A Ser75-to-Asp phospho-mimicking mutation in Src accelerates ageing-related loss of retinal ganglion cells in mice.

Src knockout mice show no detectable abnormalities in central nervous system (CNS) post-mitotic neurons, likely reflecting functional compensation by other Src family kinases. Cdk1- or Cdk5-dependent Ser75 phosphorylation in the amino-terminal Unique domain of Src, which shares no homology with other Src family kinases, regulates the stability of active Src. To clarify the roles of Src Ser75 phosphorylation in CNS neurons, we established two types of mutant mice with mutations in Src: phospho-mimicking Ser75Asp (SD) and non-phosphorylatable Ser75Ala (SA).

Transthyretin accelerates vascular Abeta deposition in a mouse model of Alzheimer's disease.

Transthyretin (TTR) binds amyloid-beta (Abeta) and prevents Abeta fibril formation in vitro. It was reported that the lack of neurodegeneration in a transgenic mouse model of Alzheimer's disease (AD) (Tg2576 mouse) was associated with increased TTR level in the hippocampus, and that chronic infusion of anti-TTR antibody into the hippocampus of Tg2576 mice led to increased local Abeta deposits, tau hyperphosphorylation and apoptosis. TTR is, therefore, speculated to prevent Abeta pathology in AD.

Estrogen actions on lactotroph proliferation are independent of a paracrine interaction with other pituitary cell types: a study using lactotroph-enriched cells.

The mitogenic action of estrogen on estrogen-responsive tissues is suggested to be mediated by paracrine growth factors secreted from neighboring estrogen receptor-positive cells. Using pituitary lactotrophs in primary culture, on which estrogen exerts both mitogenic and antimitogenic actions in a cell context-dependent manner, we investigated whether a paracrine cell-to-cell interaction with other pituitary cell types was required for estrogen action. In pituitary cells, enriched for lactotrophs by 85% using differential sedimentation on a discontinuous Percoll gradient, 17beta-estradiol (E2) showed an antimitogenic action on lactotrophs in the presence of IGF-I, which was similar to that in control unenriched cells.

High levels of dioxin-like potential in cigarette smoke evidenced by in vitro and in vivo biosensing.

Cigarette smoke contains low levels of agonists for the aryl hydrocarbon receptor (AhR; also called the dioxin receptor). However, little is understood about the whole potential of cigarette smoke for activating AhR. In this report, we evaluated the total "dioxin-like" activity of cigarette smoke using in vitro and in vivo reporter systems.

Perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin suppresses contextual fear conditioning-accompanied activation of cyclic AMP response element-binding protein in the hippocampal CA1 region of male rats.

We investigated the effect of in utero and lactational exposures to dioxin on adult offspring with contextual fear conditioning, a sex- and hippocampus-dependent learning paradigm; and we measured the conditioning-accompanied activation of cyclic AMP response element-binding protein (CREB) in the hippocampal CA1 region. Pregnant rats were treated with a low dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on gestation day 15. TCDD treatment decreased freezing time in conditioning tests of adult male offspring but not of female offspring.

Immunization in familial amyloidotic polyneuropathy: counteracting deposition by immunization with a Y78F TTR mutant.

The mechanism of amyloid formation in familial amyloidotic polyneuropathy (FAP), a hereditary disorder associated with mutant transthyretin (TTR), is still unknown. It is generally believed that altered conformations exposing cryptic regions are intermediary steps in this mechanism. A TTR mutant--Y78F (transthyretin mutant with phenylalanine replacing tyrosine at position 78)--designed to destabilize the native structure has been shown to expose a cryptic epitope recognized by a monoclonal antibody that reacts only with highly amyloidogenic mutants presenting the amyloid fold or with amyloid fibrils.

Formation of experimental murine AA amyloid fibrils in SAP-deficient mice: high resolution ultrastructural study.

Previously, the role of the serum amyloid P component (SAP) in the deposition of murine AA amyloid has been examined in SAP-deficient mice in which the deposition was significantly retarded. In this study, AA amyloid fibrillogenesis in SAP-deficient mice was examined ultrastructurally. The fibrils of wild type mice were made up of a microfibril-like main body composed of SAP, chondroitin sulfate proteoglycan (CSPG), and outermost heparan sulfate proteoglycan (HSPG), and associated on its surface were 3 nm wide AA protein 'helical rods', a possible suitable form for Congo red staining.

Expression of syndecans, a heparan sulfate proteoglycan, in malignant gliomas: participation of nuclear factor-kappaB in upregulation of syndecan-1 expression.

