Subcellular Localization Profile Research Articles

Low-CO2-inducible bestrophins outside the pyrenoid sustain high photosynthetic efficacy in diatoms.

Anion transporters sustain a variety of physiological states in cells. Bestrophins (BSTs) belong to a Cl- and/or HCO3- transporter family conserved in bacteria, animals, algae, and plants. Recently, putative BSTs were found in the green alga Chlamydomonas reinhardtii, where they are upregulated under low CO2 (LC) conditions and play an essential role in the CO2-concentrating mechanism (CCM). The putative BST orthologs are also conserved in diatoms, secondary endosymbiotic algae harboring red-type plastids, but their physiological functions are unknown. Here, we characterized the subcellular localization and expression profile of BSTs in the marine diatoms Phaeodactylum tricornutum (PtBST1 to 4) and Thalassiosira pseudonana (TpBST1 and 2). PtBST1, PtBST2, and PtBST4 were localized at the stroma thylakoid membrane outside of the pyrenoid, and PtBST3 was localized in the pyrenoid. Contrarily, TpBST1 and TpBST2 were both localized in the pyrenoid. These BST proteins accumulated in cells grown in LC but not in 1% CO2 (high CO2 [HC]). To assess the physiological functions, we generated knockout mutants for the PtBST1 gene by genome editing. The lack of PtBST1 decreased photosynthetic affinity for dissolved inorganic carbon to the level comparable with the HC-grown wild type. Furthermore, non-photochemical quenching in LC-grown cells was 1.5 to 2.0 times higher in the mutants than in the wild type. These data suggest that HCO3- transport at the stroma thylakoid membranes by PtBST1 is a critical part of the CO2-evolving machinery of the pyrenoid in the fully induced CCM and that PtBST1 may modulate photoprotection under CO2-limited environments in P. tricornutum.

Aquaporin genes in garden pea and their regulation by the nano-antioxidant fullerol in imbibing embryos under osmotic stress

Aquaporins (AQPs) are known as small membrane intrinsic proteins that help to transport water and certain solutes through biological membranes. AQPs gene families are being extensively studied in major crops, but less investigated in pea (<italic>Pisum sativum</italic> L.), which is an economically significant legume crop with a huge complex genome. Here, we present a genome-wide identification, structural characterization, subcellular localization, and expression profiling of the AQPs in pea with a particular interest in their involvement in nano fullerol-conferred osmotic stress alleviation. We identified 39 full-length aquaporin genes from the pea genome, which were classified into five subfamilies. The protein structure of aquaporins appears to have substrate-specific residues which are conserved in plants, allowing for inference of substrate specificity. In particular, the PsNIP2-2-2 was identified with a Gly-Ser-Gly-Arg (GSGR) selective filter that indicates the ability to uptake silicon. Analysis of tissue transcriptomes revealed preferred expressions of certain <italic>PsAQPs</italic> in the underground, aerial and reproductive organs, respectively. Development-regulated expressions of two <italic>PsTIPs</italic> and two <italic>PsPIPs</italic> in seeds were noticed. RNA-Seq of the imbibing embryos treated with mannitol (M) or mannitol plus 100 mg/L fullerol (MF) revealed two <italic>PsTIPs</italic> being similarly regulated by M or MF, three <italic>PsNIPs</italic> being up-regulated only by M without F, and four other genes that were only regulated under MF condition. To our knowledge, this is the first report on transcriptional regulation of AQPs by fullerols, which adds to our knowledge on the plant-carbon nano-substances interactions.

