Biology subjects

Arriagada, G.

Publications and source records attributed to Arriagada, G..

7 recordsLinked to original sources

bioRxiv2025

BDNF-induced axonal mTOR activation promotes Rab5 translation, axonal transport, and CREB phosphorylation in cortical neurons.

Brain-derived neurotrophic factor (BDNF) promotes neuronal plasticity through retrograde signaling from axon terminals to the nucleus, activating CREB-dependent transcription. While this relies on signaling endosomes, the molecular mechanisms enabling their axonal transport remain poorly understood. Using compartmentalized cultures of mouse cortical neurons, we show that axonal BDNF activates mTOR signaling and stimulates local protein synthesis. Translation inhibitors blocked both BDNF-enhanced retrograde transport and nuclear CREB phosphorylation, indicating that axonal protein synthesis is required for long-distance signaling. Among locally synthesized proteins, we identified Rab5, a master regulator of endosomal trafficking. BDNF increased axonal Rab5 levels through TrkB- and mTOR-dependent mechanisms, confirmed by puromycin-PLA for Rab5 and soma-free axon preparations. Axon-specific Rab5 knockdown abolished BDNF-induced retrograde transport and CREB activation, demonstrating that local axonal translation of Rab5 mRNA is essential for neurotrophin signaling propagation. Remarkably, even basal retrograde transport depended on ongoing axonal Rab5 synthesis, revealing a constitutive role for local translation in maintaining axonal trafficking capacity. These findings establish that local axonal translation of trafficking regulators is a prerequisite for axon-to-nucleus neurotrophin signaling, positioning on-demand protein synthesis as a central node in long-distance neuronal communication.

neuroscience↗

bioRxiv2023

Deletion of VPS50 protein in mice brain impairs synaptic function and behavior

VPS50, is an accessory protein, involved in the synaptic and dense core vesicle acidification and its alterations produce behavioral changes in C.elegans. Here, we produce the mosaic knock out (mKO) of VPS50 using CRISPR/Cas9 system in both cortical cultured neurons and whole animals to evaluate the effect of VPS50 in regulating mammalian brain function and behavior. While mKO of VPS50 does not change the number of synaptic vesicles, it produces a mislocalization of the V-ATPase pump that likely impact in vesicle acidification and vesicle content to impair synaptic and neuronal activity in cultured neurons. In mice, mKO of VPS50 in the hippocampus, alter synaptic transmission and plasticity, and generated robust cognitive impairments associate to memory formation. We propose that VPS50 is an accessory protein that aids the correct recruitment of the V-ATPase pump to synaptic vesicles, thus having a crucial role controlling synaptic vesicle acidification and hence synaptic transmission.

neuroscience↗

bioRxiv2023

KMT2C knockout generates ASD-like behaviors in mice.

Neurodevelopmental disorders have been associated with genetic mutations that affect cellular function, including chromatin regulation and epigenetic modifications. Recent studies in humans have identified mutations in KMT2C, an enzyme responsible for modifying histone tails and depositing H3K4me1 and H3K4me3, as being associated with Kleefstra syndrome 2 and autism spectrum disorder (ASD). However, the precise role of KMT2C mutations in brain disorders remains poorly understood. Here we employed CRISPR/Cas9 gene editing to analyze the effects of KMT2C knockout on animal behavior. Knocking out KMT2C expression in cortical neurons and the mouse brain resulted in decreased KMT2C levels. Importantly, KMT2C knockout animals exhibited repetitive behaviors, social deficits, and intellectual disability resembling ASD. Our findings shed light on the involvement of KMT2C in neurodevelopmental processes and establish a valuable model for elucidating the cellular and molecular mechanisms underlying KMT2C mutations and their relationship to Kleefstra syndrome 2 and ASD.

molecular biology↗

bioRxiv2022

The native mussel Mytilus chilensis genome reveals adaptative molecular signatures facing the marine environment.

The blue mussel Mytilus chilensis is a key socioeconomic species inhabiting the southern coast of Chile. This endemic marine mussel supports a booming aquaculture industry, which entirely relies on artificially collected seeds from natural beds that are translocated to a diverse physical-chemical ocean conditions for farming. Furthermore, mussel production is threatened by a broad range of microorganisms, pollution, and environmental stressors that eventually impact its survival and growth. Herein, understanding the genomic basis of the local adaption is pivotal to developing sustainable shellfish aquaculture. We present a high-quality reference genome of M. chilensis, which is the first chromosome-level genome for a Mytilidae member in South America. The assembled genome size was 1.93 Gb, with a contig N50 of 134 Mb. Through Hi-C proximity ligation, 11,868 contigs were clustered, ordered, and assembled into 14 chromosomes in congruence with the karyological evidence. The M. chilensis genome comprises 34,530 genes and 4,795 non-coding RNAs. A total of 57% of the genome contains repetitive sequences with predominancy of LTR-retrotransposons and unknown elements. Comparative genome analysis was conducted among M. chilensis and M. coruscus, revealing genic rearrangements distributed into the whole genome. Notably, Steamer-like elements associated with horizontal transmissible cancer were explored in reference genomes, suggesting putative phylogenetic relationships at the chromosome level in Bivalvia. Genome expression analysis was also conducted, showing putative genomic differences between two ecologically different mussel populations. Collectively, the evidence suggests that local genome adaptation can be analyzed to develop sustainable mussel production. The genome of M. chilensis provides pivotal molecular knowledge for the Mytilus complex evolution and will help to understand how climate change can impact mussel biology.

