Glucose-6-Phosphate Dehydrogenase Is a Regulator of Vascular Smooth Muscle Contraction

Glucose-6-phosphate dehydrogenase (G6PD) is the rate-limiting enzyme in the pentose phosphate pathway and a major source of nicotinamide adenine dinucleotide phosphate reduced (NADPH), which regulates numerous enzymatic (including glutathione reductase and NADPH oxidase that, respectively, generates reduced glutathione and reactive oxygen species) reactions involved in various cellular actions, yet its physiological function is seldom investigated. We, however, recently showed that inhibiting G6PD causes precontracted coronary artery (CA) to relax in an endothelium-derived relaxing factor- and second messenger-independent manner. Here we assessed the role of G6PD in regulating CA contractility. Treating bovine CAs for 20 min with potassium chloride (KCl; 30 mM), amphotericin B (50 μM), or U46619 (100 nM) significantly (p < 0.05) increased both G6PD activity and glucose flux through the pentose phosphate pathway. The effect was Ca2+ independent, and there was a corresponding increase in protein kinase C (PKC) activity. Activation of G6PD by KCl was blocked by the PKCδ inhibitor rottlerin (10 μM) or by knocking down PKCδ expression using siRNA. Phorbol 12, 13-dibutyrate (10 μM), a PKC activator, significantly increased G6PD phosphorylation and activity, whereas single (S210A, T266A) and double (S210A/T266A) mutations at sites flanking the G6PD active site significantly inhibited phosphorylation, shifted the isoelectric point, and reduced enzyme activity. Knocking down G6PD decreased NADPH and reactive oxygen species generation, and reduced KCl-evoked increases in [Ca2+]i and myosin light chain phosphorylation, thereby reducing CA contractility. Similarly, aortas from G6PD-deficient mice developed less KCl/phorbol 12, 13-dibutyrate-evoked force than those from their wild-type littermates. Conversely, overexpression of G6PD augmented KCl-evoked increases in [Ca2+]i, thereby augmenting CA contraction. Our findings demonstrate that G6PD activity and NADPH is increased in activated CA in a PKCδ-dependent manner and that G6PD modulates Ca2+ entry and CA contractions evoked by membrane depolarization. Antioxid. Redox Signal. 14, 543–558

Pasteurella bettyae infection requiring finger amputation due to rapid deterioration and tissue damage

We report a case of infection of the middle finger of a 69-year-old man who visited our hospital. Pus was collected from the erythematous and swollen area of the nail cage of the left-hand middle finger and evaluated in our microbiology laboratory. Gram staining of the specimen revealed multinucleated leukocytes and abundant gram-negative bacilli. Isolated colonies were identified as Pasteurella bettyae using VITEK MS and 16 S ribosomal RNA (rRNA) gene sequencing. The patient's blood test results improved after treatment with penicillin, but the local factors affecting the finger did not improve, and amputation of the middle finger had to be performed. This case represents a report of a very rare hand infection caused by P. bettyae. Polymorphic identification methods, such as MALDI-TOF MS and 16 S rRNA gene sequencing, are needed for members of the genus Pasteurella isolated from severe infections and abnormal sites, and further studies are warranted