Publications by authors named "Hsueh-Han Lu"

11 Publications

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Lumenal Galectin-9-Lamp2 interaction regulates lysosome and autophagy to prevent pathogenesis in the intestine and pancreas.

Nat Commun 2020 08 27;11(1):4286. Epub 2020 Aug 27.

Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.

Intracellular galectins are carbohydrate-binding proteins capable of sensing and repairing damaged lysosomes. As in the physiological conditions glycosylated moieties are mostly in the lysosomal lumen but not cytosol, it is unclear whether galectins reside in lysosomes, bind to glycosylated proteins, and regulate lysosome functions. Here, we show in gut epithelial cells, galectin-9 is enriched in lysosomes and predominantly binds to lysosome-associated membrane protein 2 (Lamp2) in a Asn(N)-glycan dependent manner. At the steady state, galectin-9 binding to glycosylated Asn of Lamp2 is essential for functionality of lysosomes and autophagy. Loss of N-glycan-binding capability of galectin-9 causes its complete depletion from lysosomes and defective autophagy, leading to increased endoplasmic reticulum (ER) stress preferentially in autophagy-active Paneth cells and acinar cells. Unresolved ER stress consequently causes cell degeneration or apoptosis that associates with colitis and pancreatic disorders in mice. Therefore, lysosomal galectins maintain homeostatic function of lysosomes to prevent organ pathogenesis.
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http://dx.doi.org/10.1038/s41467-020-18102-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7453023PMC
August 2020

Volatile DMNT systemically induces jasmonate-independent direct anti-herbivore defense in leaves of sweet potato (Ipomoea batatas) plants.

Sci Rep 2019 11 22;9(1):17431. Epub 2019 Nov 22.

Research Group Plant Defense Physiology, Max Planck Institute for Chemical Ecology, 07745, Jena, Germany.

Plants perceive and respond to volatile signals in their environment. Herbivore-infested plants release volatile organic compounds (VOCs) which can initiate systemic defense reactions within the plant and contribute to plant-plant communication. Here, for Ipomoea batatas (sweet potato) leaves we show that among various herbivory-induced plant volatiles, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) had the highest abundance of all emitted compounds. This homoterpene was found being sufficient for a volatile-mediated systemic induction of defensive Sporamin protease inhibitor activity in neighboring sweet potato plants. The systemic induction is jasmonate independent and does not need any priming-related challenge. Induced emission and responsiveness to DMNT is restricted to a herbivory-resistant cultivar (Tainong 57), while a susceptible cultivar, Tainong 66, neither emitted amounts comparable to Tainong 57, nor showed reaction to DMNT. This is consistent with the finding that Spodoptera larvae feeding on DMNT-exposed cultivars gain significantly less weight on Tainong 57 compared to Tainong 66. Our results indicate a highly specific, single volatile-mediated plant-plant communication in sweet potato.
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http://dx.doi.org/10.1038/s41598-019-53946-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874613PMC
November 2019

Cloning and overexpression of the ascorbate peroxidase gene from the yam (Dioscorea alata) enhances chilling and flood tolerance in transgenic Arabidopsis.

J Plant Res 2019 Nov 6;132(6):857-866. Epub 2019 Sep 6.

Institute of Dryland Crops, Sanming Academy of Agricultural Sciences, Sanming, 365000, Fujian, China.

Minghuai 1 (MH1) is a yam (Dioscorea alata) cultivar with high tolerance to flooding but sensitivity to chilling. MH1 responded differently to chilling and flooding according to various physiological parameters and antioxidant enzymes. Flooding led to an increase in ascorbate peroxidase (APX) activity in both roots and leaves, while chilling did not affect APX activity. The full length DaAPX ORF sequence from MH1 (750 bp) was then cloned. Phylogenetic analysis showed that plant cytosolic APXs into four major clusters and DaAPX was closely related to Oncidium. The DaAPX gene driven by a 35S promoter was transferred into Arabidopsis. The gene expression and enzyme activity of APX in the DaAPX transgenic lines 1-3 were significantly higher than in wild type (WT) plants. Compared to WT plants, seedling growth characteristics were significantly better in all transgenic lines under chilling, flooding, and oxidative stresses, indicating that the overexpression of DaAPX in Arabidopsis enhanced tolerance to several abiotic stresses. MH1 plants supplied with HO presented an increase in the activity of APX leading to enhanced tolerance to chilling. Functional characterization of the APX gene should improve our understanding of the chilling- and flood-response mechanism in the yam.
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http://dx.doi.org/10.1007/s10265-019-01136-4DOI Listing
November 2019

Loss of Gut Microbiota Alters Immune System Composition and Cripples Postinfarction Cardiac Repair.

