Novel types of COMP mutations and genotype-phenotype association in pseudoachondroplasia and multiple epiphyseal dysplasia

Mutations in the gene encoding cartilage oligomeric matrix protein ( COMP) cause two skeletal dysplasias, pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED). More than 40 mutations have been identified; however, genotype-phenotype relationships are not well delineated. Further, mutations other than in-frame insertion/deletions and substitutions have not been found, and currently known mutations are clustered within relatively small regions. Here we report the identification of nine novel and three recurrent COMP mutations in PSACH and MED patients. These include two novel types of mutations; the first, a gross deletion spanning an exon-intron junction, causes an exon deletion. The second, a frameshift mutation that results in a truncation of the C-terminal domain, is the first known truncating mutation in the COMP gene. The remaining mutations, other than a novel exon 18 mutation, affected highly conserved aspartate or cysteine residues in the calmodulin-like repeat (CLR) region. Genotype-phenotype analysis revealed a correlation between the position and type of mutations and the severity of short stature. Mutations in the seventh CLR produced more severe short stature compared with mutations elsewhere in the CLRs ( P=0.0003) and elsewhere in the COMP gene ( P=0.0007). Patients carrying mutations within the five-aspartates repeat (aa 469-473) in the seventh CLR were extremely short (below -6 SD). Patients with deletion mutations were significantly shorter than those with substitution mutations ( P=0.0024). These findings expand the mutation spectrum of the COMP gene and highlight genotype-phenotype relationships, facilitating improved genetic diagnosis and analysis of COMP function in humans.     

Subcellular localization of herpes simplex virus type 1 UL51 protein and role of palmitoylation in Golgi apparatus targeting

The herpes simplex virus type 1 (HSV-1) UL51 gene products are virion-associated phosphoproteins with apparent molecular masses of 27, 29, and 30 kDa in HSV-1-infected cells. In this study, we have investigated the intracellular localization and distribution of UL51 protein both in infected cells and in transfected cells expressing only UL51. We found that this protein colocalized closely with Golgi marker proteins such as the Golgi-58K protein and GM130 in transfected cells expressing only UL51. However, in infected cells, the UL51 protein localized to the juxtanuclear region but only partially colocalized with the Golgi maker proteins. Mutant protein analysis revealed that the N-terminal 15 amino acid residues of the UL51 protein sufficed for this Golgi localization property. The UL51 protein redistributed on addition of brefeldin A. This was prevented by pretreatment with 2-deoxyglucose and sodium azide, which results in ATP depletion, but not by pretreatment with NaF and AlCl(3), which activates heterotrimeric G proteins. Moreover, we found that palmitoylation of the UL51 protein through the N-terminal cysteine at position 9 was necessary for its Golgi localization. Protease digestion analysis suggested that the UL51 protein localized on the cytoplasmic face of the membrane in UL51-transfected cells, while in infected cells it localized mainly to the inside of cytoplasmic vesicles and/or the viral envelope. Transmission immunoelectron microscopy revealed an association of UL51 protein-specific labeling with cytoplasmic virions and also with some membranous structure. We infer from these observations that internalization of UL51 protein into the cytoplasmic vesicle and/or virion may occur in association with viral envelopment in HSV-infected cells.     

Effect of PKC412, a selective inhibitor of protein kinase C,on lung metastasis in mice injected with B16 melanoma cells

PKC412, a selective inhibitor of protein kinase C (PKC), is currently in clinical trials as an anti-tumor drug. In the present study, we investigated the anti-metastatic effect of PKC412 using an experimental metastatic mouse model intravenously injected with melanoma cells. One-hour exposure to various concentrations of PKC412 (0.5, 5 and 50 microM) dose-dependently reduced the lung-metastatic potential of highly metastatic B16-F10 and -BL6 mouse melanoma cells in syngeneic mice. Following the exposure, PKC activities in B16-F10 and -BL6 cells were significantly decreased, but growth curves were not influenced. To elucidate the mechanism of the anti-metastatic effect of PKC412, we examined the activity to invade the extracellular matrix and the platelet-aggregating activity of the melanoma cells incubated with PKC412 (0.5, 5 and 50 microM) for 1 hour. PKC412 significantly reduced both the invasive and platelet-aggregating activities. These results suggest that PKC412 shows an anti-metastatic function through the inhibition of the invasive and/or platelet-aggregating activities of melanoma cells. PKC412 is potentially a promising candidate for an anti-metastatic agent.     

