Differences in the impact of newly diagnosed type 2 diabetes on cardiovascular mortality between normotensive and hypertensive individuals.

OBJECTIVE: We investigated the interrelationship between hyperglycemia and hypertension on cardiovascular mortality in the middle-aged and elderly people. METHODS: In this retrospective cohort study that used data from the Hiroshima Study on Glucose Metabolism and Cardiovascular Diseases, we included 16,564 participants without cardiovascular disease (mean age: 65.8 years; 6179 normoglycemic people, 3017 people with newly diagnosed type 2 diabetes, and 7368 people with prediabetes per the 75-g oral glucose tolerance test). Hypertension was defined as the use of antihypertensive medications and/or having a systolic/diastolic blood pressure of at least 140/90 mm Hg. RESULTS: During a median follow-up period of 12.4 years, a total of 1513 cardiovascular death occurred. Cardiovascular death rates per 1000 participant-years were 4.01, 4.98, 8.33, 8.22, 8.81, and 11.1 among normotensive participants with normal glycemia, prediabetes, and diabetes and hypertensive participants with normal glycemia, prediabetes, and diabetes, respectively. Prediabetes was significantly associated with a high risk of cardiovascular mortality in normotensive individuals [hazard ratio: 1.24, 95% confidence interval (95% CI): 1.02-1.50] but not in hypertensive individuals. Type 2 diabetes was associated with a high risk of cardiovascular mortality in both normotensive (hazard ratio: 1.94, 95% CI: 1.55-2.43) and hypertensive individuals (hazard ratio: 1.35, 95% CI: 1.13-1.62). Stratified analyses revealed no significant impact of type 2 diabetes on cardiovascular mortality in hypertensive individuals aged at least 65 years. CONCLUSION: The effect of hyperglycemia on cardiovascular death differed with age and the presence or absence of hypertension, demonstrating the clinical importance of case-specific risk assessments.

Radiological features and surgical management of lung abscess directly extending into the chest wall: A case report.

INTRODUCTION AND IMPORTANCE: We presented an extremely rare case of lung abscess following bronchoscopy associated with lung cancer that extended directly into the chest wall. CASE PRESENTATION: A 49-year-old man with adenocarcinoma underwent bronchoscopy. Eight days after the biopsy, the patient presented with chills and anterior chest wall pain. Chest computed tomography (CT) scan revealed a gas-containing lung abscess, measuring 10 cm in the left upper lobe and subcutaneous emphysema. The coronal view of the CT indicated a continuous passage of air from the lung abscess to the subcutaneous emphysema beneath the pectoralis muscle. Surgical debridement of the subcutaneous abscess was performed, resulting in drainage of a large volume of purulent material. We confirmed that the lung abscess had directly extended to the chest wall, leading to a decision to perform segmentectomy of the upper division of the left lung. CLINICAL DISCUSSION: Lung abscess associated with lung cancer is a rare, life-threatening complication, which may lead to significant delays in the commencement of oncological treatment and potentially worsen long-term outcomes. In the present case, surgical findings confirmed a lung abscess extending directly to the chest wall. Surgical therapy is the treatment of choice for this rare condition, providing rapid focus control. Therefore, prompt initiation of surgical therapy is essential when conservative measures prove ineffective. CONCLUSION: Lung abscesses may extend into the chest wall during differential diagnosis of infectious diseases of the chest wall. Successful treatment of this rare condition depends on prompt surgical intervention.

Radiological features of intrathoracic chronic expanding hematoma: A case report.

