Simplified ��-Defensins: Search for New Antivirals

Peptides of the innate immune system provide intriguing templates for designing novel antiviral molecules. ??-defensins are nonhuman primate peptides with broad-spectrum antiviral activities. The activity of these compounds is mediated through interference with viral fusion, and this activity is based upon key structural features. However, two major limitations to their clinical use hampered their development as potential antivirals, namely difficult multi-step synthesis for their production with low final yield of desired product (~5%), and unfavorable pharmacokinetics (rapid enzymatic degradation and/or renal clearance). Recently we designed and screened two sub-libraries of new peptide-based entry inhibitors mimicking the structure of humanized ??-defensins, designated as Hapivirins (HpVs) and Diprovirins (DpVs). Although the new peptides are smaller (13-residues) and structurally more simple than retrocyclins, several retained their ability to protect cells from infection by HIV-1 and HSV-2. The most active compound, DpV16, was chosen for a second round of modifications based on (1) its potent antiviral activity (2) its ease of synthesis, and (3) the low cost of production. Subsequently, we created a library of a second generation DpV-analogues with enhanced properties. Collectively, our findings to date suggest that simplified ??-defensins are suitable candidates for further modifications to obtain analogues with clinically favorable pharmacokinetics that may be produced in large quantities using a standard chemical approach. Considering their small size, they could be used either topically (topical microbicides) and/or for systemic applications (entry inhibitors).     

Development of the ��Three-step MACS��: a Novel Strategy for Isolating Rare Cell Populations in the Absence of Known Cell Surface Markers from Complex Animal Tissue

To circumvent the difficulty of isolating specific cell populations by MACS from dissociated complex animal tissue, when their proportions reached levels similar to that of the background, we developed the “Three-step MACS” strategy. Cells of interest are defined by their expression of a particular gene(s) of interest rather by than their natural cell surface markers or size. A two-component transgenic cell surface protein, for two sequential rounds of MACS, is expressed under the promoter control of the endogenous gene of interest by means of gene targeting and the generation of transgenic tissue. An initial step to remove dead cells is also used. Here, we describe proof-of-concept experiments, using the biotin acceptor peptide (BAP)-low-affinity nerve growth factor receptor as the two-component protein. The first component, the BAP, can be biotinylated in specific subsets of cells expressing a particular gene by expressing the biotinylating enzyme, hBirA = humanized BirA (hBirA), under the promoter control of another gene defining the specific subpopulation. We showed that a rare population of cells (1.1% of the 13.5 days postcoital mouse embryo) could be enriched to a sufficiently high purity (84.4%). From another sample with 0.1% of our cells of interest, we achieved a 40.3% pure sample. The low cost, speed, and technical ease of the Three-step MACS also make it scalable and hence, an ideal method for preparing sufficient quantities of biological samples for sensitive, high-throughput assays.     

Search for Protein Markers for the Genetic CMS–Rf System in Sunflower

Pollen and anthers of the F₁ hybrid with the restored fertility and the parental forms, a maternal male-sterile line harboring the mitochondrial orfH522 gene and a paternal male-fertile line harboring dominant alleles of the nuclear Rf gene, were studied. In order to find protein markers for the genetic CMS–Rf system in sunflower, we analyzed cytoplasmic proteins by disc electrophoresis under denaturing conditions. As a result, a protein fraction with a mol wt of 43 kD specific for cytoplasmic proteins of the paternal anthers, and a protein fraction with a mol wt of 16 kD specific for cytoplasmic proteins of the maternal anthers, were detected. The electrophoretic patterns of water-soluble proteins from the hybrid and paternal lines did not differ.     

Identification of Novel ��-Synuclein Isoforms in Human Brain Tissue by using an Online NanoLC-ESI-FTICR-MS Method

Parkinson's disease (PD) and Dementia with Lewy bodies (DLB) are neurodegenerative diseases that are characterized by intra-neuronal inclusions of Lewy bodies in distinct brain regions. These inclusions consist mainly of aggregated α-synuclein (α-syn) protein. The present study used immunoprecipitation combined with nanoflow liquid chromatography (LC) coupled to high resolution electrospray ionization Fourier transform ion cyclotron resonance tandem mass spectrometry (ESI-FTICR-MS/MS) to determine known and novel isoforms of α-syn in brain tissue homogenates. N-terminally acetylated full-length α-syn (Ac-α-syn?????) and two N-terminally acetylated C-terminally truncated forms of α-syn (Ac-α-syn????? and Ac-α-syn?????) were found. The different forms of α-syn were further studied by Western blotting in brain tissue homogenates from the temporal cortex Brodmann area 36 (BA36) and the dorsolateral prefrontal cortex BA9 derived from controls, patients with DLB and PD with dementia (PDD). Quantification of α-syn in each brain tissue fraction was performed using a novel enzyme-linked immunosorbent assay (ELISA).