The field of lipidomics has been significantly advanced by mass spectrometric analysis. The distinction and quantitation of the unsaturated lipid isomers, however, remain a long-standing challenge. ...In this study, we have developed an analytical tool for both identification and quantitation of lipid C=C location isomers from complex mixtures using online Paternò–Büchi reaction coupled with tandem mass spectrometry (MS/MS). The potential of this method has been demonstrated with an implementation into shotgun lipid analysis of animal tissues. Among 96 of the unsaturated fatty acids and glycerophospholipids identified from rat brain tissue, 50% of them were found as mixtures of C=C location isomers; for the first time, to our knowledge, the quantitative information of lipid C=C isomers from a broad range of classes was obtained. This method also enabled facile cross-tissue examinations, which revealed significant changes in C=C location isomer compositions of a series of fatty acids and glycerophospholipid (GP) species between the normal and cancerous tissues.
As an evolutionarily conserved multi-protein complex, the Mediator complex modulates the association between transcription factors and RNA polymerase II to precisely regulate gene transcription. ...Although numerous studies have shown the diverse functions of Mediator complex in plant development, flowering, hormone signaling, and biotic stress response, its roles in the Abscisic acid (ABA) signaling pathway and abiotic stress response remain largely unclear. It has been recognized that the phytohormone, ABA, plays a predominant role in regulating plant adaption to various abiotic stresses as ABA can trigger extensive changes in the transcriptome to help the plants respond to environmental stimuli. Over the past decade, the Mediator complex has been revealed to play key roles in not only regulating the ABA signaling transduction but also in the abiotic stress responses. In this review, we will summarize current knowledge of the Mediator complex in regulating the plants' response to ABA as well as to the abiotic stresses of cold, drought and high salinity. We will particularly emphasize the involvement of multi-functional subunits of MED25, MED18, MED16, and CDK8 in response to ABA and environmental perturbation. Additionally, we will discuss potential research directions available for further deciphering the role of Mediator complex in regulating ABA and other abiotic stress responses.
Flowering is a critical agricultural trait that substantially affects tomato fruit yield. Although drought stress influences flowering time, the molecular mechanism underlying drought-regulated ...flowering in tomato remains elusive. In this study, we demonstrated that loss of function of tomato OPEN STOMATA 1 (SlOST1), a protein kinase essential for abscisic acid (ABA) signaling and abiotic stress responses, lowers the tolerance of tomato plants to drought stress. slost1 mutants also exhibited a late flowering phenotype under both normal and drought stress conditions. We also established that SlOST1 directly interacts with and phosphorylates the NAC (NAM, ATAF and CUC)-type transcription factor VASCULAR PLANT ONE-ZINC FINGER 1 (SlVOZ1), at residue serine 67, thereby enhancing its stability and nuclear translocation in an ABA-dependent manner. Moreover, we uncovered several SlVOZ1 binding motifs from DNA affinity purification sequencing analyses and revealed that SlVOZ1 can directly bind to the promoter of the major flowering-integrator gene SINGLE FLOWER TRUSS to promote tomato flowering transition in response to drought. Collectively, our data uncover the essential role of the SlOST1-SlVOZ1 module in regulating flowering in response to drought stress in tomato and offer insights into a novel strategy to balance drought stress response and flowering.
Environmental stresses have driven plants to develop various mechanisms to acclimate in adverse conditions. Extensive studies have demonstrated that a significant reprogramming occurs in the plant ...transcriptome in response to biotic and abiotic stresses. The highly conserved and large multi-subunit transcriptional co-activator of eukaryotes, known as the Mediator, has been reported to play a substantial role in the regulation of important genes that help plants respond to environmental perturbances. CDK8 module is a relatively new component of the Mediator complex that has been shown to contribute to plants' defense, development, and stress responses. Previous studies reported that CDK8 module predominantly acts as a transcriptional repressor in eukaryotic cells by reversibly associating with core Mediator. However, growing evidence has demonstrated that depending on the type of biotic and abiotic stress, the CDK8 module may perform a contrasting regulatory role. This review will summarize the current knowledge of CDK8 module as well as other previously documented Mediator subunits in plant cell signaling under stress conditions.
The sucrose non-fermenting 1 (SNF1)-related protein kinase 2 (SnRK2) family members have been discovered to regulate abiotic stress response via the abscisic acid (ABA)-independent and dependent ...signaling pathways. SnRK2.6, also known as Open Stomata 1 (OST1), is a serine/threonine protein kinase that plays critical roles in linking ABA receptor complexes and downstream components such as transcription factors and anion channels to regulate stress response. Asides from its well-known regulatory roles in stomatal movement and cold stress response, OST1 has also been demonstrated recently to modulate major developmental roles of flowering and growth in plants. In this review, we will discuss about the various roles of OST1 as well as the ‘doors’ that OST1 can ‘open’ to help plants perform stress adaptation. Therefore, we will address how OST1 can regulate stomata apertures, cold stress tolerance as well as other aspects of its emerging roles such as balancing flowering and root growth in response to drought.