New antihypertensive peptides isolated from rapeseed

Four potent angiotensin converting enzyme (ACE) inhibitory peptides, IY, RIY, VW and VWIS, were isolated from subtilisin digest of rapeseed protein. Among them RIY and VWIS are new peptides with IC(50) 28 and 30 microM, respectively. All isolated peptides lowered blood pressure of spontaneously hypertensive rats (SHR) following oral administration. The maximum effect in the case of RIY was observed 4h after administration, while maximum effect of other peptides on blood pressure occurred 2h after administration. Furthermore, the antihypertensive effect of RIY was observed even in old rats, in which ACE inhibitors become less effective, suggesting that a different mechanism other than ACE inhibition is also involved in lowering blood pressure by this peptide. Subtilisin digest of rapeseed protein also significantly lowered blood pressure of SHR after oral administration of a single dosage 0.15 g/kg, exerting maximum antihypertensive effect 4h after administration. This digest appears promising as a functional food, which may be useful in the prevention and treatment of hypertension.     

Structure-activity relationship of rubiscolins as delta opioid peptides

To study the structure-activity relationship of rubiscolins (YPLDLF and YPLDL), delta opioid peptides derived from the spinach Rubisco, we substituted the amino acid residues and evaluated their activities by mouse vas deferens (MVD) and guinea pig ileum (GPI) assays as well as receptor affinity. Replacement of Leu(3) with Ile and Met in rubiscolin-6 potentiated the delta opioid activity by about four times in MVD assay. Asp(4) cannot be replaced by Ala, Glu or His. The original Leu(5) was optimal, while substitution of Phe(6) with Val potentiated its delta opioid activity by more than 10 times. The most potent derivative we obtained was YPMDLV, which was nearly 20 times more potent than rubiscolin-6 in MVD assay. The derivatives thus obtained showed higher delta receptor affinity and more potent antinociceptive activity than rubiscolins.     

In vitro biosynthesis of galactans by membrane-bound galactosyltransferase from radish (<Emphasis Type="Italic">Raphanus sativus</Emphasis> L.) seedlings

We investigated a galactosyltransferase (GalT) involved in the synthesis of the carbohydrate portion of arabinogalactan-proteins (AGPs), which consist of a beta-(1-->3)-galactan backbone from which consecutive (1-->6)-linked beta-Gal p residues branch off. A membrane preparation from 6-day-old primary roots of radish ( Raphanus sativus L.) transferred [(14)C]Gal from UDP-[(14)C]Gal onto a beta-(1-->3)-galactan exogenous acceptor. The reaction occurred maximally at pH 5.9-6.3 and 30 degrees C in the presence of 15 mM Mn(2+) and 0.75% Triton X-100. The apparent K(m) and V(max) values for UDP-Gal were 0.41 mM and 1,000 pmol min(-1) (mg protein)(-1), respectively. The reaction with beta-(1-->3)-galactan showed a bi-phasic kinetic character with K(m) values of 0.43 and 2.8 mg ml(-1). beta-(1-->3)-Galactooligomers were good acceptors and enzyme activity increased with increasing polymerization of Gal residues. In contrast, the enzyme was less efficient on beta-(1-->6)-oligomers. The transfer reaction for an AGP from radish mature roots was negligible but could be increased by prior enzymatic or chemical removal of alpha- l-arabinofuranose (alpha- l-Ara f) residues or both alpha- l-Ara f residues and (1-->6)-linked beta-Gal side chains. Digestion of radiolabeled products formed from beta-(1-->3)-galactan and the modified AGP with exo-beta-(1-->3)-galactanase released mainly radioactive beta-(1-->6)-galactobiose, indicating that the transfer of [(14)C]Gal occurred preferentially onto consecutive (1-->3)-linked beta-Gal chains through beta-(1-->6)-linkages, resulting in the formation of single branching points. The enzyme produced mainly a branched tetrasaccharide, Galbeta(1-->3)[Galbeta(1-->6)] Galbeta(1-->3)Gal, from beta-(1-->3)-galactotriose by incubation with UDP-Gal, confirming the preferential formation of the branching linkage. Localization of the GalT in the Golgi apparatus was revealed on a sucrose density gradient. The membrane preparation also incorporated [(14)C]Gal into beta-(1-->4)-galactan, indicating that the membranes contained different types of GalT isoform catalyzing the synthesis of different types of galactosidic linkage.     