INTRODUCTION AND IMPORTANCE: We present a relatively rare case of intrathoracic chronic expanding hematoma (CEH) after thoracic surgery for lung cancer. CEH is often difficult to distinguish from malignant tumors because of its large size and slow progressive enlargement. In this report, we describe the radiological features of CEH in detail. CASE PRESENTATION: A 67-year-old man who underwent a left upper lobectomy for lung cancer at 46 years of age presented with hemosputum. Computed tomography revealed a large mass with central low attenuation. Calcification was detected in peripheral lesions of the mass. T2-weighted magnetic resonance imaging (MRI) revealed a mass with mixed low and high signal intensities. Based on the clinical course, the patient was diagnosed with an intrathoracic CEH. A left posterolateral thoracotomy was performed with the patient in the lateral position, and a mass encased in a tough capsule was resected. The postoperative histopathological findings were consistent with CEH. CLINICAL DISCUSSION: CT of intrathoracic CEH shows a lesion with heterogeneous content, a thick wall, and calcifications. However, differentiation from malignant tumors is difficult using CT alone. MRI is a good diagnostic modality for CEH and often shows a mixture of low- and high-intensity areas on T2-weighted images. In addition, the patient's medical history is important because most cases of CEH have a history of trauma or surgery. CONCLUSION: To diagnose intrathoracic CEH, it is essential to consider the patient's clinical course and MRI findings.

Pleomorphic adenoma of the trachea: A case report.

INTRODUCTION AND IMPORTANCE: Although pleomorphic adenoma is the most common type of parotid gland tumor, its occurrence in the trachea is rare. Here, we describe a successfully resected pleomorphic adenoma of the trachea in a woman with severe respiratory failure that had been preoperatively misdiagnosed as asthma. CASE PRESENTATION: A 69-year-old woman presented to the emergency department with symptoms of worsening dyspnea and subsequent loss of consciousness. She had a history of progressively worsening wheezing and stridor over the course of 2-years and had been diagnosed with asthma. Arterial blood gas sample analysis indicated type II respiratory failure. A chest computed tomographic scan revealed a tumor in the trachea, which was almost completely obstructing the lower tracheal lumen. The tumor was located just above the carina. To alleviate airway constriction and achieve complete resection, carinal resection with reconstruction was performed. The postoperative diagnosis was pleomorphic adenoma of the trachea. CLINICAL DISCUSSION: Pleomorphic adenoma is a rare tracheal tumor that may present with obstructive airway symptoms that mimic asthma. CONCLUSION: Tracheal tumors should be considered in patients with chronic respiratory symptoms that do not improve with medication.

Differences in response to treatment in children with severe IgA nephropathy according to patient age.

AIM: To clarify whether the response to treatment of IgA nephropathy (IgAN) differs depending on patient age, we examined the response to treatment according to age of onset in children with IgAN. METHODS: We collected data for 44 children with severe IgAN. The children were retrospectively divided into three groups based on their age at disease onset. Group 1 consisted of 24 children under 11 years old, group 2 consisted of 9 children aged 12 to 13 years, and group 3 consisted of 11 children aged over 14 years old. The clinical features and prognosis were analyzed for each group. RESULTS: The urinary protein excretion and serum IgA values in group 3 were higher than those in groups 1 and 2 at the most recent follow up, and histological findings showed that the MESTCG scores in group 3 were higher than those in group 1. Furthermore, the incidence of patients with persistent nephropathy or renal insufficiency in group 3 was higher than those in groups 1 and 2. CONCLUSIONS: Patients aged 14 years and older with IgAN may respond poorly to treatment compared with those younger than 14 years old. Therefore, care must be taken regarding response to treatment and relapse when treating older children.

CDYL reinforces male gonadal sex determination through epigenetically repressing Wnt4 transcription in mice.