A Picea wilsonii NAC transcription factor, PwNAC1, interacts with RNA-binding protein PwRBP1 and synergistically enhances drought and salt tolerance of transgenic Arabidopsis

NAC transcription factors play crucial roles in plant resistance to a variety of adverse circumstances. Here, we characterized a NAC transcription factor PwNAC1 from Picea wilsonii and subcellular localization showed that PwNAC1 was localized in the cytoplasm and nucleus. Yeast hybrid assays showed that PwNAC1 had transcriptional activation activity and could form homodimer by itself. The expression level of PwNAC1 can be significantly induced by drought, salt stress and ABA treatment. Overexpression of PwNAC1 in Arabidopsis thaliana conferred seeds stronger vitality and improved plants tolerance to salt and drought stress via reducing membrane oxidative damage, eliminating ROS and regulating ABA-dependent stomata conductance. RT-qPCR assay showed that the ABA-dependent CBF pathway marker genes (KIN1, COR15A, COR15B) and SOS2 gene were evidently upregulated in PwNAC1-overexpressing lines under salt or drought stress. An RNA-binding protein PwRBP1 was screened to interact with PwNAC1 and the interaction occurred in the cytoplasm and nucleus of cells combined with bimolecular fluorescence complementation (BiFC), GST-pull down and co-immunoprecipitation (Co-IP) assays. PwRBP1 showed the similar subcellular localization and expression profile to PwNAC1 under different adverse condition. Overexpression of PwRBP1 in Arabidopsis showed higher drought and salt tolerance compared to wild type. Notably, compared with PwNAC1 or PwRBP1 transgenic lines alone, PwNAC1/PwRBP1 co-expressing lines have stronger seed vigor, higher seedling survival rate and stronger ability of free radical scavenging, especially under drought stress. Collectively, our study suggests that PwNAC1 interacts with PwRBP1 to synergistically enhance plant resistance to drought and salt stress probably through the ABA-dependent CBF pathway.

The MKK2a Gene Involved in the MAPK Signaling Cascades Enhances Populus Salt Tolerance.

Mitogen-activated protein kinase (MAPK) cascades are highly conserved signal transduction modules, which transmit environmental signals in plant cells through stepwise phosphorylation and play indispensable roles in a wide range of physiological and biochemical processes. Here, we isolated and characterized a gene encoding MKK2 protein from poplar through the rapid amplification of cDNA ends (RACE). The full-length PeMKK2a gene was 1571 bp, including a 1068 bp open reading frame (ORF) encoding 355 amino acids, and the putative PeMKK2a protein belongs to the PKc_like (protein kinase domain) family (70–336 amino acids) in the PKc_MAPKK_plant subfamily and contains 62 sites of possible phosphorylation and two conserved domains, DLK and S/T-xxxxx-S/T. Detailed information about its gene structure, sequence similarities, subcellular localization, and transcript profiles under salt-stress conditions was revealed. Transgenic poplar lines overexpressing PeMKK2a exhibited higher activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) than non-transgenic poplar under salt stress conditions. These results will provide insight into the roles of MAPK signaling cascades in poplar response to salt stress.

A deep learning framework for identifying essential proteins based on multiple biological information

BackgroundEssential Proteins are demonstrated to exert vital functions on cellular processes and are indispensable for the survival and reproduction of the organism. Traditional centrality methods perform poorly on complex protein–protein interaction (PPI) networks. Machine learning approaches based on high-throughput data lack the exploitation of the temporal and spatial dimensions of biological information.ResultsWe put forward a deep learning framework to predict essential proteins by integrating features obtained from the PPI network, subcellular localization, and gene expression profiles. In our model, the node2vec method is applied to learn continuous feature representations for proteins in the PPI network, which capture the diversity of connectivity patterns in the network. The concept of depthwise separable convolution is employed on gene expression profiles to extract properties and observe the trends of gene expression over time under different experimental conditions. Subcellular localization information is mapped into a long one-dimensional vector to capture its characteristics. Additionally, we use a sampling method to mitigate the impact of imbalanced learning when training the model. With experiments carried out on the data of Saccharomyces cerevisiae, results show that our model outperforms traditional centrality methods and machine learning methods. Likewise, the comparative experiments have manifested that our process of various biological information is preferable.ConclusionsOur proposed deep learning framework effectively identifies essential proteins by integrating multiple biological data, proving a broader selection of subcellular localization information significantly improves the results of prediction and depthwise separable convolution implemented on gene expression profiles enhances the performance.

