Browsing Applied Microbiology Research Group by Title
Now showing items 4-6 of 6
Identification and biological applications of rhegnylogically-organized cell penetrating peptides.Introduction: Many different cell penetrating peptides (CPPs) have been utilized as vectors to affect the highly efficient intracellular delivery of bioactive moieties. A majority of such studies employ sychnologically-organized tandem combinations of a cargo (message) and a CPP (address). To date, bioactive cargoes have included peptides, proteins and a range of oligonucleotides attached either by direct chemical conjugation or as a component of a larger macromolecular complex. Moreover, a majority of CPPs, including the commonly used sequences Tat and penetratin, are designed to be both biologically and toxicologically inert. More recently, a QSAR-based algorithm has been developed to predict cryptic polycationic CPP motifs within the primary sequences of proteins. As described here, this novel technology has enabled the study of rhegnylogic CPPs in which multiple pharmacophores for cellular penetration and desirable biological activities are discontinuously organized within the primary sequence of single peptide. This organization differs from the more commonly utilized sychnologic strategy which joins functionally discrete and continous address and messages together in a tandem construct.
Mitoparans: mitochondriotoxic cell penetrating peptides and novel inducers of apoptosis.Introduction: The amphipathic helical peptide mastoparan (MP; H-INLKALAALAKKIL-NH2) inserts into biological membranes to modulate the activity of heterotrimeric G proteins and other targets. Moreover, whilst cell free models of apoptosis demonstrate MP to facilitate mitochondrial permeability transition and release of apoptogenic cytochrome c, MP-induced death of intact cells has been attributed to its non-specific membrane destabilising properties (necrotic mechanisms). However, MP and related peptides are known to activate other signalling systems, including p42/p44 MAP kinases and could therefore, also modulate cell fate and specific apoptotic events. The ability of MP to facilitate mitochondrial permeability in cell free systems has lead to proposals that MP could be of utility in tumour therapeutics provided that it conferred features of cellular penetration and mitochondrial localization. We have recently reported that our highly potent amphipathic MP analogue mitoparan (mitP; [Lys5,8Aib10]MP; Aib = -aminoisobutyric acid) specifically promotes apoptosis of human cancer cells, as was confirmed by in situ TUNEL staining and activation of caspase-3. Moreover, we have also demonstrated that mitP penetrates plasma membranes and redistributes to co-localize with mitochondria. Complementary studies, using isolated mitochondria, further demonstrated that mitP, through co-operation with a protein of the permeability transition pore complex voltage-dependent anion channel (VDAC), induced swelling and permeabilization of mitochondria, leading to the release of the apoptogenic factor cytochrome c. An expanding field of peptide and cell penetrating peptide (CPP) research has focussed on the selective targeting of tumours by engineering constructs that incorporate cell-specific or tissue–specific address motifs. Peptidyl address motifs could enhance the selectivity of drug delivery whilst the improved cellular uptake offered by CPP enhances bioavailability. Thus and as a potential therapeutic strategy, we extended our findings to design target-specific mitP analogues. The integrin-specific address motif RGD and a Fas ligand mimetic WEWT were incorporated by N-terminal acylation of mitP to produce novel tandem-linked chimeric peptides.