Direct phosphorylation of histamine H1 receptor by various protein kinases in vitro

Phosphorylation of G protein-coupled receptors (GPCRs) by various kinases is suggested to be an important step in initiating receptor desensitization. Some reports have indirectly demonstrated the involvement of protein kinase C (PKC)-mediated receptor phosphorylation in the desensitization of the histamine H1 receptor (H1R). In this study, human c-myc-epitope-tagged H1R (hm mcH1R) was expressed in Sf9 cells, and an in vitro approach was taken to obtain direct evidence that H1R could be phosphorylated by various kinases. When hm mcH1R, which had been immunoprecipitated with anti-c-myc antibody from Sf9 cell membranes, was incubated with PKC, cAMP-dependent protein kinase (PKA), calcium/calmodulin-dependent protein kinase II (CaMKII) or cGMP-dependent protein kinase (PKG), the immunoprecipitated receptor was phosphorylated by these kinases. Membrane-bound hm mcH1R, whose conformation is closer to its physiological state than that of the immunoprecipitated receptor, was also phosphorylated by PKC, PKA, CaMKII and PKG. Phosphorylation of immunoprecipitated and membrane-bound hm mcH1R was inhibited by kinase inhibitors. These data are the first demonstration of the phosphorylation of H1R by four protein kinases, i.e., PKC, PKA, CaMKII and PKG, and provide fundamental information to help us further understand the relationship between H1R phosphorylation and desensitization of this receptor.

An insertional mutation in the rice PAIR2 gene, the ortholog of Arabidopsis ASY1, results in a defect in homologous chromosome pairing during meiosis

To elucidate the genetic system that establishes homologous chromosome pairing in monocot plants, we have isolated an asynaptic mutant of rice, designated pair2 (homologous pairing aberration in rice meiosis 2), in which 24 completely unpaired univalents are observed at pachytene and diakinesis. The mutation was caused by an insertion of the retrotransposon Tos17, as demonstrated by complementation of the mutation by transformation with the corresponding wild-type gene. The gene in which the element was inserted is orthologous to the ASY1 gene of Arabidopsis thaliana and the HOP1 gene of Saccharomyces cerevisiae. Mature PAIR2 mRNA and several splicing variants were found to be highly expressed in wild-type reproductive tissues, and lower expression was also detected in vegetative tissues. In situ hybridization and BrdU incorporation experiments revealed that PAIR2 expression is specifically enhanced in male and female meiocytes, but not in those at pre-meiotic S phase or in the pollen maturation stages. The results obtained in this study suggest that the PAIR2 gene is essential for homologous chromosome pairing in meiosis, as in the case of the genes ASY1 and HOP1. The study also suggested the possibility that a highly homologous copy of the PAIR2 gene located on a different chromosome is in fact a pseudogene.

Ex vivo perfusion of canine pancreaticoduodenal allografts using class-II-specific monoclonal antibody delays the onset of acute rejection

In the following study, we investigated whether ex vivo perfusion of canine pancreaticoduodenal allografts prior to transplantation using a class-II-specific monoclonal antibody (MoAb) OKIa1) could prevent acute rejection. Untreated grafts were rejected within 6 days after transplantation, and all of these recipients suffered severe hyperglycemia. In contrast, in recipients who received grafts which underwent ex vivo class-II-specific MoAb perfusion treatment, the mean urinary amylase levels were sustained significantly higher (11,733 +/- 4493 vs. 3274 +/- 2108 U/L on day 7, P < 0.005), and mean fasting blood glucose (FBG) levels remained within the normal range (13.4 +/- 5.8 vs. 23.4 +/- 3.9 mM on day 7, P < 0.0005). Low doses of cyclosporin A (CsA) were necessary in order to maintain lower FBG levels. Histopathology analysis on day 7 after transplantation showed that endotheliitis and necrosis were much less prominent in the MoAb-treated grafts. In the light of our results, we conclude that ex vivo perfusion of canine pancreaticoduodenal allografts using a class-II-specific MoAb is effective in delaying the onset of acute rejection, and low doses of CsA could extend this effect.

