Biology subjects

Datta, R.

Publications and source records attributed to Datta, R..

At least 37 records · Page 2Linked to original sources

bioRxiv2023

Naive primary neutrophils play a dual role in the tumor microenvironment

The tumor microenvironment (TME) is characterized by a network of cancer cells, recruited immune cells and extracellular matrix (ECM) in a hypoxic microenvironment. However, the specific role of neutrophils during tumor development, and their interactions with other immune cells is still not well understood. Thus, there is a need to investigate the interaction between primary neutrophils and natural killer cells and the resulting effects on tumor development. Here we use both standard well plate culture and an under oil microfluidic (UOM) assay with an integrated extracellular cell matrix (ECM) bridge to elucidate how naive primary neutrophils respond to both patient derived tumor cells and tumor cell lines. Our data demonstrated that both patient derived head and neck squamous cell carcinoma (HNSCC) tumor cells and MDA-MB-231 breast cancer cells trigger cluster formation in neutrophils, and the swarm of neutrophils restricts tumor invasion through the generation of reactive oxygen species (ROS) and neutrophil extracellular trap (NETs) release within the neutrophil cluster. However, we also observed that the presence of neutrophils downregulates granzyme B in NK-92 cells and the resulting NETs can obstruct NK cells from penetrating the tumor mass in vitro suggesting a dual role for neutrophils in the TME. Further, using label-free optical metabolic imaging (OMI) we observed changes in the metabolic activities of primary neutrophils during the different swarming phases when challenged with tumor cells. Finally, our data demonstrates that neutrophils in direct contact, or in close proximity, with tumor cells exhibit greater metabolic activities (lower nicotinamide adenine dinucleotide phosphate (NAD(P)H) mean lifetime) compared to non-contact neutrophils.

cell biology↗

bioRxiv2023

Leishmania major-induced alteration of host cellular and systemic copper homeostasis drives the fate of infection

Copper plays a key role in host-pathogen interaction. We found that during Leishmania major infection, the parasite-harboring macrophage regulates its copper homeostasis pathway in a way to facilitate copper-mediated neutralization of the pathogen. Copper-ATPase ATP7A transports copper to amastigote-harboring phagolysosomes to induce stress on parasites. Leishmania in order to evade the copper stress, utilizes a variety of manipulative measures to lower the host-induced copper stress. It induces deglycosylation and degradation of host-ATP7A and downregulation of copper importer, CTR1 by cysteine oxidation. Additionally, Leishmania induces CTR1 endocytosis that arrests copper uptake. In mouse model of infection, we report an increase in systemic bioavailable copper in infected animals. Heart acts as the major organ for diverting its copper reserves to systemic circulation to fight-off infection by downregulating its CTR1. Our study explores reciprocal mechanism of manipulation of host copper homeostasis pathway by macrophage and Leishmania to gain respective advantages in host-pathogen interaction.

cell biology↗

bioRxiv2023

MFGE8 inhibits insulin signaling through PTP1B

The role of integrins in regulating insulin signaling is incompletely understood. We have previously shown that binding of the integrin ligand milk fat globule epidermal growth factor like 8 (MFGE8) to the v{beta}5 integrin promotes termination of insulin receptor signaling in mice. Upon ligation of MFGE8, {beta}5 complexes with the insulin receptor beta (IR{beta}) in skeletal muscle resulting in dephosphorylation of IR{beta} and reduction of insulin-stimulated glucose uptake. Here we investigate the mechanism by which the interaction between {beta}5 and IR{beta} impacts IR{beta} phosphorylation status. We show that {beta}5 blockade inhibits and MFGE8 promotes PTP1B binding to and dephosphorylation of IR{beta} resulting in reduced or increased insulin-stimulated myotube glucose uptake respectively. The {beta}5-PTP1B complex is recruited by MFGE8 to IR{beta} leading to termination of canonical insulin signaling. {beta}5 blockade enhances insulin-stimulated glucose uptake in wild type but not Ptp1b KO mice indicating that PTP1B functions downstream of MFGE8 in modulating insulin receptor signaling. Furthermore, in a human cohort, we report serum MFGE8 levels correlate with indices of insulin resistance. These data provide mechanistic insights into the role of MFGE8 and {beta}5 in regulating insulin signaling.

