Conservation of Genetically-Embedded Virus Assembly Instructions: A Novel Route to Antiviral Therapy

Many single-stranded RNA viruses, including major viral pathogens, present RNA-encoded virus assembly instructions (VAIs) within their genetic message that can be isolated from the genetic code and repurposed for the design of virus-like particles. These VAIs rely on multiple dispersed RNA secondary structure elements with a consensus recognition motif for the capsid (core) protein, called packaging signals (PSs), which collectively promote capsid assembly. In this talk, I will provide evidence for the evolutionary conservation of the PS-encoded assembly instructions among different viruses in a viral family and discuss the implications of this discovery for viral evolution. I will then demonstrate how the VAIs can be exploited for therapy. In particular, defective interfering particles occur spontaneously in viral evolution as mutant strains lacking essential parts of the viral genome. Their ability to replicate in the presence of wild-type virus at the expense of virally produced resources can be mimicked by therapeutic interfering particles (TIPs). I will introduce a novel approach to the design of such TIPs based on synthetic nucleic acid sequences containing the VAIs but otherwise lacking genetic information. Using multiscale models of a viral infection, I will demonstrate the potential of these particles in both the prophylaxis and treatment of RNA viral infections.

Assembly Defects Abrogate Proofreading by Initiation Factors and License the Entry of Premature Ribosomes into the Translation Cycle:

Numerous quality control steps are deployed by the translational machinery to ensure faithful decoding of genetic message to synthesize proteins. However, what transpires to quality control mechanism during protein synthesis when the ribosomes are produced with assembly defects remains enigmatic. In E. coli, we show that ribosomes with assembly defects evade the proofreading steps during translation initiation and participate in the translation cycle. Such ribosomes show severely compromised decoding capabilities that give rise to errors in initiation and elongation. Tracing the genesis, we discovered that the assembly defects compromise the binding of initiation factors, thus licensing the rapid transitioning of 30S (pre) initiation complex to 70S initiation complex by tempering the proofreading mechanism. Overall, our work highlights that a mass balance deficit between premature ribosomes and initiation factors steers the entry of premature ribosomes into the translation cycle.

Proteomics of the Spermatozoon

ABSTRACT The study of the sperm proteins is crucial for understanding its normal function and alterations in infertile patients. The sperm is a highly specialized cell with a very large flagella, with little cytoplasm and a highly condensed nucleus. The most abundant proteins in the nucleus of mammalian sperm are the protamines. The main functions of the protamines are the condensation of the DNA, possibly contributing to the generation of a more hydrodynamic sperm head and to the protection of the genetic message. However, in addition to protamines, about 5.0-15.0% of the paternal genome is also complexed with histones and histone variants. It has also demonstrated a differential distribution of genes in regions associated with histone and protamine-associated regions, suggesting a potential epigenetic relevance in embryonic development. More recently, detailed lists of proteins have been described corresponding to the different compartments of the sperm cell thanks to the application of recent proteomic techniques based on mass spectrometry (MS). Differential proteomics is also being applied to identify the presence of protein abnormalities found in infertile patients

Hypertension may be transplanted with the kidney in humans: a long-term historical prospective follow-up of recipients grafted with kidneys coming from donors with or without hypertension in their families.

In several genetic hypertensive rat strains, transplantation studies have established that the kidney carries at least a portion of the genetic message for hypertension. In man it has, of course, been more difficult to obtain clearcut results. This historical prospective observational study, double-blinded for knowledge of donors' and recipients' family history for hypertension, concerns 85 transplanted patients, not treated with cyclosporine and with stable renal function, followed up for an average of 8 yr. Both the donors' and the recipients' families were carefully characterized for presence or absence of hypertension. After transplantation, in recipients without hypertension in their own families, a kidney coming from a "hypertensive" family determines less withdrawal and more introduction of antihypertensive therapy (AHT) than a kidney from a "normotensive" family (odds ratio for AHT introduction 5.0, confidence interval, 1.4 to 17.8; P = 0.017). In recipients with familial hypertension, the origin of the kidney does not influence the prevalence of hypertension after transplantation. More detailed analyses show that, in recipients without familial hypertension, the transplantation of a "hypertensive" kidney determines a tenfold larger increase in the requirement of antihypertensive therapy than the transplantation of a "normotensive" kidney, to obtain a similar blood pressure control (P = 0.003). This results is confirmed by the analysis of time-profile trends for antihypertensive therapy, adjusted for missing data, in the most clinically stable period (2nd to 10th yr after transplantation). The transmission of familial hypertension with the kidney is thus seen only in recipients coming from "normotensive" families, because a familial tendency for hypertension blunts the effect of receiving a "hypertensive" kidney.