Genome-wide Identification, Characterization and Expression Profiling of bZIP Gene Family in Wheat using Bioinformatics Approach

Background: The basic leucine zipper (bZIP) represents one of the largest as well as most diverse transcription factor (TFs) families, and well-studied for critical role in stress response, growth and sustainable devel opment of the plant. Methods: In the current study a total of 266 bZIP genes were identified in wheat genome using BLAST algorithm against the fully annotated reference genome (International Wheat Genome Sequencing Consortium - IWGSC) available in Ensembl Plants 42.0 using AtbZIP11 protein from A. thaliana as a query. Coding sequence (CDS) analysis, physicochemical property analysis, homology model ling, structure validation, subcellular localization, phylogenetic analysis and expression profiling has been done to determine bZIP TFs in Triticum aestivum. Overall quality factor of protein has been studied using ERRAT, while expression profiling has been done using Wheat Expression Browser powered by expVIP. Result: Sequence analysis revealed that the coding sequence (CDS) length of deduced TabZIP TFs genes ranged from 422 to 3669 bp and corresponding protein length ranged from 131 to 649aa. All the 266 genes were studied for the stability of their proteins. 26 out of them were considered further to study their overall quality factor using ERRAT and thereby 13 genes were found to have an ERRAT score of more than 95 for their deduced protein, further studied for their physicochemical properties revealed a molecular weight ranging from 18035.44 to 37304.66 and isoelectric point from 6.08 to 9.42. The subcellular location of all the encoding proteins is found in nucleus. RNA-Seq based expression profiling obtained through Wheat Expression Browser powered by expVIP reveals that many of the identified TabZIP were induced by heat and drought stress. Conclusively the discovered members of bZIP gene family may provide resource for genetic improvement and promote stress tolerance efficiency in wheat.

Epileptic channelopathies caused by neuronal Kv7 (KCNQ) channel dysfunction.

Seizures are the most common neurological manifestation in the newborn period, with an estimated incidence of 1.8-3.5 per 1000 live births. Prolonged or intractable seizures have a detrimental effect on cognition and brain function in experimental animals and are associated with adverse long-term neurodevelopmental sequelae and an increased risk of post-neonatal epilepsy in humans. The developing brain is particularly susceptible to the potentially severe effects of epilepsy, and epilepsy, especially when refractory to medications, often results in a developmental and epileptic encephalopathy (DEE) with developmental arrest or regression. DEEs can be primarily attributed to genetic causes. Given the critical role of potassium (K+) currents with distinct subcellular localization, biophysical properties, modulation, and pharmacological profile in regulating intrinsic electrical properties of neurons and their responsiveness to synaptic inputs, it is not too surprising that genetic research in the past two decades has identified several K+ channel genes as responsible for a large fraction of DEE. In the present article, we review the genetically determined epileptic channelopathies affecting three members of the Kv7 family, namely Kv7.2 (KCNQ2), Kv7.3 (KCNQ3), and Kv7.5 (KCNQ5); we review the phenotypic spectrum of Kv7-related epileptic channelopathies, the different genetic and pathogenetic mechanisms, and the emerging genotype-phenotype correlations which may prove crucial for prognostic predictions, disease management, parental counseling, and individually tailored therapeutic attempts.

Serotonin 5-HT2C Receptor Cys23Ser Single Nucleotide Polymorphism Associates with Receptor Function and Localization In Vitro

A non-synonymous single nucleotide polymorphism of the human serotonin 5-HT2C receptor (5-HT2CR) gene that converts a cysteine to a serine at amino acid codon 23 (Cys23Ser) appears to impact 5-HT2CR pharmacology at a cellular and systems level. We hypothesized that the Cys23Ser alters 5-HT2CR intracellular signaling via changes in subcellular localization in vitro. Using cell lines stably expressing the wild-type Cys23 or the Ser23 variant, we show that 5-HT evokes intracellular calcium release with decreased potency and peak response in the Ser23 versus the Cys23 cell lines. Biochemical analyses demonstrated lower Ser23 5-HT2CR plasma membrane localization versus the Cys23 5-HT2CR. Subcellular localization studies demonstrated O-linked glycosylation of the Ser23 variant, but not the wild-type Cys23, may be a post-translational mechanism which alters its localization within the Golgi apparatus. Further, both the Cys23 and Ser23 5-HT2CR are present in the recycling pathway with the Ser23 variant having decreased colocalization with the early endosome versus the Cys23 allele. Agonism of the 5-HT2CR causes the Ser23 variant to exit the recycling pathway with no effect on the Cys23 allele. Taken together, the Ser23 variant exhibits a distinct pharmacological and subcellular localization profile versus the wild-type Cys23 allele, which could impact aspects of receptor pharmacology in individuals expressing the Cys23Ser SNP.

