Chemo-enzymatic synthesis of eel calcitonin glycosylated at two sites with the same and different carbohydrate structures

Naturally occurring glycopeptides and glycoproteins usually contain more than one glycosylation site, and the structure of the carbohydrate attached is often different from site to site. Therefore, synthetic methods for preparing peptides and proteins that are glycosylated at multiple sites, possibly with different carbohydrate structures, are needed. Here, we report a chemo-enzymatic approach for accomplishing this. Complex-type oligosaccharides were introduced to the calcitonin derivatives that contained two N-acetyl-D-glucosamine (GlcNAc) residues at different sites by treatment with Mucor hiemalis endo-beta-N-acetylglucosaminidase. Using this enzymatic transglycosylation reaction, three glycopeptides were produced, a calcitonin derivative with the same complex-type carbohydrate at two sites, and two calcitonin derivatives each with one complex-type carbohydrate and one GlcNAc. Starting from the derivatives with one complex-type carbohydrate and one GlcNAc, a high-mannose-type oligosaccharide was successfully transferred to the remaining GlcNAc using another endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae. Thus, we were able to obtain glycopeptides containing not only two complex-type carbohydrates, but also both complex and high-mannose-type oligosaccharides in a single molecule. Using the resultant glycosylated calcitonin derivatives, the effects of di-N-glycosylation on the structure and the activity of calcitonin were studied. The effect appeared to be predictable from the results of mono-N-glycosylated calcitonin derivatives.     

Discovery of potent and selective PARP-1 and PARP-2 inhibitors: SBDD analysis via a combination of X-ray structural study and homology modeling

We disclose herein our efforts aimed at discovery of selective PARP-1 and PARP-2 inhibitors. We have recently discovered several novel classes of quinazolinones, quinazolidinones, and quinoxalines as potent PARP-1 inhibitors, which may represent attractive therapeutic candidates. In PARP enzyme assays using recombinant PARP-1 and PARP-2, the quinazolinone derivatives displayed relatively high selectivity for PARP-1 and quinoxaline derivatives showed superior selectivity for PARP-2, and the quinazolidinone derivatives did not have selectivity for PARP-1/2. Structure-based drug design analysis via a combination of X-ray structural study utilizing the complexes of inhibitors and human PARP-1 catalytic domain, and homology modeling using murine PARP-2 suggested distinct interactions of inhibitors with PARP-1 and PARP-2. These findings provide a new structural framework for the design of selective inhibitors for PARP-1 and PARP-2.     

A molecule that is associated with Toll-like receptor 4 and regulates its cell surface expression

Toll-like receptors (TLRs) recognize microbial products and induce immune responses. Their subcellular distribution is believed to be optimized for their pathogen recognition. Little is known, however, about molecular mechanisms regulating the subcellular distribution of TLR. Lipopolysaccharide, a principal membrane component of the Gram-negative bacteria, is recognized by the receptor complex consisting of Toll-like receptor 4 (TLR4) and MD-2. We here show that a novel molecule, a PRotein Associated with Tlr4 (PRAT4B), regulates cell surface expression of TLR4. PRAT4B has a signal peptide followed by a mature peptide. PRAT4B is associated with the hypoglycosylated, immature form of TLR4 but not with MD-2 or TLR2. Downregulation of PRAT4B mRNA with small interfering RNA decreased cell surface TLR4 on HEK293 cells. These results suggest a novel mechanism regulating the subcellular distribution of TLR4.     

Dual-color system for simultaneously monitoring intracellular Ca(2+) and ATP dynamics

Although Ca(2+) regulates energy metabolism through diverse pathways, there have been no methods to monitor both Ca(2+) dynamics and metabolic activity simultaneously. Here we report a novel system for simultaneously monitoring intracellular Ca(2+) and ATP levels using a blue-emitting photoprotein and a red-emitting beetle luciferase. Using this system, we monitored the dynamic changes simultaneously in both intracellular Ca(2+) and ATP levels during chondrogenesis. We have found that both intracellular Ca(2+) and ATP levels oscillated and their oscillations have a nearly antiphase relationship with each other. The dual-color monitoring system is useful for studying the relationship between Ca(2+) dynamics and energy metabolic pathways.     

GABAergic interneuron migration and the evolution of the neocortex

A neocortex is present in all mammals but is not present in other classes of vertebrates, and the neocortex is extremely elaborate in humans. Changes in excitatory projection neurons and their progenitors within the developing dorsal pallium in the most recent common ancestor of mammals are thought to have been involved in the evolution of the neocortex. Our recent findings suggest that changes in the migratory ability of inhibitory interneurons derived from outside the neocortex may also have been involved in the evolution of the neocortex. In this article we review the literature on the migratory profile of inhibitory interneurons in several different species and the literature on comparisons between the intrinsic migratory ability of interneurons derived from different species. Finally, we propose a hypothesis about the mammalian-specific evolution of the migratory ability of interneurons and its potential contribution to the establishment of a functional neocortex.     

Weight loss reduces plasma endothelin-1 concentration in obese men

Obesity is associated with endothelial dysfunction that may contribute to the development of diabetes, hypertension, and atherosclerosis. Endothelin-1 (ET-1), which is produced mostly by vascular endothelial cells, has potent vasoconstrictor and proliferative activity in vascular smooth muscle cells and, therefore, has been implicated in regulation of vascular tonus and the progression of atherosclerosis, suggesting that ET-1 may be important in endothelial dysfunction. We studied whether diet-induced weight loss (i.e., lifestyle modification) affects plasma ET-1 concentration in obese individuals. We measured plasma ET-1 concentration in seven obese men (age: 48 +/- 4 years old, body mass index: 27.7 +/- 0.5 kg/m2) before and after a 3-month, diet-induced weight reduction program (i.e., lifestyle modification program). Caloric restriction reduced body weight from 78 +/- 3 to 68 +/- 2 kg (P < 0.001) and resulted in 12.1 +/- 1.2% reduction in body mass index (24.3 +/- 0.3 kg/m(2), P < 0.0001). After the weight reduction program, systolic and diastolic blood pressure significantly decreased (128 +/- 7 vs. 115 +/- 4 mm Hg, P < 0.05 and 88 +/- 4 vs. 77 +/- 2 mm Hg, P < 0.01, respectively). The plasma level of ET-1 significantly decreased after the program (5.1 +/- 0.4 vs. 4.0 +/- 0.3 pg/ml, P < 0.05). The percentage systolic blood pressure reduction and percentage plasma ET-1 concentration reduction was in a linear relationship (r = 0.86, P < 0.05). Furthermore, the relationship between percentage weight reduction and percentage plasma ET-1 concentration reduction was linear (r = 0.87, P < 0.05). We conclude that weight loss by low-calorie diet (i.e., lifestyle modification) reduces plasma ET-1 concentration in obese individuals. This reduction may contribute to the improvement of obesity-induced endothelial dysfunction.     

Synthesis and biological evaluation of vitamin K derivatives as angiogenesis inhibitor

Ten vitamin K₃ derivatives were synthesized and screened for anti-angiogenic activity. Results indicated that amine derivatives (1a–d) exerted a stronger inhibition effect on angiogenesis compared to alkyl derivatives (2a–d). In addition to being the most potent inhibitor, 1b also suppressed human umbilical vein endothelial cell tube formation and proliferation. These results suggest that vitamin K₃ amine derivatives with shorter alkyl chains, such as 1b, could be useful for developing anti-angiogenic agents.