Legionella pneumophila modulates host energy metabolism by ADP-ribosylation of ADP/ATP translocases

The intracellular pathogen Legionella pneumophila delivers more than 330 effectors into host cells by its Dot/Icm secretion system. Those effectors direct the biogenesis of the Legionella-containing vacuole (LCV) that permits its intracellular survival and replication. It has long been documented that the LCV is associated with mitochondria and a number of Dot/Icm effectors have been shown to target to this organelle. Yet, the biochemical function and host cell target of most of these effectors remain unknown. Here, we found that the Dot/Icm substrate Ceg3 (Lpg0080) is a mono-ADP-ribosyltransferase that localizes to the mitochondria in host cells where it attacks ADP/ATP translocases by ADP-ribosylation, and blunts their ADP/ATP exchange activity. The modification occurs on the second arginine residue in the -RRRMMM- element, which is conserved among all known ADP/ATP carriers from different organisms. Our results reveal modulation of host energy metabolism as a virulence mechanism for L. pneumophila.

Selective Moonlighting Cell-Penetrating Peptides

Cell penetrating peptides (CPPs) are molecules capable of passing through biological membranes. This capacity has been used to deliver impermeable molecules into cells, such as drugs and DNA probes, among others. However, the internalization of these peptides lacks specificity: CPPs internalize indistinctly on different cell types. Two major approaches have been described to address this problem: I) targeting, in which a receptor-recognizing sequence is added to a CPP, and ii) activation, where a non-active form of the CPP is activated once it interacts with cell target components. These strategies result in multifunctional peptides (i.e., penetrate and target recognition) that increase the CPP’s length, the cost of synthesis and the likelihood to be degraded or become antigenic. In this work we describe the use of machine-learning methods to design short selective CPP; the reduction in size is accomplished by embedding two or more activities within a single CPP domain, hence we referred to these as moonlighting CPPs. We provide experimental evidence that these designed moonlighting peptides penetrate selectively in targeted cells and discuss areas of opportunity to improve in the design of these peptides.

Lipotoxicity Disrupts Erythrocyte Function: A Perspective

Background: Lipid accumulation in the liver, skeletal and cardiac muscle, kidneys and pancreas causes cell dysfunction, death and inflammation, a biological phenomenon named lipotoxicity. Erythrocytes participate in the transport of lipids in the circulation, and their lipidome is determined by exchange with blood components. Objective: To summarize the current knowledge regarding the effect of toxic lipid accumulation in erythrocytes Results: Erythrocyte lipidome is altered in lipotoxic diseases like fatty liver disease, heart failure, and diabetes. In addition, ceramide, lysophosphatidylcholine, lysophosphatidic acid, palmitic acid, and free cholesterol induce erythrocyte malfunction. Conclusion: Erythrocytes are an additional cell target of lipotoxicity. Further exploration of the implicated molecular mechanisms could lead to novel therapeutic targets for cardiometabolic and hematological diseases.

Mini-Review: PDPK1 (3-phosphoinositide dependent protein kinase-1), An Emerging Cancer Stem Cell Target

Cancer stem cells (CSCs) are subpopulations of tumor cells that possess abilities for self-renewal, differentiation, and tumor initiation. These rare but therapy-recalcitrant cells are assumed to repopulate tumors following administration of systemic chemotherapy driving therapy failure, tumor recurrence, and disease progression. In early clinical trials, anti-CSC therapies have found limited success to-date possibly due to the inherent heterogeneity and plasticity of CSCs and the incomplete characterization of essential CSC targets. Here, we review the role of 3-phosphoinositide dependent protein kinase-1 (PDPK1) as an emerging CSC target. While most previous studies have relied on CSC models which are based on lineage and tissue-specific marker profiles to define the relationships between putative target and CSC traits, this review discusses PDPK1 and its role in CSC biology with an emphasis on CSC systems which are based on proposed function like label-retaining cancer cells (LRCCs).

Enhanced cell target specificity and uptake of lipid nanoparticles using RNA aptamers and peptides

Lipid nanoparticles (LNPs) constitute a facile and scalable approach for delivery of payloads to human cells. LNPs are relatively immunologically inert and can be produced in a cost effective and scalable manner. However, targeting and delivery of LNPs across the blood brain barrier (BBB) has proven challenging. In an effort to target LNPs to particular cell types as well as generating LNPs that can cross the BBB, we developed and assessed two approaches whereby BBB penetrating peptides Tat or T7, and RNA aptamers targeted to gp160 from HIV or CCR5, a HIV-1 co-receptor, were incorporated into LNPs. We report here that a CCR5 selective RNA aptamer acts to facilitate entry through a simplified BBB model and to drive the uptake of LNPs into CCR5 expressing cells, while the gp160 aptamer did not. We further observed that the addition of cell penetrating peptides, Tat, did not increase BBB penetration above the aptamer loaded LNPs alone. Moreover, we find that these targeted LNPs exhibit low immunogenic and low toxic profiles and that targeted LNPs can traverse the BBB to potentially deliver drugs into the target tissue. This approach highlights the usefulness of aptamer loaded LNPs to increase target cell specificity and potentially, deliverability across the BBB.

Enhanced production of 99Mo in inverse kinematics heavy ion reactions

The reaction of a 100Mo beam at 12 MeV/nucleon impinging on a 4He gas-cell target was performed. The 99Mo alongside other coproduced isotopes were collected after the gas target on an aluminum catcher foil and their respective radioactivities were measured by offline γ-ray analysis. In this contribution, preliminary experimental results which are used to discuss the possibility of optimal large-scale production conditions of the produced radioisotopes are presented.