Synthesis, Biological Evaluation of Fluorescent 23-Hydroxybetulinic Acid Probes, and Their Cellular Localization Studies.

23-Hydroxybetulinic acid (23-HBA) is a complex lupane triterpenoid, which has attracted increasing attention as an anticancer agent. However, its detailed mechanism of anticancer action remains elusive so far. To reveal its anticancer mode of action, a series of fluorescent 23-HBA derivatives conjugated with coumarin dyes were designed, synthesized, and evaluated for their antiproliferative activities. Subcellular localization and uptake profile studies of representative fluorescent 23-HBA probe 26c were performed in B16F10 cells, and the results suggested that probe 26c was rapidly taken up into B10F10 cells in a dose-dependent manner and mitochondrion was the main site of its accumulation. Further mode of action studies implied that the mitochondrial pathway was involved in 23-HBA-mediated apoptosis. Together, our results provided new clues for revealing the molecular mechanism of natural product 23-HBA for its further development into an antitumor agent.

Ubiquitin Proteasome pathway proteins as potential drug targets in parasite Trypanosoma cruzi

Trypanosomiasis infects more than 21 million people and claims approximately 2 million lives annually. Due to the development of resistance against currently available anti-trypanosomal drugs, there is a growing need for specific inhibitors and novel drug targets. Of late, the proteins from the Ubiquitin Proteasome Pathway (UPP): ubiquitin ligases and deubiquitinase have received attention as potential drug targets in other parasites from the apicomplexan family. The completion of Trypanosoma cruzi (Tc) genome sequencing in 2005 and subsequent availability of database resources like TriTrypDB has provided a platform for the systematic study of the proteome of this parasite. Here, we present the first comprehensive survey of the UPP enzymes, their homologs and other associated proteins in trypanosomes and the UPPs from T. cruzi were explored in detail. After extensive computational analyses using various bioinformatics tools, we have identified 269 putative UPP proteins in the T. cruzi proteome along with their homologs in other Trypanosoma species. Characterization of T. cruzi proteome was done based on their predicted subcellular localization, domain architecture and overall expression profiles. Specifically, unique domain architectures of the enzymes and the UPP players expressed exclusively in the amastigote stage provide a rationale for designing inhibitors against parasite UPP proteins.

Isoform-specific subcellular localization of Zea mays lipoxygenases and oxo-phytodienoate reductase 2

Plant 9- and 13-lipoxygenases (9- and 13-LOXs) function in an early step of the oxylipin biosynthesis pathway. Here we report diverse subcellular localization profiles of four maize LOX family proteins and one oxo-phytodienoate reductase 2, subcellular localization of which could not be predicted by bioinformatics tools. Fluorescent protein-tagged LOX proteins were transiently expressed in maize B73 protoplasts as well as in stably transformed Arabidopsis thaliana. Localization profiles of maize 9-LOXs were more diverse than that of reported 13-LOX isoforms and spanned cytoplasm, plastids and tonoplasts, suggesting compartmentation of different oxylipin production inside of the cells. Localization profiles of maize 9-LOX were mostly consistent between maize and Arabidopsis, suggesting subcellular targeting mechanisms of these isoforms are conserved between monocots and dicots.

Litchi Fruit LcNAC1 is a Target of LcMYC2 and Regulator of Fruit Senescence Through its Interaction with LcWRKY1.