Disrupted-In-Schizophrenia 1, a candidate gene for schizophrenia, participates in neurite outgrowth

Disrupted-In-Schizophrenia 1 (DISC1) was identified as a novel gene disrupted by a (1;11)(q42.1;q14.3) translocation that segregated with schizophrenia in a Scottish family. Predicted DISC1 product has no significant homology to other known proteins. Here, we demonstrated the existence of DISC1 protein and identified fasciculation and elongation protein zeta-1 (FEZ1) as an interacting partner of DISC1 by a yeast two-hybrid study. FEZ1 and its nematode homolog are reported to represent a new protein family involved in axonal outgrowth and fasciculation. In cultured hippocampal neurons, DISC1 and FEZ1 colocalized in growth cones. Interactions of these proteins were associated with F-actin. In the course of neuronal differentiation of PC12 cells, upregulation of DISC1/FEZ1 interaction was observed as along with enhanced extension of neurites by overexpression of DISC1. The present study shows that DISC1 participates in neurite outgrowth through its interaction with FEZ1. Recent studies have provided reliable evidence that schizophrenia is a neurodevelopmental disorder. As there is a high level of DISC1 expression in developing rat brain, dysfunction of DISC1 may confer susceptibility to psychiatric illnesses through abnormal development of the nervous system.

Suppression of the morphine-induced rewarding effect and G-protein activation in the lower midbrain following nerve injury in the mouse: involvement of G-protein-coupled receptor kinase 2

The present study was designed to investigate whether a state of neuropathic pain induced by sciatic nerve ligation could alter the rewarding effect, antinociception, and G-protein activation induced by a prototype of mu-opioid receptor agonist morphine in the mouse. The sciatic nerve ligation caused a long-lasting and profound thermal hyperalgesia. Under this neuropathic pain-like state, an i.c.v. morphine-induced place preference was observed in sham-operated mice but not in sciatic nerve-ligated mice. However, no differences in the antinociceptive effect of i.c.v.-administered morphine were noted between the groups. The increases in the binding of guanosine-5'-o-(3-[(35)S]thio)triphosphate induced by morphine in lower midbrain membranes including the ventral tegmental area, which contributes to the expression of the rewarding effect of opioid, were significantly attenuated in sciatic nerve-ligated mice. On the other hand, there were no differences in the stimulation of guanosine-5'-o-(3-[(35)S]thio)triphosphate binding to pons/medulla membranes, which plays an important role in the antinociception of mu-opioid receptor agonists, between the groups. In addition, no changes in levels of guanosine-5'-o-(3-[(35)S]thio)triphosphate binding by either the selective delta- or kappa-opioid receptor agonists were noted in membrane of the lower midbrain and limbic forebrain membranes obtained from sciatic nerve-ligated mice. Reverse transcription-polymerase chain reaction analysis showed that sciatic nerve ligation did not alter the mRNA product of mu-opioid receptors in the lower midbrain, indicating that a decrease in some mu-opioid receptor functions may result from the uncoupling of mu-opioid receptors from G-proteins. We found a significant increase in protein levels of G-protein-coupled receptor kinase 2, which causes receptor phosphorylation in membranes of the lower midbrain but not in the pons/medulla, obtained from mice with nerve injury, whereas there were no changes in the protein level of phosphorylated-protein kinase C in the lower midbrain. These results suggest that the uncoupling of mu-opioid receptors from G-proteins by G-protein-coupled receptor kinase 2 in the lower midbrain may, at least in part, contribute to the suppression of the rewarding effect of morphine under neuropathic pain.