Familial early onset macular degeneration in cynomolgus monkeys (Macaca fascicularis)

The mode of inheritance of macular degeneration was determined with 45 cynomolgus monkeys (18 females and 27 males) who were the offspring of one breeding male with typical macular degeneration. In the first generation, 27 offspring (10 females and 17 males) were born from mating between the macular degeneration-affected founder male and 5 normal female breeders. Among them, 18 monkeys (9 females and 9 males) were judged as having macular degeneration (affected). Next, the distribution of affected offspring was examined with 18 offspring who were born from 3 different mating pairs, normal vs normal, affected vs normal and affected vs affected, when they became 2 years old. All of the 9 monkeys (4 females and 5 males) obtained from the 2 pairs of normal vs normal were normal. On the other hand, 6 affected monkeys (3 females and 3 males) were detected in 8 offspring from the mating pair of affected vs normal, and the single offspring produced by the mating pair of affected vs affected was affected. These results showed that this degeneration must be early onset familial macular degeneration controlled by autosomal dominant gene(s).     

Cepharanthine, an anti-inflammatory drug, suppresses mitochondrial membrane permeability transition

Cepharanthine (CEP), a biscocrourine alkaloid, has been widely used in Japan for the treatment of several disorders. Furthermore, accumulated evidence shows that CEP protects against some cell death systems but not others. Recently, it was found that mitochondria play an important role in a mechanism of apoptosis involving membrane permeability transition (MPT). Although CEP stabilizes the mitochondrial membrane structure and protects some functions of mitochondria from damage, the mechanism of action of CEP on MPT remains obscure. In this study, therefore, we examined the effect of CEP on Ca2+- and Fe2+/ADP-induced MPT of isolated mitochondria. CEP inhibited Ca2+-induced swelling, depolarization, Cyt.c release, and the release of Ca2+ in a concentration dependent manner. CEP also inhibited Ca2+-induced generation of reactive oxygen species and Fe/ADP-induced swelling and lipid peroxidation. Furthermore, CEP suppressed Ca2+-induced thiol modification of adenine nucleotide transloase (ANT). These results suggested that CEP suppressed MPT by a decrease in affinity of cyclophilin D for ANT. From these results it was concluded that the suppression of MPT by CEP might be due to its inhibitory action on Ca2+ release and antioxidant activity and that CEP might suppress the mechanism of apoptotic cell death when directly interacted with mitochondria in cells.     

A possible role of NADPH-dependent cytochrome P450nor isozyme in glycolysis under denitrifying conditions

The denitrifying fungus Cylindrocarpon tonkinense contains two isozymes of cytochrome P450nor. One isozyme, P450nor1, uses NADH specifically as its electron donor whereas the other isozyme P450nor2 prefers NADPH to NADH. Here we show that P450nor1 is localized in both cytosol and mitochondria, like P450nor of Fusarium oxysporum, while P450nor2 is exclusively in cytosol. We also found that the addition of glucose as a carbon source to the culture media leads to the production of much more P450nor2 in the fungal cells than a non-fermentable substrate (glycerol or acetate) does. These results suggest that the NADP-dependent pentose phosphate cycle acts predominantly in C. tonkinense as the glycolysis pathway under the denitrifying conditions, which was confirmed by the observation that glucose induced enzyme activities involved in the cycle. These results showed that P450nor2 should act as the electron sink under anaerobic, denitrifying conditions to regenerate NADP+ for the pentose phosphate cycle.     

Damage to cultivated Japanese pearl oysters by oxidative stress that was related to "mass mortality"

Increased blood-DNA breakage was observed in diseased pearl oysters. They showed significant formation of 8-hydroxydeoxyguanosine (8-OHdG) and malondialdehyde (MDA), whereas the oysters that had a low mortality rate from the disease had high activity of superoxide dismutase (SOD) and low amounts of 8-OHdG and MDA. These results suggest that radical damage had occurred only in the diseased pearl oysters with the cytolysis of their haemocytes, which was related to the mass mortality of the Japanese pearl oysters.