Senescence is a key factor resulting in deterioration of non-climacteric fruit. NAC transcription factors are important regulators in plant development and abiotic stress responses, yet little information regarding the role of NACs in regulating non-climacteric fruit senescence is available. In this study, we cloned 13 NAC genes from litchi (Litchi chinensis) fruit, and analyzed subcellular localization and expression profiles of these genes during post-harvest natural and low-temperature-delayed senescence. Of the 13 NAC genes, expression of LcNAC1 was up-regulated in the pericarp and pulp as senescence progressed, and was significantly higher in senescence-delayed fruit than that in naturally senescent fruit. LcNAC1 was induced by exogenous ABA and hydrogen peroxide. Yeast one-hybrid analysis and transient dual-luciferase reporter assay showed that LcNAC1 was positively regulated by the LcMYC2 transcription factor. LcNAC1 activated the expression of LcAOX1a, a gene associated with reactive oxygen species regulation and energy metabolism, whereas LcWRKY1 repressed LcAOX1a expression. In addition, LcNAC1 interacted with LcWRKY1 in vitro and in vivo. These results indicated that LcNAC1 and LcWRKY1 form a complex to regulate the expression of LcAOX1a antagonistically. Taken together, the results reveal a hierarchical and co-ordinated regulatory network in senescence of harvested litchi fruit.

Mass Spectrometry Analysis of Spatial Protein Networks by Colocalization Analysis (COLA).

A major challenge in systems biology is comprehensive mapping of protein interaction networks. Crucially, such interactions are often dynamic in nature, necessitating methods that can rapidly mine the interactome across varied conditions and treatments to reveal change in the interaction networks. Recently, we described a fast mass spectrometry-based method to reveal functional interactions in mammalian cells on a global scale, by revealing spatial colocalizations between proteins (COLA) (Mardakheh et al., Mol Biosyst 13:92-105, 2017). As protein localization and function are inherently linked, significant colocalization between two proteins is a strong indication for their functional interaction. COLA uses rapid complete subcellular fractionation, coupled with quantitative proteomics to generate a subcellular localization profile for each protein quantified by the mass spectrometer. Robust clustering is then applied to reveal significant similarities in protein localization profiles, indicative of colocalization.

Sub-Functionalization in Rice Gene Families with Regulatory Roles in Abiotic Stress Responses

ABSTRACTPlants have developed intricate mechanisms to overcome abiotic stresses. The process of signal perception and activation of signaling cascades involves a large number of factors and molecules belonging to diverse classes of gene families. In comparison to animals, plants harbor larger multigene families along with the occurrence of plant-specific ones. Gene families with abiotic-stress-responsive members were analyzed and categorized into classes such as transcription factors, signal transduction components, transporters, epigenetic regulators, and other regulatory components. The number of members, phylogeny, family expansion, domain composition, subcellular localization, and expression profiling during varied abiotic stresses have been summarized. Candidate genes from families, functionally characterized for abiotic stress responses, have been described. Based on our compilation, the expansion of abiotic-stress-responsive gene families in rice has occurred via segmental and tandem duplication events to accommodate sub-functionalization needed for regulating diverse abiotic stress responses at expression, localization, and functional levels. The information documented here can be further utilized as a primer for selecting candidate genes for improvement of rice yield under abiotic stresses.

Incubation of cocaine cue reactivity associates with neuroadaptations in the cortical serotonin (5-HT) 5-HT2C receptor (5-HT2CR) system

Intensification of craving elicited by drug-associated cues during abstinence occurs over time in human cocaine users while elevation of cue reactivity (“incubation”) is observed in rats exposed to extended forced abstinence from cocaine self-administration. Incubation in rodents has been linked to time-dependent neuronal plasticity in the medial prefrontal cortex (mPFC). We tested the hypothesis that incubation of cue reactivity during abstinence from cocaine self-administration is accompanied by lower potency and/or efficacy of the selective serotonin (5-HT) 5-HT2C​ receptor (5-HT2CR) agonist WAY163909 to suppress cue reactivity and a shift in the subcellular localization profile of the mPFC 5-HT2CR protein. We observed incubation of cue reactivity (measured as lever presses reinforced by the discrete cue complex) between Day 1 and Day 30 of forced abstinence from cocaine relative to sucrose self-administration. Pharmacological and biochemical analyses revealed that the potency of the selective 5-HT2CR agonist WAY163909 to suppress cue reactivity, the expression of synaptosomal 5-HT2CR protein in the mPFC, and the membrane to cytoplasmic expression of the 5-HT2CR in mPFC were lower on Day 30 vs. Day 1 of forced abstinence from cocaine self-administration. Incubation of cue reactivity assessed during forced abstinence from sucrose self-administration did not associate with 5-HT2CR protein expression in the mPFC. Collectively, these outcomes are the first indication that neuroadaptations in the 5-HT2CR system may contribute to incubation of cocaine cue reactivity.

