Disulfide Bonds of Thyroid Peroxidase Are Critical Elements for Subcellular Localization, Proteasome-Dependent Degradation, and Enzyme Activity.

Background: Congenital hypothyroidism (CH) is caused by mutations in cysteine residues, including Cys655 and Cys825 that form disulfide bonds in thyroid peroxidase (TPO). It is highly likely that these disulfide bonds could play an important role in TPO activity. However, to date, no study has comprehensively analyzed cysteine mutations that form disulfide bonds in TPO. In this study, we induced mutations in cysteine residues involved in disulfide bonds formation and analyzed their effect on subcellular localization, degradation, and enzyme activities to evaluate the importance of disulfide bonds in TPO activity. Methods: Vector plasmid TPO mutants, C655F and C825R, known to occur in CH, were transfected into HEK293 cells. TPO activity and protein expression levels were measured by the Amplex red assay and Western blotting. The same procedure was performed in the presence of MG132 proteasome inhibitor. Subcellular localization was determined using immunocytochemistry and flow cytometry. The locations of all disulfide bonds within TPO were predicted using in silico analysis. All TPO mutations associated with disulfide bonds were induced. TPO activity and protein expression levels were also measured in all TPO mutants associated with disulfide bonds using the Amplex red assay and Western blotting. Results: C655F and C825R showed significantly decreased activity and protein expression compared with the wild type (WT) (p < 0.05). In the presence of the MG132 proteasome inhibitor, the protein expression level of TPO increased to a level comparable with that of the WT without increases in its activity. The degree of subcellular distribution of TPO to the cell surface in the mutants was lower compared with the WT TPO. Twenty-four cysteine residues were involved in the formation of 12 disulfide bonds in TPO. All TPO mutants harboring an amino acid substitution in each cysteine showed significantly reduced TPO activity and protein expression levels. Furthermore, the differences in TPO activity depended on the position of the disulfide bond. Conclusions: All 12 disulfide bonds play an important role in the activity of TPO. Furthermore, the mutations lead to misfolding, degradation, and membrane insertion.

Predictive patterns of lower urinary tract symptoms and bacteriuria in adults with type 2 diabetes.

Background: Numerous studies demonstrated the risk factors for urological complications in patients with diabetes before sodium-glucose co-transporter 2 inhibitor (SGLT2i) became commercially available. This study aimed to comprehensively investigate urological characteristics in patients with type 2 diabetes (T2DM) after SGLT2i became commercially available. Methods: We examined 63 outpatients with T2DM suspected of bacteriuria based on urinary sediment examinations. Urine cultures were performed, and lower urinary tract symptoms (LUTS) were assessed via questionnaires. Patients with bacteriuria were assessed using ultrasonography to measure post-void residual volume (PVR). Utilizing demographic and laboratory data, a random forest algorithm predicted LUTS, bacteriuria, and symptomatic bacteriuria (SB). Results: Thirty-two patients had LUTS and 31 had bacteriuria. High-density lipoprotein cholesterol level was crucial in predicting LUTS, while age was crucial in predicting bacteriuria. In predicting SB among patients with bacteriuria, creatinine level and estimated glomerular filtration rate were crucial. Our models had high predictive accuracy for LUTS (area under the curve [AUC] = 0.846), followed by bacteriuria (AUC = 0.770) and SB (AUC = 0.938) in receiver operating characteristic curve analysis. These predictors were previously reported as risk factors for urological complications. Although SGLT2i use was not an important predictor in our study, all SGLT2i users with bacteriuria had SB and exhibited higher PVR compared to non-SGLT2i users with bacteriuria. Conclusion: This study's random forest model highlighted distinct essential predictors for each urological condition. The predictors were consistent before and after SGLT2i became commercially available. Supplementary Information: The online version contains supplementary material available at 10.1007/s13340-023-00687-1.

Corticosteroid-triggered acute skeletal muscle loss in lipodystrophy: A case report.

