PEGylation is considered one of the most successful techniques to improve the characteristics of protein drugs including to increase the circulating half-life of proteins in blood and to decrease their immunogenicity and antigenicity. One known PEG modification method is to attach PEG to the free amino group, typically at lysine residues or at the N-terminal amino acid with no selectivity, resulting in a heterogeneous product mixture. This lack of selectivity can present problems when a therapeutic PEGylated protein is being developed, because predictability of activity and manufacturing reproducibility are needed for regulatory approval. Enzymatic PEGylation of proteins is one route to overcome this limitation. Transglutaminases (TGase) are enzyme candidates for site-specific PEGylation. We use human interferon alpha 2a (IFN α2a) as a test case, and predict that the potential modification residues are Gln101 by computational approach as it contains 12 potential PEGylation sites. IFN α2a was PEGylated by Y shaped PEG40k-NH2 mediated by microbial transglutaminase. Our results show that the microbial transglutaminase mediated PEGylation of IFN α2a was site-specific only at the site of Gln101 in IFN α2a, yielding the single mono-conjugate PEG-Gln101-IFN α2a with a mass of 59 374.66 Da. Circular dichroism studies showed that PEG-Gln101-IFN α2a preserved the same secondary structures as native IFN α2a. As expected, the bioactivity and pharmacokinetic profile in rats of PEG-Gln101-IFN α2a revealed a significant improvement to unmodified IFN α2a, and better than PEGASYS.
Animals ; Antiviral Agents ; Humans ; Interferon alpha-2 ; metabolism ; Interferon-alpha ; biosynthesis ; pharmacokinetics ; Polyethylene Glycols ; pharmacokinetics ; Protein Structure, Secondary ; Rats ; Recombinant Proteins ; biosynthesis ; pharmacokinetics ; pharmacology ; Reproducibility of Results ; Transglutaminases ; metabolism

An abrupt increase of intracellular Ca2+ is observed in cells under hypoxic or oxidatively stressed conditions. The dysregulated increase of cytosolic Ca2+ triggers apoptotic cell death through mitochondrial swelling and activation of Ca2+-dependent enzymes. Transglutaminase 2 (TG2) is a Ca2+-dependent enzyme that catalyzes transamidation reaction producing cross-linked and polyaminated proteins. TG2 activity is known to be involved in the apoptotic process. However, the pro-apoptotic role of TG2 is still controversial. In this study, we investigate the role of TG2 in apoptosis induced by Ca2+-overload. Overexpression of TG2 inhibited the A23187-induced apoptosis through suppression of caspase-3 and -9 activities, cytochrome c release into cytosol, and mitochondria membrane depolarization. Conversely, down-regulation of TG2 caused the increases of cell death, caspase-3 activity and cytochrome c in cytosol in response to Ca2+-overload. Western blot analysis of Bcl-2 family proteins showed that TG2 reduced the expression level of Bax protein. Moreover, overexpression of Bax abrogated the anti-apoptotic effect of TG2, indicating that TG2-mediated suppression of Bax is responsible for inhibiting cell death under Ca2+-overloaded conditions. Our findings revealed a novel anti-apoptotic pathway involving TG2, and suggested the induction of TG2 as a novel strategy for promoting cell survival in diseases such as ischemia and neurodegeneration.
*Apoptosis ; Apoptosis Regulatory Proteins/metabolism ; Calcimycin/pharmacology ; Calcium/*metabolism ; Caspases/metabolism ; Cell Death ; Cell Survival ; Cytochromes c/metabolism ; Down-Regulation ; GTP-Binding Proteins/*metabolism ; HEK293 Cells ; Hela Cells ; Humans ; Ionophores/pharmacology ; Mitochondria/metabolism ; Transglutaminases/*metabolism ; bcl-2-Associated X Protein/genetics/*metabolism

OBJECTIVETo investigate the expression of tissue transglutaminase( tTG) in unilateral ureteral obstruction (UUO) rats and the intervention of Folium Ginkgo (GBE).

METHODThe animal models of unilateral ureteral obstruction (UUO) were used. Wistar rats were randomly divided into four groups, the Sham-operated group, the UUO group, the benazepril (Bena)-treated UUO group and the GBE-treated group. The rats were sacrificed at day 14. Histological changes in renal tubular interstitium were observed with HE and Masson staining, and the mRNA and protein levels of tTG and FN were detected by RT-PCR and immunohistochemistry.

