Yoshimasa Kamei

Preimplantation exposure to bisphenol A advances postnatal development

Prenatal exposure to bisphenol A (BPA), an estrogenic compound, has been shown to alter postnatal development at an environmentally relevant exposure level. To elucidate these low dose effects of preimplatation exposure to BPA, two-cell mouse embryos were cultured with 1 nM BPA. More embryos exposed to 1 nM BPA than controls reached the blastocyst stage. When the blastocysts with or without BPA exposure were transferred to uterine horns of pseudopregnant recipient mice not treated with BPA, the number of pups per litter and body weight at birth did not differ. At weaning on postnatal day 21, however, pups treated with 1 nM BPA during the preimplantation period were significantly heavier than controls. These findings suggest that BPA may not only affect early embryonic development even at low, environmentally relevant doses, but also may exert late effects on postnatal development.

Visualization of mitotic radial glial lineage cells in the developing rat brain by Cdc2 kinase-phosphorylated vimentin

Although accumulating data reveal patterns of proliferation, migration, and differentiation of neuronal lineage cells in the developing brain, gliogenesis in the brain has not been well elucidated. In the rat brain, vimentin is selectively expressed in radial glia and in their progeny, not in oligodendrocytes or neurons from embryonic day 15 (E15) until postnatal day 15 (P15). Here we examined mitotic radial glial lineage cells in the rat brain E17–P7, using the monoclonal antibody 4A4, which recognizes vimentin phosphorylated by a mitosis‐specific kinase, cdc2 kinase. In the neocortex, mainly radial glia in the ventricular zone, but not their progeny, underwent cell division. In contrast, not only radial glia but also various types of radial glial progeny including Bergmann glia continued to proliferate in the cerebellum. Radial glia in the neocortex divided horizontally, obliquely, and vertically against the ventricular surface. The percentage of the vertical division increased with progress in the stage of development, concurrently with the decrease of the population of horizontal divisions. Thus, the monoclonal antibody 4A4 provides an useful tool to label mitotic glia in the developing brain and revealed different patterns of gliogenesis in the neocortex and cerebellum. A possibility is discussed that the dynamics of mitotic orientation observed here may be related to the change of the pattern of gliogenesis during development. GLIA 23:191–199, 1998.

ASK1 and ASK2 differentially regulate the counteracting roles of apoptosis and inflammation in tumorigenesis

Apoptosis and inflammation generally exert opposite effects on tumorigenesis: apoptosis serves as a barrier to tumour initiation, whereas inflammation promotes tumorigenesis. Although both events are induced by various common stressors, relatively little is known about the stress‐induced signalling pathways regulating these events in tumorigenesis. Here, we show that stress‐activated MAP3Ks, ASK1 and ASK2, which are involved in cellular responses to various stressors such as reactive oxygen species, differentially regulate the initiation and promotion of tumorigenesis. ASK2 in cooperation with ASK1 functioned as a tumour suppressor by exerting proapoptotic activity in epithelial cells, which was consistent with the reduction in ASK2 expression in human cancer cells and tissues. In contrast, ASK1‐dependent cytokine production in inflammatory cells promoted tumorigenesis. Our findings suggest that ASK1 and ASK2 are critically involved in tumorigenesis by differentially regulating apoptosis and inflammation.

Maternal Epidermal Growth Factor Deficiency Causes Fetal Hypoglycemia and Intrauterine Growth Retardation in Mice: Possible Involvement of Placental Glucose Transporter GLUT3 Expression1

We investigated the physiological role of epidermal growth factor (EGF) in fetal growth in mice in which midgestational sialoadenectomy induced maternal EGF deficiency. Sialoadenectomy decreased the fetal weight significantly, indicating that maternal EGF deficiency caused intrauterine growth retardation. The weight of the fetal liver in the sialoadenectomized mice was reduced in proportion to the decrease in body weight (82.7 ± 10.2 vs. 70.9 ± 10.9 mg), whereas the brain weight was not reduced. Sialoadenectomy significantly decreased the glucose concentration in fetal plasma (86.0 ± 13.0 vs. 63.0 ± 11.8 mg/dl) without affecting the maternal plasma level of glucose. Transplacental transfer of 3H-2-deoxyglucose was significantly decreased by sialoadenectomy (5.17 ± 1.25 vs. 2.94 ± 1.02%), but transfer of 14C-aminoisobutyric acid was not affected. Northern blot analysis and in situ hybridization of glucose transporter isoform GLUT1 and GLUT3 messenger RNAs (mRNAs) in placenta revealed that sialoadenectomy s...

Bax-inhibiting peptide protects glutamate-induced cerebellar granule cell death by blocking Bax translocation

Glutamate-induced excitotoxicity has been implicated in the pathogenesis of various neurological damages and disorders. In the brain damage of immature animals such as neonatal hypoxic-ischemic brain injury, the excitotoxicity appears to be more intimately involved through apoptosis. Bax, a member of the Bcl-2 family proteins, plays a key role in the promotion of apoptosis by translocation from the cytosol to the mitochondria and the release of apoptogenic factors such as cytochrome c. Recently, Bax-inhibiting peptide (BIP), a novel membrane-permeable peptide which can bind Bax in the cytosol and inhibit its translocation to the mitochondria, was developed. To investigate the possibility of a new neuroprotection strategy targeting Bax translocation in glutamate-induced neuronal cell death, cerebellar granule neurons (CGNs) were exposed to glutamate with or without BIP. Pretreatment of CGNs with BIP elicited a dose-dependent reduction of glutamate-induced neuronal cell death as measured by MTT assay. BIP significantly suppressed both the number of TUNEL-positive cells and the increase in caspases 3 and 9 activities induced by glutamate. In addition, immunoblotting after subcellular fractionation revealed that BIP prevented the glutamate-induced Bax translocation to the mitochondria and the release of cytochrome c from the mitochondria. These results suggest that agents capable of inhibiting Bax activity such as BIP might lead to new drugs for glutamate-related diseases in the future.