The potential liability to hypercatabolism in lipodystrophy remains to be fully elucidated. Here we report a 28-year-old Japanese woman with acquired generalized lipodystrophy, who presented with recurrence of panniculitis and anemia. After corticosteroid treatment was started, she showed rapid reductions in body weight and lean mass by 15% at maximum, accompanied by an elevated urea nitrogen/creatinine ratio, which recovered almost fully as the corticosteroid treatment was tapered and discontinued. She had multiple risk factors for hypercatabolism: lack of metabolic reserves, insulin resistance, and hyperglycemia due to lipodystrophy, lowered daily activity due to anemia, persistent inflammation, and wasting associated with panniculitis, and relatively insufficient energy and protein intake during hospitalization. More attention should be paid to the potential liability to hypercatabolism in patients with lipodystrophy, and to skeletal muscle loss as an adverse effect of corticosteroid treatment in patients at high risk, such as those with diabetes or decreased metabolic reserves.

Clinical characteristics and human leukocyte antigens in patients with immune checkpoint inhibitor-induced type 1 diabetes and pituitary dysfunction: a single center prospective study.

PURPOSE: Immune checkpoint inhibitor (ICI) induced type 1 diabetes (T1D) and pituitary dysfunction are life-threatening adverse events, yet there is little clinical data available. We aimed to investigate the clinical characteristics of patients with these adverse events and report their human leukocyte antigen (HLA) profile to determine its relevance. METHODS: This is a single-center prospective study. We enrolled patients with cancers who were administered ICI and diagnosed as ICI induced T1D (ICI-T1D) and pituitary dysfunction (ICI-PD). Clinical data and extracted DNA from blood samples were collected. HLA typing was performed using next-generation sequencing. We compared our results with those previously reported in healthy controls and investigated the correlation between HLA and the occurrence of ICI-T1D and ICI-PD. RESULTS: We identified 914 patients treated with ICI in our facility from 1st September, 2017 to 30th June, 2022. Six of these patients developed T1D and 15 developed pituitary dysfunction. The duration from the initiation of ICI treatment to the onset of T1D or pituitary dysfunction averaged 492 ± 196 days and 191 ± 169 days. Among the six patients with T1D, two were positive for anti-GAD antibody. The frequencies of HLA-DR11, -Cw10, -B61, -DRB1*11:01, and -C*03:04 were significantly higher in patients with ICI-T1D than in controls. The frequencies of HLA-DR15 and -DRB*15:02 were significantly higher in patients with ICI-PD than in controls. CONCLUSION: This study revealed the clinical characteristics of ICI-T1D and ICI-PD and the association between specific HLAs and these adverse events.

Hematocrit elevation after SGLT2 inhibitor administration may be associated with the degree of proximal tubular damage.

The renal protective effects of SGLT2 inhibitors are known to be due to the elimination of glomerular hypertension and improvement of hypoxia and oxidative stress in the proximal tubule. Therefore, this increased hematocrit (ΔHct) level has been hypothesized to indicate restored tubular function and improved renal prognosis. To analyze the relationship between ΔHct and decreased estimated glomerular filtration rate (eGFR) after SGLT2 inhibitor administration backward from medical record data. Data from 206 patients who continued SGLT2 inhibitors for >3 years were analyzed. The decreased eGFR after administration of SGLT2 inhibitors was defined as Slope B. Factors statistically significantly associated with Slope B in multiple regression analysis were systolic blood pressure (sBP) (ß -.211, P = .03), short-term decreased eGFR after SGLT2 inhibitor administration (initial dip) (ß -.235, P = .003), ΔHct (ß -.185, P = .026), and urine protein (ß -.204, P = .015). These findings were the opposite of our hypothesis. ΔHct was not a marker indicating improved renal prognosis and may reflect the extent of the proximal tubular disorder before administering SGLT2 inhibitors.

Ventricular fibrillation immediately after the treatment of Graves' disease coexisting with atypical angina and long QT syndrome: a case report.

