Biomedical subjects

Jae-Sam Hwang

Publications and source records attributed to Jae-Sam Hwang.

7 recordsLinked to original sources

PubMed2005

The analysis of differentially expressed novel transcripts in diapausing and diapause-activated eggs of Bombyx mori.

As an initial step to define the molecular mechanism of initiation and termination of diapause during the embryogenesis of silkworms, Bombyx mori, mRNA transcripts from maintained and activated diapause eggs were compared with differential expression using cDNA array. Twenty-four individual cDNA transcripts were expressed differentially in a total of 1,468 different cDNAs. Among those clones, mRNA transcript from cytochrome oxidase subunit I (COI), which was detected to be 2-kb transcripts, gradually increased in diapause-activated eggs during early embryogenesis. Further analysis revealed that mRNA transcripts from silkworm COI were highly expressed in testis, fat body, and midgut during the larval stage. These results may indicate that the expression of silkworm COI mRNA is regulated developmentally as well as tissue-specifically.

Animals↗

PubMed2005

Galatosylation and sialylation of mammalian glycoproteins produced by baculovirus-madiated gene expression in insect cells.

The baculovirus expression vector system (BEVS) is used extensively for the production of proteins from exogenous cDNAs. However, BEVS is not ideal for pharmaceutical production of glycoproteins owing to the properties of the N-glycans in the expressed products and that insect cells lack several of the enzymes required for mammalian-type N-glycan synthesis. This study describes the effective mammalian-like production of glycoproteins, such as beta-1,4-galactosyltransferase and alpha-2,6-sialyltransferase, in the insect cell line Sf9.

Animals↗

PubMed2005

Changes in cellular secretory processing during baculovirus infection.

In the baculovirus expression vector system (BEVS), secretory green fluorescent protein (sGFP) transcripts were expressed from day 2 to day 5 post-infection (p.i.), while transcripts of the endoplasmic reticulum (ER) molecular chaperone Bombyx mori protein disulfide isomerase (bPDI) were measurable in mock cells and in cells at day 1 p.i. The GFP was expressed from day 3 to day 5 p.i. whereas the levels of two ER chaperone proteins, bPDI and calnexin, decreased from day 3 p.i. and were not detected from day 4 p.i. These findings suggest that the rate-limited expression of ER molecular chaperones is strongly associated with the maximal expression of exogenous proteins in BEVS.

Animals↗

PubMed2004

cDNA cloning and mRNA expression of LIM protein gene homologue from the silkworm, Bombyx mori.

LIM protein cDNA, from Bombyx mori that contains an open reading frame of 622 bp encoding 94 amino acids, was identified and characterized. The B. mori LIM protein homologue is classified into group 2 LIM proteins that contain glycine-rich LIM domain. B. mori LIM protein mRNA is up-regulated at late embryogenesis and detected in the mid-gut of 5th instar larvae.

Amino Acid Sequence↗

PubMed2003

cDNA cloning and mRNA expression of L-3,4-dihydroxyphenylalanine decarboxylase gene homologue from the silkworm, Bombyx mori.

L-3,4-Dihydroxyphenylalanine decarboxylase (DDC) cDNA, from Bombyx mori that contains an open reading frame of 1437 bp encoding 478 amino acids, was cloned and characterized. Expression analyses of B. mori DDC mRNA by Northern and in situ hybridization indicated that expression of silkworm DDC expression is possibly controlled by neuropeptide hormones in tissue- and stage-specific manners.

Amino Acid Sequence↗

PubMed2002

Molecular characterization of a Bombyx mori protein disulfide isomerase (bPDI).

We have isolated a complementary deoxyribonucleic acid clone that encodes the protein disulfide isomerase of Bombyx mori (bPDI). This protein has a putative open reading frame of 494 amino acids and a predicted size of 55.6 kDa. In addition, 2 thioredoxin active sites, each with a CGHC sequence, and an endoplasmic reticulum (ER) retention signal site with a KDEL motif were found at the C-terminal. Both sites are typically found in members of the PDI family of proteins. The expression of bPDI messenger ribonucleic acid (mRNA) was markedly increased during ER stress induced by stimulation with calcium ionophore A23187, tunicamycin, and dithiothreitol, all of which are known to cause an accumulation of unfolded proteins in the ER. We also examined the tissue distribution of bPDI mRNA and found pronounced expression in the fat body of insects. Hormonal regulation studies showed that juvenile hormone, insulin, and a combination of juvenile hormone and transferrin (although not transferrin alone) affected bPDI mRNA expression. A challenge with exogenous bacteria also affected expression, and the effect peaked 16 hours after infection. These results suggest that bPDI is a member of the ER-stress protein group, that it may play an important role in exogenous bacterial infection of the fat body, and that its expression is hormone regulated.

Amino Acid Sequence↗

PubMedDate not supplied

Phylogenetic relationship of Bombyx mori protein disulfide isomerase.

A cDNA that encodes protein disulfide isomerase was isolated from Bombyx mori (bPDI), in which an open reading frame of 494 amino acids contained two PDI-typical thioredoxin active sites of WCGHCK and an ER retention signal of the KDEL motif at its C-terminal. The bPDI protein shared less than 55% of the amino acid sequence homology with other reported PDIs. bPDI is most genetically similar to the D. melanogaster PDI. The most serious evolutional diversity was observed between the metazoa and nematoda through PDI evolutional processing. Although bPDI shows a relatively low amino acid homology with other PDIs, in which both sites of the two thioredoxin active sites and the endoplasmic reticulum (ER) retention signal are completely conserved, it was successfully recognized by anti-rat PDI antibodies. This suggests that bPDI may have the activity of a protein isomerase and a chaperone.

Amino Acid Sequence↗