Inhibition of histamine H1 receptor downregulation by KT5823, a protein kinase G inhibitor

The role of various protein kinases in the downregulation of histamine H(1) receptors was studied by using their inhibitors and activators. Human histamine H(1) receptors (H(1)Rs) expressed in CHO cells were downregulated by histamine in a dose- and time-dependent manner, and this downregulation continued to increase over a 24-h period. KT5823, an inhibitor of protein kinase G, remarkably but not completely reversed the histamine-induced H(1)R downregulation over 24 h. HA1004, another inhibitor of protein kinase G, showed a similar inhibitory effect. However, both 8-Br-cGMP and 8-pCPT-cGMP, membrane-permeable analogues of cGMP, did not show any effects on H(1)R downregulation in the absence or presence of histamine. Ro 31-8220, an inhibitor of protein kinase C (PKC), did not affect histamine-induced downregulation of H(1)R; nor did phorbol 12-myristate 13-acetate, a PKC-activating phorbol ester. Similarly, histamine-induced downregulation of H(1)R was unaffected by either H-89, an inhibitor of protein kinase A, or 8-Br-cAMP, a membrane-permeable analogue of cAMP.

A genetic and physical map of the region containing PLASTOCHRON1, a heterochronic gene, in rice ( Oryza sativa L.)

The rice heterochronic gene plastochron1, pla1, shows shorter plastochron and ectopic expression of the vegetative program during the rice reproductive phase resulting in aberrant panicle formation. A genetic and physical map was constructed to isolate the causal gene for the pla1 syndrome. Small-scale mapping was carried out to determine the approximate map position of the pla1 locus, and then a high-resolution genetic map was made for pla1-1, one of the pla1 alleles, using an F(2) population comprising 578 pla1-1 homozygous plants. In a high-resolution genetic map, the pla1-1 locus was found to map between RFLP markers C961 and R1738A on chromosome 10, within a 3.6-cM genetic distance. A physical map encompassing the pla1-1 locus was constructed by overlapping Bacterial Artificial Chromosome (BAC) clones through chromosome walking. PCR-based RFLP markers from BAC-end clones were developed and mapped relative to the pla1 locus. Physical map construction using BAC clones indicated that a BAC clone, B44A10 (167-kb), contained the pla1 locus within 74-kb corresponding to a 0.52-cM genetic distance. Gene prediction of 74-kb region carrying the pla1 locus suggested several candidate genes for the pla1 gene. Identification of a candidate gene for pla1 will be made by sequence analysis of allele variation and cDNA screening.

Rapidly progressive dementia syndrome associated with a novel four extra repeat mutation in the prion protein gene

OBJECTIVE

To gain a better understanding of how mutations of the prion protein (PrP) gene are responsible for progressive dementia syndrome and to clarify the correlation between genotype and phenotype, which should help to explain how the prion promotes neurological symptoms.

BACKGROUND

Genetic prion diseases are associated with point or insertional mutations in the PrP gene. The insertional mutations described so far consist of one to nine extra octapeptide repeats, except three repeats. Insertions of one to four extra octapeptide repeats cause Creutzfeldt-Jakob disease (CJD) in patients without a family history of neurological disorders. CJD generally presents as progressive dementia.

METHODS

Routine clinical assessment and sequence analysis of the PrP gene of DNA from a 56 year old Japanese man with progressive dementia syndrome.

RESULTS

Sequence analysis disclosed a novel four octapeptide repeat insertion within the PrP gene. The patient was initially affected by progressive cerebellar and brainstem signs; a few months later myoclonus and rapidly progressive dementia appeared. These symptoms were similar to those of sporadic CJD.

CONCLUSION

Taken together with previous investigations of CJD patients with insertional mutations, the current observation strengthens the notion that small octapeptide insertions from one to four extra repeats within the PrP gene cause CJD, which is characterised by late onset after the sixth decade, rapid progression, death within a few months, and lack of a family history of neurological disorders, the latter suggesting incomplete penetrance. Different patients with four extra octapeptide repeats have different patterns of extra insertions, suggesting that progression of the disease depends on the number of extra repeats.