BACKGROUND: Palpitations due to Graves' disease are often caused by supraventricular arrhythmia. However, in rare cases, the background of coronary artery disease, genetic abnormalities, or channel abnormalities can cause ventricular fibrillation, which is a lethal arrhythmia. Here, we report a case of ventricular fibrillation after administration of beta-blockers early in the course of treatment for Graves' disease coexisting with atypical angina and long QT syndrome. CASE PRESENTATION: A 48-year-old man consulted a local general physician for chest discomfort and palpitations for approximately 2 weeks. He was diagnosed with Graves' disease and treated with thiamazole 15 mg, bisoprolol 1.25 mg, and nitroglycerin 0.3 mg. The patient continued to experience chest discomfort the next day and visited our hospital. The patient was treated with landiolol 0.125 mg/kg/min for heart rate control, and 20 min later, electrocardiography showed a change from the R-on-T phenomenon to ventricular fibrillation. After cardiopulmonary resumption and improvement of thyroid function, a stress test was performed, which revealed coronary angina and long QT syndrome. An implantable cardioverter defibrillator (ICD) was implanted in the patient for secondary prevention. Since then, no fatal arrhythmia has been observed to date. CONCLUSIONS: When beta-blockers are administered to patients with Graves' disease who have severe chest symptoms, fatal arrhythmias are possible. ICD implantation should be considered for the secondary prevention of fatal arrhythmias.

Machine learning approach to predict subtypes of primary aldosteronism is helpful to estimate indication of adrenal vein sampling.

INTRODUCTION: Primary aldosteronism (PA) is a common disease. Especially in unilateral PA (UPA), the risk of cardiovascular disease is high and proper localization is important. Adrenal vein sampling (AVS) is commonly used to localize PA, but its availability is limited. Therefore, it is important to predict the unilateral or bilateral PA and to choose the appropriate cases for AVS or watchful observation. AIM: The purpose of this study is to develop a model using machine learning to predict bilateral or unilateral PA to extract cases for AVS or watchful observation. METHODS: We retrospectively analyzed 154 patients diagnosed with PA and who underwent AVS at our hospital between January 2010 and June 2021. Based on machine learning, we determined predictors of PA subtypes diagnosis from the results of blood and loading tests. RESULTS: The accuracy of the machine learning was 88% and the top predictors of the UPA were plasma aldosterone concentration after the saline infusion test, aldosterone to renin ratio after the captopril challenge test, serum potassium and aldosterone-to-renin ratio. By using these factors, the accuracy, sensitivity, specificity and the area under the curve (AUC) were 91%, 70%, 99% and 0.91, respectively. Furthermore, we examined the surgical outcomes of UPA and found that the group diagnosed as unilateral by the predictors showed improvement in clinical findings, while the group diagnosed as bilateral by the predictors showed no improvement. CONCLUSION: Our predictive model based on machine learning can support to choose the performance of adrenal vein sampling or watchful observation.

Hypercalcemia associated with dysgerminoma and elevation of calcitriol: A case report and review of the literature.

We report on the case of a patient with dysgerminoma, a rare germ cell tumor, which showed hypercalcemia with an elevation of 1α,25-dihydroxycholecalciferol (calcitriol). A 27-year-old nulliparous woman presented with hypercalcemia during the examination of a right ovarian tumor with an elevation of calcitriol, lactate dehydrogenase, and alkaline phosphatase. Fractional excretion of calcium was elevated, and intact parathyroid hormone was suppressed. After undergoing right salpingo-oophorectomy, the patient's serum calcium and calcitriol returned to the normal range within a week. A literature search was conducted on the topic by reviewing databases for dysgerminoma showing hypercalcemia. We identified 14 patients from the literature and performed a pooled analysis, including the results of our case. However, most cases lack data that can help investigate the potential association between parathyroid hormone, parathyroid hormone-related protein, calcitriol, and phosphorus in hypercalcemia. Thus, more case reports that include additional information are required to fully elucidate the mechanism of hypercalcemia associated with dysgerminoma.

