Transient Acceleration of Epidermal Growth Factor Receptor Dynamics Produces Higher-Order Signaling Clusters

Cell signaling depends on spatiotemporally regulated molecular interactions. Although the movements of signaling proteins have been analyzed with various technologies, how spatial dynamics influence the molecular interactions that transduce signals is unclear. Here, we developed a single-molecule method to analyze the spatiotemporal coupling between motility, clustering, and signaling. The analysis was performed with the epidermal growth factor receptor (EGFR), which triggers signaling through its dimerization and phosphorylation after association with EGF. Our results show that the few EGFRs isolated in membrane subdomains were released by an EGF-dependent increase in their diffusion area, facilitating molecular associations and producing immobile clusters. Using a two-color single-molecule analysis, we found that the EGF-induced state transition alters the properties of the immobile clusters, allowing them to interact for extended periods with the cytoplasmic protein, GRB2. Our study reveals a novel correlation between this molecular interaction and its mesoscale dynamics, providing the initial signaling node.     

Identification of the Gene Encoding Isoprimeverose-producing Oligoxyloglucan Hydrolase in Aspergillus oryzae

Aspergillus oryzae produces a unique β-glucosidase, isoprimeverose-producing oligoxyloglucan hydrolase (IPase), that recognizes and releases isoprimeverose (α-d-xylopyranose-(1→6)-d-glucopyranose) units from the non-reducing ends of oligoxyloglucans. A gene encoding A. oryzae IPase, termed ipeA, was identified and expressed in Pichia pastoris. With the exception of cellobiose, IpeA hydrolyzes a variety of oligoxyloglucans and is a member of the glycoside hydrolase family 3. Xylopyranosyl branching at the non-reducing ends was vital for IPase activity, and galactosylation at a α-1,6-linked xylopyranosyl side chain completely abolished IpeA activity. Hepta-oligoxyloglucan saccharide (Xyl₃Glc₄) substrate was preferred over tri- (Xyl₁Glc₂) and tetra- (Xyl₂Glc₂) oligoxyloglucan saccharides substrates. IpeA transferred isoprimeverose units to other saccharides, indicating transglycosylation activity. The ipeA gene was expressed in xylose and xyloglucan media and was strongly induced in the presence of xyloglucan endo-xyloglucanase-hydrolyzed products. This is the first study to report the identification of a gene encoding IPase in eukaryotes.     

Primary pulmonary malignant peripheral nerve sheath tumor: a case report

BACKGROUND: Although the histologic features of malignant peripheral nerve sheath tumor (MPNST) have been described, the cytologic features of primary pulmonary MPNST have not been reported in the literature. CASE: We report a case of primary pulmonary MPNST in a 78-year-old man. Follow-up computed tomography of colon cancer, renal cancer, penile cancer and gingival cancer revealed a nodular lesion, 12 mm in diameter, in the right upper lobe of the lung. In frozen section, a diagnosis of malignant neoplasm, not otherwise specified, was rendered for the imprinting specimen and histologic specimen. Imprinting specimens were composed of small cellular aggregates and discohesive neoplastic cells with obvious malignant features. Histologically, spindle cells with pleomorphic nuclei arranged infascicular patterns and multinucleated tumor giant cells were also observed. More than 25 mitotic figures were observed per 10 high-power fields. Tumor cells were positive only for vimentin and S-100, and the Ki-67 labeling index was 10%. Clinical and imaging investigation failed to identify an alternative primary site. We histologically diagnosed this case as primary pulmonary MPNST. CONCLUSION: MPNST has a varied cytomorphology with frank nuclear atypia showing no definite differentiation. Multinucleated neoplastic giant cells with immunopositivity for S-100 may permit more accurate diagnosis of MPNST.     