Visualization of protein kinase activities in single cells by antibodies against phosphorylated vimentin and GFAP

Vimentin and glial fibrillary acidic protein (GFAP) are intermediate filament proteins expressed in the cytoplasm of various types of cells. The head domains of these proteins are phosphoralated by various protein kinases. Site- and phosphorylation-specific antibodies which recognize a phosphorylated serine/threonine residue in the head domains and its flanking sequence provide a useful tool to monitor and visualize protein kinase activities in single cells.

Hypothermia‐induced increase of oligodendrocyte precursor cells: Possible involvement of plasmalemmal voltage‐dependent anion channel 1

Hypothermia is believed to suppress cell proliferation by inducing apoptosis/necrosis and phase‐specific/nonspecific cell cycle arrest, which are, directly or indirectly, related to a reduced energy supply. Intriguingly, hypothermia is known to improve neurological recovery of animals and humans exposed to focal brain hypoxic‐ischemic injury. The underlying mechanism of the neuroprotective effect of hypothermia is unclear, although the prevention of neural cell apoptosis is thought to play a role. Herein we demonstrate that in vitro cell culture of oligodendrocyte precursor cells (OPCs) under conditions of mild hypothermia (31.5°C) results in an increase in cell number relative to cells cultured under normothermic conditions (37°C). Cell cycle analysis, immunoblotting of cyclins, TUNEL assay, and immunocytochemistry of OPC differentiation markers suggest that hypothermia shifts the balance between proliferation and apoptosis/differentiation toward proliferation. A combination of transcriptome analysis, pharmacological intervention, and immunoaffinity‐based assays suggests a possible involvement of the Gα13–Rho GTPase Cdc42–ERK1/2 signaling cascade and voltage‐dependent anion channel 1 (VDAC1), which associate or dissociate with Gα13 protein at 37°C and 31.5°C, respectively. Immunoelectron microscopy revealed the presence of VDAC1 in the plasma membrane of OPCs. Furthermore, the exogenous addition of impermeable VDAC1 inhibitors enhanced proliferation of OPCs at 37°C. These results may contribute to the elucidation of the mechanism of hypothermic neuroprotection as well as the possible novel role of plasmalemmal VDAC1.

Uterine leiomyoma confounding a noninvasive prenatal test result

Sequenom Laboratories, San Diego, CA, USA Department of Obstetrics and Gynecology, Saitama Medical University Hospital, Saitama, Japan Perinatal Medical Center, Saitama Medical Center, Jichi Medical University, Saitama, Japan GeneTech Inc., Tokyo, Japan Sequenom Laboratories, Grand Rapids, MI, USA Department of Obstetrics, Gynecology and Reproductive Medicine, Michigan State University, East Lansing, MI, USA *Correspondence to: Nilesh G. Dharajiya. E-mail: ndharajiya@sequenom.com These authors contributed equally to this article.

Tissue elastography imaging of the uterine cervix during pregnancy.

Tissue elastography is a recently developed tissue characterization method for estimating tissue stiffness. We investigated the feasibility of using US tissue elastography by evaluating uterine cervical maturation during pregnancy. The principle underlying elastography is that tissue compression produces strain (displacement) within the tissue, and that less strain occurs in hard tissue than in soft tissue. Tissue elastography thus enables the estimation of tissue stiffness by measuring compression-induced tissue strain. Malignant tumors are generally known to be harder than benign tumors in the breast, thyroid, and prostate. Various studies on these organs have demonstrated the usefulness of tissue elastography for differentiating malignant from benign masses in the clinical setting. Based on these results, we have begun to investigate the possibility of using tissue elastography to identify the population at high risk of preterm labor. We used a Hitachi EUB-8500 (Tokyo, Japan) ultrasound system equipped with a 7.5-MHz transvaginal sector probe to carry out transvaginal US examinations. After selecting the transvaginal sagittal image of the uterine cervix as the region of interest (ROI) in B-mode, we began real-time elastography of the ROI using only slight pressure, and displayed both the Bmode and elasticity images side by side on the same monitor screen (Fig. 1).

cDNA cloning and chromosomal localization of neural adhesion molecule NB-3 in human

Neural adhesion molecules in the immunoglobulin superfamily play essential roles in axonal guidance during development, plasticity, and maintenance of synaptic connections in the adult brain. Recently, we reported two novel cDNAs encoding adhesion molecules, NB‐2 and NB‐3, in the contactin/F3 subgroup of the immunoglobulin superfamily from rat brain. We have now isolated cDNA encoding human NB‐3. The cDNA clone, hNB‐3, consists of 3,530 nucleotides with an open reading frame of 3,084 nucleotides encoding 1,028 amino acids. It shares with rat NB‐3 86% identity in nucleotide sequences and 90% identity in amino acid sequences. Likewise, hNB‐3 exhibits 53% and 51% identity in nucleotide sequences and 43% and 44% identity in amino acid sequences with human contactin/F3 and human TAG‐1/axonin‐1, respectively. Northern blot analysis of mRNA isolated from different regions of the adult human nervous system showed that the hNB‐3 mRNA content was regionally different by dozens‐fold, although the mRNA was detected in all regions, as a transcript of 3.7 kb. The cerebellum showed the highest expression of hNB‐3 mRNA among various regions of the nervous system. Chromosomal localization of hNB‐3, using fluorescence in situ hybridization, was assigned to 3p25‐26. J. Neurosci. Res. 51:275–283, 1998.