A cross-sectional study of the correlation between diabetic therapy and serum zinc concentrations.

AIM: Zinc, an essential trace element, has various functions in humans. Zinc deficiency is associated with the elderly, patients with diabetes, and patients with frailty, a common geriatric syndrome. As few studies have reported the effects of anti-diabetic medication on zinc levels, we examined serum zinc concentrations in patients with diabetes and their correlation with anti-diabetic medications, especially in the elderly and patients with frailty, in Japan. METHODS: This cross-sectional study was conducted in 2014 and included 1033 patients with diabetes. Blood samples were taken, and a survey for the 8-item Short Form Health Survey of the Medical Outcomes Study was conducted. RESULTS: Because of renal dysfunction (with an estimated glomerular filtration rate of < 60 mL/min/1.73 m2), 337 patients out of 1033 were excluded. Hypozincemia was observed in 43.8% of the patients with diabetes. In 177 elderly patients with a low physical component summary score, multivariable logistic regression analysis revealed two anti-diabetic medications associated with hypozincemia: GLP-1RA (multivariable-adjusted odds ratio [OR] 0.08, 95% confidence interval [CI] 0.010-0.657, p = 0.019) and metformin (OR 0.415, 95% CI 0.222-0.774, p = 0.006). In addition, metformin had a dose-dependent correlation with zinc levels (R = 0.3067, p < 0.0001). CONCLUSIONS: Oral administration of metformin in the elderly with diabetes and non-progressive renal dysfunction was not associated with hypozincemia, even at high doses. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13340-021-00521-6.

A case of diabetic ketoacidosis in a patient with COVID-19 and newly diagnosed type 1 diabetes.

To improve severe ketoacidosis with COVID-19, insulin treatment, invasive mechanical ventilation therapy, and continuous hemodiafiltration with sodium bicarbonate infusion were effective.

MEK/ERK Signaling in ß-Cells Bifunctionally Regulates ß-Cell Mass and Glucose-Stimulated Insulin Secretion Response to Maintain Glucose Homeostasis.

In diabetic pathology, insufficiency in ß-cell mass, unable to meet peripheral insulin demand, and functional defects of individual ß-cells in production of insulin are often concurrently observed, collectively causing hyperglycemia. Here we show that the phosphorylation of ERK1/2 is significantly decreased in the islets of db/db mice as well as in those of a cohort of subjects with type 2 diabetes. In mice with abrogation of ERK signaling in pancreatic ß-cells through deletion of Mek1 and Mek2, glucose intolerance aggravates under high-fat diet-feeding conditions due to insufficient insulin production with lower ß-cell proliferation and reduced ß-cell mass, while in individual ß-cells dampening of the number of insulin exocytosis events is observed, with the molecules involved in insulin exocytosis being less phosphorylated. These data reveal bifunctional roles for MEK/ERK signaling in ß-cells for glucose homeostasis, i.e., in regulating ß-cell mass as well as in controlling insulin exocytosis in individual ß-cells, thus providing not only a novel perspective for the understanding of diabetes pathophysiology but also a potential clue for new drug development for diabetes treatment.

A Rare Case of Ectopic Adrenocorticotropic Hormone Syndrome with Recurrent Olfactory Neuroblastoma.

A 40-year-old woman who had a history of recurrent olfactory neuroblastoma presented with full moon face, central obesity, buffalo hump, impaired glucose tolerance and bilateral cervical lymph node swelling. Laboratory tests showed morbidly elevated levels of adrenocorticotropic hormone (ACTH) and cortisol, which were not suppressed by high-dose (8 mg) dexamethasone. Biopsies of the enlarged cervical lymph nodes revealed ACTH-positive metastatic olfactory neuroblastoma, and ectopic ACTH syndrome was diagnosed. Metyrapone was used to suppress cortisol production and resulted in decreased levels of ACTH and cortisol. Bilateral cervical tumor resection further reduced the ACTH and cortisol levels, accompanied by a reduction in the metyrapone dosage. Cushing's syndrome was alleviated through ACTH-producing tumor removal.

