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Martinez-Montero, S.

Publications and source records attributed to Martinez-Montero, S..

2 recordsLinked to original sources

The MIR-NAT MAPT-AS1 does not regulate Tau expression in human neurons

The MAPT gene encodes Tau protein, a member of the large family of microtubule-associated proteins. Tau forms large insoluble aggregates that are toxic to neurons in several neurological disorders and neurofibrillary Tau tangles represent a key pathological hallmark of Alzheimers disease (AD) and other tauopathies1,2. Several Tau-lowering strategies are being investigated as a potential treatment for AD but the mechanisms that regulate Tau expression at the transcriptional or translational level are not well understood3,4. Recently, Simone et al.5 reported the discovery of a new type of natural antisense transcripts called MIR-NATs (referring to Mammalian-wide Interspersed Repeats - Natural Antisense Transcripts). Simone and colleagues used MAPT-AS1, a MIR-NAT associated to the MAPT gene as an archetype of this new class of long non-coding RNAs. According to Simone et al., MAPT-AS1 represses Tau translation by competing for ribosomal RNA. We investigated the potential functions of MAPT-AS1 in neurons using the same gain- and loss-of-function experiments as described in the original report and expanded our analysis with complementary approaches. Our data do not support a role for MAPT-AS1 in regulating Tau expression in human neurons and urge to cautiously interpret the data provided by Simone et al.5.

neuroscience↗

A conserved homo-dimerization interface in human IFIT1 provides insights into IFIT interactome assembly

The Interferon-Induced Proteins with Tetratricopeptide Repeats (IFITs) are a group of potently expressed Interferon Stimulated Genes that mediate antiviral innate immunity. Previous studies have revealed that most IFITs partake in higher order structures, potentially as part of an IFIT interactome that results in viral inhibition. Recent crystal structures of a mutated, monomeric form of IFIT1 revealed the molecular basis of how it recognizes non-self, capped viral mRNAs to selectively inhibit their translation. However, wild-type IFIT1 forms dimers in solution and the role of dimerization was not examined in detail. Here we present a structural and biochemical analysis of wild-type IFIT1 in complex with capped and uncapped RNA. Wild-type IFIT1 forms an antiparallel, elongated dimer that is in stark contrast to the domain-swapped, parallel dimer found in IFIT2. Dimerization takes place through a small, C-terminal interface that is evolutionarily conserved in IFIT1 and IFIT1B proteins. The interface is modular and can be grafted onto IFIT5, which is natively monomeric, to induce dimerization. Mutational analysis of this interface showed that homo-dimerization is not required for full RNA binding or translational inhibition by IFIT1. Sedimentation velocity analytical ultracentrifugation measurements demonstrated a reversible monomer-dimer equilibrium, suggesting that dimerization is of low affinity and could play a role under physiological concentrations, possibly in regulating IFIT interactome assembly. Finally, conformational changes in IFIT1 that occur upon RNA binding provide insight into how RNA enters its binding site in solution.

biochemistry↗