Effects of HLA single chain trimer design on peptide presentation and stability.

MHC class I "single-chain trimer" molecules, coupling MHC heavy chain, ß2-microglobulin, and a specific peptide into a single polypeptide chain, are widely used in research. To more fully understand caveats associated with this design that may affect its use for basic and translational studies, we evaluated a set of engineered single-chain trimers with combinations of stabilizing mutations across eight different classical and non-classical human class I alleles with 44 different peptides, including a novel human/murine chimeric design. While, overall, single-chain trimers accurately recapitulate native molecules, care was needed in selecting designs for studying peptides longer or shorter than 9-mers, as single-chain trimer design could affect peptide conformation. In the process, we observed that predictions of peptide binding were often discordant with experiment and that yields and stabilities varied widely with construct design. We also developed novel reagents to improve the crystallizability of these proteins and confirmed novel modes of peptide presentation.

Identification of novel mitochondrial localization signals in human Tafazzin, the cause of the inherited cardiomyopathic disorder Barth syndrome.

Mutations in the gene tafazzin (TAZ) result in Barth syndrome (BTHS). Patients present with hypotonia, cyclic neutropenia, 3-methyglutaconic aciduria, and cardiomyopathy, which is the major cause of mortality. The recessive, X-linked TAZ gene encodes a mitochondrial membrane-associated phospholipid modifying enzyme, which adds unsaturated fatty acid species to monolysocardiolipin to generate mature cardiolipin in the mitochondrial membrane that is essential for mitochondrial morphology and function. To identify intrinsic mitochondrial localization sequences in the human TAZ protein, we made sequential TAZ peptide-eGFP fusion protein expression constructs and analyzed the localization of eGFP fluorescence by confocal microscopy. We assessed these fusion proteins for mitochondrial localization through cotransfection of H9c2 cells with plasmids encoding organellar markers linked to TdTomato. We have identified two peptides of TAZ that are independently responsible for mitochondrial localization. Using CRISPR-generated TAZ knock out cell lines, we found that these peptides are able to direct proteins to mitochondria in the absence of endogenous TAZ. These peptides are not located within the predicted enzymatic clefts of TAZ, implying that some BTHS disease causing mutations may affect mitochondrial localization without affecting transacylase activity. These novel peptides improve our understanding of TAZ intracellular trafficking, provide insight into the molecular basis of BTHS and provide molecular reagents for developing targeted mitochondrial therapies.

Injection-Based Delivery of Cell-Permeable Peptide-Tagged Cre.

The technique of Cre-mediated DNA recombination at loxP sites has been used widely in manipulation of the genome in cultured cells and in living organisms. Local delivery of Cre recombinase protein tagged with a cell-penetrating (or permeable) peptide (Cre-CPP) has the advantage of additional spatial and temporal control when compared to genetic delivery methods. In this chapter, we describe protocols for injection-based intramuscular delivery of Cre-CPP dissolved in hydrogel to skeletal muscle and by ultrasound-guided injection to cardiac muscle in mice.

Intracellular Delivery of Proteins with Cell-Penetrating Peptides for Therapeutic Uses in Human Disease.

Protein therapy exhibits several advantages over small molecule drugs and is increasingly being developed for the treatment of disorders ranging from single enzyme deficiencies to cancer. Cell-penetrating peptides (CPPs), a group of small peptides capable of promoting transport of molecular cargo across the plasma membrane, have become important tools in promoting the cellular uptake of exogenously delivered proteins. Although the molecular mechanisms of uptake are not firmly established, CPPs have been empirically shown to promote uptake of various molecules, including large proteins over 100 kiloDaltons (kDa). Recombinant proteins that include a CPP tag to promote intracellular delivery show promise as therapeutic agents with encouraging success rates in both animal and human trials. This review highlights recent advances in protein-CPP therapy and discusses optimization strategies and potential detrimental effects.

A Naturalistic, Single-blind Comparison of Rapid Dose Administration of Divalproex ER Versus Quetiapine in Patients with Acute Bipolar Mania.

OBJECTIVE: When treating acute bipolar mania, the speed of onset of anti-manic effects is crucial. Quetiapine and divalproex ER are widely used agents to treat acute mania. Rapid dose administration regimens for divalproex ER and for quetiapine have been described. We conducted a naturalistic, head-to-head, pilot study comparing the efficacy and safety of rapidly titrated divalproex ER and quetiapine in acutely manic inpatients, with the primary outcome being improvement within the first seven days. METHOD: Thirty consenting bipolar patients with acute mania (Young Mania Rating Scale >17 ) needing hospitalization due to acute mania were randomized to receive rapidly loaded divalproex ER (30mg/kg/day) or rapidly titrated quetiapine (200mg Day 1, raised by 200mg/day up to 800mg as tolerated). Assessments were made on Day 1 (baseline), Day 3, Day 7, Day 14, and Day 21 and included Young Mania Rating Scale, Clinical Global Impressions-Severity, Clinical Global Impressions-Improvement, and Montgomery-Asberg Depression Rating Scale. Raters but not patients or treating physicians were blinded (single-blinded study). RESULTS: Subjects in both treatment groups exhibited significant and rapid improvement in their mania starting at Day 3 with few significant adverse effects; however, there were no significant differences in the degree or rate of improvement between the two treatment groups in any of the efficacy or adverse effects scales. CONCLUSION: RESULTS of this small study indicate that rapid-dose administration of both quetiapine and divalproex ER produce rapid improvement in acute mania within the first seven days and both seem to be well tolerated.