In mammals, male and female gonads initially develop from bipotential progenitor cells, which can differentiate into either testicular or ovarian cells. The decision to adopt a testicular or ovarian fate relies on robust genetic forces, i.e., activation of the testis-determining gene Sry, as well as a delicate balance of expression levels for pro-testis and pro-ovary factors. Recently, epigenetic regulation has been found to be a key element in activation of Sry. Nevertheless, the mechanism by which epigenetic regulation controls the expression balance of pro-testis and pro-ovary factors remains unclear. Chromodomain Y-like protein (CDYL) is a reader protein for repressive histone H3 methylation marks. We found that a subpopulation of Cdyl-deficient mice exhibited XY sex reversal. Gene expression analysis revealed that the testis-promoting gene Sox9 was downregulated in XY Cdyl-deficient gonads during the sex determination period without affecting Sry expression. Instead, we found that the ovary-promoting gene Wnt4 was derepressed in XY Cdyl-deficient gonads prior to and during the sex-determination period. Wnt4 heterozygous deficiency restored SOX9 expression in Cdyl-deficient XY gonads, indicating that derepressed Wnt4 is a cause of the repression of Sox9. We found that CDYL directly bound to the Wnt4 promoter and maintained its H3K27me3 levels during the sex-determination period. These findings indicate that CDYL reinforces male gonadal sex determination by repressing the ovary-promoting pathway in mice.

Role of Monomer/Tetramer Equilibrium of Rod Visual Arrestin in the Interaction with Phosphorylated Rhodopsin.

The phototransduction cascade in vertebrate rod visual cells is initiated by the photoactivation of rhodopsin, which enables the activation of the visual G protein transducin. It is terminated by the phosphorylation of rhodopsin, followed by the binding of arrestin. Here we measured the solution X-ray scattering of nanodiscs containing rhodopsin in the presence of rod arrestin to directly observe the formation of the rhodopsin/arrestin complex. Although arrestin self-associates to form a tetramer at physiological concentrations, it was found that arrestin binds to phosphorylated and photoactivated rhodopsin at 1:1 stoichiometry. In contrast, no complex formation was observed for unphosphorylated rhodopsin upon photoactivation, even at physiological arrestin concentrations, suggesting that the constitutive activity of rod arrestin is sufficiently low. UV-visible spectroscopy demonstrated that the rate of the formation of the rhodopsin/arrestin complex well correlates with the concentration of arrestin monomer rather than the tetramer. These findings indicate that arrestin monomer, whose concentration is almost constant due to the equilibrium with the tetramer, binds to phosphorylated rhodopsin. The arrestin tetramer would act as a reservoir of monomer to compensate for the large changes in arrestin concentration in rod cells caused by intense light or adaptation.

Tobacco Exposure During Pregnancy and Infections in Infants up to 1 Year of Age: The Japan Environment and Children's Study.

BACKGROUND: Tobacco exposure during pregnancy is associated with several adverse outcomes in infants. We investigated the association between tobacco exposure during pregnancy (both active and second-hand) and various infections in infants up to 1 year. METHODS: This prospective cohort study used a fixed dataset (jecs-an-20180131) from the Japan Environment and Children's Study of registered births in Japan during 2011-2014 that included 104,065 fetal records from enrolled pregnant women. Based on the participants' responses to the questionnaire on smoking status, mothers were first divided into "never smoked," "quit smoking," and "current smoker" groups and then into "no second-hand smoking (SHS)" and "SHS" groups. Infectious diseases included central nervous system infection, otitis media (OM), upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), gastroenteritis (GI), and urinary tract infection. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated using logistic regression analysis and adjusted for maternal, socioeconomic, and postnatal confounding factors. RESULTS: Among the 73,205 newborns enrolled, multivariable analysis revealed that the aOR of LRTI and GI was 1.20 (95% CI, 1.07-1.33) and 1.18 (95% CI, 1.04-1.35), respectively, for the "current smoker with/without SHS" group compared with the "never smoked without SHS" group. "Quit smoking without SHS" was not associated with the risk of LRTI. SHS was associated with an increased risk of OM, URTI, LRTI, and GI, especially with LRTI and GI. CONCLUSION: Exposure to tobacco smoke during pregnancy was associated with an increased risk of OM, URTI, LRTI, and GI in infants during their first year of life.

