Biology subjects

Rubio, J.

Publications and source records attributed to Rubio, J..

4 recordsLinked to original sources

bioRxiv2026

Gαq-mediated contact release is required for efficient mitochondrial quality control

Lysosomes and mitochondria are highly dynamic organelles whose coordinated interactions are essential for cellular homeostasis, while their dysfunction contributes to numerous human diseases. Here, we identify the mitochondrial outer membrane protein Fis1 and the RabGAPs TBC1D15 and TBC1D17 as novel interacting partners of the heterotrimeric G protein -subunit Gq. Using mitochondrial proteomics, co-immunoprecipitation, proximity ligation assays, and in vitro binding studies with purified proteins, we demonstrate that Gq forms a complex with Fis1 and TBC1D15/TBC1D17 through a non-canonical interaction interface. Gq localizes to mitochondria-lysosome contact sites, where it regulates the dynamic balance between contact formation and dissociation. Loss of Gq resulted in enlarged and clustered lysosomes and increased the extent and duration of mitochondria-lysosome contacts. Live-cell imaging revealed prolonged organelle tethering in Gq-deficient cells, while proximity ligation and three-dimensional reconstruction analyses localized Gq and TBC1D15 to mitochondrial tips closely associated with lysosomes. This localization, together with increased mitochondrial fission and altered mitophagic turnover following Gq loss, links the regulation of contacts at mitochondrial tips to mitochondrial fragmentation and quality control. Re-expression of Gq, but not the non-canonical interaction-deficient mutant, restored normal lysosomal morphology, contact-site dynamics, mitochondrial fragmentation, and mitophagy. Together, these findings identify a Gq as a dynamic regulator of mitochondria-lysosome untethering and connect contact site turnover with mitochondria fragmentation and mitophagy. Our work uncovers a novel link between G protein signaling, organelle communication, and mitochondrial quality control.

cell biology↗

bioRxiv2021

A novel Alex3/Gαq protein complex regulating mitochondrial dynamics, dendritic complexity, and neuronal survival

In neurons, mitochondrial dynamics and trafficking are essential to provide the energy required for neurotransmission and neuronal activity. Recent studies point to GPCR and G proteins as important regulators of mitochondrial dynamics and energy metabolism. Here we show that activation of Gq negatively regulates mitochondrial dynamics and trafficking in neurons. Gq interacts with the mitochondrial trafficking protein Alex3. By generating a CNS-specific armcx3 knock-out mouse line, we demonstrate that Alex3 is required for Gq effects on mitochondrial dynamics and trafficking, and dendritic growth. Armcx3-deficient mice present decreased OXPHOS complex and ER stress response protein levels, which correlate with increased neuronal death, motor neuron and neuromuscular synaptic loss, and severe motor alterations. Finally, we show that Alex3 disassembles from the Miro1/Gq complex upon calcium rise. These data uncover a novel Alex3/Gq complex that regulates neuronal mitochondrial dynamics and neuronal death and allows the control of mitochondrial functions by GPCRs.

cell biology↗

bioRxiv2021

Chilean blind spots in soil biodiversity and ecosystem function research

Soil harbor up to a quarter of the worlds biodiversity, contributing to many ecosystem functions. It is of great importance to identify distribution patterns of soil organisms and their ecosystem functions to support their conservation and policy building. This has been recently analyzed at macroecological scales, but analyses at national/local scales are scarce. Here we identify and analyze the blind spots in soil taxa and ecosystem functioning data in continental Chile, through a Web of Science articles (1945-2020) search, and focusing on ten soil taxonomic groups and four ecosystem functions (nutrient cycling, decomposition, water infiltration, soil respiration). A total of 741 sampling sites were obtained from 239 articles. In 49.25% of the sites soil biodiversity was studied, while this percentage was 32.65% for ecosystem functions; in 18.10% of the sites both soil biodiversity and ecosystem functions were investigated at the same time, a surprisingly high percentage compared to global studies. By far, Bacteria/Fungi and nutrient cycling were the most investigated taxa and function, respectively. There is a significant number of soil taxa (Acari, Collembola, Nematoda, Formicoidea, Protista, Rotifera) represented by just a few sites concentrated in specific Chilean regions. Places like the central regions, the Atacama desert, and the Valdivian temperate forests present a proliferation of studies on soil Fungi, Bacteria, and nutrient cycling, reflecting historical interests of established research groups. Based on this research, we are identifying the causes of the data blind spots and invite the Chilean soil ecology community to propose ideas on how to fill them.

ecology↗

bioRxiv2020

The SINGLE FLOWER (SFL) gene encodes a MYB transcription factor that regulates the number of flowers produced by the inflorescence of chickpea.

research conducted & rationaleLegume species usually have compound inflorescences, where flowers appear in secondary inflorescences (I2), at lateral positions of the primary inflorescence (I1), in contrast to simple inflorescences, as in Arabidopsis, where flowers are formed in the primary inflorescence stem. The number of flowers per I2, characteristic of each legume species, determines inflorescence diversity, and the number of pods produced, which can affect yield. Gene Regulatory Network that controls the activity of I2 meristems, and therefore the number of flowers per secondary inflorescence is mostly unknown, as well as how specific are factors controlling this trait and whether they share this function in other meristems. methodsChickpea produces one flower per I2 but single flower (sfl) mutants produce two (double-pod phenotype). By mapping the sfl-d mutation and identification and analysis of a second mutant allele we have isolated SFL. We used scanning electron microscopy to study the effect of sfl mutations on inflorescence ontogeny and in situ hybridization to study the expression of SFL and of meristem identity genes in the developing chickpea inflorescence. key resultWe show that the SFL gene corresponds to CaRAX1/2a, encoding a MYB transcription factor. Our results show that CaRAX1/2a / SFL is specifically expressed in the I2 meristem, possibly activated by CaVEGETATIVE1. main conclusion & key points for discussionOur findings reveal that SFL plays a central role in the control of chickpea inflorescence architecture, specifically acting in the I2 meristem to control the time length for which it is active, and therefore determining the number of floral meristems that it can produce.

plant biology↗