RNA interference provides great opportunities for treating diseases from genetic disorders, infection, and cancer. The successful application of small interference RNA (siRNA) in cells with high transfection efficiency and low cytotoxicity is, however, a major challenge in gene-mediated therapy. Several pH-responsive core shell architectures have been designed that contain a nitrogen shell motif and a polyglycerol core, which has been prepared by a two-step protocol involving the activation of primary and secondary hydroxyl groups by phenyl chloroformate and amine substitution. Each polymer was analyzed by particle size and ζ potential measurements, whereas the respective polyplex formation was determined by ethidium bromide displacement assay, atomic force microscopy (AFM), and surface charge analysis. The in vitro gene silencing properties of the different polymers were evaluated by using a human epithelial carcinoma cell (HeLaS3) line with different proteins (Lamin, CDC2, MAPK2). Polyplexes yielded similar knockdown efficiencies as HiPerFect controls, with comparably low cytotoxicity. Therefore, these efficient and highly biocompatible dendritic polyamines are promising candidates for siRNA delivery in vivo.

RNA interference (RNAi)-mediated knockdown of target gene expression represents a powerful approach for functional genomics and therapeutic applications. However, for T lymphocytes, central regulators of immunity and immunopathologies, the application of RNAi has been limited due to the lack of efficient small interfering RNA (siRNA) delivery protocols, and an inherent inefficiency of the RNAi machinery itself. Here, we use nucleofection, an optimized electroporation approach, to deliver siRNA into primary T lymphocytes with high efficiency and negligible impairment of cell function. We identify siRNA stability within the cells as the critical parameter for efficient RNAi in primary T cells. While generally short-lived and immediately lost upon T-cell activation when conventional siRNA is used, target gene knockdown becomes insensitive to cell activation and can persist for up to 2 wk in non-dividing cells with siRNA stabilized by chemical modifications. Targeting CD4 and the transcription factor GATA-3, we show that the use of stabilized siRNA is imperative for functional gene analysis during T lymphocyte activation and differentiation in vitro as well as in vivo.Key words: Gene expression . Immune regulation . T cells Introduction RNA interference (RNAi) is an evolutionarily conserved process by which double-stranded small interfering RNA (siRNA) induces sequence-specific, post-transcriptional gene silencing [1][2][3]. Given its ease of application, its high efficiency and remarkable specificity, RNAi holds great promise for broad in vitro and in vivo application in all biomedical areas. Most importantly, RNAi is directly applicable to essentially all somatic cell types including human primary cells, which makes it an invaluable tool to study human gene function and may enable new therapeutic approaches [4,5].Within the immune system T lymphocytes are one major target for siRNA-based gene silencing, since they are key regulators of immune responses and involved in many immune related disorders, like autoimmunity, chronic inflammation or lymphoma.Despite this high potential, the lack of protocols for efficient and sustained siRNA delivery into primary mammalian cells is currently the major obstacle to the use of RNAi. In particular, primary lymphocytes are highly resistant to non-viral transfection using cationic lipids and polymer reagents [6][7][8]. Although lymphocytes can be transfected by electroporation in vitro, this method so far has been rather inefficient, limited to activated cells and was complicated by a severe impairment of cell function and cell viability [9,10]. Recently, a promising approach for the 2616in vivo targeting of lymphocytes has been reported using antibody-protamine fusion proteins to deliver siRNA [11]. However, recent data from small-hairpin RNA transgenic mice indicate that in T lymphocytes the RNAi machinery itself works inefficiently as compared with other cell types [12]. In fact, due to the aforementioned problems with siRNA delivery, the parameters determining RNAi efficien...

In this paper we report on the synthesis of diversified linear polyamine architectures with different chain lengths and compositions and their interaction with phosphate groups of DNA/siRNA. The polyplex formation between model nucleotide (dsDNA) and these linear polyamines has been determined at different nitrogen to phosphorus (N/P) ratios using small-angle neutron scattering (SANS) and atomic force microscopy (AFM) techniques. AFM images showed that while linear poly(ethylene imine) (PEI)/DNA complex results in bigger spherical aggregates, poly(propylene imine)s forms torroid and cigar shaped structures upon complexation with DNA. The poly(butylene imine)s (LPBI)s form compact and soluble DNA complexes with a radii range of R(g) = 15-30 nm. Among the studied linear polyamines, the LPBIs did show the best transfection efficiency.