Long-term effects of jejunal pouch added to Roux-en-Y reconstruction after total gastrectomy

BACKGROUND

Jejunal pouch reconstruction after total gastrectomy has been demonstrated to ameliorate postgastrectomy symptoms, with the process of adaptation taking several months. In contrast to the short-term effects of pouch reconstruction, there are few reports about the long-term consequences (more than 2 years after surgery).

METHODS

In this study, 22 patients with jejunal pouch (PRY group) and 12 patients without jejunal pouch (RY group) who survived for more than 2 years without any recurrence and were available for follow-up were compared. Patients in the two groups were compared 2 years after surgery in terms of postgastrectomy symptoms, and improvements in body weight and nutritional parameters.

RESULTS

Eating capacity at a single meal compared with that in the pre-illness state was significantly better in the PRY group than in the RY group. The total score on the gastrointestinal symptom rating scale (GSRS) in the PRY group was less than that in the RY group (3.17 vs 5.25). The GSRS score for reflux syndrome in the PRY group was significantly better than that in the RY group. Assessment according to Cuschieri's gradings revealed that the total score in the PRY group was lower than that in the RY group (2.73 vs 5.92). Among the various symptoms examined, the incidence of dietary restriction and that of heartburn were significantly lower in the PRY group.

CONCLUSION

We conclude that, 2 years after total gastrectomy, the pouch reconstruction had alleviated postgastrectomy symptoms to a greater extent than simple Roux-en-Y reconstruction, but the effectiveness could be improved. The long-term effects of pouch reconstruction should be examined more precisely with an adequate and valid scoring system for determining quality of life.

Identification of sequence polymorphisms of the COMP (cartilage oligomeric matrix protein) gene and association study in osteoarthrosis of the knee and hip joints

Osteoarthrosis (OA) is a common cause of musculoskeletal disability characterized by late-onset degeneration of articular cartilage. Although several candidate genes have been reported, susceptibility genes for OA remain to be determined. Hereditary osteochondral dysplasias produce severe, early-onset OA and hence are models for common idiopathic OA. Among them are pseudoachondroplasia and multiple epiphyseal dysplasia, both of which are caused by mutations in the cartilage oligomeric matrix protein (COMP) gene. Therefore, COMP may be a susceptibility gene for OA. We screened for polymorphisms by direct sequencing of all exons of the COMP gene with their flanking intron sequences and the promoter region. We identified 16 polymorphisms, of which 12 were novel. Using six polymorphisms spanning the entire COMP gene, we examined the association of COMP in Japanese patients with OA of the knee and hip joints. Genotype and allele frequencies of the polymorphisms were not significantly different between OA and control groups, and there was no significant difference in haplotypes. These results do not support an association between COMP and OA in the Japanese population.

Induction of the cytokine signal regulator SOCS3/CIS3 as a therapeutic strategy for treating inflammatory arthritis

Immune and inflammatory systems are controlled by multiple cytokines, including ILs and INFs. These cytokines exert their biological functions through Janus tyrosine kinases and STAT transcription factors. One such cytokine, IL-6, has been proposed to contribute to the development of rheumatoid arthritis (RA). We found that STAT3 was strongly tyrosine phosphorylated in synovial tissue of RA patients, but not those with osteoarthritis. Blockade of the IL-6-gp130-JAK-STAT3-signaling pathway might therefore be beneficial in the treatment of RA. We show here that the mRNA for the endogenous cytokine signaling repressor CIS3/SOCS3 is abundantly expressed in RA patients. To determine whether CIS3 is effective in treating experimental arthritis, a recombinant adenovirus carrying the CIS3 cDNA was injected periarticularly into the ankle joints of mice with antigen-induced arthritis or collagen-induced arthritis (CIA). Periarticular injection of CIS3 adenovirus drastically reduced the severity of arthritis and joint swelling compared with control groups. CIS3 was more effective than a dominant-negative form of STAT3 in the CIA model. Thus, induction of CIS3 could represent a new approach for effective treatment of RA.