RESULTCompared with the sham group, the expression of tTG and FN were significantly increased (P < 0.01), and decreased after been treated by Bena and GBE (P < 0.05).

CONCLUSIONBena and GBE may suppress the development of fibrosis partially via down-regulation of tTG expression.

Animals ; Drugs, Chinese Herbal ; pharmacology ; Fibrosis ; Gene Expression Regulation, Enzymologic ; drug effects ; Ginkgo biloba ; chemistry ; Immunohistochemistry ; Kidney ; drug effects ; enzymology ; metabolism ; pathology ; Male ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Wistar ; Transglutaminases ; genetics ; metabolism

Effect of CTAB addition on the accumulation of microbial transglutaminase (MTG) with Streptomyces hygroscopicus was investigated. The results showed that the addition of CTAB enhanced MTG accumulation, and the optimal addition time and concentration of CTAB were 32 h and 1%. The maximum MTG activity in the culture broth was 5.04 u/mL and increased by 21.8% compared with the control. With the addition of CTAB, pro-MTG was activated to become MTG. CTAB could enhance the production of pro-MTG by relieving the product inhibition, and the accumulation of MTG was improved.
Bacterial Proteins ; metabolism ; Cetrimonium Compounds ; pharmacology ; Dose-Response Relationship, Drug ; Electrophoresis, Polyacrylamide Gel ; Enzyme Activation ; drug effects ; Enzyme Precursors ; metabolism ; Industrial Microbiology ; methods ; Streptomyces ; drug effects ; enzymology ; metabolism ; Surface-Active Agents ; pharmacology ; Time Factors ; Transglutaminases ; metabolism

To study the effect of tTG fully phosphorothioated antisense oligodeoxynucleotides (tTG-ASDON) on tTG expression in cultured bovine trabecular meshwork cells (BTMCs) in vitro and explore a new treatment alternative for primary open angle glaucoma (POAG), the ASDON1 and ASDON2 complementary to the protein codogram region of tTG were designed, synthesized and phosphorothioated according to the secondary structure of tTG. The ASDON1 and ASDON2 were embedded in Lipofectamine and transfected into BTMCs. The untreated group served as negative controls. The expression of tTG in the mRNA and protein level were measured by semi-quantitative RT-PCR and immunohistochemical technique-Supervision method respectively. Our results showed that both the mRNA and the protein of tTG with tTG-ASDON and tTG-ASDON2 were significantly decreased as compared with that of the controls (P < 0.05). On the other hand, no significant difference was found between the ASDON1 group and the ASDON2 group. It is concluded that the expression of tTG mRNA and protein in cultured BTMC are down-regulated by tTG- ASDON. As a result, tTG-ASDON may be used for the treatment of POAG through the inhibitory effect on the expression of tTG.
Cells, Cultured ; Glaucoma, Open-Angle/metabolism ; Oligonucleotides, Antisense/*pharmacology ; RNA, Messenger/biosynthesis ; RNA, Messenger/genetics ; Trabecular Meshwork/cytology ; Trabecular Meshwork/*metabolism ; Transglutaminases/*biosynthesis ; Transglutaminases/genetics ; Transglutaminases/*pharmacology

The treatment of cystamine, a transglutaminase (TGase) inhibitor, has beneficial effects in several diseases including CAG-expansion disorders and cataract. We compared the inhibition characteristics of cystamine with those of cysteamine, a reduced form of cystamine expected to be present inside cells. Cystamine is a more potent inhibitor for TGase than cysteamine with different kinetics pattern in a non- reducing condition. By contrast, under reducing conditions, the inhibitory effect of cystamine was comparable with that of cysteamine. However, cystamine inhibited intracellular TGase activity more strongly than cysteamine despite of cytoplasmic reducing environment, suggesting that cystamine itself inhibits in situ TGase activity by forming mixed disulfides.
Cell Line, Tumor ; Comparative Study ; Cystamine/*pharmacology ; Cysteamine/*pharmacology ; Enzyme Inhibitors/*pharmacology ; Humans ; Research Support, Non-U.S. Gov't ; Transglutaminases/*antagonists & inhibitors