physiology↗

bioRxiv2023

Designer grass pea for transgene-free minimal neurotoxin-containing seeds with CRISPR-Cas9

Grass pea seeds are consumed as food in several South Asian and Sub-Saharan African nations. However, the presence of the neurotoxic compound N-oxalyl-L-diamino propionic acid ({beta}-ODAP) has restricted its cultivation. Although various cultivars with low {beta}-ODAP levels have been developed, their cultivation is still limited due to the risk of neurolathyrism from long-term grass pea seed ingestion. In this study, we employed the CRISPR-Cas9-mediated gene editing technique to generate grass pea seeds with zero or minimal {beta}-ODAP levels. We targeted the BAHD-AT3 gene that encodes a key enzyme in the {beta}-ODAP biosynthesis pathway. We developed bahd-at3 knock-out lines using three gRNAs targeting different regions of this gene and characterized them. Cas9-free independent lines from each event carrying the desired on-target mutation were selected and backcrossed twice with the wild-type to eliminate any off-target mutation present therein. Various agronomical parameters were analyzed from the backcrossed mutant lines and they displayed no phenotypic abnormalities. Interestingly, the seed {beta}-ODAP content ranged between 0.001 % - 0.002 % of dry weight which is 99 % lower than the wild-type. Together, our study reports the development of transgene-free, genome-edited grass peas with insignificant levels of {beta}-ODAP in seeds for safer food in the future.

plant biology↗

bioRxiv2023

A novel role of macrophage PIST protein in regulating Leishmania major infection

PDZ protein interacting specifically with Tc10 or PIST is a mammalian trans-Golgi resident protein that regulates subcellular sorting of plasma membrane receptors. PIST has recently been found to play an important role in regulating viral pathogenesis. Alteration in PIST expression is linked to the reprogramming of cell surface receptors which is crucial in determining herpes simplex virus1 infection. In this context, PIST is crucial in triggering autophagy via Beclin 1 -PI3KC3 pathway. However, there is complete lack in our knowledge on the role of this protein in any parasitic infection. Leishmania parasites infect their host macrophage cells via phagocytosis and their survival within the parasitophorous compartment has recently been found to be dependent on host autophagy by a yet to be identified mechanism. Using Leishmania major (L. major)-macrophage infection model system we, for the first-time report here that in infected macrophages Golgi resident PIST protein migrates towards the parasite containing compartment. We have also found that PIST associates with Beclin 1, however, not with LC3 within L. major parasite containing compartment of infected macrophages. Further, we performed genetic ablation of PIST by siRNA and observed that knockdown of macrophage PIST in turn helps in parasite replication. Contrary to this, overexpression of PIST in macrophages restricted the multiplication of L. major. Collectively, our study for the first time reveals that PIST is essential in regulating intracellular parasite, L. major infection within macrophage cells. Summary StatementMammalian PIST protein plays a crucial role in regulating cellular trafficking events. Here, we showed that PIST status is altered within Leishmania major parasite infected macrophages. Further, we confirmed that PIST is essential in restricting parasite growth. Additionally, a potential interacting axis between PIST and Beclin 1 is identified during infection.

cell biology↗

bioRxiv2023

Genome-wide screens identify SEL1L as an intracellular rheostat controlling collagen turnover