Conditional deletion of the bcl-x gene from mouse mammary epithelium results in accelerated apoptosis during involution but does not compromise cell function during lactation

In the mammary gland Bcl-x is the most abundant cell survival factor from the Bcl-2 family. Since Bcl-x null mice die around day 12 of embryogenesis, the relevance of this protein in organ development and function is poorly understood. In erythroid cells bcl-x gene expression is controlled by cytokines and the transcription factor Stat5 (signal transducer and activator of transcription). However, we identified that bcl-x RNA levels in mammary tissue from prolactin receptor- and Stat5-null mice were indistinguishable from wild type mice. We have proposed that Bcl-x might control the survival of mammary epithelial cells throughout pregnancy, lactation, and the early stages of involution, and we have now tested this hypothesis through the conditional deletion of the bcl-x gene from mouse mammary epithelium. Conditional (floxed) bcl-x alleles were excised from alveolar cells during pregnancy using a Cre transgene under the control of the whey acidic protein gene promoter. Deletion of the bcl-x gene from the entire epithelial compartment (ducts and alveoli) was achieved by expressing Cre-recombinase under control of the mouse mammary tumor virus long terminal repeat. The absence of Bcl-x did not compromise proliferation and differentiation of mammary ductal and alveolar epithelial cells in virgin mice and during pregnancy and lactation. However, epithelial cell death and tissue remodeling were accelerated in the bcl-x conditional knockout mice during the first stage of involution. Concomitant deletion of the bax gene did not significantly modify the Bcl-x phenotype. Our results suggest that Bcl-x is not essential during mammopoiesis, but is critical for controlled apoptosis during the first phase of involution.

Signal transducer and activator of transcription (Stat) 5 controls the proliferation and differentiation of mammary alveolar epithelium

Functional development of mammary epithelium during pregnancy depends on prolactin signaling. However, the underlying molecular and cellular events are not fully understood. We examined the specific contributions of the prolactin receptor (PrlR) and the signal transducers and activators of transcription 5a and 5b (referred to as Stat5) in the formation and differentiation of mammary alveolar epithelium. PrlR- and Stat5-null mammary epithelia were transplanted into wild-type hosts, and pregnancy-mediated development was investigated at a histological and molecular level. Stat5-null mammary epithelium developed ducts but failed to form alveoli, and no milk protein gene expression was observed. In contrast, PrlR-null epithelium formed alveoli-like structures with small open lumina. Electron microscopy revealed undifferentiated features of organelles and a perturbation of cell-cell contacts in PrlR- and Stat5-null epithelia. Expression of NKCC1, an Na-K-Cl cotransporter characteristic for ductal epithelia, and ZO-1, a protein associated with tight junction, were maintained in the alveoli-like structures of PrlR- and Stat5-null epithelia. In contrast, the Na-Pi cotransporter Npt2b, and the gap junction component connexin 32, usually expressed in secretory epithelia, were undetectable in PrlR- and Stat5-null mice. These data demonstrate that signaling via the PrlR and Stat5 is critical for the proliferation and differentiation of mammary alveoli during pregnancy.

Production of transgenic bovine embryos by transfer of transfected granulosa cells into enucleated oocytes