MED25 has been implicated as a negative regulator of the abscisic acid (ABA) signaling pathway. However, it is unclear whether other Mediator subunits could associate with MED25 to participate in the ...ABA response. Here, we used affinity purification followed by mass spectrometry to uncover Mediator subunits that associate with MED25 in transgenic plants. We found that at least 26 Mediator subunits, belonging to the head, middle, tail, and CDK8 kinase modules, were co‐purified with MED25 in vivo. Interestingly, the tail module subunit MED16 was identified to associate with MED25 under both mock and ABA treatments. We further showed that the disruption of MED16 led to reduced ABA sensitivity compared to the wild type. Transcriptomic analysis revealed that the expression of several ABA‐responsive genes was significantly lower in med16 than those in wild type. Furthermore, we discovered that MED16 may possibly compete with MED25 to interact with the key transcription factor ABA INSENSITIVE 5 (ABI5) to positively regulate ABA signaling. Consistently, med16 and med25 mutants displayed opposite phenotypes in ABA response, cuticle permeability, and differential ABI5‐mediated EM1 and EM6 expression. Together, our data indicate that MED16 and MED25 differentially regulate ABA signaling by antagonistically affecting ABI5‐mediated transcription in Arabidopsis.
In the Mediator complex, the tail module subunit MED16 associates with MED25 in response to abscisic acid and these subunits differentially regulate the expression of abscisic acid‐responsive genes by competitively interacting with the key transcription factor ABSCISIC ACID INSENSITIVE5.
Retinal degeneration is often progressive. This feature has provided a therapeutic window for intervention that may extend functional vision in patients. Even though this approach is feasible, few ...promising drug candidates are available. The scarcity of new drugs has motivated research to discover novel compounds through different sources. One such example is Schisandrin B (SchB), an active component isolated from the five-flavor fruit (Fructus Schisandrae) that is postulated in traditional Chinese medicines to exert prophylactic visual benefit. This SchB benefit was investigated in this study in pde6cw59, a zebrafish retinal-degeneration model. In this model, the pde6c gene (phosphodiesterase 6C, cGMP-specific, cone, alpha prime) carried a mutation which caused cone degeneration. This altered the local environment and caused the bystander rods to degenerate too. To test SchB on the pde6cw59 mutants, a treatment concentration was first determined that would not cause morphological defects, and would initiate known physiological response. Then, the mutants were treated with the optimized SchB concentration before the appearance of retinal degeneration at 3 days postfertilization (dpf). The light sensation of animals was evaluated at 6 dpf by the visual motor response (VMR), a visual startle that could be initiated by drastic light onset and offset. The results show that the VMR of pde6cw59 mutants towards light onset was enhanced by the SchB treatment, and that the initial phase of the enhancement was primarily mediated through the mutants' eyes. Further immunostaining analysis indicates that the treatment specifically reduced the size of the abnormally large rods. These observations implicate an interesting hypothesis: that the morphologically-improved rods drive the observed VMR enhancement. Together, these investigations have identified a possible visual benefit of SchB on retinal degeneration, a benefit that can potentially be further developed to extend functional vision in patients.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Lipid dysregulation has been implicated in multiple sclerosis due to its involvement during and after inflammation. In this study, we have profiled fatty acids (FAs) in the mouse model of multiple ...sclerosis with new capabilities of assigning carbon-carbon double bond (C=C) location(s) and quantifying C=C location isomers. These new capabilities are enabled by pairing the solution phase Paternò-Büchi (PB) reaction that modifies C=C bonds in FAs, with tandem mass spectrometry (MS/MS), termed as PB-MS/MS. A series of unsaturated FAs and C=C location isomers have been identified, including FA17:1 (Δ10), FA18:1 (Δ9 and Δ11), FA18:2 (Δ9 and Δ12), and FA 20:4 (Δ5, Δ8, Δ11, Δ14). Notable differences in saturated and unsaturated FAs between normal and experimental autoimmune encephalomyelitis (EAE) mice spinal cords have been detected. Furthermore, the effects of hydralazine, a scavenger of acrolein, on profile changes of FAs in mice were studied. Increased Δ11-to-Δ9 isomer ratios for FA 18:1 were noted in the diseased samples as compared to the control. The present work provides a facile and robust analytical method for the quantitation of unsaturated FAs as well as identification of FA C=C location isomers, which will facilitate discovering prospective lipid markers in multiple sclerosis.
MYB-related genes, a subclass of MYB transcription factor family, have been documented to play important roles in biological processes such as secondary metabolism and stress responses that affect ...plant growth and development. However, the regulatory roles of MYB-related genes in drought stress response remain unclear in maize. In this study, we discovered that a 1R-MYB gene,
ZmRL6
, encodes a 96-amino acid protein and is highly drought-inducible. We also found that it is conserved in both barley (
Hordeum vulgare
L
.
) and
Aegilops tauschii
. Furthermore, we observed that overexpression of
ZmRL6
can enhance drought tolerance while knock-out of
ZmRL6
by CRISPR-Cas9 results in drought hypersensitivity. DAP-seq analyses additionally revealed the
ZmRL6
target genes mainly contain ACCGTT, TTACCAAAC and AGCCCGAG motifs in their promoters. By combining RNA-seq and DAP-seq results together, we subsequently identified eight novel target genes of
ZmRL6
that are involved in maize's hormone signal transduction, sugar metabolism, lignin synthesis, and redox signaling/oxidative stress. Collectively, our data provided insights into the roles of
ZmRL6
in maize’s drought response.
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