Potent antiobesity effect of a short-length peptide YY-analogue continuously administered in mice

The gastrointestinal peptide, peptide YY_3–36 (PYY_3–36) and its shorter peptide analogues have been reported to reduce appetite by activating the neuropeptide Y2 receptor (Y2R), which is associated with obesity and other metabolic diseases. A 14-amino acid PYY analogue, Ac-[d-Pro²⁴,Cha^27,28,36,Aib³¹]PYY(23–36) (3), showed high binding affinity and agonist activity for the Y2R, similar to that of PYY_3–36, but had weak anorectic activity upon continuous administration in lean mice. Three amino acid substitutions [Pya(4)²⁶, Aib²⁸, Lys³⁰], which contributed to the decreased hydrophobicity of 3, efficiently increased its anorectic activity. The compound containing these three amino acids, Ac-[d-Pro²⁴,Pya(4)²⁶,Cha^27,36,Aib^28,31,Lys³⁰]PYY(23–36) (22), exerted more potent and durable food intake suppression than that by PYY_3–36 in lean mice, as well as excellent Y2R agonist activity (EC₅₀: 0.20 nM) and good subcutaneous bioavailability (66.6%). The 11-day continuous administration of 22 at 1 mg/kg/day successfully produced antiobese and antidiabetic effects, with more than 20% body weight loss in obese and Type 2 diabetes ob/ob model mice.     

Caffeic acid production by simultaneous saccharification and fermentation of kraft pulp using recombinant Escherichia coli

Caffeic acid (3,4-dihydroxycinnamic acid) serves as a building block for thermoplastics and a precursor for biologically active compounds and was recently produced from glucose by microbial fermentation. To produce caffeic acid from inedible cellulose, separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) reactions were compared using kraft pulp as lignocellulosic feedstock. Here, a tyrosine-overproducing Escherichia coli strain was metabolically engineered to produce caffeic acid from glucose by introducing the genes encoding a 4-hydroxyphenyllactate 3-hydroxylase (hpaBC) from Pseudomonas aeruginosa and tyrosine ammonia lyase (fevV) from Streptomyces sp. WK-5344. Using the resulting recombinant strain, the maximum yield of caffeic acid in SSF (233 mg/L) far exceeded that by SHF (37.9 mg/L). In the SSF with low cellulase loads (≤2.5 filter paper unit/g glucan), caffeic acid production was markedly increased, while almost no glucose accumulation was detected, indicating that the E. coli cells experienced glucose limitation in this culture condition. Caffeic acid yield was also negatively correlated with the glucose concentration in the fermentation medium. In SHF, the formation of by-product acetate and the accumulation of potential fermentation inhibitors increased significantly with kraft pulp hydrolysate than filter paper hydrolysate. The combination of these inhibitors had synergistic effects on caffeic acid fermentation at low concentrations. With lower loads of cellulase in SSF, less potential fermentation inhibitors (furfural, 5-hydroxymethyfurfural, and 4-hydroxylbenzoic acid) accumulated in the medium. These observations suggest that glucose limitation in SSF is crucial for improving caffeic acid yield, owing to reduced by-product formation and fermentation inhibitor accumulation.

     

Muscle architectural properties in the common marmoset (<Emphasis Type="Italic">Callithrix jacchus</Emphasis>)

The common marmoset, Callithrix jacchus, is a small New World monkey that has recently gained attention as an important experimental animal model in the field of neuroscience as well in rehabilitative and regenerative medicine. This attention reflects the closer phylogenetic relationship between humans and common marmosets compared to that between humans and other experimental animals. When studying the neuronal mechanism behind various types of neurological motor disorders using the common marmoset, possible differences in muscle parameters (e.g., the force-generating capacity of each of the muscles) between the common marmoset and other animals must be taken into account to permit accurate interpretation of observed motor behavior. Differences in the muscle architectural properties are expected to affect biomechanics, and hence to affect neuronal control of body movements. Therefore, we dissected the forelimbs and hind limbs of two common marmosets, including systematic analysis of the muscle mass, fascicle length, and physiological cross-sectional area (PCSA). Comparisons of the mass fractions and PCSA fractions of the forelimb and hind limb musculature among the common marmoset, human, Japanese macaque, and domestic cat demonstrated that the overall muscle architectural properties of the forelimbs and hind limbs in the common marmoset are very similar to those of the Japanese macaque, a typical quadrupedal primate. However, muscle architectural properties of the common marmoset differ from those of the domestic cat, which has relatively larger hamstrings and pedal digital flexor muscles. Compared to humans, the common marmoset exhibits relatively smaller shoulder protractor, retractor, and abductor muscles and larger elbow extensor and rotator-cuff muscles in the forelimb, and smaller plantarflexor muscles in the hind limb. These differences in the muscle architectural properties must be taken into account when interpreting motor behaviors such as locomotion and arm-reaching movements in the common marmoset.