Adult granulosa donor cells used in the nuclear transfer (NT) procedure can result in cloned cattle. Subsequently, it may be possible to use the same cell type to produce cloned transgenic cattle. Therefore, this study examined the effect of genetic manipulation and serum levels in culture of donor granulosa cells on developmental rates and cell number of bovine NT embryos. A primary cell line was established from granulosa cells collected by aspirating ovarian follicles. Cells transfected with a plasmid containing the enhanced green fluorescence protein (EGFP) gene, and non-transfected cells were used for cloning between passage 10 and 15 as serum-starved and serum-fed donor cells. There were no significant differences (P > 0.1) in cleavage rates or development to the blastocyst stage for NT embryos from transfected (60.4 and 13.5%, respectively) or non-transfected (61.9 and 14.1%, respectively) and serum-starved (60.6 and 13.4%, respectively) or serum-fed (61.3 and 14%, respectively) cells. Development rates to blastocyst stage of embryos produced using cells at passage 15 (27.1%) were significantly higher than those produced with cells at passage 10,11, and 13 (7, 11.5, and 14%, respectively, P < 0.05). Green fluorescence was observed at different intensity levels in all blastocyst stage embryos resulting from transfected donor cells. The results of the present study indicated that genetically modified granulosa cells can be used to produce transgenic NT embryos and primary transgenic adult cells at late passage may be more effective donor cells than earlier passaged cells.

Repression of rRNA synthesis due to a secretory defect requires the C-terminal silencing domain of Rap1p in Saccharomyces cerevisiae

A secretory defect causes specific transcriptional repression of both ribosomal protein and ribosomal RNA genes, suggesting the coupling of plasma membrane and ribosome syntheses. We previously reported that the rap1-17 allele, which produced C-terminally truncated Rap1p, derepressed transcription of ribosomal protein genes when the secretory pathway was blocked. In this paper, we demonstrate that the rap1-17 mutation also leads to significant attenuation of transcriptional repression of rRNA genes due to a secretory defect. In contrast, the rap1-2 temperature-sensitive allele containing a unique missense mutation in the middle of the coding sequence has only a weak effect on repression. These results suggest that the C-terminal silencing domain of Rap1p is required for transcriptional repression of rDNA in response to a secretory defect. We also demonstrated that transcriptional regulation of ribosomal protein genes in response to nitrogen limitation was not affected by the rap1-17 allele, suggesting that the mechanism of nitrogen response is distinct from that of the secretory response.

Spred is a Sprouty-related suppressor of Ras signalling

Cellular proliferation, and differentiation of cells in response to extracellular signals, are controlled by the signal transduction pathway of Ras, Raf and MAP (mitogen-activated protein) kinase. The mechanisms that regulate this pathway are not well known. Here we describe two structurally similar tyrosine kinase substrates, Spred-1 and Spred-2. These two proteins contain a cysteine-rich domain related to Sprouty (the SPR domain) at the carboxy terminus. In Drosophila, Sprouty inhibits the signalling by receptors of fibroblast growth factor (FGF) and epidermal growth factor (EGF) by suppressing the MAP kinase pathway. Like Sprouty, Spred inhibited growth-factor-mediated activation of MAP kinase. The Ras-MAP kinase pathway is essential in the differentiation of neuronal cells and myocytes. Expression of a dominant negative form of Spred and Spred-antibody microinjection revealed that endogenous Spred regulates differentiation in these types of cells. Spred constitutively associated with Ras but did not prevent activation of Ras or membrane translocation of Raf. Instead, Spred inhibited the activation of MAP kinase by suppressing phosphorylation and activation of Raf. Spred may represent a class of proteins that modulate Ras-Raf interaction and MAP kinase signalling.

Tooth movement and changes in periodontal tissue in response to orthodontic force in rats vary depending on the time of day the force is applied

The purpose of this study was to investigate whether there are any differences in tooth movement or in the response of periodontal tissue to orthodontic force when the force is applied at different times of the day. One hundred 6-week-old male Wistar rats were divided into one control group without force application and three experimental groups based on the time of day the force was applied to the upper first molars. Animals in the whole-day group received force continuously throughout the experimental period, while animals in the light- and dark-period groups received force only during the light (07:00-19:00) or dark period (19:00-07:00), respectively. Tooth movement was measured using the occlusal view of a precise plaster model with a profile projector. Periodontal tissues were evaluated histologically. The time course of tooth movement varied among the groups. Tooth movement over 21 days in the whole-day and light-period groups was about twice that as in the dark-period group. The formation of new bone on the tension side in the whole-day and light-period groups was more than twice that as in the dark-period group. On the pressure side, more osteoclasts appeared on the alveolar bone in the whole-day and light-period groups than in the dark-period group. The light-period group showed less extensive hyalinization of the periodontal ligament (PDL) than the whole-day group. The area of root resorption on day 21 also varied among the groups. Interference by masticatory forces did not seem to be a principal cause of the decreased tooth movement in the dark-period group. These results indicate that there are considerable variations in tooth movement and in the response of periodontal tissue to orthodontic force when the force is applied at different times of the day in rats. The results suggest that diurnal rhythms in bone metabolism have important implications in orthodontic treatment.

