The fusion protein MEN 11303 (granulocyte-macrophage colony stimulating factor/erythropoietin) acts as a potent inducer of erythropoiesis

Erythropoiesis-stimulating protein delivery in providing erythropoiesis and neuroprotection

Erythropoietin (EPO), a glycoprotein, plays an important role in erythropoiesis and neuroprotection. EPO therapies for anemia or neurodegenerative diseases require frequent injections or high-dose systemic administration which may cause unwanted side effects. Various strategies for EPO delivery have been investigated for increasing EPO bioavailability and decreasing side effects, including nano/micro particles, PEGylation of EPO and transport-mediated delivery systems. Nano/micro particles provide EPO with long-term effect and protect EPO against proteolytic cleavage. PEGylated EPO prolong circulating time and reduce injection frequency of anemia treatment. A transport-mediated delivery system enables protein to cross biological barriers. Presently, there is no report about an effective delivery system of EPO for neuroprotection. This review focuses on EPO delivery systems for erythropoiesis or neuroprotection with prolonged duration and enhanced bioavailability.

A recombinant allosteric lectin antagonist of HIV-1 envelope gp120 interactions

The first, critical stage of HIV-1 infection is fusion of viral and host cellular membranes initiated by a viral envelope glycoprotein gp120. We evaluated the potential to form a chimeric protein entry inhibitor that combines the action of two gp120-targeting molecules, an allosteric peptide inhibitor 12p1 and a higher affinity carbohydrate-binding protein cyanovirin (CVN). In initial mixing experiments, we demonstrated that the inhibitors do not interfere with each other and instead show functional synergy in inhibiting viral cell infection. Based on this, we created a chimera, termed L5, with 12p1 fused to the C-terminal domain of CVN through a linker of five penta-peptide repeats. L5 revealed the same broad specificity as CVN for gp120 from a variety of clades and tropisms. By comparison to CVN, the L5 chimera exhibited substantially increased inhibition of gp120 binding to receptor CD4, coreceptor surrogate mAb 17b and gp120 antibody F105. These binding inhibition effects by the chimera reflected both the high affinity of the CVN domain and the allosteric action of the 12p1 domain. The results open up the possibility to form high potency chimeras, as well as noncovalent mixtures, as leads for HIV-1 envelope antagonism that can overcome potency limits and potential virus mutational resistance for either 12p1 or CVN alone.

Cloning and Expression of Human Stem Cell Factor Fused with Thrombopoietin Mimetic Peptide in Escherichia coli

Thrombopoietin (TPO) acts synergistically with stem cell factor (SCF) in hematopoiesis and megakaryopoiesis. In this work, we designed the expression of SCF fused with the monomer or the dimer of TPO mimetic peptide through a flexible peptide linker. The recombinant fusion proteins were produced in E. coli DH5alpha at up to 25% of total cell proteins. The resultant inclusion bodies were refolded by dilution and purified by ion-exchange chromatography. Subsequent biological activity assays showed that the fusion proteins exhibited higher potency than recombinant human SCF, indicating that they have a potential role for pharmaceutical applications.

Constitutive and inducible expression of the epithelial antigen MUC1 (CD227) in human T cells

MUC1 (CD227) is a large glycoprotein normally produced by epithelial tissue and expressed aberrantly in carcinomas. Here we show that resting human T cells express basal levels of MUC1 mRNA and protein forms with molecular masses of approximately 150 and approximately 250 intracellularly, but lack surface expression. Mitogenic stimulation induces the appearance of new MUC1 mRNA and >300-kDa MUC1 forms. Concomitantly, MUC1 is translocated to the outer cell membrane and its density is continuously modulated according to the cycling status. Inhibitors of mRNA and protein synthesis and of Golgi-dependent protein transport prevent MUC1 induction. Ligation of surface MUC1 has no effect on T-cell proliferation. Also, altering the overall protein structure by preventing glycosylation has no effect. Sizable amounts of >300-kDa glycosylated MUC1 forms are shed by proliferating T cells. This soluble MUC1 does not appear to influence T-cell response, and we found no evidence for MUC1 binding sites on T cells or for transfer of the protein on cell-cell contact. We therefore suggest that MUC1 fulfills the criteria for an early T-cell activation marker but its function remains to be determined. Finally, although we found that cancer- and T cell-associated MUC1 expose common protein core and sialylated epitopes, there is a peptide region, accessible in carcinomas due to an aberrant glycosylation, that is stably not accessible in T cells with potential implications for cancer immunotherapy.