Comprehensive Gene Analysis of IgG4-Related Ophthalmic Disease Using RNA Sequencing.

High-throughput RNA sequencing (RNA-seq) uses massive parallel sequencing technology, allowing the unbiased analysis of genome-wide transcription levels and tumor mutation status. Immunoglobulin G4-related ophthalmic disease (IgG4-ROD) is a fibroinflammatory disease characterized by the enlargement of the ocular adnexal tissues. We analyzed RNA expression levels via RNA-seq in the biopsy specimens of three patients diagnosed with IgG4-ROD. Mucosa-associated lymphoid tissue (MALT) lymphoma, reactive lymphoid hyperplasia (RLH), normal lacrimal gland tissue, and adjacent adipose tissue were used as the controls (n = 3 each). RNA-seq was performed using the NextSeq 500 system, and genes with |fold change| ≥ 2 and p < 0.05 relative to the controls were defined as differentially expressed genes (DEGs) in IgG4-ROD. To validate the results of RNA-seq, real-time polymerase chain reaction (PCR) was performed in 30 IgG4-ROD and 30 orbital MALT lymphoma tissue samples. RNA-seq identified 35 up-regulated genes, including matrix metallopeptidase 12 (MMP12) and secreted phosphoprotein 1 (SPP1), in IgG4-ROD tissues when compared to all the controls. Many pathways related to the immune system were included when compared to all the controls. Expressions of MMP12 and SPP1 in IgG4-ROD tissues were confirmed by real-time PCR and immunohistochemistry. In conclusion, we identified novel DEGs, including those associated with extracellular matrix degradation, fibrosis, and inflammation, in IgG4-ROD biopsy specimens. These data provide new insights into molecular pathogenetic mechanisms and may contribute to the development of new biomarkers for diagnosis and molecular targeted drugs.

A Novel Homozygous Mutation of Thyroid Peroxidase Gene Abolishes a Disulfide Bond Leading to Congenital Hypothyroidism.

Congenital hypothyroidism (CH) is the most prevalent congenital endocrine disorder and causes mental retardation. A male Japanese patient with first cousin marriage parents was diagnosed as CH at 10 months. He was born before introduction of mass screening for CH. With continuous thyroid hormone replacement therapy, normal thyroid hormone status was maintained until adulthood. Genetic screening of next-generation sequencing was performed at the age of 52 years, and we identified a new homozygous thyroid peroxidase (TPO) gene mutation (GRCh38.p13, chromosome 2 at position 1493997, c.1964 G>T, p.Cys655Phe). TPO is an important enzyme to produce thyroid hormone. As demonstrated by a homology analysis of TPO proteins among different species, cysteine 655 residue is highly conserved, suggesting an important role in maintaining TPO function and structure. An in silico study with three-dimensional structure of the novel mutation was performed and suggested that the mutation abolished disulfide bond between cysteines at positions 598 and 655. An in vitro functional analysis using HEK293 cells revealed that TPO activity of the mutant was significantly impaired compared with that of the wild type. Furthermore, study of immunohistochemistry showed that localization of TPO in cells did not differ between the wild type and the mutant. In conclusion, this single disulfide bond loss mutation of a new TPO homozygous mutation, p.Cys655Phe, reduced TPO activity and caused congenital hypothyroidism without affecting subcellular localization of TPO proteins.

Dipeptidyl Peptidase-4 Inhibitor Reduces the Risk of Developing Hypertrophic Scars and Keloids following Median Sternotomy in Diabetic Patients: A Nationwide Retrospective Cohort Study Using the National Database of Health Insurance Claims of Japan.

