Abstract:Recently, in order to elucidate the role of rab3B in porosome, we have observed the incorporation of rab3B in the secretion of GH through porosome under confocal laser scanning microscopy (CLSM). Transfected cells with GH-EYFP fusion protein and rab3B-ECFP fusion protein were observed under CLSM, which showed the colocalization of EYFP-GH and ECFP-rab3B in the budding configuration of secretory process. These structural and functional images of rab3B imply the incorporation of rab3B in the secretion of GH through porosome.
Key words: GH, rab3B, porosome, EYFP, ECFPCorrespondence: A. Matsuno, Dept. of Neurosurgery, Teikyo University Chiba Medical Center, 3426-3 Anesaki, Ichihara City, Chiba 299-0111, Japan; tel.: (+81) 436621211 ext. 2621, fax.: (+81) 436621357, e-mail: akirakun@med.teikyo-u.ac.jp ship in GH secretion [8,9]. In order to examine more specific relationship among molecules that play important roles in transportation and secretion of pituitary hormone, we developed an experimental pituitary cell line that has secretory granules of GH linked to enhanced yellow fluorescein protein (EYFP), which enabled us to visualize the real-time movement of the molecules in a living cell [10]. Recently, in order to elucidate the role of rab3B in porosome, we have observed the incorporation of rab3B in the secretion of GH through porosome under confocal laser scanning microscopy (CLSM). In this paper, we describe the synergistic dynamics of rab3B and GH in porosome with illustrative fluorescein imaging of rab3B and GH in an experimental cell line.
Materials and methodsConstruction of rat EYFP-GH-1 plasmid for transfection of GH3 cell. The rat GH cDNA clone pRGH-1 and the EYFP-expression construct pEYFP-N1 were obtained from the American Type Culture Collection (Manassas, VA, USA) and Clontech Laboratories, Inc., (Palo Alto, CA, USA), respectively. The GH-EYFP fusion construct pCMV-Sig-EYFP-GH-1 was derived from pEYFP-N1 and contained a sequence encoding the rat GH signal peptide (1 to 26 in the rat GH amino-acid sequence) and the EYFPcoding segment, followed by another rat GH coding sequence (27 to 217 in the rat GH amino-acid sequence).Construction of rat rab3B-enhanced cian fluorescein protein (ECFP) plasmid for transfection of GH3 cell. prab3B-ECFP was constructed as follows. A cDNA fragment encoding rat rab3B was amplified by RT-PCR and cloned in-frame into the EcoRI/BamHI sites of pECFP-N1 (Clontech Laboratories, Inc.), which expresses rab3B-ECFP fusion proteins in the mammalian cell. Plasmids were purified using Qiagen midi-prep kit (Qiagen GmbH, Hilden, Germany), and were verified by nucleotide sequencing.GH3 cell culture. GH3 cells were maintained at 37°C in a 5% CO 2 in DMEM/Ham's F-12 medium supplemented with 2.5% heatinactivated fetal bovine serum (FBS), 10% horse serum (HS), 100U/ml of penicillin and 100 μg/ml of streptomycin at 70% confluency on poly-L-lysin coated 35-mm glass base dishes.Transfection. Transfection of GH3 cells was performed using lipofectamine 2000 (Invitrogen Corp., Carlsba...