Temporal Change of Calbindin-D28k Immunoreactivity in the Dentate Gyrus of Voluntary Running Mouse / 대한해부학회지

Voluntary running is known to dramatically increase the cell proliferation and neurogenesis in the dentate gyrus of the adult mouse hippocampus. However, it is crucial to realize that adding excitatory neurons could result in serious maladaptive outcomes for hippocampal circuit function. To investigate the response of mature granule cells on the increase of cell proliferation during voluntary running, we investigated the temporal change of calbindin-D28k (a marker for mature granule cells) using immunohistochemistry during voluntary running with upregulated neurogenesis. By using immunohistochemsitry for Ki-67 and doublecortin (DCX), we observed that the cell proliferation and differentiation of granule cells increased at 1 week of voluntary running. We found that, at 6 weeks of voluntary running, the cell proliferation and differentiation of granule cells returned to sedentary control levels. On the other hand, calbindin-D28k immunoreactivity decreased in the granular cell layer of the dentate gyrus and CA3 region of hippocampus after 1 week of voluntary running. At 6 weeks of voluntary running, the density of the calbindin-D28k in the granular cell layer and CA3 region was returned to the sedentary control level. These results demonstrate that the cell proliferation and differentiation are increased at early point of voluntary running, and the granule cell activity in the dentate gyrus is temporally changed for response to the increase of cell proliferation and differentiation during voluntary running.

The Effects of Repeated Restraint Stress on the Synaptic Plasticity in the Inner Molecular Layer of Mouse Dentate Gyrus / 체질인류학회지

Stress induces degeneration of brain structures and functions. Particularly, hippocampus is sensitive to stressful stimulations. In the present study, the change of synaptic related molecules in the mouse dentate gyrus was examined with immunohistochemistry after restraint stress. We subjected mice to restraint stress for 6 h per day for 4 days. As a result, the number of Ki-67, a marker for proliferation, and doublecortin (DCX), a marker for neurogenesis, immunoreactive cells was decreased in the stress group. On the other hand, the intensity of calbindinD-28k, a marker of pre-existing granule cells, immunoreactivity was increased in the granule cell layer after 4 days restraint stress. As well as, the immunoreactivity of synaptic related molecules, postsynaptic density-95 (PSD-95), growth association protein-43 (GAP-43) and beta-NADPH-d reactivity were increased in the inner molecular layer of dentate gyrus after 4 days restraint stress. In conclusion, this study shows that repeated restraint stress suppresses neurogenesis in dentate gyrus and strengthens synaptic plasticity of existing granule cells.

Hypoxia-inducible factor (HIF-1)alpha: its protein stability and biological functions

Hypoxia-inducible factor (HIF-1) is an oxygen-dependent transcriptional activator, which plays crucial roles in the angiogenesis of tumors and mammalian development. HIF-1 consists of a constitutively expressed HIF-1beta subunit and one of three subunits (HIF-1alpha, HIF-2alpha or HIF-3alpha). The stability and activity of HIF-1alpha are regulated by various post-translational modifications, hydroxylation, acetylation, and phosphorylation. Therefore, HIF-1alpha interacts with several protein factors including PHD, pVHL, ARD-1, and p300/CBP. Under normoxia, the HIF-1alpha subunit is rapidly degraded via the von Hippel-Lindau tumor suppressor gene product (pVHL)- mediated ubiquitin-proteasome pathway. The association of pVHL and HIF-1alpha under normoxic conditions is triggered by the hydroxylation of prolines and the acetylation of lysine within a polypeptide segment known as the oxygen-dependent degradation (ODD) domain. On the contrary, in the hypoxia condition, HIF-1alpha subunit becomes stable and interacts with coactivators such as p300/CBP to modulate its transcriptional activity. Eventually, HIF-1 acts as a master regulator of numerous hypoxia-inducible genes under hypoxic conditions. The target genes of HIF-1 are especially related to angiogenesis, cell proliferation/survival, and glucose/iron metabolism. Moreover, it was reported that the activation of HIF-1alpha is closely associated with a variety of tumors and oncogenic pathways. Hence, the blocking of HIF-1a itself or HIF-1alpha interacting proteins inhibit tumor growth. Based on these findings, HIF-1 can be a prime target for anticancer therapies. This review summarizes the molecular mechanism of HIF-1a stability, the biological functions of HIF-1 and its potential applications of cancer therapies.

Membrane-type Matrix Metalloproteinase-1 Induced Invasive and Angiogenic Activities in Chick Chorioallantoic Membrane (CAM) Model / 대한암학회지

PURPOSE: Matrix metalloproteinases (MMPs) have been reported to play critical roles in the endothelial cell migration and matrix remodeling during angiogenic process. To investigate the roles of the membrane type MMP (MT1-MMP) by the matrix remodeling of endothelial cells, MT1-MMP expression vector was transfected into bovine aortic endothelial cells (BAECs). Increased ex+pression of MT1-MMP in BAECs enhanced the activation of MMP-2, invasion and migration of BAECs. Moreover, the capacity of tube formation was increased by MT1-MMP transfectants. These observations indicate that MT1-MMP is involved in the angiogenic process of endothelial cells in vitro. In this study, we attempted these effects were confirmed in vivo system. MATERIALS AND METHODS: In this study, we used MT1- MMP or Antisense MT1-MMP stable transfectants in HT1080 human fibrosarcoma cells. Chorioallantoic membrane (CAM) assay was used for the detection of angiogenesis in vivo and modified CAM assay for quantification of invasion of MT1-MMP transfected cells. RESULTS: In CAM assay, the formation of microvessels was stimulated by MT1-MMP transfectants. Invasive capacity of HT1080 cells was also increased in a novel in vivo metastasis model, PCR based CAM assay. CONCLUSION: These results identify the function of MT1- MMP during the neovascularization process.