Accumulating evidence has implicated impaired extracellular matrix (ECM) clearance as a key factor in fibrotic disease. Despite decades of research elucidating the effectors of ECM clearance, relatively little is understood regarding the upstream regulation of this process. Collagen is the most abundant constituent of normal and fibrotic ECM in mammalian tissues. Its catabolism occurs through extracellular proteolysis and cell-mediated uptake of collagen fragments for intracellular degradation. Given the paucity of information regarding the regulation of this latter process, we executed unbiased genome-wide screens to understand the molecular underpinnings of cell-mediated collagen clearance. Using this approach, we discovered a previously unappreciated mechanism through which collagen biosynthesis is sensed by cells internally and directly regulates clearance of extracellular collagen. The sensing mechanism is dependent on endoplasmic reticulum-resident protein SEL1L and occurs via a noncanonical function of SEL1L. This pathway functions as a homeostatic negative feedback loop that limits collagen accumulation in tissues. In human fibrotic lung disease, the induction of this collagen clearance pathway by collagen synthesis is impaired, thereby contributing to the pathological accumulation of collagen in lung tissue. Thus cell-autonomous, rheostatic collagen clearance is a previously unidentified pathway of tissue homeostasis.

cell biology↗

bioRxiv2022

Glutathione activates PHT1;5 gene via WRKY75 transcription factor to regulate phosphate homeostasis in Arabidopsis

Phosphorus (P) is essential for plant growth, yet inorganic phosphate (Pi) is often limiting in soil. Plants respond to Pi limitation by activating P transporters and starvation genes, which boost Pi uptake or redistribute P. While glutathione (GSH) regulates iron and zinc homeostasis in Arabidopsis, its role in P homeostasis under Pi limitation remains elusive. Here, we show that GSH-S-nitrosoglutathione (GSNO) module regulates source-to-sink P allocation in Arabidopsis by transcriptionally activating the phloem-localised transporter AtPHT1;5 via the transcription factor AtWRKY75. GSH-deficient mutants, cad2-1 and pad2-1, exhibited sensitivity to Pi-starvation with altered root system architecture, reduced anthocyanin accumulation, and disrupted root-to-shoot P transport. AtPHT1;5 transcript levels were markedly reduced in these mutants but were positively responsive to exogenous GSH or GSNO. The pht1;5 mutant failed to respond to GSH treatments, demonstrating that AtPHT1;5 is essential for GSH-mediated P mobilisation. Pharmacological and genetic manipulation of nitric oxide (NO)/GSNO levels implicated GSNO as an essential intermediary. In depth molecular analyses identified AtWRKY75 as a Pi- and GSH/GSNO-responsive activator that binds w-box motifs in the AtPHT1;5 promoter. This was further supported by the lack of AtPHT1;5 induction in the wrky75 mutants. Finally, AtWRKY75 is S-nitrosylated and stabilised by GSH/GSNO, providing a mechanistic link between redox/NO signalling and transcriptional control of P transport. We propose that elevated GSH under Pi limitation is converted to GSNO, which S-nitrosylates AtWRKY75 and promotes AtPHT1;5 expression, thus driving source-to-sink P reallocation. This pathway integrates redox and NO signalling with transcriptional regulation to maintain P homeostasis under Pi starvation. Summary statementGlutathione-S-nitrosoglutathione module regulates phosphate translocation in Arabidopsis under phosphate starvation via transcriptional activation of AtPHT1;5 gene by AtWRKY75 transcription factor.

plant biology↗

bioRxiv2022

Localized Leishmania major infection causes systemic iron deficiency that can be controlled by oral iron supplementation

Leishmania major (L. major) and its related parasitic species infection causes human cutaneous leishmaniasis that results into disfiguring skin lesion. Although L. major infection has been found to alter macrophage iron homeostasis we have limited understanding on whether it can also manipulate the same at systemic level. In fact, localized L. major infection found to promote iron deficiency anemia in children by an unknown mechanism. To address these unresolved issues, Balb/c mouse were infected with L. major and iron status in different organs were monitored systematically with the development of cutaneous lesion. At week 10 post infection when there was maximum lesion development in the parasite infected left hind footpad, the iron content increased significantly in this tissue with the concomitant increase in parasite burden. L. major infection mediated iron accumulation in infected mouse footpad was found to be due to transferrin receptor upregulation and natural resistance-associated macrophage protein 1 (Nramp1) downregulation. Surge in iron level was found to be associated with the reduced hepatic iron storage that resulted increased serum iron. Limited iron storage in liver and bone-marrow of infected mice caused reduced hemoglobin level and production of deformed erythrocytes. Interestingly, L. major infected mice developed splenomegaly with significant upregulation of erythroid related genes. Importantly, oral iron supplementation post infection rescued the development of cutaneous lesion in infected mice. Together, our study unravelled a comprehensive mechanism behind developing iron deficiency anemia during cutaneous leishmaniasis and a novel therapeutic route of treating this infection by delivering iron.