Circulation 2019 01;139(5):647-659

Program in Molecular Medicine, National Yang Ming University and Academia Sinica, Taipei, Taiwan (T.W.H.T., P.C.C.H.).

Background: The impact of gut microbiota on the regulation of host physiology has recently garnered considerable attention, particularly in key areas such as the immune system and metabolism. These areas are also crucial for the pathophysiology of and repair after myocardial infarction (MI). However, the role of the gut microbiota in the context of MI remains to be fully elucidated.

Methods: To investigate the effects of gut microbiota on cardiac repair after MI, C57BL/6J mice were treated with antibiotics 7 days before MI to deplete mouse gut microbiota. Flow cytometry was applied to examine the changes in immune cell composition in the heart. 16S rDNA sequencing was conducted as a readout for changes in gut microbial composition. Short-chain fatty acid (SCFA) species altered after antibiotic treatment were identified by high-performance liquid chromatography. Fecal reconstitution, transplantation of monocytes, or dietary SCFA or Lactobacillus probiotic supplementation was conducted to evaluate the cardioprotective effects of microbiota on the mice after MI.

Results: Antibiotic-treated mice displayed drastic, dose-dependent mortality after MI. We observed an association between the gut microbiota depletion and significant reductions in the proportion of myeloid cells and SCFAs, more specifically acetate, butyrate, and propionate. Infiltration of CX3CR1+ monocytes to the peri-infarct zone after MI was also reduced, suggesting impairment of repair after MI. Accordingly, the physiological status and survival of mice were significantly improved after fecal reconstitution, transplantation of monocytes, or dietary SCFA supplementation. MI was associated with a reorganization of the gut microbial community such as a reduction in Lactobacillus. Supplementing antibiotic-treated mice with a Lactobacillus probiotic before MI restored myeloid cell proportions, yielded cardioprotective effects, and shifted the balance of SCFAs toward propionate.

Conclusions: Gut microbiota-derived SCFAs play an important role in maintaining host immune composition and repair capacity after MI. This suggests that manipulation of these elements may provide opportunities to modulate pathological outcome after MI and indeed human health and disease as a whole.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.118.035235DOI Listing
January 2019

ATF3 Sustains IL-22-Induced STAT3 Phosphorylation to Maintain Mucosal Immunity Through Inhibiting Phosphatases.

Front Immunol 2018 5;9:2522. Epub 2018 Nov 5.

Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.

In gut epithelium, IL-22 transmits signals through STAT3 phosphorylation (pSTAT3) which provides intestinal immunity. Many components in the IL-22-pSTAT3 pathway have been identified as risk factors for inflammatory bowel disease (IBD) and some of them are considered as promising therapeutic targets. However, new perspectives are still needed to understand IL-22-pSTAT3 signaling for effective clinical interventions in IBD patients. Here, we revealed activating transcription factor 3 (ATF3), recently identified to be upregulated in patients with active IBD, as a crucial player in the epithelial IL-22-pSTAT3 signaling cascade. We found ATF3 is central to intestinal homeostasis and provides protection during colitis. Loss of ATF3 led to decreased crypt numbers, more shortened colon length, impaired ileal fucosylation at the steady state, and lethal disease activity during DSS-induced colitis which can be effectively ameliorated by rectal transplantation of wild-type colonic organoids. Epithelial stem cells and Paneth cells form a niche to orchestrate epithelial regeneration and host-microbe interactions, and IL-22-pSTAT3 signaling is a key guardian for this niche. We found ATF3 is critical for niche maintenance as ATF3 deficiency caused compromised stem cell growth and regeneration, as well as Paneth cell degeneration and loss of anti-microbial peptide (AMP)-producing granules, indicative of malfunction of Paneth/stem cell network. Mechanistically, we found IL-22 upregulates ATF3, which is required to relay IL-22 signaling leading to STAT3 phosphorylation and subsequent AMP induction. Intriguingly, ATF3 itself does not act on STAT3 directly, instead ATF3 regulates pSTAT3 by negatively targeting protein tyrosine phosphatases (PTPs) including SHP2 and PTP-Meg2. Furthermore, we identified ATF3 is also involved in IL-6-mediated STAT3 activation in T cells and loss of ATF3 leads to reduced capacity of Th17 cells to produce their signature cytokine IL-22 and IL-17A. Collectively, our results suggest that via IL-22-pSTAT3 signaling in the epithelium and IL-6-pSTAT3 signaling in Th17 cells, ATF3 mediates a cross-regulation in the barrier to maintain mucosal homeostasis and immunity.
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http://dx.doi.org/10.3389/fimmu.2018.02522DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6230592PMC
September 2019

Galectin-9 Is Critical for Mucosal Adaptive Immunity through the T Helper 17-IgA Axis.