[Parkinson's disease]

Depression is a most common psychiatric complication of Parkinson's patients. Approximately 30% of Parkinson's patients show depressive mood changes. Loss of interest, feelings of hopelessness, marked loss of energy and psychomotor retardation are common depressive symptoms with parkinsonism. Suicidal ideations and delusions are less frequent in Parkinson's patients with depression in compared to endogenous depression. Somatic symptoms, like fatigue, constipation, headache, insomnia, loss of appetite, dizzinees and sweating are usually seen in Parkinson's patient with depression. Serotonin reuptake inhibitors and selegiline are recommended for the treatment of depression in parkinsonian patients.

Tas-301, a new synthetic inhibitor of neointimal thickening after balloon injury, inhibits calcium-dependent signal transduction and cytoskeletal reorganization

We previously demonstrated that a recently synthesized drug, TAS-301 [3-bis(4-methoxyphenyl)methylene-2-indolinone], inhibited neointimal thickening after single-balloon injury to the rat common carotid artery by inhibiting both the migration and proliferation processes of vascular smooth muscle cells (VSMCs). The purpose of this current study was to elucidate the possible mechanism of action for its inhibition of the migration process of VSMCs. We also determined the efficacy of TAS-301 on second neointimal formation 14 days after a double-balloon injury to the rat common carotid artery. Neointimal thickening, 14 days after second balloon injury, was reduced by the oral administration of TAS-301 in a dose-dependent manner. In in vitro assays using rat VSMCs, Western blot analysis showed that TAS-301 inhibited platelet-derived growth factor (PDGF)-induced tyrosine phosphorylation of both focal adhesion kinase and paxillin. Tyrosine phosphorylation of these proteins depended on the increment of intracellular calcium concentration ([Ca2+]i). The PDGF-induced elevation of [Ca2+]i and activation of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) were also inhibited by TAS-301. Additionally, TAS-301 at 10 micromol/l reduced the extent of F-actin stress fiber depolymerization observed in response to PDGF. These results indicate that TAS-301 reduced the intimal thickening after denudation to a pre-existing lesion to the same extent as it reduced that after a single-balloon injury to the normal artery. Furthermore, the results of our in vitro experiments suggest that antimigratory mechanisms of TAS-301 that contribute to preventing the intimal thickening might be mediated by drug inhibition of Ca2+ -dependent signal molecules and the following cytoskeletal depolymerization.

The unfolded protein response and Alzheimer's disease

Disruption of calcium homeostasis, inhibition of protein glycosylation, and reduction of disulfide bonds provoke accumulation of unfolded protein in the endoplasmic reticulum (ER), and are therefore a type of 'ER stress'. Normal cells respond to ER stress by increasing transcription of genes encoding ER-resident chaperones such as GRP78/BiP, GRP94 and protein disulfide isomerase to facilitate protein folding. This induction system is termed the unfolded protein response. Familial Alzheimer's disease-linked presenilin-1 (PS1) mutation downregulates the unfolded protein response and leads to vulnerability to ER stress. The mechanisms by which mutant PS1 affects the ER stress response are attributed to the inhibited activation of ER stress transducers such as IRE1, PERK and ATF6.