immunology↗

bioRxiv2022

MFGE8 links absorption of dietary fatty acids with catabolism of enterocyte lipid stores through HNF4 γ- dependent transcription of CES enzymes

Enterocytes modulate the extent of postprandial lipemia, a potent risk factor for developing atherosclerotic disease, by storing dietary fats in cytoplasmic lipid droplets (cLDs). We have previously demonstrated that the integrin ligand MFGE8 links absorption of dietary fats with activation of triglyceride (TG) hydrolases that catabolize cLDs for chylomicron production. The hydrolase(s) responsible for mobilization of TG from diet-derived cLDs is unknown though recent evidence indicates that this process is independent of the canonical pathway of TG hydrolysis mediated by ATGL. Here we identify CES1D as the key hydrolase downstream of the MFGE8-v{beta}5 integrin pathway that regulates catabolism of diet-drive cLDs. Mfge8 KO enterocytes have reduced CES1D transcript and protein levels and reduced protein levels of the transcription factor HNF4{gamma}. Mice KO for Ces1d or Hnf4{gamma} have decreased enterocyte TG hydrolase activity coupled with retention of TG in cLDs. Mechanistically, MFGE8-dependent fatty acid uptake through CD36 leads to stabilization of HNF4{gamma} protein levels; HNF4{gamma} then increases Ces1d transcription. Our work identifies a regulatory network by which MFGE8 and v{beta}5 regulate the severity of postprandial lipemia by linking dietary fat absorption with protein stabilization of a transcription factor that increases expression of enterocyte TG hydrolases that catabolize diet-derived cLDs.

physiology↗

bioRxiv2021

Adipose deficiency and aberrant autophagy in a Drosophila model of MPS VII is corrected by pharmacological stimulators of mTOR

Mucopolysaccharidosis type VII (MPS VII) is a recessively inherited lysosomal storage disorder caused due to {beta}-glucuronidase ({beta}-GUS) enzyme deficiency. Prominent clinical symptoms include hydrops fetalis, musculoskeletal deformities, neurodegeneration and hepatosplenomegaly leading to premature death in most cases. Apart from these, MPS VII is also characterized as adipose storage deficiency disorder although the underlying mechanism of this lean phenotype in the patients or {beta}-GUS-deficient mice still remains a mystery. We addressed this issue using our recently developed Drosophila model of MPS VII (the CG2135-/- fly), which also exhibited a significant loss of adiposity. We report here that the lean phenotype of the CG2135-/- fly is due to fewer number of adipocytes, smaller lipid droplets and reduced adipogenesis. Our data further revealed that there is an abnormal accumulation of autophagosomes in the CG2135-/- larvae due to autophagosome-lysosome fusion defect. Decreased lysosome-mediated turnover also led to attenuated mTOR activity in the CG2135-/- flies. Interestingly, treatment of the CG2135-/- larvae with mTOR stimulators, 3BDO or glucose, led to the restoration of mTOR activity with simultaneous correction of the autophagy defect and adipose storage deficiency. Our finding thus established a hitherto unknown mechanistic link between autophagy dysfunction, mTOR downregulation and reduced adiposity in MPS VII.

cell biology↗

bioRxiv2021

Glutathione regulates subcellular iron homeostasis via transcriptional activation of iron responsive genes in Arabidopsis

