The adaptor AP2 is required for initiation of clathrin-mediated endocytosis. Kadlecova et al. delineate the functional hierarchy of AP2 interactions with phosphatidylinositol lipids and cargo and their relationship to distinct steps in clathrin-coated pit nucleation and maturation in living cells.

No abstract

Lysine-based polycations are widely used as nonviral carriers for gene delivery. This manuscript reports the results of a comparative study on the in vitro cytotoxicity of a library of three structural polylysine variants, namely, linear polylysine (LPL), dendritic polylysine (DPL), and hyperbranched polylysine (HBPL). The aim of this study was to identify possible effects of polymer molecular weight and architecture on both immediate and delayed cytotoxicity and also to provide a mechanistic understanding for possible differences. Acute cytotoxicities were evaluated using cell viability assays with CHO DG44 cells. At comparable molecular weights, the EC(50) values for the LPL analogues were ∼5-250 times higher as compared to the DPL and HBPL samples. For low molecular weight polycations, osmotic shock was found to be an important contributor to immediate cell death, whereas for the higher molecular weight analogues, direct cell membrane disruption was identified to play a role. Delayed cytotoxicity (≥3 h) was assessed by identifying several of the hallmark events that characterize apoptosis, including phosphatidyl serine translocation, mitochondrial membrane depolarization, cytoplasmic cytochrome C release, and caspase 3 activation. At comparable molecular weights, apoptosis was found to be more pronounced for DPL and HBPL as compared to LPL. This difference was ascribed to the fact that LPL is completely enzymatically degradable, in contrast to DPL and HBPL, which also contain ε-peptidic bonds and are only partially degradable. Because their toxicity profiles are similar, HBPL is an interesting (i.e., synthetically easily accessible and inexpensive) alternative to DPL for the nonviral delivery of DNA.

The synthesis of a novel family of optically active 4-(N,N-dimethylamino)pyridine carbamate derivatives has been achieved with excellent isolated yields using different linear diamines as starting materials to produce dimeric compounds of variable length. Optically active homodimeric 4-(N,N-dimethylamino)pyridine carbamate derivatives obtained through this chemoenzymatic route present interesting structural properties as possible ligands or nucleophilic catalysts in asymmetric catalysis.

No abstract