Neutralizing and Epitope-Specific Antibodies against Respiratory Syncytial Virus in Maternal and Cord Blood Paired Samples.

Only a few qualitative studies of neutralizing antibody titers (NATs) against respiratory syncytial virus (RSV) have focused on epitope-specific antibody (ESA) levels. Here, NATs against RSV in sera were measured using the blood of 412 mothers and cord blood (CB) of 95 of the 412 mother-child pairs. ESA levels against sites zero (Ø) and IIa of the F protein of RSV were measured in 87 of the 95 mother-child pairs. The median gestational age was 39 weeks. The NATs and ESA levels in CB were slightly higher than those in maternal blood (MB). The NATs for RSV subtype A (RSV-A) in MB and CB showed a positive correlation (r = 0.75). The ESA levels against sites Ø and IIa in MB and CB showed positive correlations, r = 0.76 and r = 0.69, respectively. In MB, the NATs and ESA levels against RSV were positively correlated, more significantly against site Ø (RSV-A: r = 0.70, RSV-B: r = 0.48) than against site IIa (RSV-A: r = 0.19, RSV-B: r = 0.31). Sufficient amounts of ESAs against sites Ø and IIa of RSV were transferred from mothers to term infants. ESA levels against site Ø contribute to NATs.

A spontaneous reduction in tumor size of a thymic carcinoma: a case report.

BACKGROUND: Spontaneous regression of thymic carcinoma is extremely rare. We report a case of a resected thymic carcinoma with preoperative spontaneous regression in a 67-year-old woman. CASE PRESENTATION: The patient presented with low-grade fever and anterior chest pain. Chest computed tomography (CT) showed a 55 × 43 mm exophytic heterogeneously enhancing mass showing some areas of necrosis. Chest CT done one day preoperatively revealed that the tumor had rapidly shrunk for one month. Surgical resection was performed to obtain a definitive diagnosis and achieve complete resection, yielding a postoperative diagnosis of thymic carcinoma. The patient survived without signs of recurrence for 12 months postoperatively. CONCLUSIONS: Mediastinal tumors with necrosis demonstrating spontaneous regression should include thymic carcinomas in the differential diagnosis.

Early-Phase Changes in Serum Free Fatty Acid Levels After Glucose Intake Are Associated With Type 2 Diabetes Incidence: The Hiroshima Study on Glucose Metabolism and Cardiovascular Diseases.

OBJECTIVE: Experimental studies suggest that excess serum free fatty acid (FFA) levels result in impaired glucose metabolism. This study investigated the relationship between changes in serum FFA levels after glucose intake and type 2 diabetes risk. RESEARCH DESIGN AND METHODS: This observational study included 6,800 individuals without diabetes who underwent a 75-g oral glucose tolerance test. Serum FFA levels were measured before and 30 and 60 min after glucose intake. The percentages of changes in serum FFA levels from 0 to 30 and from 30 to 60 min were compared, and a low rate of change in FFA levels was determined using the receiver operating characteristic curve analysis. RESULTS: Over a mean 5.3-year follow-up period, 485 participants developed type 2 diabetes. After adjusting for plasma glucose levels and indices of insulin resistance and ß-cell function, low rates of change in FFA levels at 0-30 min (adjusted odds ratio [aOR] 1.91; 95% CI 1.54-2.37) and 30-60 min (aOR 1.48; 95% CI 1.15-1.90) were associated with the incidence of type 2 diabetes. Stratified analysis revealed that the low rate of change in FFA levels at 30-60 min (aOR 1.97; 95% CI 1.05-3.69) was associated with the incidence of type 2 diabetes even in participants with normal fasting glucose levels or glucose tolerance. CONCLUSIONS: Changes in serum FFA levels within the 1st h after glucose intake could be a primary predictor of type 2 diabetes. This change may occur prior to the onset of impaired glucose metabolism.

Adipose tissue insulin resistance predicts the incidence of hypertension: The Hiroshima Study on Glucose Metabolism and Cardiovascular Diseases.