While glutathione (GSH) is known to regulate iron (Fe) deficiency response in plants, its involvement in modulating subcellular Fe homeostasis remained elusive. In this study, we report that the GSH depleted mutants, cad2-1 and pad2-1 displayed increased sensitivity to Fe deficiency with significant down-regulation of the vacuolar Fe exporters, AtNRAMP3 and AtNRAMP4 and the chloroplast Fe importer, AtPIC1. Moreover, the pad2-1 mutant accumulated higher Fe content in vacuoles and lower in chloroplasts compared with Col-0 under Fe limited condition. Exogenous GSH treatment could enhance the chloroplast Fe content in Col-0 plants but failed to do so in the nramp3nramp4 double mutant demonstrating the role of GSH in modulating subcellular Fe homeostasis. Pharmacological experiments, mutant analysis and promoter assay revealed that this regulation involved transcriptional activation of the transporter genes by a GSH-GSNO module. The Fe responsive bHLH transcription factors (TFs), AtbHLH29, AtbHLH38 and AtbHLH101 were identified to interact with the promoters of these genes which were in turn activated via S-nitrosylation. Together, the present study delineates the role of GSH-GSNO module in regulating subcellular Fe homeostasis by transcriptional activation of the Fe transporters AtNRAMP3, AtNRAMP4 and AtPIC1 via S-nitrosylation of the bHLH TFs during Fe deficiency. Summary statementGlutathione regulates subcellular iron homeostasis under iron deficiency via GSNO dependent transcriptional activation of AtNRAMP3, AtNRAMP4 and AtPIC1 genes by S-nitrosylation of the iron responsive bHLH transcription factors, AtbHLH29, AtbHLH38 and AtbHLH101.

plant biology↗

bioRxiv2021

Leishmania major formins are cytosolic actin bundler play an important role in cell physiology

Formins are a highly conserved eukaryotic family of proteins that regulate actin dynamics. They play important physiological roles in cell adhesion, motility, vesicular trafficking and cytokinesis. Although sequence analysis of Trypanosomatida genomes predicted multiple formin-encoding genes, none of them are functionally characterized yet. We report here experimental identification and functional characterization of two constitutively expressed formins from the trypanosomatid protozoa Leishmania major viz. LmForminA and LmForminB. These formins exhibited irregular cytosolic distribution that co-localized with actin patches. Co-sedimentation assay and surface plasmon resonance confirmed that purified LmForminA and B FH2 domains can bind actin, albeit with differential affinity. Interestingly, both LmForminA and B FH2 domains were found to be actin bundlers as revealed by low-speed co-sedimentation assay and TIRF microscopy. LmForminA and B also had actin-nucleating activities, which was abolished by mutating their conserved Ile residue crucial for actin assembly. The Ile-mutant formins, however, retained their actin binding and bundling properties. Treatment of Leishmania cells with formin inhibitor SMIFH2 severely perturbed parasite growth and morphology indicating that Lmformins are physiologically important and may be considered as novel drug targets.

cell biology↗

bioRxiv2021

The novel leishmanial Copper P-type ATPase plays a vital role in intracellular parasite survival

Copper is essential for all life forms; however in excess it is extremely toxic. Toxic properties of copper are utilized by hosts against various pathogenic invasions. Leishmania, in its both free-living and intracellular forms, was found to exhibit appreciable tolerance towards copper-stress. To determine the mechanism of copper-stress evasion employed by Leishmania we identified and characterized the hitherto unknown Copper-ATPase in Leishmania major and determined its role in parasites survival in host macrophage cells. L. major Cu-ATPase, LmATP7, exhibits high homology with its orthologues at multiple conserved motifs. In promastigotes, LmATP7 localized to the plasma membrane with a fraction in intracellular puncta. Upon copper treatment, LmATP7 expression increases few folds. LmATP7 is capable of complementing copper transport in Cu-ATPase-{Delta} yeast strain. Promastigotes overexpressing LmATP7 exhibits higher survival upon copper stress indicating efficacious copper export compared to wild type and heterozygous LmATP7 knock-out parasites. We explored macrophage-Leishmanial interaction with respect to copper stress subjected by the host upon parasite and the parasites reciprocating response thereon to evade the stress. The Copper-P-type-ATPases ATP7A/7B serve as major copper exporters in mammals that maintain cellular copper levels. We found that Leishmania infection triggers ATP7A upregulation in macrophages. Additionally, as part of host response, ATP7A traffics from trans-Golgi network and transports copper to the endosomal and endolysosomal compartments harbouring the Leishmania amastigotes. Finally, we show LmATP7 overexpression in this parasite increased amastigote survivability within infected macrophages whereas knocking it down reduces that drastically, establishing its role in combating host-induced copper stress.