Protein Subcellular localization profiling of Prostate Cells by Dissociable Antibody MicroArray (DAMA) Staining Technology

Background: Dissociable Antibody MicroArray (DAMA) staining technology is a new approach for global analysis of protein expression and subcellular localization profiles in fixed cells. We have developed the technology and demonstrated its application on identifying differentially expressed proteins in breast cancer cells. We have determined the subcellular localization profiles of 360 proteins in breast cells and identified a protein with unique subcellular localization in breast cancer cells, by combining data from four 96-antibody format arrays. In this report, we have further developed the technology to determine the subcellular localization profiles of 400 proteins simultaneously from single chip, in a 400-antibody format. Method: We have determined the subcellular localization profiles of 400 arrayed antibodies in two normal prostate cell lines (PWR-1E and PZ-HPV-7), and three cancer cell lines (Du145, LNCap and VCap). The subcellular localization profiles were compared and analyzed by Chipview, the program for image database management and analysis. Results: A protein, GRK2 was identified to have unique localization in some of the cancer cells: localized in the membrane of two cancer cell lines, and in the cytosol of normal cell lines and one cancer cell line. The identified subcellular localization difference was confirmed by individual immunostaining. Conclusion: DAMA staining technology could be a powerful method for global subcellular localization profiling in high throughput format.

Expression of a rice glutaredoxin in aleurone layers of developing and mature seeds: subcellular localization and possible functions in antioxidant defense.

A rice glutaredoxin isoform (OsGrxC2;2) with antioxidant capacity is expressed abundantly in seed tissues and is localized to storage vacuoles in aleurone layers in developing and mature seeds. Seed tissues undergo drastic water loss at the late stage of seed development, and thus need to tolerate oxidative injuries associated with desiccation. We previously found a rice glutaredoxin isoform, OsGrxC2;2, as a gene expressed abundantly in developing seeds. Since glutaredoxin is involved in antioxidant defense, in the present study we investigated the subcellular localization and expression profile of OsGrxC2;2 and whether OsGrxC2;2 has a role in the defense against reactive oxygen species. Western blotting and immunohistochemistry revealed that the OsGrxC2;2 protein accumulated at a high level in the embryo and aleurone layers of developing and mature seeds. The OsGrxC2;2 in developing seeds was particularly localized to aleurone grains, which are storage organelles derived from vacuoles. Overexpression of OsGrxC2;2 resulted in an enhanced tolerance to menadione in yeast and methyl viologen in green leaves of transgenic rice plants. These results suggest that OsGrxC2;2 participates in the defense against oxidative stress in developing and mature seeds.

Comparative study of the aldehyde dehydrogenase (ALDH) gene superfamily in the glycophyte Arabidopsis thaliana and Eutrema halophytes.