The fatty acid synthase (FAS) from Brevibacterium ammoniagenes is a homohexameric multienzyme complex that catalyzes the synthesis of both saturated and unsaturated fatty acids. By immunological screening of a B. ammoniagenes expression library, an fas DNA fragment was isolated and subsequently used to clone the entire gene together with its flanking sequences. Within 10,525 bp of sequenced DNA, the 9,189-bp FAS coding region was identified, corresponding to a protein of 3,063 amino acids with a molecular mass of 324,910 Da. This gene (fasA) encodes, at its 5 end, the same amino acid sequence as is observed with purified B. ammoniagenes FAS. A second reading frame encoding another B. ammoniagenes FAS variant (FasB) had been identified previously. Both sequences are colinear and exhibit 61 and 47% identity at the DNA and protein levels, respectively. By using specific antibodies raised against a unique peptide sequence of FasB, this enzyme was shown to represent only 5 to 10% of the cellular FAS protein. Unlike the majority of procaryotes, the coryneform bacterium Brevibacterium ammoniagenes contains an aggregated type I fatty acid synthase (FAS) multienzyme complex (5, 6). Apart from B. ammoniagenes, FAS proteins with this structural organization have also been found within the genera Mycobacterium (7, 26) and Corynebacterium (1). The taxonomic relatedness of B. ammoniagenes to corynebacteria in particular had already been proposed earlier, mainly on the basis of the occurrence of mycolic acid as a common constituent of their cell walls (24). In type I FASs, at least eight functionally different catalytic domains are integrated into either a single (bacteria, animals) or two different (fungi) multifunctional proteins (13). According to the pioneering work of Kawaguchi and coworkers (17), the B. ammoniagenes FAS complex is an ␣ 6 homomultimer with a molecular mass of about 2.0 MDa. In contrast to the eucaryotic FAS enzymes, but like the dissociated type II bacterial FAS systems (3, 14), the B. ammoniagenes type I FAS contains a 3-hydroxydecanoyl-␤,␥-dehydratase as an additional component; thus, both saturated and unsaturated fatty acids are synthesized by this enzyme (5). In a first attempt to investigate the molecular structure of this exceptional multifunctional FAS protein in more detail, we recently isolated and sequenced a 9,312-bp fas-like reading frame from B. ammoniagenes (16). The gene product encoded by this DNA exhibited 46% sequence similarity to yeast FAS, and its order of catalytic domains was colinear to a hypothetical head-to-tail fusion of the two yeast FAS subunits (16). However, disruption of this fas-like reading frame produced no FAS-defective B. ammoniagenes mutants, indicating that either it is not an FAS coding gene of B. ammoniagenes at all or it is not the only one. As will be reported in this paper, a continued immunological search indeed resulted in the isolation of a second B. ammoniagenes fas gene. Unlike the previously isolated fas-like DNA, the coding region for the N-terminal amin...

In humans, Factor VIII (F8) deficiency leads to hemophilia A and F8 is largely synthesized and secreted by the liver sinusoidal endothelial cells (LSECs). However, the specificity and characteristics of these cells in comparison to other endothelial cells is not well known. In this study, we performed genome wide expression and CpG methylation profiling of fetal and adult human primary LSECs together with other fetal primary endothelial cells from lung (micro-vascular and arterial), and heart (micro-vascular). Our results reveal expression and methylation markers distinguishing LSECs at both fetal and adult stages. Differential gene expression of fetal LSECs in comparison to other fetal endothelial cells pointed to several differentially regulated pathways and biofunctions in fetal LSECs. We used targeted bisulfite resequencing to confirm selected top differentially methylated regions. We further designed an assay where we used the selected methylation markers to test the degree of similarity of in-house iPS generated vascular endothelial cells to primary LSECs; a higher similarity was found to fetal than to adult LSECs. In this study, we provide a detailed molecular profile of LSECs and a guide to testing the effectiveness of production of in vitro differentiated LSECs.