cell biology↗

bioRxiv2020

Interactions with stromal cells promote a more oxidized cancer cell redox state in pancreatic tumors

Access to electron acceptors supports oxidized biomass synthesis and can be limiting for cancer cell proliferation, but how cancer cells overcome this limitation in tumors is incompletely understood. Non-transformed cells in tumors can help cancer cells overcome metabolic limitations, particularly in pancreatic cancer, where pancreatic stellate cells (PSCs) promote cancer cell proliferation and tumor growth. However, whether PSCs affect the redox state of cancer cells is not known. By taking advantage of the endogenous fluorescence properties of reduced nicotinamide adenine dinucleotide cofactors and oxidized flavin adenine dinucleotide, we use optical imaging to assess the redox state of pancreatic cancer cells and PSCs and find that the redox state of cancer cells is more reduced while the redox state of PSCs is more oxidized. Direct interactions between PSCs and cancer cells promote a more oxidized state in cancer cells, suggesting that metabolic interactions between cancer cells and PSCs is a mechanism to overcome the redox limitations of cell proliferation in pancreatic cancer.

cancer biology↗

bioRxiv2020

The influence of axial length upon the retinal ganglion cell layer of the human eye

PurposeWe examined the relationship between axial length and the thickness and volume of the ganglion cell layer (GCL) of the retina, and related these measures to the size of the optic chiasm. MethodsWe used optical coherence tomography to measure the thickness of the GCL over a 50{degrees} extent of the horizontal meridian in 50 normally-sighted participants with a wide range of axial lengths. Using a model eye informed by individual biometry, we converted GCL thickness to tissue volume per square degree. The volume of the optic chiasm was measured for 40 participants using magnetic resonance imaging. ResultsWhile GCL thickness decreases with increasing axial length, there is a positive relationship between GCL tissue volume and axial length, leading us to conclude that increasing axial length is associated with decreased retinal ganglion cell packing, increased cell size, or both. We characterize how retinal ganglion cell tissue varies systematically in volume and spatial distribution as a function of axial length. This model allows us to remove the effect of axial length from individual difference measures of GCL volume. We find that variation in GCL volume correlates well with the size of the optic chiasm as measured using magnetic resonance imaging. ConclusionsOur results provide the volume of ganglion cell tissue in the retina, adjusted for the effects of axial length upon ganglion cell size and/or packing. The resulting volume measure accounts for individual differences in the size of the optic chiasm, supporting its use to characterize the post-retinal visual pathway.

neuroscience↗

bioRxiv2020

Functional partnership between carbonic anhydrase and malic enzyme in promoting gluconeogenesis in Leishmania major

Leishmania has a remarkable ability to proliferate under widely fluctuating levels of essential nutrients, such as glucose. For this the parasite is heavily dependent on its gluconeogenic machinery. One perplexing aspect of gluconeogenesis in Leishmania is the lack of the crucial pyruvate carboxylase (PC) gene. PC-catalyzed conversion of pyruvate to oxaloacetate is a key entry point through which gluconeogenic amino acids are funnelled into this pathway. Absence of PC in Leishmania thus raises question about the mechanism of pyruvate entry into the gluconeogenic route. We report here that this task is accomplished in Leishmania major through a novel functional partnership between its mitochondrial malic enzyme (LmME) and cytosolic carbonic anhydrase (LmCA1). Using a combination of pharmacological inhibition studies with genetic manipulation, we showed that both these enzymes are necessary in promoting gluconeogenesis and supporting parasite growth under glucose limiting condition. Functional crosstalk between LmME and LmCA1 was evident when it was observed that the growth retardation caused by inhibition of any one of these enzymes could be protected to a significant extent by overexpressing the other enzyme. We also found that while LmCA1 exhibited constitutive expression, LmME protein level was strongly upregulated in low glucose condition. Notably, both LmME and LmCA1 were found to be important for survival of Leishmania amastigotes within host macrophages. Taken together, our results indicate that LmCA1 by virtue of its CO2 concentrating ability stimulates LmME-catalyzed pyruvate carboxylation, thereby driving gluconeogenesis through pyruvate-malate-oxaloacetate bypass pathway. Additionally, our study establishes LmCA1 and LmME as promising therapeutic targets.