We investigated the association of adipose tissue insulin resistance with blood pressure and hypertension incidence, comparing it with hepatic and skeletal muscle insulin resistance. The cross-sectional analysis included 6892 general health checkup examinees (mean age: 69.3 years; 51.3% women and 48.7% men) who had no cardiovascular disease. Of those, 3948 normotensive participants (mean age: 68.4 years; 54.8% women and 45.2% men) were enrolled in the retrospective cohort analysis. The adipose insulin resistance index (Adipo-IR) was calculated as the product of fasting serum insulin and free fatty acid levels. A high adipo-IR, high homeostasis model assessment of insulin resistance (HOMA-IR), and low Matsuda index were indicated based on the optimal cutoff values in a receiver operating characteristic curve analysis. Adipo-IR (ß = 0.096, P < 0.001), HOMA-IR (ß = 0.052, P < 0.001), and Matsuda index (ß = -0.055, P < 0.001) were associated with systolic blood pressure in the cross-sectional analysis. Over a mean 5.3-year follow-up period, 1310 participants developed hypertension. A high adipo-IR (adjusted OR, 1.29; 95% CI, 1.11-1.51), but not HOMA-IR or Matsuda index, was significantly associated with the incidence of hypertension. Moreover, the combination of high adipo-IR with high HOMA-IR or low Matsuda index showed no higher odds of hypertension than a high adipo-IR alone. These results suggest that insulin resistance is associated with blood pressure control regardless of the tissue in which it occurs; however, the risk of hypertension is determined by insulin resistance in adipose tissue rather than in liver or muscle tissue.

Intrapulmonary solitary fibrous tumor coexisting with lung adenocarcinomas.

BACKGROUND: Solitary fibrous tumor (SFT) is a rare tumor of mesenchymal origin and accounts for < 2% of all soft tissue masses. Although SFT has been identified in multiple anatomic locations and can grow anywhere in the body, intrapulmonary SFT are rare. CASE PRESENTATION: In this report, we presented a rare case of intrapulmonary solitary fibrous tumor (SFT) coexisting with lung adenocarcinoma in a 74-year-old man. Chest computed tomography showed a well-defined nodule with punctate calcification and measuring 2.3 × 2.1 cm and two ground-grass nodules with solid component. To obtain a definitive diagnosis and achieve complete resection, surgery was performed. The postoperative diagnosis was intrapulmonary SFT coexisting with lung adenocarcinoma. After surgery, he survived for 6 months without any signs of recurrence. CONCLUSION: Complete resection may be the best treatment for intrapulmonary SFT. Careful follow-up of the postoperative course is important, because differentiating between benignity and malignancy is difficult by histologic findings alone.

Threonine phosphorylation regulates the molecular assembly and signaling of EGFR in cooperation with membrane lipids.

The cytoplasmic domain of receptor tyrosine kinases (RTKs) plays roles as a kinase and a protein scaffold; however, the allocation of these two functions is not fully understood. Here, we analyzed the assembly of the transmembrane (TM)-juxtamembrane (JM) region of EGFR, one of the best studied members of RTKs, by combining single-pair fluorescence resonance energy transfer (FRET) imaging and a nanodisc technique. The JM domain of EGFR contains a threonine residue (T654) that is phosphorylated after ligand association. We observed that the TM-JM peptides of EGFR form anionic lipid-induced dimers and cholesterol-induced oligomers. The two forms involve distinct molecular interactions, with a bias toward oligomer formation upon threonine phosphorylation. We further analyzed the functions and oligomerization of whole EGFR molecules, with or without a substitution of T654 to alanine, in living cells. The results suggested an autoregulatory mechanism in which T654 phosphorylation causes a switch of the major function of EGFR from kinase-activating dimers to scaffolding oligomers.