Am J Pathol 2018 05 17;188(5):1225-1235. Epub 2018 Feb 17.

Ph.D. Program in Translational Medicine, China Medical University and Academia Sinica, Taichung, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan; Department of Dermatology, School of Medicine, University of California-Davis, Sacramento, California. Electronic address:

Impairment of the intestinal mucosal immunity significantly increases the risk of acute and chronic diseases. IgA plays a major role in humoral mucosal immunity to provide protection against pathogens and toxins in the gut. Here, we investigated the role of endogenous galectin-9, a tandem repeat-type β-galactoside-binding protein, in intestinal mucosal immunity. By mucosal immunization of Lgals9 and littermate control mice, it was found that lack of galectin-9 impaired mucosal antigen-specific IgA response in the gut. Moreover, Lgals9 mice were more susceptible to developing watery diarrhea and more prone to death in response to high-dose cholera toxin. The results indicate the importance of galectin-9 in modulating intestinal adaptive immunity. Furthermore, bone marrow chimera mice were established, and galectin-9 in hematopoietic cells was found to be critical for adaptive IgA response. In addition, immunized Lgals9 mice exhibited lower expression of Il17 and fewer T helper 17 (Th17) cells in the lamina propria, implying that the Th17-IgA axis is involved in this mechanism. Taken together, these findings suggest that galectin-9 plays a role in mucosal adaptive immunity through the Th17-IgA axis. By manipulating the expression or activity of galectin-9, intestinal mucosal immune response can be altered and may benefit the development of mucosal vaccination.
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http://dx.doi.org/10.1016/j.ajpath.2018.01.017DOI Listing
May 2018

The Sweet Potato NAC-Domain Transcription Factor IbNAC1 Is Dynamically Coordinated by the Activator IbbHLH3 and the Repressor IbbHLH4 to Reprogram the Defense Mechanism against Wounding.

PLoS Genet 2016 Oct 25;12(10):e1006397. Epub 2016 Oct 25.

Institute of Plant Biology, National Taiwan University, Taipei, Taiwan.

IbNAC1 is known to activate the defense system by reprogramming a genetic network against herbivory in sweet potato. This regulatory activity elevates plant defense potential but relatively weakens plants by IbNAC1-mediated JA response. The mechanism controlling IbNAC1 expression to balance plant vitality and survival remains unclear. In this study, a wound-responsive G-box cis-element in the IbNAC1 promoter from -1484 to -1479 bp was identified. From a screen of wound-activated transcriptomic data, one transcriptional activator, IbbHLH3, and one repressor, IbbHLH4, were selected that bind to and activate or repress, respectively, the G-box motif in the IbNAC1 promoter to modulate the IbNAC1-mediated response. In the early wound response, the IbbHLH3-IbbHLH3 protein complex binds to the G-box motif to activate IbNAC1 expression. Thus, an elegant defense network is activated against wounding stress. Until the late stages of wounding, IbbHLH4 interacts with IbbHLH3, and the IbbHLH3-IbbHLH4 heterodimer competes with the IbbHLH3-IbbHLH3 complex to bind the G-box and suppress IbNAC1 expression and timely terminates the defense network. Moreover, the JAZs and IbEIL1 proteins interact with IbbHLH3 to repress the transactivation function of IbbHLH3 in non-wounded condition, but their transcription is immediately inhibited upon early wounding. Our work provides a genetic model that accurately switches the regulatory mechanism of IbNAC1 expression to adjust wounding physiology and represents a delicate defense regulatory network in plants.
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http://dx.doi.org/10.1371/journal.pgen.1006397DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5079590PMC
October 2016

Toward live-cell imaging of dopamine neurotransmission with fluorescent neurotransmitter analogues.

Chem Commun (Camb) 2015 Sep;51(74):14080-3

Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.

