Biology subjects

Lin, Y.-C.

Publications and source records attributed to Lin, Y.-C..

7 recordsLinked to original sources

bioRxiv2018

A seed resource for screening functionally redundant genes and isolation of new mutants impaired in CO2 and ABA responses

The identification of homologous genes with functional overlap in forward genetic screens is severely limited. Here we report the generation of over 14,000 amiRNA-expressing plants that enable screens of the functionally redundant gene space in Arabidopsis. A protocol is developed here for isolating robust and reproducible amiRNA-mutants. Examples of validation approaches and essential controls are presented for two new amiRNA mutants that exhibit genetically redundant phenotypes and circumvent double mutant lethality. In a forward genetic screen for abscisic acid (ABA)-mediated inhibition of seed germination, amiRNAs that target combinations of known redundant ABA receptor and SnRK2 kinase genes were rapidly isolated, providing a strong proof of principle for this approach. A new ABA insensitive amiRNA line is isolated, which targets three genes encoding avirulence-induced gene2-like (AIG2) genes. A thermal imaging screen for plants with impaired stomatal opening in response to low CO2 exposure led here to isolation of a new amiRNA targeting two essential proteasomal subunits, PAB1 and PAB2. The seed library of 14,000 T2 amiRNA lines generated here provides a new platform for forward genetic screens and is being made available to the Arabidopsis Biological Resource Center (ABRC) and optimized procedures for amiRNA screening and controls are described.\n\nHighlightThe generation of over 14,000 amiRNA-expressing plants is reported that are being made publicly available enabling screens of redundant genes in Arabidopsis. Identification of known and new genes is reported.

plant biology↗

bioRxiv2018

FUS/TLS undergoes calcium-mediated nuclear egress during excitotoxic stress and is required for Gria2 mRNA processing

Excitotoxic levels of glutamate represent a physiological stress that is strongly linked to amyotrophic lateral sclerosis (ALS) and other neurological disorders. Emerging evidence indicates a role for neurodegenerative disease linked RNA-binding proteins (RBPs) in the cellular stress response. However, the relationships between excitotoxicity, RBP function and pathology have not been explored. Here, we found that excitotoxicity induced the translocation of select ALS-linked RBPs from the nucleus to the cytoplasm within neurons. RBPs affected by excitotoxicity include TAR DNA-binding protein 43 (TDP-43) and, most robustly, fused in sarcoma/translocated in liposarcoma (FUS/TLS). FUS translocation occurs through a calcium-dependent mechanism and coincides with striking alterations in nucleocytoplasmic transport. Further, glutamate-induced upregulation of Gria2 in neurons was dependent on FUS expression, consistent with a functional role for FUS under excitotoxic stress. These findings reveal a link between prominent factors in neurodegenerative disease, namely excitotoxicity, disease-associated RBPs and nucleocytoplasmic transport.

neuroscience↗

bioRxiv2018

The Pseudomonas aeruginosa complement of lactate dehydrogenases enables use of D- and L-lactate and metabolic crossfeeding

Pseudomonas aeruginosa is the most common cause of chronic, biofilm-based lung infections in patients with cystic fibrosis (CF). Sputum from patients with CF has been shown to contain oxic and hypoxic subzones as well as millimolar concentrations of lactate. Here, we describe the physiological roles and expression patterns of P. aeruginosa lactate dehydrogenases in the contexts of different growth regimes. P. aeruginosa produces four enzymes annotated as lactate dehydrogenases, three of which are known to contribute to anaerobic or aerobic metabolism in liquid cultures. These three are LdhA, which reduces pyruvate to D-lactate during anaerobic survival, and LldE and LldD, which oxidize D-lactate and L-lactate, respectively, during aerobic growth. We demonstrate that the fourth enzyme, LldA, performs redundant L-lactate oxidation during growth in aerobic cultures in both a defined MOPS-based medium and synthetic CF sputum medium. However, LldA differs from LldD in that its expression is induced specifically by the L-enantiomer of lactate. We also show that all four enzymes perform functions in colony biofilms that are similar to their functions in liquid cultures. Finally, we provide evidence that the enzymes LdhA and LldE have the potential to support metabolic cross-feeding in biofilms, where LdhA can catalyze the production of D-lactate in the anaerobic zone that is then used as a substrate in the aerobic zone. Together, these observations further our understanding of the metabolic pathways that can contribute to P. aeruginosa growth and survival during CF lung infection.\n\nIMPORTANCELactate is thought to serve as a carbon and energy source during chronic infections. Sites of bacterial colonization can contain two enantiomers of lactate: the L-form, generally produced by the host, and the D-form, which is usually produced by bacteria including the pulmonary pathogen Pseudomonas aeruginosa. Here, we characterize P. aeruginosas set of four enzymes that it can use to interconvert pyruvate and lactate, the functions of which depend on the availability of oxygen and specific enantiomers of lactate. We also show that anaerobic pyruvate fermentation triggers production of the aerobic D-lactate dehydrogenase in both liquid cultures and biofilms, thereby enabling metabolic cross-feeding of lactate over time and space between subpopulations of cells. These metabolic pathways could contribute to P. aeruginosa growth and survival in the lung.

