Formation of spray-dried powder of S-adenosyl-L-methionine

S-Adenosyl-L -methionine (SAM) is an essential metabolite in all living organisms. In clinical research, SAM has also been suggested as a chemotherapeutic agent in various diseases. The main problem of SAM is its instability at high temperatures, at neutral and alkaline pH, and in the presence of humidity. SAM retention in spray-dried powder was determined under various conditions of spray-drying. The highest SAM retention was obtained when maltodextrin (dextrose equivalent, DE, of 25) was used as the carrier solid with the SAM feed liquid at pH 4.0. The water content in the powder had a significant effect on the stability of SAM. SAM powder with lower water content exhibited higher stability.     

Effects of the methoxy group in the side chain of debromoaplysiatoxin on its tumor-promoting and anti-proliferative activities

Debromoaplysiatoxin (DAT) is a tumor promoter isolated from sea hare and exhibits anti-proliferative activity against several cancer cell lines. To clarify key residues that are responsible for its tumor-promoting activity, we focused on the chiral methoxy group in the side chain, whose role had not yet been discussed or examined before. Demethoxy-DAT (8) was derived from DAT and we evaluated its tumor-promoting activity, anti-proliferative activity, and ability to bind to protein kinase C (PKC) isozymes. Compound 8 showed somewhat weaker tumor-promoting activity than that of DAT both in vitro and in vivo, but showed higher anti-proliferative activity against several cancer cell lines. Although the affinity to novel PKC isozymes of 8 was comparable to that of DAT, the affinity to conventional PKC isozymes decreased slightly. These results suggest that the methoxy group of DAT is one of the key residues critical for tumor-promoting activity but not for anti-proliferative activity. Since the methoxy group has little influence on the molecular hydrophobicity, this is the first report showing that structural factors other than hydrophobicity in the side chain of DAT affected its biological activities.     

Nematocidal activity of 6-O-octanoyl- and 6-O-octyl-d-allose against larvae of Caenorhabditis elegans

ABSTRACT

The nematocidal activities of the fatty acid esters of d-allose were examined using the larvae of C. elegans. Among the fatty acid esters, 6-O-octanoyl-d-allose (3) showed significant activity. 6-O-octanoyl-d-glucose (5) showed no activity, indicating that the D-allose moiety is essential for the nematocidal activity of 3. A nonhydrolyzable alkoxy analog 6-O-octyl-d-allose (6) also showed activity equivalent to that of 3.     

A neural-specific F-box protein Fbs1 functions as a chaperone suppressing glycoprotein aggregation

Fbs1 is an F-box protein present abundantly in the nervous system. Similar to the ubiquitously expressed Fbs2, Fbs1 recognizes N-glycans at the innermost position as a signal for unfolded glycoproteins, probably in the endoplasmic reticulum-associated degradation pathway. Here, we show that the in vivo majority of Fbs1 is present as Fbs1-Skp1 heterodimers or Fbs1 monomers but not SCF(Fbs1) complex. The inefficient SCF complex formation of Fbs1 and the restricted presence of SCF(Fbs1) bound on the endoplasmic reticulum membrane were due to the short linker sequence between the F-box domain and the sugar-binding domain. In vitro, Fbs1 prevented the aggregation of the glycoprotein through the N-terminal unique sequence of Fbs1. Our results suggest that Fbs1 assists clearance of aberrant glycoproteins in neuronal cells by suppressing aggregates formation, independent of ubiquitin ligase activity, and thus functions as a unique chaperone for those proteins.     

Induction of steady-state glomeruloid sphere by self-assembly from human embryonic kidney cells

The glomerulus is a network of capillaries known as a tuft, located at the beginning of a nephron in the kidney. Here we describe a novel method for the induction of a macroscopically visible three-dimensional glomerulus-like sphere (GLS). This procedure did not require any additional cytokines and completed the formation of spheres within 24?h. After the formation was complete, GLS maintained a steady state for at least five days without proliferation and without a decrease in viability. Therefore, this procedure assists various assays for a prolong period of time. Overall, our protocol allows for a very simple mixing of cells from different sources to obtain fine-grained and highly dispersed GLSs. The kidney filtration barrier is a unique structure characterized by a complex three-dimensional framework of podocytes and endothelial cells. GLS exhibited the induction of many podocyte-specific gene profiles similar to those in adult human kidneys, suggesting that the sphere formation process is important for the maturation of podocytes. Focal segmental glomerulosclerosis (FSGS) is one of the major causes of steroid-resistant nephrotic syndrome, and some circulating permeability factors in the patient's serum FSGS have been implicated in the pathogenesis of the disease. Serum from patients with FSGS induced the collapse of GLS, which imitates the appearance of glomerulosclerosis in patients. In conclusion, the investigation and use of GLS may provide a novel method to elucidate the molecular mechanisms underlying complicated and unexplained events in glomeruli in a similar condition in adult kidneys.