Invasion of tumor cells into the surrounding normal brain tissues is a prominent feature of malignant gliomas. Malignant glioma cells secrete thrombospondin-1 which participates in the motility of glioma cells and binds cell surface heparan sulfate proteoglycan. To clarify the invasion mechanism of tumor cells, expression of the syndecans (syndecan-1, -2, -3, and -4), a major cell surface heparan sulfate proteoglycan family, was analyzed in malignant gliomas.

Influence of cAMP on reporter bioassays for dioxin and dioxin-like compounds.

In reporter assays for detection of dioxins, the dioxin-responsive element (DRE) is generally used as a sensor sequence. In several systems, the CYP1A1 promoter containing DREs (DRE(cyp)) is inserted into a part of the long terminal repeat of mouse mammary tumor virus (LTR(MMTV)) to improve sensitivity of assays. We found that DRE(cyp)-LTR(MMTV) responds not only to dioxins and dioxin-like compounds but also to forskolin, a cAMP-elevating agent.

Overexpression of heparin-binding growth-associated molecule in malignant glioma cells.

The highly invasive and angiogenic characteristics of malignant gliomas depend on the production of growth factors and angiogenic factors. Heparin-binding growth-associated molecule (HB-GAM) is a secreted growth factor that is mitogenic for endothelial cells. To examine the expression profile of HB-GAM in malignant glioma cells, messenger ribonucleic acid (mRNA) expression was analyzed in 10 malignant glioma cell lines, two glioblastoma tissue specimens, and two normal brain tissue specimens by the reverse transcription-polymerase chain reaction.

Fast-track DRESSA: a bioassay for fast, sensitive, and selective detection of halogenated and polycyclic aromatic hydrocarbons.

Dioxin and related chemicals cause a variety of toxic and biological effects via the aryl hydrocarbon receptor (AhR). We recently reported a mammalian cell-based bioassay system (dioxin-responsive-element-based sensing via secreted alkaline phosphatase; DRESSA) that can detect dioxin and dioxin-like chemicals with high sensitivity. In this report, we describe an advanced method (designated "fast-track DRESSA") that achieves fast, selective, and sensitive detection of dioxin and other toxic compounds.

DRESSA: biosensing of dioxin and dioxin-like chemicals using secreted alkaline phosphatase.

In this article, we describe a highly sensitive biosensing system, DRESSA, for detection of dioxin and dioxin-like chemicals. Tandem copies of the dioxin-responsive element (DRE) fused to a minimal viral promoter were subcloned into an expression plasmid upstream of a secreted alkaline phosphatase (SEAP) gene. When murine hepatoma cell line Hepa-1c1c7 was stably transfected with this construct, established sensor clones secreted SEAP following stimulation with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

Deposition of transthyretin amyloid is not accelerated by the same amyloid in vivo.

Acceleration of amyloid deposition by administration of amyloid fibrils and transmissibility of disease have been reported in several types of amyloidoses. Families with a variant transthyretin (TTR V30M)-associated familial amyloidotic polyneuropathy (FAP) exhibit genetic anticipation, with TTR V30M-amyloid depositing at an earlier age in successive generations. The molecular bases of anticipation in FAP have remained to be determined.

AP-1-independent sensitization to oxidative stress-induced apoptosis by proteasome inhibitors.

Hydrogen peroxide (H(2)O(2)) induces apoptosis of mesangial cells via c-Jun N-terminal kinase (JNK)-activator protein-1 (AP-1) and extracellular signal-regulated kinase (ERK)-AP-1 pathways. We recently found that subtoxic doses of proteasome inhibitors, MG132 and lactacystin, dramatically enhanced H(2)O(2)-induced apoptosis in mesangial cells. In this report, we examined molecular mechanisms involved in this phenomenon, especially focusing on AP-1 pathways.

Use of genetically altered mice to study the role of serum amyloid P component in amyloid deposition.

A precise role for serum amyloid P component (SAP), a common component of all known types of amyloid fibrils, in amyloid deposition in vivo is not known. Thus we investigated the relationship between SAP and amyloid deposition, using the transgenic mouse model of familial amyloidotic polyneuropathy (FAP). Because high serum levels of mouse endogenous or human SAP did not affect human transthyretin-derived amyloid deporsition in the transgenic mouse model of FAP, we approached this question by analyzing the induction of experimental AA amyloidosis in SAP-deficient and wild-type mice.

Production of mouse ES cells homozygous for Cdk5-phosphorylated site mutation in c-Src alleles.

c-Src-null mutants have not provided a full understanding of the cellular functions of c-Src, reflecting the functional redundancy among Src family members. c-Src is phosphorylated by cyclin-dependent kinase 1 (Cdk1) and Cdk5 at Ser75 in the unique amino terminal c-Src-specific domain. The specific roles of c-Src may be assessed by establishing mouse embryonic stem (ES) cells homozygous for a point mutation at Ser75.