Identification of a protein–protein interaction between KCNE1 and the activation gate machinery of KCNQ1

KCNQ1 channels assemble with KCNE1 transmembrane (TM) peptides to form voltage-gated K+ channel complexes with slow activation gate opening. The cytoplasmic C-terminal domain that abuts the KCNE1 TM segment has been implicated in regulating KCNQ1 gating, yet its interaction with KCNQ1 has not been described. Here, we identified a protein–protein interaction between the KCNE1 C-terminal domain and the KCNQ1 S6 activation gate and S4–S5 linker. Using cysteine cross-linking, we biochemically screened over 300 cysteine pairs in the KCNQ1–KCNE1 complex and identified three residues in KCNQ1 (H363C, P369C, and I257C) that formed disulfide bonds with cysteine residues in the KCNE1 C-terminal domain. Statistical analysis of cross-link efficiency showed that H363C preferentially reacted with KCNE1 residues H73C, S74C, and D76C, whereas P369C showed preference for only D76C. Electrophysiological investigation of the mutant K+ channel complexes revealed that the KCNQ1 residue, H363C, formed cross-links not only with KCNE1 subunits, but also with neighboring KCNQ1 subunits in the complex. Cross-link formation involving the H363C residue was state dependent, primarily occurring when the KCNQ1–KCNE1 complex was closed. Based on these biochemical and electrophysiological data, we generated a closed-state model of the KCNQ1–KCNE1 cytoplasmic region where these protein–protein interactions are poised to slow activation gate opening

A Genome-Wide Association Study Identifies Susceptibility Variants for Type 2 Diabetes in Han Chinese

To investigate the underlying mechanisms of T2D pathogenesis, we looked for diabetes susceptibility genes that increase the risk of type 2 diabetes (T2D) in a Han Chinese population. A two-stage genome-wide association (GWA) study was conducted, in which 995 patients and 894 controls were genotyped using the Illumina HumanHap550-Duo BeadChip for the first genome scan stage. This was further replicated in 1,803 patients and 1,473 controls in stage 2. We found two loci not previously associated with diabetes susceptibility in and around the genes protein tyrosine phosphatase receptor type D (PTPRD) (P = 8.54×10−10; odds ratio [OR] = 1.57; 95% confidence interval [CI] = 1.36–1.82), and serine racemase (SRR) (P = 3.06×10−9; OR = 1.28; 95% CI = 1.18–1.39). We also confirmed that variants in KCNQ1 were associated with T2D risk, with the strongest signal at rs2237895 (P = 9.65×10−10; OR = 1.29, 95% CI = 1.19–1.40). By identifying two novel genetic susceptibility loci in a Han Chinese population and confirming the involvement of KCNQ1, which was previously reported to be associated with T2D in Japanese and European descent populations, our results may lead to a better understanding of differences in the molecular pathogenesis of T2D among various populations

ACTINOMYCOSE BRONCHIQUE DEVELOPPEE APRES INHALATION D'UN CORPS ETRANGER (A PROPOS DE QUATRE OBSERVATIONS)

REIMS-BU Santé (514542104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Accounting for cardiac t-tubule increase with age and myocyte volume to improve measurements of its membrane area and ionic current densities

International audienceIn-silico models of cardiac myocytes allow simulating experiments in numbers on series of myocytes as well as on large populations of myocytes assembled in 3D structures. The simulated myocyte populations should have realistic values and statistical dispersions of biophysical parameters such as myocyte dimensions and volume and areas of the peripheral membrane and transverse-axial tubular system (TATS). Dependencies among these variables also have to be taken into account. In this work, we propose a quantitative representation of the changes in the fraction of membrane area in the TATS that integrates published dependencies with body weight (age) and size of rat ventricular cardiac myocytes while respecting the above constraints. Imposing a constant total membrane area-to-volume ratio appears to account for the increase of this fraction with myocyte size (i.e.: volume) within a given age group. The agreement of our results with published data was discussed and reasons for discrepancies were analysed. On the basis of our framework, strategies are proposed for minimizing the influence of non-random dispersion related to myocyte volume on measurements of the area of TATS and surface membrane compartments and of ionic current densities. The next step will be to quantitatively compare these strategies by evaluating the impact of myocyte morphological parameters and their dependencies, sample size, biases and errors, on the output of experiments

Immune-related pancreatitis due to anti-PD-L1 therapy in a patient with non–small cell lung cancer: A case report

International audienceRationale: Despite clinical-proven benefits of immune checkpoint inhibitors (ICIs) on advanced lung cancer, rare but life-threatening immune-related adverse events (irAEs) have been reported. Pancreatitis is a rare irAE that can occur with any ICI.Patient concerns: A 53-year-old man with locally advanced non–small cell lung carcinoma was treated with radiochemotherapy and then durvalumab (anti–programmed cell death ligand 1 therapy). Twelve weeks after the beginning of ICI, he reported abdominal pain and anorexia. Blood test showed high level of lipase. Abdominal computed tomography revealed a swollen pancreas. These findings were confirmed by magnetic resonance cholangiopancreatography and biliopancreatic endoscopic ultrasonography.Diagnoses: Grade IV immune-related pancreatitis.Interventions: The patient was treated with corticosteroid therapy, resulting in clinical, radiological, and biological improvement.Outcomes: During the first month, corticosteroid therapy could not be decreased under 1 mg/kg/d because of symptoms recurrence and lipasemia rerising. Four months after this episode, the patient died from acute ischemia of the lower limbs while he was on <20 mg/d of corticosteroid.Lessons: To the best of our knowledge, immune-related pancreatitis has been reported only with anti–programmed cell death 1 or anti–cytotoxic T lymphocyte antigen 4 therapies but never with anti–programmed cell death ligand 1 therapy. It is important to report such rare cases to improve diagnosis and management of irAEs