Phospho-Azatyrosine, a less effective protein-tyrosine phosphatase substrate than phosphotyrosine

Azatyrosine (AzaTyr, 4) is a natural product isolated from Streptomyces chibanesis, whose structure is characterized by a nitrogen atom in the aryl ring of a tyrosyl residue. This seemingly minor modification to the tyrosyl residue results in profound physiological effects, as AzaTyr has been shown to promote permanent reversion of ras-dependent transformed cells to the normal phenotype in culture and to inhibit chemical induction of carcinogenesis in transgenic mice bearing oncogenic human ras. The mechanisms underlying these effects are not known, however ras-pathways involve an intricate balance between both protein-tyrosine kinases (PTKs) and protein-tyrosine phosphatases (PTPs). The present study was undertaken to examine the general utility of AzaTyr as a structural motif for PTP inhibitor design by examining the phospho-azatyrosine (pAzaTyr)-containing peptide Ac-Asp-Ala-Asp-Glu-pAzaTyr-Leu-amide (8) in a PTP1 enzyme system. Kinetic analysis indicated that 8 binds with a Km value of 210 microM and a catalytic turnover rate, kcat of 52 s(-1). This represents a greater than 50-fold reduction in binding affinity relative to the parent phosphotyrosine-containing peptide, indicating that the aryl nitrogen adversely affects binding affinity. The much lower PTP affinity of the pAzaTyr-containing peptide reduces the potential utility of the AzaTyr pharmacophore for PTP inhibitor design. These results are discussed from the point of view that incorporation of AzaTyr residues into proteins could result in perturbation of protein-tyrosine phosphorylation,dephosphorylation cascades that control signal transduction processes, including ras-dependent pathways.

Weekly dosing with the platelet-derived growth factor receptor tyrosine kinase inhibitor SU9518 significantly inhibits arterial stenosis

The platelet-derived growth factor (PDGF) ligands and their receptors have been implicated as critical regulators of the formation of arterial lesions after tissue injury. SU9518 (3[5-(5-bromo-2-oxo-1,2-dihydroindol-3-ylidenemethyl)-2,4-dimethyl-1H-pyrrol-3-yl]propionic acid) is a novel synthetic indolinone that potently and selectively inhibits the cellular PDGF receptor kinase and PDGF receptor-induced cell proliferation. Inhibition of PDGF receptor phosphorylation in cell-based assays occurs within 5 minutes after drug exposure and persists for >6 hours after drug removal. The pharmacokinetics indicate plasma levels that exceeded the effective concentration required to inhibit the PDGF receptor in cells for up to 8 hours or 7 days after a single oral or subcutaneous administration, respectively. In the rat balloon arterial injury-induced stenosis model, once-daily oral or once-weekly subcutaneous administration of SU9518 reduced intimal thickening of the carotid artery (ratio of neointimal to medial area, 1.94+/-0.38 versus 1.03+/-0.29 [P<0.01] 2.21+/-0.32 versus 1.34+/-0.45 [P<0.01], respectively). These studies provide the rationale to evaluate PDGF receptor tyrosine kinase inhibitors, including inhibitors related to the indolinone, SU9518, for the treatment of arterial restenosis.

Measurement of the back fat layer in beagles for estimation of obesity using two-dimensional ultrasonography

The purpose of this study was to select a suitable location for measuring the subcutaneous fat layer in beagles as an indicator of excess body fat deposition. A location suitable for such a measurement should meet five conditions--it should be easy to: (1) apply the probe, (2) detect the anatomical character of the measurement location, and (3) obtain a reproducible ultrasonogram at all times. In addition, the fat layer should be (4) thick enough for measuring, and (5) located in an area that varies markedly with the degree of obesity. Ultrasonograms made in the transverse planes on the top of the spinous process of the sixth lumbar vertebra, the seventh lumbar vertebra and the first sacral vertebra were found to be suitable for measurement. The depth and area of the back fat layer at these locations were closely related to the degree of obesity.