Biology subjects

Santos-Ledo, A.

Publications and source records attributed to Santos-Ledo, A..

5 recordsLinked to original sources

bioRxiv2022

Oligodendrocyte origin and development in the zebrafish visual system

Oligodendrocytes are the myelinating cells in the central nervous system (CNS). Their developmental origin and specification are well known in birds and mammals but remains unclear in fish. To fulfill this gap, we have studied their early progression during zebrafish visual morphogenesis using the transgenic line Olig2:GFP. We have tracked the Olig2+ cells in the visual system from 48 hours post fertilization (hpf) until 11 days post fertilization (dpf). We have also analyzed the differential expression of the Sox2 and Sox10 transcription factors in this cellular line. Oligodendrocyte progenitor cells (OPCs) originate at 48hpf in regions close to the preoptic area, near to the ventral hypothalamus. Then, at 5 dpf, they migrate to the optic chiasm, where they invade the optic nerve, extending towards the retina. While OPCs in the retina also express Sox2, in the the optic tectum they express Sox10. Within the optic nerve tract, they express both. We have also observed that these Olig2:GFP line do not colocalize with the expression of Mbpa, a myelin marker, but are intimately intertwined. Our data matches with other animal models, where OPCs are specified in the preoptic area and migrate to the optic nerve through the optic chiasm. We revealed that oligodendrocyte is a complex population of cells expressing different transcription factors.

developmental biology↗

bioRxiv2020

A Transgenic System for Targeted Ablation of Reproductive and Maternal-Effect genes

Maternally provided gene products regulate the earliest events of embryonic life, including formation of the oocyte that will develop into an egg, and eventually an embryo. Forward genetic screens have provided invaluable insights into the molecular regulation of embryonic development, including essential contributions of some genes whose products must be provided to the transcriptionally silent early embryo for normal embryogenesis, maternal-effect genes. However, other maternal-effect genes are not accessible due to their essential zygotic functions during embryonic development. Identifying these regulators is essential to fill the large gaps in our understanding of the mechanisms and molecular pathways contributing to fertility and maternally regulated developmental processes. To identify these maternal factors, it is necessary to bypass the earlier requirement for these genes so that their potential later functions can be investigated. Here we report reverse genetic systems to identify genes with essential roles in reproductive and maternal-effect processes, as proof of principal and to assess the efficiency and robustness of mutagenesis we used these transgenic systems to disrupt two genes with known maternal-effect functions, kif5Ba and bucky ball. Summary StatementWe report reverse genetic systems to identify essential regulators of reproductive and maternal-effect processes, as proof of principal we used these transgenic systems to disrupt genes with known maternal-effect functions.

developmental biology↗

bioRxiv2019

mTORC1-Plin3 pathway is essential to activate lipophagy and protects against hepatosteatosis.

During postprandial state, the liver is exposed to high levels of dietary fatty acids (FAs) and carbohydrates. FAs are re-esterified into triglycerides, which can be stored in lipid droplets (LDs) in the liver. Aberrant accumulation of LDs can lead to diseases such as alcoholic liver disease and non-alcoholic fatty liver disease, the latter being the most common liver pathology in western countries. Improved understanding of LD biology has potential to unlock new treatments for these liver diseases. The Perilipin (Plin) family is the group of proteins that coat LDs, controlling their biogenesis, stabilization, and preventing their degradation. Recent studies have revealed that autophagy is involved in LD degradation and, therefore, may be crucial to avoid lipid accumulation. Here, we show that a phosphorylated form of Plin3 is required for selective degradation of LDs in fibroblasts, primary hepatocytes and human liver slices. We demonstrate that oleic acid treatment induces the recruitment of the autophagy machinery to the surface of LDs. When Plin3 is silenced, this recruitment is suppressed resulting in accumulation of lipid. Plin3 pulldowns revealed interactions with the autophagy initiator proteins Fip200 and Atg16L indicating that Plin3 may function as a docking protein involved in lipophagy activation. Of particular importance, we define Plin3 as a substrate for mTORC1-dependent phosphorylation and show that this event is decisive for lipophagy. Our study therefore reveals that Plin3, and its phosphorylation by mTORC1, is crucial for degradation of LDs by autophagy. We propose that stimulating this pathway to enhance LD autophagy in hepatocytes will help protect the liver from lipid-mediated toxicity thus offering new therapeutic opportunities in human steatotic liver diseases.

cell biology↗

bioRxiv2019

Selective autophagy, lipophagy and mitophagy, in the Harderian gland along the estrous cycle: a potential retrieval effect of melatonin

Sexual dimorphism has been reported in many processes. However, sexual bias in favor of the use of males is very present in science. One of the main reasons is that the impact of hormones in diverse pathways and processes such as autophagy have not been properly addressed in vivo. The Harderian gland is a perfect model to study autophagic modulation as it exhibits important changes during the estrous cycle. The aim of this study is to identify the main processes behind Harderian gland differences under estrous cycle and their modulator. In the present study we show that redox-sensitive transcription factors have an essential role: NF-{kappa}B may activate SQSTM1/p62 in estrus, promoting selective types of autophagy: mitophagy and lipophagy. Nrf2 activation in diestrus, leads the retrieval phase and restoration of mitochondrial homeostasis. Melatonins receptors show higher expression in diestrus, leading to decreases in pro-inflammatory mediators and enhanced Nrf2 expression. Consequently, autophagy is blocked, and porphyrin release is reduced. All these results point to melatonin as one of the main modulators of the changes in autophagy during the estrous cycle.

cell biology↗

bioRxiv2019

An alternatively spliced zebrafish jnk1a transcript has an essential and non-redundant role in development of the first heart field derived proximal ventricular chamber.

Alternative splicing is a ubiquitous mechanism for producing different mRNA species from a single gene, resulting in proteomic diversity. Despite potential for regulating embryogenesis, its developmental role remains under-investigated. The Jun kinase (Jnk) genes, considered downstream effectors of the non-canonical Wnt planar cell polarity pathway, utilise extensive and evolutionarily-conserved alternative splicing. Although many PCP members are associated with heart malformation, the role of Jnk genes in cardiac development, and specifically which alternatively spliced transcripts orchestrate these processes, remain unknown. In this study we exploit the jnk1 duplication and subspecialisation found in zebrafish to reveal an essential and non-redundant requirement for jnk1a in cardiac development. We characterise alternatively spliced jnk1a/jnk1b transcripts and demonstrate that hypoplasia of the proximal ventricular component, which corresponds to human hypoplastic left ventricle, can only be rescued by the jnk1a Ex7 Lg transcript. These studies highlight the importance of Jnk signalling and alternative splicing in heart development

developmental biology↗