genomics↗

bioRxiv2022

Centuries of genome instability and evolution in soft-shell clam transmissible cancer

Transmissible cancers are infectious parasitic clones of malignant cells that metastasize to new hosts, living past the death of the founder animal in which the cancer initiated. Several lineages of transmissible cancer have recently been identified in bivalves, including one that has spread through the soft-shell clam (Mya arenaria) population along the east coast of North America. To investigate the evolutionary history of this transmissible cancer lineage, we assembled a highly contiguous 1.2 Gb soft-shell clam reference genome and characterized somatic mutations from cancer sequences. We show that all cancer cases observed descend from a single founder and cluster into two geographically distinct sub-lineages. We discover a previously unreported clock-like mutational signature that predicts the cancer lineage to be 344 to 877 years old, indicating that it spread undetected long before it was first observed in the 1970s. We observe high mutation density, widespread copy number gain, structural rearrangement, loss of heterozygosity, variable telomere lengths, mitochondrial genome expansion, and transposable element activity, all indicative of an unstable cancer genome. Our study reveals the ability for an invertebrate cancer lineage to survive for centuries while its genome continues to structurally mutate, likely contributing to the ability of this lineage to adapt as a parasitic cancer. SUMMARYThe genome of a contagious cancer in clams reveals structural instability of multiple types throughout the [~]500 years since its origin.

cancer biology↗

bioRxiv2020

Ancient evolution of hepadnaviral paleoviruses and their impact on host genomes.

Hepadnaviruses (family Hepadnaviviridae) are reverse-transcribing animal viruses that infect vertebrates. Vertebrate genomes contain DNA sequences derived from ancient hepadnaviruses, and these endogenous hepatitis B viruses (eHBVs) reveal aspects of the long-term coevolutionary relationship between hepadnaviruses and their vertebrate hosts. Here, we use a novel, data-oriented approach to recover and analyse the complete repertoire of eHBV elements in published animal genomes. We show that germline incorporation of hepadnaviruses is exclusive to a single vertebrate group (Sauria) and that the eHBVs contained in saurian genomes represent a far greater diversity of hepadnaviruses than previously recognised. Through in-depth characterisation of eHBV elements we establish the existence of four distinct subgroups within the genus Avihepadnavirus and trace their evolution through the Cenozoic Era. Furthermore, we provide a completely new perspective on hepadnavirus evolution by showing that the metahepadnaviruses (genus Metahepadnavirus) originated >300 million years ago in the Paleozoic Era, and has historically infected a broad range of vertebrates. We also show that eHBVs have been intra-genomically amplified in some saurian lineages, and that eHBVs located at approximately equivalent genomic loci have been acquired in entirely distinct germline integration events. These findings indicate that selective forces have favoured the accumulation of hepadnaviral sequences at specific loci in the saurian germline. Our investigation provides a range of new insights into the long-term evolutionary history of reverse-transcribing DNA viruses and demonstrates that germline incorporation of hepadnaviruses has played an important role in shaping the evolution of saurian genomes.

evolutionary biology↗

bioRxiv2019

Molecular properties and evolutionary origins of a parvovirus-derived myosin fusion gene in guinea pigs

Sequences derived from parvoviruses (family Parvoviridae) are relatively common in animal genomes, but the functional significance of these endogenous parvoviral element (EPV) sequences remains unclear. In this study we use a combination of in silico and molecular biological approaches to investigate a fusion gene encoded by guinea pigs (genus Cavia) that is partially derived from an EPV. This gene, named enRep-Myo9, encodes a predicted polypeptide gene product comprising a partial myosin9 (Myo9)-like gene fused to a 3 truncated, EPV- encoded replicase. We first examined the genomic and phylogenetic characteristics of the EPV locus that encodes the viral portions of enRep-Myo9. We show that this locus, named enRep, is specific to guinea pigs and derives from an ancient representative of the parvoviral genus Dependoparvovirus that integrated into the guinea pig germline 22-35 million years ago. Despite these ancient origins, however, the regions of enRep that are incorporated into the coding sequence of the enRep-Myo9 gene are conserved across multiple species in the family Caviidae (guinea pigs and cavies) consistent with purifying selection. Using molecular biological approaches, we further demonstrate that: (i) enRep-Myo9 mRNA is broadly transcribed in guinea pig cells; (ii) the cloned enRep-Myo9 transcript can express a protein of the expected size in guinea pig cells in vitro, and; (iii) the expressed protein localizes to the cytosol. Our findings demonstrate that, consistent with a functional role, the enRep-Myo9 fusion gene is evolutionarily conserved, broadly transcribed, and capable of expressing protein.\n\nImportanceDNA from viruses has been horizontally transferred to mammalian genomes during evolution, but the impact of this process on mammalian biology remains poorly understood. The findings of our study indicate that in guinea pigs a novel gene has evolved through fusion of host and virus genes.

evolutionary biology↗