biochemistry↗

bioRxiv2020

Spatial distribution of the lectin protein Osr40g3 determines its dual regulatory function in imparting salinity tolerance while impeding seed development in rice

Under changing environmental conditions, salt stress has posed a severe threat to agriculture. Although the R40 family lectins are known to be associated with osmotic stress response, their mechanism of action remains elusive. Among them, Osr40g3 displays the highest expression under salt stress. Here, we report that the constitutive overexpression of Osr40g3 imparts salt tolerance but displays pollen sterility and poor seed development in rice. Promoter analysis and gene expression studies revealed that the gene follows a precise tissue-specific expression pattern, which is essential for proper seed development. Overexpressing the gene under the control of its native promoter rescued the pollen-sterile phenotype while significantly improving salt tolerance. Protein-protein interaction studies demonstrated that Osr40g3 positively regulates an expansin protein, OsEG45, while decreasing the stability of a 14-3-3 protein, OsGF14e. Correspondingly, the OsEG45 overexpression and OsGF14e silencing lines display a salt-tolerant phenotype. Again, silencing OsEG45 in the background of OsGF14e silencing lines resulted in a salt-sensitive phenotype, indicating that salt tolerance of the OsGF14e silencing lines is OsEG45-dependent. Notably, the OsGF14e gene displays early salt responsiveness, while Osr40g3 and OsEG45 display a late response, indicating a spatio-temporal regulation of these genes. Interestingly, constitutive overexpression of Osr40g3 or silencing of OsGF14e leads to diminished gibberellic acid (GA) accumulation that activates the OsEG45 gene. Together, our study demonstrates that during salt stress, Osr40g3, a late salt-responsive gene, confers salt tolerance by negatively regulating OsGF14e while positively regulating OsEG45 via a GA-mediated pathway. This mechanistic insight broadens our understanding of lectin-mediated regulation of salt tolerance.

plant biology↗

bioRxiv2020

Rice lectin protein Osr40c1 imparts drought tolerance by modulating OsSAM2, OsSAP8 and chromatin-associated proteins

Lectin proteins play an important role in biotic and abiotic stress responses in plants. Although the rice lectin protein, Osr40c1, has been reported to be regulated by drought stress, the mechanism of its drought tolerance activity has not been studied so far. In this study, it has been depicted that expression of Osr40c1 gene correlates with the drought tolerance potential of various rice cultivars. Transgenic rice plants overexpressing Osr40c1 were significantly more tolerant to drought stress over the wild-type plants. Furthermore, ectopic expression of the Osr40c1 gene in tobacco yielded a similar result. Interestingly, the protein displayed a nucleo-cytoplasmic localization and was found to interact with a number of drought-responsive proteins like OsSAM2, OsSAP8, OsMNB1B, and OsH4. Fascinatingly, silencing of each of these protein partners led to drought susceptibility in the otherwise tolerant Osr40c1 expressing transgenic tobacco lines indicating that these partners were crucial for the Osr40c1-mediated drought tolerance in planta. Together, the present investigation delineated the novel role of Osr40c1 protein in imparting drought tolerance by regulating the chromatin proteins, OsMNB1B and OsH4, which presumably enables OsSAP8 to induce downstream gene expression. In addition, its interaction with OsSAM2 might induce polyamine biosynthesis thus further improving drought tolerance in plants. HighlightsA rice lectin protein, Osr40c1, plays a crucial role in imparting drought stress tolerance in plants by modulating OsSAM2 as well as the transcriptional regulators OsSAP8, OsMNB1B and OsH4.

plant biology↗