Biomedical subjects

Hyung-Lae Kim

Publications and source records attributed to Hyung-Lae Kim.

4 recordsLinked to original sources

PubMed2002

Molecular basis of R-type calcium channels in central amygdala neurons of the mouse.

R-type Ca2+ channels play a critical role in coupling excitability to dendritic Ca2+ influx and neuronal secretion. Unlike other types of voltage-sensitive Ca2+ channels (L, N, P/Q, and T type), the molecular basis for the R-type Ca2+ channel is still unclear, thereby limiting further detailed analyses of R-type Ca2+ channel physiology. The prevailing hypothesis is that alpha(1E) (Ca(V)2.3) gene encodes for R-type Ca2+ channels, but the dearth of critical evidence has rendered this hypothesis controversial. Here we generated alpha1E-deficient mice (alpha1E-/-) and examined the status of voltage-sensitive Ca2+ currents in central amygdala (CeA) neurons that exhibit abundant alpha1E expression and R-type Ca2+ currents. The majority of R-type currents in CeA neurons were eliminated in alpha1E-/- mice whereas other Ca2+ channel types were unaffected. These data clearly indicate that the expression of alpha1E gene underlies R-type Ca2+ channels in CeA neurons. Furthermore, the alpha1E-/- sign mice exhibited signs of enhanced fear as evidenced by their vigorous escaping behavior and aversion to open-field conditions. These latter findings imply a possible role of alpha1E-based R-type Ca2+ currents in amygdala physiology associated with fear.

Amygdala↗

PubMed2002

Expression of MUC1 on corneal endothelium of human.

PURPOSE: To determine the expression of MUC1 in the human corneal endothelium. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) for MUC1 was performed with total RNA from endothelial cells extracted from the human cornea. In situ hybridization with sense and antisense probes of human MUC1 was performed on the human corneal endothelium, immunoblot analysis using monoclonal antibody specific for human MUC1 (HMFG-1, or VU4H5) was performed on collected human corneal endothelial cells, and immunohistochemistry on the human cornea, using the same antibodies. RESULTS: MUC1 mRNA expression was observed by RT-PCR in the human corneal endothelium, and the nucleotide sequence from the amplified band was matched with known human MUC1. In situ hybridization studies showed the localization of MUC1 mRNA in the human corneal endothelium, and immunoblot assay demonstrated the presence of MUC1 protein (MW > 200 kd). In addition, MUC1 protein was observed on the apical surface of cells and at the superficial layer of the cytoplasm in immunohistochemical studies. CONCLUSIONS: Human corneal endothelial cells produce MUC1, which is known to have protective and lubricative roles.

Adolescent↗

PubMed2002

Decrease in apoptosis and increase in polyploidization of megakaryocytes by stem cell factor during ex vivo expansion of human cord blood CD34+ cells using thrombopoietin.

Thrombopoietin (TPO) is widely used for ex vivo expansion of hematopoietic stem cells. Previously, we have reported that TPO induces a characteristic pattern of apoptosis, and the TPO-induced apoptosis is closely associated with megakaryocyte (MK) differentiation. In the present study, several cytokines, flt3-ligand, stem cell factor (SCF), interleukin-3 (IL-3), IL-6, IL-11, leukemia inhibitory factor, G-CSF, and erythropoietin, which are known to affect megakaryocytopoiesis, have been evaluated to elucidate their effects on the TPO-induced apoptosis. Measurement of apoptosis by flow cytometry revealed that only SCF absolutely reduced the TPO-induced apoptosis in MK fractions, particularly in the late phase of ex vivo expansion. Platelet production was demonstrated by electron microscopy in a later phase when SCF was added. Simultaneous measurement of DNA contents with immunophenotyping demonstrated a significant increase in polyploidization in the CD41+ cell fraction when cultured with SCF. These results suggested that SCF not only inhibited premature senescence but also enhanced maturation of the differentiating cells of MK lineage during ex vivo expansion using TPO.

Antigens, CD34↗

PubMed2002

Gene expression profile of megakaryocytes from human cord blood CD34(+) cells ex vivo expanded by thrombopoietin.

Previously, we investigated the process of megakaryocytopoiesis during ex vivo expansion of human cord blood (CB) CD34(+) cells using thrombopoietin (TPO) and found that megakaryocytopoiesis was closely associated with apoptosis. To understand megakaryocytopoiesis at the molecular level, we performed a microserial analysis of gene expression (microSAGE) in megakaryocytes (MKs) and nonmegakaryocytes (non-MKs) derived from human CB CD34(+) cells by ex vivo expansion using TPO, and a total of 38909 tags, representing 8976 unique genes, were identified. In MKs, many of the known genes, including coagulation factor VII, P-selectin (CD62P), pim-1, azurocidin, defensin, and CD48 were highly expressed; meanwhile, those genes encoding some small G proteins of the Ras family (Rab 7 and Rab 11A) and glutathione S transferase family (1, 4, A2, omega, and pi) showed lower expression levels in MKs. These gene expression profiles will be useful to understand megakaryocytopoiesis at the molecular level, including apoptosis and related signal transduction pathways.

Antigens, CD34↗