Gene expression profile and injury sites in mice treated with Shiga toxin 2 and lipopolysaccharide as a Shiga toxin-associated hemolytic uremic syndrome model.

Shiga toxin 2 (Stx2) and lipopolysaccharide (LPS) contribute to the development of hemolytic uremic syndrome (HUS). Mouse models of HUS induced by LPS/Stx2 have been used for elucidating HUS pathophysiology and for therapeutic development. However, the underlying molecular mechanisms and detailed injury sites in this model remain unknown. We analyzed mouse kidneys after LPS/Stx2 administration using microarrays. Decreased urinary osmolality and urinary potassium were observed after LPS/Stx2 administration, suggestive of distal nephron disorders. A total of 1,212 and 1,016 differentially expressed genes were identified in microarrays at 6 h and 72 h after LPS/Stx2 administration, respectively, compared with those in controls. Ingenuity pathway analysis revealed activation of TNFR1/2, iNOS, and IL-6 signaling at both time points, and inhibition of pathways associated with lipid metabolism at 72 h only. The strongly downregulated genes in the 72-h group were expressed in the distal nephrons. In particular, genes associated with distal convoluted tubule (DCT) 2/connecting tubule (CNT) and principal cells of the cortical collecting duct (CCD) were downregulated to a greater extent than those associated with DCT1 and intercalated cells. Stx receptor globotriaosylceramide 3 (Gb3) revealed no colocalization with DCT1-specific PVALB and intercalated cell-specific SLC26A4 but did present colocalization with SLC12A3 (present in both DCT1 and DCT2), and AQP2 in principal cells. Gb3 localization tended to coincide with the segment in which the downregulated genes were present. Thus, the LPS/Stx2-induced kidney injury model represents damage to DCT2/CNT and principal cells in the CCD, based on molecular, biological, and physiological findings.

HP1 maintains protein stability of H3K9 methyltransferases and demethylases.

Di- or tri-methylated H3K9 (H3K9me2/3) is an epigenetic mark of heterochromatin. Heterochromatin protein 1 (HP1) specifically recognizes H3K9me2/3, contributing to transcriptional suppression and spread of H3K9me2/3. Here, we demonstrate another role of HP1 in heterochromatin organization: regulation of protein stability of H3K9 methyltransferases (H3K9 MTs) and demethylases (H3K9 DMs). We show that HP1 interaction-defective mutants of H3K9 MTs, Suv39h1 and Setdb1, undergo protein degradation. We further establish mouse embryonic stem cell lines lacking all three HP1 paralogs. In the HP1-deficient cells, Suv39h1, Suv39h2, Setdb1, and G9a/GLP complex decrease at the protein level, and the enzymes are released from chromatin. HP1 mutants that cannot recognize H3K9me2/3 or form dimers cannot stabilize these enzymes, indicating that the tethering of H3K9 MTs to chromatin is critical for their protein stability. We show that HP1 also stabilizes H3K9 DMs, Jmjd1a and Jmjd1b. Our study indicates that mammalian HP1 forms a heterochromatin hub that governs protein stability of H3K9 MTs and H3K9 DMs.

Association of obesity with serum free fatty acid levels in individuals at different stages of prediabetes.

We investigated the associations of prediabetes categories and obesity with serum free fatty acid (FFA) levels and adipose tissue insulin resistance. This study included 5006 male participants (1779, 1025, 629, 874, and 699 with normal fasting glucose/normal glucose tolerance, isolated impaired fasting glucose [IFG], isolated impaired glucose tolerance [IGT], IFG plus IGT, and diabetes, respectively). Serum FFA levels were assessed before and 30, 60, and 120 min after glucose ingestion, and the total area under the FFA curve (AUCFFA ) was calculated. Adipose insulin resistance index (adipo-IR) was assessed based on fasting FFA and insulin concentrations. Isolated IFG was associated with high fasting FFA levels (OR, 1.35; p < 0.001) and high adipo-IR (OR, 1.82; p < 0.001) only in the nonobesity group. Isolated IGT, IFG plus IGT, and diabetes were associated with high fasting FFA levels, regardless of obesity. Obesity was significantly associated with AUCFFA , and the duration of obesity-related impairment in lipolysis inhibition after glucose ingestion was prolonged in IFG plus IGT and diabetes. These results suggest that IFG and obesity may overlap in their effects on FFA metabolism whereas IGT has significant effects on FFA independent of obesity. Obesity impact on lipolysis may be involved in worsening glucose metabolism.

