although they maintain redox balance during anaerobiosis, the underlying mechanism is not understood. Here, we report the crystal structure of a eukaryotic soluble fumarate reductase, which is unique among soluble fumarate reductases as it lacks a heme domain. Structural and enzymatic analyses indicate that Osm1 has a specific binding pocket for flavin molecules, including FAD, FMN, and riboflavin, catalyzing their oxidation while reducing fumarate to succinate. Moreover, ER-resident Osm1 can transfer electrons from the Ero1 FAD cofactor to fumarate either by free FAD or by a direct interaction, allowing de novo disulfide bond formation in the absence of oxygen. We conclude that soluble eukaryotic fumarate reductases can maintain an oxidizing environment under anaerobic conditions, either by oxidizing cellular flavin cofactors or by a direct interaction with flavoenzymes such as Ero1.

Efficacy and safety of electrical moxibustion for knee osteoarthritis: study protocol for a randomized controlled trial.

BACKGROUND: Knee osteoarthritis (KOA) is a significant health issue because it causes pain and functional limitation. Many studies have reported that moxibustion, a treatment in traditional Korean medicine, is effective in treating KOA. However, conventional moxibustion produces smoke, harmful gases, and odors that can adversely affect the eyes, skin, and throat. It is also difficult to control the intensity of stimulation in conventional moxibustion. An electrical moxibustion device was developed to circumvent these problems, but there are few studies of that device. We will evaluate the efficacy and safety of electrical moxibustion as a treatment for KOA, and compare it with traditional indirect moxibustion and usual care. METHODS: This is a multicenter, randomized, open, assessor-blinded, parallel-group clinical trial. A total of 138 eligible participants with KOA will be randomly allocated into three groups (electrical moxibustion, traditional indirect moxibustion, or usual care) with a 1:1:1 ratio. Participants in each moxibustion group will receive 12 sessions of moxibustion treatment at 6 acupoints (ST36, ST35, ST34, SP9, EX-LE4, SP10) plus up to 2 points of "ashi", if needed, over a period of 6 weeks (2 sessions per week). A specifically designed device that provides thermal stimulation using electrical energy will be used for the electrical moxibustion group. Participants in the usual care group will receive usual treatment and self-care. The primary outcome measure is change in pain on a numerical rating scale (NRS) from week 1 to week 6. The secondary outcome measures are pain assessed on a visual analog scale (VAS), the Korean version of the Western Ontario and McMaster osteoarthritis index (K-WOMAC), patient global assessment (PGA), and the European quality of life five dimension five level scale (EQ-5D-5 L). Safety will be assessed by monitoring adverse events at each visit. Follow-up measurements will be performed at 12 weeks after baseline measurements. DISCUSSION: This trial will provide evidence on the efficacy and safety of electrical moxibustion as a treatment for KOA. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03287570 . Registered on 19 September 2017.

Stat5 phosphorylation is responsible for the excessive potency of HB-EGF.

Heparin-binding EGF-like growth factor (HB-EGF) is a potent growth factor involved in wound healing and tumorigenesis. Despite the sequence similarity between HB-EGF and EGF, HB-EGF induces cellular proliferation and migration more potently than EGF. However, the differential regulation by HB-EGF and EGF has not been thoroughly elucidated. In this study, we compared signaling pathways activated by HB-EGF and EGF to understand the details of the molecular mechanism of the high potency induced by HB-EGF. HB-EGF specifically induced the phosphorylation of EGFR-Y1045 and activated Stat5, which is responsible for promoting cell proliferation, and migration. The competition of phosphorylated EGFR-Y1045 inhibited Stat5 activation and consequently lowered the effect of HB-EGF on cell proliferation, suggesting that the phosphorylation of EGFR-Y1045 is essential for the activation of Stat5. The phosphorylation of EGFR-Y1045 and Stat5 induced by HB-EGF was prevented by sequestering the heparin-binding domain, suggesting that the heparin-binding domain is critical for HB-EGF-mediated signaling and cellular responses. In conclusion, the heparin-binding domain of HB-EGF was responsible for EGFR-mediated Stat5 activation, resulting in a more potent cellular proliferation, and migration than that mediated by EGF. This molecular mechanism is useful for understanding ligand-specific EGFR signaling and developing biomedicines for wound healing or cancer therapy.