microbiology↗

bioRxiv2018

Spatiotemporal manipulation of ciliary glutamylation reveals its roles in intraciliary trafficking and Hedgehog signaling

Tubulin post-translational modifications (PTMs) occur spatiotemporally throughout cells and are suggested to be involved in a wide range of cellular activities. However, the complexity and dynamic distribution of tubulin PTMs within cells have hindered the understanding of their physiological roles in specific subcellular compartments. Here we develop a method to rapidly deplete tubulin glutamlyation inside the primary cilia, a microtubule-based sensory organelle protruding on the cell surface, by targeting an engineered deglutamylase to the cilia in minutes. This rapid deglutamylation quickly leads to altered ciliary functions such as kinesin-2-mediated anterograde intraflagellar transport and Hedgehog signaling, along with no apparent crosstalk to other PTMs such as acetylation and detyrosination. Our study offers a feasible approach to spatiotemporally manipulate tubulin PTMs in living cells. Future expansion of the repertoire of actuators that regulate PTMs may facilitate a comprehensive understanding of how diverse tubulin PTMs encode ciliary as well as cellular functions.

cell biology↗

bioRxiv2017

Drug discovery to counteract antinociceptive tolerance with mu-opioid receptor endocytosis

Morphine antinociceptive tolerance is highly correlated with its poor ability to promote mu-opioid- receptor (MOR) endocytosis. Our objective was to discover a novel positive allosteric modulator of MOR to enhance morphine-induced MOR endocytosis. We used high-throughput screening to identify several cardiotonic steroids as positive allosteric modulators of morphine-induced MOR endocytosis having high potency and efficacy, independently of Na+/K+-ATPase inhibition. Convallatoxin was found to enhance morphine-induced MOR endocytosis through an adaptor protein 2/clathrin-dependent mechanism without regulating G protein- or {beta}-arrestin-mediated pathways. Both F243 and I292 residues of MOR were essential to the effect of convallatoxin on MOR endocytosis. Co-treatment with chronic morphine and convallatoxin reduced morphine tolerance in animal models of acute thermal pain and chronic inflammatory pain. Acute convallatoxin administration reversed morphine tolerance in morphine-tolerant mice. These findings suggest that cardiotonic steroids are potentially therapeutic for morphine side effects and open a new avenue for the study of MOR trafficking.

neuroscience↗

bioRxiv2017

Genome-Wide Characterization Of Isoform Switching In Arabidopsis thaliana

SUMMARYAlternative splicing and the usage of alternate transcription start- or stop sites allows a single gene to produce multiple transcript isoforms. Most plant genes express one isoform at a significantly higher level than others, but under specific conditions this expression dominance can switch to different isoforms. These isoform switches have been observed for thousands of Zea mays and Vitis vinifera genes and have been linked to development and stress response. In Arabidopsis thaliana however, isoform switches have only been reported for 812 genes and the characteristics of these genes, nor the implications of the isoform switches on their protein functions, are currently well understood. Here we present a dataset of isoform dominance and switching for all genes in the AtRTD2 annotation based on a protocol that was benchmarked on simulated data and validated through comparison with a published RT-PCR panel. We report 138,722 isoform switches for 8,162 genes across 206 public RNA-Seq samples and find that these switches change the protein sequences in 23% of the cases. The observed isoform switches show high consistency across replicates and reveal reproducible patterns in response to treatment and development. We also demonstrate that genes with different ages, expression breadths, and functions show large differences in the frequency at which they switch isoforms and in the effect that these isoform switches have on their protein sequences. Finally, we showcase how the detected isoform switches can be applied to gain further insight in the regulation of a genes expression and function.\n\nSIGNIFICANCE STATEMENTIsoform switching through alternative splicing has been reported for thousands of genes in plants, yet genome-wide datasets to study the implications for gene functions are thus far not available. Here we present the first reference dataset of isoform dominance and switching for Arabidopsis thaliana based on 206 public RNA-Seq samples and provide novel insights in the regulation and functional consequences of alternative splicing.

plant biology↗

bioRxiv2017

Intracellular production of hydrogels and synthetic RNA granules by multivalent enhancers

Non-membrane bound, hydrogel-like entities, such as RNA granules, nucleate essential cellular functions through their unique physico-chemical properties. However, these intracellular hydrogels have not been as extensively studied as their extracellular counterparts, primarily due to technical challenges in probing these materials in situ. Here, by taking advantage of a chemically inducible dimerization paradigm, we developed iPOLYMER, a strategy for rapid induction of protein-based hydrogels inside living cells. A series of biochemical and biophysical characterizations, in conjunction with computational modeling, revealed that the polymer network formed in the cytosol resembles a physiological hydrogel-like entity that behaves as a size-dependent molecular sieve. We studied several properties of the gel and functionalized it with RNA binding motifs that sequester polyadenine-containing nucleotides to synthetically mimic RNA granules. Therefore, we here demonstrate that iPOLYMER presents a unique and powerful approach to synthetically reconstitute hydrogel-like structures including RNA granules in intact cells.

synthetic biology↗