Association of Flow Parameters and Diameter in the Common Carotid Artery with Impaired Glucose Metabolism.

AIM: Diameter, intima-media thickness (IMT), and flow parameters, including resistance index (RI) and pulsatility index (PI), in the common carotid artery (CCA) are markers of arterial remodeling, atherosclerosis, and vascular resistance, respectively. We investigated the differences among these markers in association with plasma glucose level, serum insulin level, and insulin resistance in participants without cardiovascular disease. METHODS: CCA parameters (including the CCA interadventitial diameter and mean IMT at the time of 75-g oral glucose tolerance testing) were assessed in 4218 participants. RI and PI were assessed in 3380 of these participants. To assess plasma glucose and serum immunoreactive insulin profiles during oral glucose tolerance testing, we used the total areas under the curves (AUCglu and AUCins, respectively). We used the homeostasis model assessment of insulin resistance (HOMA-IR) and the Matsuda index to assess insulin resistance. Insulin secretion was assessed with the HOMA-ß. RESULTS: AUCglu was significantly associated with CCA interadventitial diameter (ß=0.048, P＜0.001), RI (ß=0.144, P＜0.001), and PI (ß=0.103, P＜0.001) but not with mean IMT. AUCins (ß=-0.064, P＜0.001) and HOMA-ß (ß=-0.054, P＜0.001) were significantly and negatively associated with CCA interadventitial diameter, but not with mean IMT. Both HOMA-IR and Matsuda index were significantly associated with RI and PI. CONCLUSIONS: These findings indicate that all CCA parameters except IMT are associated with impaired glucose metabolism in patients without cardiovascular disease.

Common Carotid Artery Flow Parameters Predict the Incidence of Hypertension.

[Figure: see text].

Structural and thermodynamical insights into the binding and inhibition of FIH-1 by the N-terminal disordered region of Mint3.

Mint3 is known to enhance aerobic ATP production, known as the Warburg effect, by binding to FIH-1. Since this effect is considered to be beneficial for cancer cells, the interaction is a promising target for cancer therapy. However, previous research has suggested that the interacting region of Mint3 with FIH-1 is intrinsically disordered, which makes investigation of this interaction challenging. Therefore, we adopted thermodynamic and structural studies in solution to clarify the structural and thermodynamical changes of Mint3 binding to FIH-1. First, using a combination of circular dichroism, nuclear magnetic resonance, and hydrogen/deuterium exchange-mass spectrometry (HDX-MS), we confirmed that the N-terminal half, which is the interacting part of Mint3, is mostly disordered. Next, we revealed a large enthalpy and entropy change in the interaction of Mint3 using isothermal titration calorimetry (ITC). The profile is consistent with the model that the flexibility of disordered Mint3 is drastically reduced upon binding to FIH-1. Moreover, we performed a series of ITC experiments with several types of truncated Mint3s, an effective approach since the interacting part of Mint3 is disordered, and identified amino acids 78 to 88 as a novel core site for binding to FIH-1. The truncation study of Mint3 also revealed the thermodynamic contribution of each part of Mint3 to the interaction with FIH-1, where the core sites contribute to the affinity (ΔG), while other sites only affect enthalpy (ΔH), by forming noncovalent bonds. This insight can serve as a foothold for further investigation of intrinsically disordered regions (IDRs) and drug development for cancer therapy.