BACKGROUND: Hypertrophic scars and keloids, which are abnormalities of fibrosis, often occur in surgical wounds; however, their exact cause and preventive measures are unknown. The administration of dipeptidyl peptidase-4 inhibitors to humans is expected to suppress fibrosis in wounds and minimize hypertrophic scar and keloid formation. METHODS: This study aimed to verify the suppressive effect of dipeptidyl peptidase-4 inhibitors on the formation of hypertrophic scars or keloids using real world data from the National Database of Health Insurance Claims and Specific Health Checkups of Japan. It is a retrospective cohort study, and data were extracted from the National Database between April of 2013 and March of 2015. Patients who underwent median sternotomy were included in the study based on their claimed surgical codes. Subjects who were prescribed dipeptidyl peptidase-4 inhibitors constituted the treatment group; subjects who were not prescribed or administered dipeptidyl peptidase-4 inhibitors during that period constituted the nontreatment group. RESULTS: Subjects included 5430 patients throughout Japan (3509 men and 1921 women). Of the 446 subjects who were treated with dipeptidyl peptidase-4 inhibitors within 1 year before the procedure, fewer than 10 (<2 percent) developed either hypertrophic scars or keloids. Of the 4984 subjects who were not treated, 152 (3.05 percent) were at significantly lower risk for hypertrophic scars and keloids (p = 0.04). A logistic regression analysis was performed to adjust for confounding factors, with history of hypertrophic scar formation as the explained variable. CONCLUSION: This study revealed that dipeptidyl peptidase-4 inhibitors suppress the onset of hypertrophic scars or keloids after surgery in humans. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Insulin- and Lipopolysaccharide-Mediated Signaling in Adipose Tissue Macrophages Regulates Postprandial Glycemia through Akt-mTOR Activation.

The physiological role of immune cells in the regulation of postprandial glucose metabolism has not been fully elucidated. We have found that adipose tissue macrophages produce interleukin-10 (IL-10) upon feeding, which suppresses hepatic glucose production in cooperation with insulin. Both elevated insulin and gut-microbiome-derived lipopolysaccharide in response to feeding are required for IL-10 production via the Akt/mammalian target of rapamycin (mTOR) pathway. Indeed, myeloid-specific knockout of the insulin receptor or bone marrow transplantation of mutant TLR4 marrow cells results in increased expression of gluconeogenic genes and impaired glucose tolerance. Furthermore, myeloid-specific Akt1 and Akt2 knockout results in similar phenotypes that are rescued by additional knockout of TSC2, an inhibitor of mTOR. In obesity, IL-10 production is impaired due to insulin resistance in macrophages, whereas adenovirus-mediated expression of IL-10 ameliorates postprandial hyperglycemia. Thus, the orchestrated response of the endogenous hormone and gut environment to feeding is a key regulator of postprandial glycemia.

Clinical Features of Type B Insulin Resistance in Japanese Patients: Case Report and Survey-Based Case Series Study.

Type B insulin resistance (TBIR) is an extremely rare disease characterized by marked hyperglycemia and insulin resistance and often coexists with autoimmune diseases. The characteristics, symptoms, blood glucose patterns, comorbidities, and treatments of TBIR all vary and are not defined. In this study, we described a case of TBIR that developed 6 months after DPP-4 inhibitor administration and immediately after the patient caught a cold. Treatment using prednisolone and insulin-like growth factor-1 was effective. We also conducted an observational survey-based case series study in a Japanese cohort comprising 21 cases. The average age of onset of TBIR was 62.3 ± 14.8 (17-84) years, and 61.9% of subjects were male. The majority of patients (90.4%) were 50 years old and over. During the study period, there was a high percentage (85.7%) of episodes of hypoglycemia, which was the trigger for diagnosis in more than 50% of cases. Glycemic patterns included 7 cases of hyperglycemia (33.3%), 10 cases of hypoglycemia (47.6%), and 4 cases of both hyperglycemia and hypoglycemia (19.1%). In the hypoglycemic group, 90.0% of patients were male. Furthermore, 71.4% of cases were antinuclear antibody positive, and 81.0% of cases were complicated with autoimmune disease. Systemic lupus erythematosus (38.1%) and Sjögren's syndrome (23.8%) were relatively common as coexisting autoimmune diseases. Treatment was based on prednisolone use, which was used in 88.9% of patients. On the other hand, the effect of IGF-1 was limited. Overall, the prognosis of TBIR was good.

