Encapsulation of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor in liposomes prepared by thin film hydration and their transfer to mesenchymal stem cells and cord blood hematopoietic stem cells.

Introduction: Cytokines are important immune modulator factors controlling homeostasis of the body and are involved in tissue regeneration after wound healing. The encapsulation of cytokines in liposomes has many advantages potentially useful for their transfer to the cells. Liposomes protect cytokines from neutralization, improving their pharmacokinetics or biologic activity in vivo. They are targeted to specific cell types and may delay the release of cytokines, allowing their sustained paracrine delivery. Their physicochemical characteristics such as size, shape, charge, and stability are important parameters improving bio-distribution and prolonged pharmacokinetics of encapsulated cytokines. Material and methods: We developed an efficient protocol for the encapsulation of two types of cytokines, granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF), in liposomes that can be stored long term in the active state. Results: This method allows for the encapsulation of 12-13% of the total amount of cytokines and 50% of encapsulated cytokines are entrapped in liposomes of more than ≤ 600 nm in diameter. We show that in the studied cell lines the liposome-encapsulated cytokines do not affect cell morphology, proliferation or mortality. Conclusions: The G-CSF or GM-CSF can be delivered to the cells in working concentrations through the encapsulation in the liposomes. Before the clinical application, the efficiency of these liposomes should be confirmed by an in vivo study.

Molecular and Functional Characterization of MobK Protein-A Novel-Type Relaxase Involved in Mobilization for Conjugational Transfer of Klebsiella pneumoniae Plasmid pIGRK.

Conjugation, besides transformation and transduction, is one of the main mechanisms of horizontal transmission of genetic information among bacteria. Conjugational transfer, due to its essential role in shaping bacterial genomes and spreading of antibiotics resistance genes, has been widely studied for more than 70 years. However, new and intriguing facts concerning the molecular basis of this process are still being revealed. Most recently, a novel family of conjugative relaxases (Mob proteins) was distinguished. The characteristic feature of these proteins is that they are not related to any of Mobs described so far. Instead of this, they share significant similarity to tyrosine recombinases. In this study MobK-a tyrosine recombinase-like Mob protein, encoded by pIGRK cryptic plasmid from the Klebsiella pneumoniae clinical strain, was characterized. This study revealed that MobK is a site-specific nuclease and its relaxase activity is dependent on both a conserved catalytic tyrosine residue (Y179) that is characteristic of tyrosine recombinases and the presence of Mg2+ divalent cations. The pIGRK minimal origin of transfer sequence (oriT) was also characterized. This is one of the first reports presenting tyrosine recombinase-like conjugative relaxase protein. It also demonstrates that MobK is a convenient model for studying this new protein family.

Molecular dissection of the replication system of plasmid pIGRK encoding two in-frame Rep proteins with antagonistic functions.

BACKGROUND: Gene overlapping is a frequent phenomenon in microbial genomes. Excluding so-called "trivial overlapping", there are significant implications of such genetic arrangements, including regulation of gene expression and modification of protein activity. It is also postulated that, besides gene duplication, the appearance of overlapping genes (OGs) is one of the most important factors promoting a genome's novelty and evolution. OGs coding for in-frame proteins with different functions are a particularly interesting case. In this study we identified and characterized two in-frame proteins encoded by OGs on plasmid pIGRK from Klebsiella pneumoniae, a representative of the newly distinguished pHW126 plasmid family. RESULTS: A single repR locus located within the replication system of plasmid pIGRK encodes, in the same frame, two functional polypeptides: a full-length RepR protein and a RepR' protein (with N-terminal truncation) translated from an internal START codon. Both proteins form homodimers, and interact with diverse DNA regions within the plasmid replication origin and repR promoter operator. Interestingly, RepR and RepR' have opposing functions - RepR is crucial for initiation of pIGRK replication, while RepR' is a negative regulator of this process. Nevertheless, both proteins act cooperatively as negative transcriptional regulators of their own expression. CONCLUSIONS: Regulation of the initiation of pIGRK replication is a complex process in which a major role is played by two in-frame proteins with antagonistic functions. In-frame encoded Rep proteins are uncommon, having been described in only a few plasmids. This is the first description of such proteins in a plasmid of the pHW126 family.

Expression and purification of recombinant human insulin from E. coli 20 strain.

The number of people with diabetes is estimated to be over 370 million, in 2030 it will increase to 552 million. In Poland, the number of people with diabetes is estimated to be 3.5 million (9.1%). According to the estimates of the International Diabetes Federation, the percentage of patients in the adult Polish population will increase to around 11% over the next 20 years. Despite the appearance of insulin analogues on the pharmaceutical market, insulin delivery is still the most effective method of pharmacotherapy in cases of extremely high hyperglycemia. A new bacterial host strain (Escherichia coli 20) was obtained at the Institute of Biotechnology and Antibiotics and a new pIBAINS expression vector was constructed that provides greater efficiency in the production of recombinant human insulin. In the IBA Bioengineering Department, successful attempts were made to produce recombinant human insulin on a laboratory and quarter-technical scale, and several batches were performed on a semi-technical scale. The production process has been divided into several stages: 1. biosynthesis of insulin in the fermenter, 2. isolation, purification and dissolution of inclusion bodies, 3. protein renaturation, 4. enzymatic reaction with trypsin, 5. multi-stage purification of insulin using low-pressure and HPLC techniques. At each stage of insulin production, qualitative and quantitative analyses were performed to confirm identity and purity. In particular, the molecular weight of insulin, the amount of insulin and the content of protein impurities were studied. The results of these experiments are presented in this work.

Effects of genistein on insulin pathway-related genes in mouse differentiated myoblast C2C12 cell line: evidence for two independent modes of action.

INTRODUCTION: Genistein (plant isoflavone) is a well-known anti-cancer drug with estrogenic-like properties. Genistein also regulates sugar and lipid metabolism; thus, it has anti-diabetic properties. The aim of the study was to evaluate in vitro effects of genistein on glucose transport, fatty acids oxidation, activation of PKB, and expression of genes related to insulin pathway in differentiated myoblast C2C12 mouse cell line. MATERIAL AND METHODS: Differentiated myoblast C2C12 mouse cell line was used to assess the effects of different genistein concentrations on glucose transport and fatty acids oxidation measured by radioactivity technique, activation of PKB, and expression of selected genes related to insulin signaling pathway (IR-a, IR-b, IRS-1, PKB, GLUT-4, PP2A, SH-PTP2) at the mRNA and protein levels. Cells were incubated with various concentrations of genistein under standard conditions for 0-48 hours. RESULTS: Genistein in low concentrations (0.1-1 µM) significantly increased glucose transport and decreased fatty acids oxidation in C2C12 cells after 48 h of incubation. High concentration of genistein (50 µM) had the opposite effect. Genistein stimulated PKB phosphorylation during the first 5-10 minutes of incubation. There was no significant impact on the protein expression of selected genes (IR-a, IR-b, IRS-1, PKB, GLUT-4, PP2A-Ca, ER-a and ER-b) after 48 h treatment. We observed inverse correlation between genistein concentration and the expression of SH-PTP2 protein. Genistein affected the expression pattern of mRNAs for genes related to the insulin pathway, however, not the expression of the encoded proteins. CONCLUSIONS: The results of this study showed that depending on the concentration and time of incubation genistein significantly affects glucose and lipid metabolism and at low concentration modifies expression pattern of a few genes in C2C12 cells.