Stresses such as drought or salinity induce the generation of reactive oxygen species, which subsequently cause excessive accumulation of aldehydes in plant cells. Aldehyde dehydrogenases (ALDHs) are considered as 'aldehyde scavengers' to eliminate toxic aldehydes caused by oxidative stress. The completion of the genome sequencing projects of the halophytes Eutrema parvulum and E. salsugineum has paved the way to explore the relationships and the roles of ALDH genes in the glycophyte Arabidopsis thaliana and halophyte model plants. Protein sequences of all plant ALDH families were used as queries to search E. parvulum and E. salsugineum genome databases. Evolutionary analyses compared the phylogenetic relationships of ALDHs from A. thaliana and Eutrema. Expression patterns of several stress-associated ALDH genes were investigated under different salt conditions using reverse transcription-PCR. Putative cis-elements in the promoters of ALDH10A8 from A. thaliana and E. salsugineum were compared in silico. Sixteen and 17 members of ten ALDH families were identified from E. parvulum and E. salsugineum genomes, respectively. Phylogenetic analysis of ALDH protein sequences indicated that Eutrema ALDHs are closely related to those of Arabidopsis, and members within these species possess nearly identical exon-intron structures. Gene expression analysis under different salt conditions showed that most of the ALDH genes have similar expression profiles in Arabidopsis and E. salsugineum, except for ALDH7B4 and ALDH10A8. In silico analysis of promoter regions of ALDH10A8 revealed different distributions of cis-elements in E. salsugineum and Arabidopsis. Genomic organization, copy number, sub-cellular localization and expression profiles of ALDH genes are conserved in Arabidopsis, E. parvulum and E. salsugineum. The different expression patterns of ALDH7B4 and ALDH10A8 in Arabidopsis and E. salsugineum suggest that E. salsugineum uses modified regulatory pathways, which may contribute to salinity tolerance.

Identification of wheat non-specific lipid transfer proteins involved in chilling tolerance.

Three TaLTPs were found to enhance chilling tolerance of transgenic Arabidopsis, which were characterized by analyzes of promoter-GUS activity, subcellular localization, chromosomal location and transcriptional profile. Non-specific lipid transfer proteins (nsLTP) are abundantly expressed in plants, however, their functions are still unclear. In this study, we primarily characterized the functions of 3 type I TaLTP genes that were localized on chromosomes 3A, 3B, and 5D, respectively. The transcripts of TaLTPIb.1 and TaLTPIb.5 were induced under chilling, wound, and drought conditions, while TaLTPId.1 was only up-regulated by dark treatment. All the 3 TaLTP genes could be stimulated by the in vitro treatment of salicylic acid, while TaLTPId.1 was also positively regulated by methyljasmonic acid. Furthermore, the promoter-reporter assay of TaLTPIb.1 in the transgenic brachypodium showed a typical epidermis-specific expression pattern of this gene cluster. When fused with EGFP, all the 3 proteins were shown to localize on the plasma membrane in transgenic tobacco, although a signal in chloroplasts was also observed for TaLTPId.1. Heterogeneous overexpression of each of the TaLTP genes in Arabidopsis resulted in longer root length compared with wild type plants under chilling condition. These results suggest that type I TaLTPs may have a conserved functionality in chilling tolerance by lipid permeation in the plasma membrane of epidermal cells. On the other hand, the type I TaLTPs may exert functional divergence mainly through regulatory subfunctionalization.

Homeostasis of functional maps in active dendrites emerges in the absence of individual channelostasis

The maintenance of ion channel homeostasis, or channelostasis, is a complex puzzle in neurons with extensive dendritic arborization, encompassing a combinatorial diversity of proteins that encode these channels and their auxiliary subunits, their localization profiles, and associated signaling machinery. Despite this, neurons exhibit amazingly stereotypic, topographically continuous maps of several functional properties along their active dendritic arbor. Here, we asked whether the membrane composition of neurons, at the level of individual ion channels, is constrained by this structural requirement of sustaining several functional maps along the same topograph. We performed global sensitivity analysis on morphologically realistic conductance-based models of hippocampal pyramidal neurons that coexpressed six well-characterized functional maps along their trunk. We generated randomized models by varying 32 underlying parameters and constrained these models with quantitative experimental measurements from the soma and dendrites of hippocampal pyramidal neurons. Analyzing valid models that satisfied experimental constraints on all six functional maps, we found topographically analogous functional maps to emerge from disparate model parameters with weak pairwise correlations between parameters. Finally, we derived a methodology to assess the contribution of individual channel conductances to the various functional measurements, using virtual knockout simulations on the valid model population. We found that the virtual knockout of individual channels resulted in variable, measurement- and location-specific impacts across the population. Our results suggest collective channelostasis as a mechanism behind the robust emergence of analogous functional maps and have significant ramifications for the localization and targeting of ion channels and enzymes that regulate neural coding and homeostasis.