Role for DNA methylation in the control of cell type specific maspin expression

The major histocompatibility complex (MHC) is a source of unique individual odors that influence individual recognition, mating preferences, nesting behavior and selective block of pregnancy in animals. Such phenomena have been difficult to study in humans, because the human leukocyte antigen (HLA, human MHC) loci are the most polymorphic loci in the human genome, with the potential to generate millions of unique combinations of genotypes. In addition, high variability in background odors, encoded by the rest of the genome and influenced by cultural practices, contribute to a low signal-to-noise ratio that could mask HLA-based olfactory cues. Here we show that women can detect differences of one HLA allele among male odor donors with different MHC genotypes. Notably, the mechanism for a woman's ability to discriminate and choose odors is based on HLA alleles inherited from her father but not her mother. The parents' HLA alleles that she does not inherit show no relationship with odor choice, despite exposure to these HLA-encoded odors throughout her life. Our data indicate that paternally inherited HLA-associated odors influence odor preference and may serve as social cues.     

Antibody-based protection against HIV infection by vectored immunoprophylaxis

Despite tremendous efforts, development of an effective vaccine against human immunodeficiency virus (HIV) has proved an elusive goal. Recently, however, numerous antibodies have been identified that are capable of neutralizing most circulating HIV strains. These antibodies all exhibit an unusually high level of somatic mutation, presumably owing to extensive affinity maturation over the course of continuous exposure to an evolving antigen. Although substantial effort has focused on the design of immunogens capable of eliciting antibodies de novo that would target similar epitopes, it remains uncertain whether a conventional vaccine will be able to elicit analogues of the existing broadly neutralizing antibodies. As an alternative to immunization, vector-mediated gene transfer could be used to engineer secretion of the existing broadly neutralizing antibodies into the circulation. Here we describe a practical implementation of this approach, which we call vectored immunoprophylaxis (VIP), which in mice induces lifelong expression of these monoclonal antibodies at high concentrations from a single intramuscular injection. This is achieved using a specialized adeno-associated virus vector optimized for the production of full-length antibody from muscle tissue. We show that humanized mice receiving VIP appear to be fully protected from HIV infection, even when challenged intravenously with very high doses of replication-competent virus. Our results suggest that successful translation of this approach to humans may produce effective prophylaxis against HIV.     

Necroptosis and ferroptosis are alternative cell death pathways that operate in acute kidney failure

Ferroptosis is a recently recognized caspase-independent form of regulated cell death that is characterized by the accumulation of lethal lipid ROS produced through iron-dependent lipid peroxidation. Considering that regulation of fatty acid metabolism is responsible for the membrane-resident pool of oxidizable fatty acids that undergo lipid peroxidation in ferroptotic processes, we examined the contribution of the key fatty acid metabolism enzyme, acyl-CoA synthetase long-chain family member 4 (ACSL4), in regulating ferroptosis. By using CRISPR/Cas9 technology, we found that knockout of Acsl4 in ferroptosis-sensitive murine and human cells conferred protection from erastin- and RSL3-induced cell death. In the same cell types, deletion of mixed lineage kinase domain-like (Mlkl) blocked susceptibility to necroptosis, as expected. Surprisingly, these studies also revealed ferroptosis and necroptosis are alternative, in that resistance to one pathway sensitized cells to death via the other pathway. These data suggest a mechanism by which one regulated necrosis pathway compensates for another when either ferroptosis or necroptosis is compromised. We verified the synergistic contributions of ferroptosis and necroptosis to tissue damage during acute organ failure in vivo. Interestingly, in the course of pathophysiological acute ischemic kidney injury, ACSL4 was initially upregulated and its expression level correlated with the severity of tissue damage. Together, our findings reveal ACSL4 to be a reliable biomarker of the emerging cell death modality of ferroptosis, which may also serve as a novel therapeutic target in preventing pathological cell death processes.     

Mutations in the phospholipid remodeling gene SERAC1 impair mitochondrial function and intracellular cholesterol trafficking and cause dystonia and deafness

Using exome sequencing, we identify SERAC1 mutations as the cause of MEGDEL syndrome, a recessive disorder of dystonia and deafness with Leigh-like syndrome, impaired oxidative phosphorylation and 3-methylglutaconic aciduria. We localized SERAC1 at the interface between the mitochondria and the endoplasmic reticulum in the mitochondria-associated membrane fraction that is essential for phospholipid exchange. A phospholipid analysis in patient fibroblasts showed elevated concentrations of phosphatidylglycerol-34:1 (where the species nomenclature denotes the number of carbon atoms in the two acyl chains:number of double bonds in the two acyl groups) and decreased concentrations of phosphatidylglycerol-36:1 species, resulting in an altered cardiolipin subspecies composition. We also detected low concentrations of bis(monoacyl-glycerol)-phosphate, leading to the accumulation of free cholesterol, as shown by abnormal filipin staining. Complementation of patient fibroblasts with wild-type human SERAC1 by lentiviral infection led to a decrease and partial normalization of the mean ratio of phosphatidylglycerol-34:1 to phosphatidylglycerol-36:1. Our data identify SERAC1 as a key player in the phosphatidylglycerol remodeling that is essential for both mitochondrial function and intracellular cholesterol trafficking.