Protein kinase C promotes choline transporter­like protein 1 function via improved cell surface expression in immortalized human hepatic cells.

Choline is used to synthesize phospholipids and a lack of choline induces a number of liver­related diseases, including non­alcoholic steatohepatitis. The current study characterized the choline uptake system, at molecular and functional levels, in the immortalized human hepatic cell line, Fa2N­4, to identify the specific choline transporter involved in choline uptake. The present study also assesed whether choline deficiency or the inhibited choline uptake affected cell viability and apoptosis. Reverse transcription­quantitative polymerase chain reaction (PCR) revealed choline transporter­like protein 1 (CTL1) and CTL2 mRNA and protein expression in Fa2N­4 cells. [Methyl­3H]choline studies revealed choline uptake was saturable and mediated by a single transport system that functioned in a Na+­independent but pH­dependent manner, which was similar to CTL1. Hemicholinium­3 (HC­3), which is a choline uptake inhibitor, and choline deficiency inhibited cell viability, increased caspase­3 and ­7 activities, and increased fluorescein isothiocyanate­Annexin V immunofluorescent staining indicated apoptosis. Immunofluorescent staining also revealed CTL1 and CTL2 localized in plasma and mitochondrial membranes, respectively. [Methyl­3H]choline uptake was enhanced by a protein kinase C (PKC) activator, phorbol­12­myristate 13­acetate (PMA). Immunofluorescence staining and western blot analysis demonstrated increased CTL1 expression on the cell membrane following PMA treatment. The results of current study indicated that extracellular choline is primarily transported via CTL1, relying on a direct H+ gradient that functions as a driving force in Fa2N­4 cells. Furthermore, it was hypothesized that CTL1 and the choline uptake system are strongly associated with cell survival, and that the choline uptake system is modulated by PKC signaling via increased CTL1 expression on the cell surface. These findings provide further insights into the pathogenesis of liver disease involving choline metabolism.

IL-7R-Dependent Phosphatidylinositol 3-Kinase Competes with the STAT5 Signal to Modulate T Cell Development and Homeostasis.

T cell development and homeostasis requires IL-7R α-chain (IL-7Rα) signaling. Tyrosine Y449 of the IL-7Rα is essential to activate STAT5 and PI3K, whereas PI3K recruitment requires IL-7Rα methionine M452. How IL-7Rα activates and regulates both signaling pathways differentially remains unclear. To characterize differential signaling, we established two lines of IL-7Rα mutant mice: IL-7R-Y449F mice and IL-7R-M452L mice. IL-7R-Y449F mice showed decreased PI3K and STAT5 signals, whereas IL-7R-M452L mice showed decreased PI3K but significantly increased STAT5 signaling, owing to a competition between PI3K and STAT5 signaling through Y449 of IL-7Rα. The number of T, B, and mature innate lymphoid cells were markedly reduced in IL-7R-Y449F mice, whereas IL-7R-M452L mice showed impaired early T cell development and memory precursor effector T cell maintenance with the downregulation of transcription factor T cell factor-1. Peripheral T cell numbers increased in IL-7R-M452L mice with enhanced survival and homeostatic proliferation. Furthermore, although wild type and IL-7R-Y449F mice showed comparable Th1/Th2 differentiation, IL-7R-M452L mice exhibited impaired Th17 differentiation. We conclude that PI3K competes with STAT5 under IL-7Rα and maintains an appropriate signal balance for modulating T cell development and homeostasis. To our knowledge, this study provides a new insight into complex regulation of IL-7Rα signaling, which supports immune development and responses.