We report a novel 'fluorescent dopamine' that possesses essential features of natural dopamine. Our method is simple and is readily extended to monoamine neurotransmitters such as L-norepinephrine, serotonin and GABA, providing a more practical approach. Because of its compatibility with sensitive fluorescent measurements, we envisage that our approach will have a broad range of applications in neural research.
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http://dx.doi.org/10.1039/c5cc03050aDOI Listing
September 2015

Molecular imaging of ischemia and reperfusion in vivo with mitochondrial autofluorescence.

Anal Chem 2014 May 5;86(10):5024-31. Epub 2014 May 5.

Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University , Hsinchu 300, Taiwan.

Ischemia and reperfusion (IR) injury constitutes a pivotal mechanism of tissue damage in pathological conditions such as stroke, myocardial infarction, vascular surgery, and organ transplant. Imaging or monitoring of the change of an organ at a molecular level in real time during IR is essential to improve our understanding of the underlying pathophysiology and to guide therapeutic strategies. Herein, we report molecular imaging of a rat model of hepatic IR with the autofluorescence of mitochondrial flavins. We demonstrate a revelation of the histological characteristics of a liver in vivo with no exogenous stain and show that intravital autofluorescent images exhibited a distinctive spatiotemporal variation during IR. The autofluorescence decayed rapidly from the baseline immediately after 20-min ischemia (approximately 30% decrease in 5 min) but recovered gradually during reperfusion (to approximately 99% of the baseline 9 min after the onset of reperfusion). The autofluorescent images acquired during reperfusion correlated strongly with the reperfused blood flow. We show further that the autofluorescence was produced predominantly from mitochondria, and the distinctive autofluorescent variation during IR was mechanically linked to the altered balance between the flavins in the oxidized and reduced forms residing in the mitochondrial electron-transport chain. Our approach opens an unprecedented route to interrogate the deoxygenation and reoxygenation of mitochondria, the machinery central to the pathophysiology of IR injury, with great molecular specificity and spatiotemporal resolution and can be prospectively translated into a medical device capable of molecular imaging. We envisage that the realization thereof should shed new light on clinical diagnostics and therapeutic interventions targeting IR injuries of not only the liver but also other vital organs including the brain and heart.
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http://dx.doi.org/10.1021/ac5006469DOI Listing
May 2014

Selective and absolute quantification of endogenous hypochlorous acid with quantum-dot conjugated microbeads.

Anal Chem 2011 Nov 13;83(21):8267-72. Epub 2011 Oct 13.

Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu, Taiwan.

Endogenous hypochlorous acid (HOCl) secreted by leukocytes plays a critical role in both the immune defense of mammalians and the pathogenesis of various diseases intimately related to inflammation. We report the first selective and absolute quantification of endogenous HOCl produced by leukocytes in vitro and in vivo with a novel quantum dot-based sensor. An activated human neutrophil secreted 6.5 ± 0.9 × 10(8) HOCl molecules into its phagosome, and kinetic measurement for the secretions showed that the extracellular generation of HOCl was temporally retarded, but the quantity eventually attained a level comparable with its intraphagosomal counterpart with a delay of about 1.5 h. The quantity of HOCl secreted from the hepatic leukocytes of rats with or without stimulation of lipopolysaccharide was also determined. These results indicate a possibility to extend our approach to not only clinical settings for quantitative assessment of the bactericidal capability of isolated leukocytes of patients but also fundamental biomedical research that requires critical evaluation of the inflammatory response of animals.
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http://dx.doi.org/10.1021/ac202077xDOI Listing
November 2011

Spatiotemporal characterization of phagocytic NADPH oxidase and oxidative destruction of intraphagosomal organisms in vivo using autofluorescence imaging and Raman microspectroscopy.

J Am Chem Soc 2010 Feb;132(6):1744-5

National Taiwan University College of Medicine and Hospital, Taipei, Taiwan.

The ability to generate antimicrobial reactive-oxygen species (ROS) by reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is critical for the host to defend against invading microbes. We have demonstrated the application of confocal autofluorescence microscopy and Raman microspectroscopy to characterize dynamically the phagocytic process of living macrophages in a label-free manner. In particular, we visualized the translocation of NADPH oxidases in living macrophages that are undergoing phagocytosis of invading yeasts and monitored dynamically the change at the molecular level of single intraphagosomal yeasts caused by phagocytic ROS.
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http://dx.doi.org/10.1021/ja9086038DOI Listing
February 2010
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