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1.
Prog Lipid Res ; 91: 101234, 2023 07.
Article in English | MEDLINE | ID: mdl-37169310

ABSTRACT

Plasmalogen is a major phospholipid of mammalian cell membranes. Recently it is becoming evident that the sn-1 vinyl-ether linkage in plasmalogen, contrasting to the ester linkage in the counterpart diacyl glycerophospholipid, yields differential molecular characteristics for these lipids especially related to hydrocarbon-chain order, so as to concertedly regulate biological membrane processes. A role played by NMR in gaining information in this respect, ranging from molecular to tissue levels, draws particular attention. We note here that a broad range of enzymes in de novo synthesis pathway of plasmalogen commonly constitute that of diacyl glycerophospholipid. This fact forms the basis for systematic crosstalk that not only controls a quantitative balance between these lipids, but also senses a defect causing loss of lipid in either pathway for compensation by increase of the counterpart lipid. However, this inherent counterbalancing mechanism paradoxically amplifies imbalance in differential effects of these lipids in a diseased state on membrane processes. While sharing of enzymes has been recognized, it is now possible to overview the crosstalk with growing information for specific enzymes involved. The overview provides a fundamental clue to consider cell and tissue type-dependent schemes in regulating membrane processes by plasmalogen and diacyl glycerophospholipid in health and disease.


Subject(s)
Mammals , Plasmalogens , Animals , Plasmalogens/metabolism , Cell Membrane/metabolism , Mammals/metabolism
2.
Gan To Kagaku Ryoho ; 49(10): 1121-1124, 2022 Oct.
Article in Japanese | MEDLINE | ID: mdl-36281607

ABSTRACT

Respiratory symptoms are rarely reported as side effects of oxaliplatin, 5-fluorouracil, and Leucovorin(FOLFOX)therapy. We report a case of a patient with FOLFOX-induced unilateral interstitial pneumonia. The patient was a 68-year-old man who underwent ileocecal resection of cecum cancer. FOLFOX regimen was started as an adjuvant chemotherapy. After the administration of 11 courses, he visited our hospital with fever, dyspnea, and anorexia. We diagnosed this as FOLFOX- induced unilateral interstitial pneumonia through a blood test, chest radiograph, computed tomography, and bronchoscopy. Treatment was started with 30 mg of prednisolone, and the dosage was gradually decreased. The patient responded well to the treatment and was discharged from the hospital without any complications on the 33th day after admission.


Subject(s)
Colorectal Neoplasms , Lung Diseases, Interstitial , Male , Humans , Aged , Leucovorin/adverse effects , Oxaliplatin/adverse effects , Fluorouracil/adverse effects , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Lung Diseases, Interstitial/chemically induced , Lung Diseases, Interstitial/drug therapy , Lung Diseases, Interstitial/surgery , Prednisolone/adverse effects , Colorectal Neoplasms/drug therapy
3.
J Int Med Res ; 50(8): 3000605221115158, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35915581

ABSTRACT

A 31-year-old man presented to our hospital's Emergency Department with sudden epigastric pain and vomiting. He had undergone endoscopic resection via the retroperitoneal route for a retroperitoneal tumor located in the left diaphragmatic crus of the esophageal hiatus at another hospital 8 months previously. Radiography and computed tomography showed inversion of the stomach beyond the diaphragm into the thoracic cavity, with the gastroesophageal junction serving as the fulcrum point. This finding led to a diagnosis of postoperative diaphragmatic hernia accompanied by an upside-down stomach (UDS). The prolapsed stomach in the thoracic cavity was reduced to the abdominal cavity using laparoscopic surgery. The postoperative course was favorable, and the patient was discharged from the hospital on postoperative day 7. No recurrence has been observed in the past 5 years. The pathological condition of a UDS observed in esophageal hiatal hernias may be found in postoperative diaphragmatic hernias. Laparoscopic surgery for a postoperative diaphragmatic hernia with a UDS is considered a useful surgical procedure. Laparoscopic surgery can simultaneously confirm the viability of the herniated organs, reduce the organs to the abdominal cavity, and close and reinforce the diaphragm.


Subject(s)
Hernia, Hiatal , Hernias, Diaphragmatic, Congenital , Laparoscopy , Adult , Diaphragm/diagnostic imaging , Diaphragm/pathology , Diaphragm/surgery , Esophagogastric Junction/pathology , Hernia, Hiatal/diagnostic imaging , Hernia, Hiatal/surgery , Hernias, Diaphragmatic, Congenital/surgery , Humans , Laparoscopy/methods , Male
4.
Org Lett ; 24(26): 4835-4839, 2022 07 08.
Article in English | MEDLINE | ID: mdl-35758853

ABSTRACT

An efficient and scalable synthesis of N-perfluoroacylimino-λ3-iodanes was achieved via an unprecedented metathesis between iodosoarenes and perfluoroalkanenitriles. The perfluoroacylamino groups of the iodanes could be introduced to aromatic and heteroaromatic rings using photoirradiation.


Subject(s)
Nitriles , Molecular Structure
6.
Int J Surg Case Rep ; 78: 130-132, 2021 Jan.
Article in English | MEDLINE | ID: mdl-33340980

ABSTRACT

INTRODUCTION: Extreme lateral interbody fusion is a minimally invasive lateral transpsoas approach for spine surgery. We herein report a case of an incisional hernia after an extreme lateral interbody fusion on the lumbar spine that was successfully treated by laparoscopic surgery with intraperitoneal onlay mesh repair. PRESENTATION OF CASE: A 78-year-old woman was referred to our hospital with a complaint of left abdominal bulge and pain. She had undergone an extreme lateral interbody fusion for a lumbar spinal canal stenosis from L1 to L4 a year prior. Abdominal computerized tomography showed a left lumbar incisional hernia, and laparoscopic surgery was performed. The hernia orifice was sutured closed and covered with mesh. The patient was discharged five days after the operation with no complications. DISCUSSION: When performing XLIF for a spinal disorder, the muscles should be separated bluntly along their fibers to prevent muscle atrophy, and the incised fascia should be securely sutured closed. Abdominal wall incisional hernias can occur after spinal surgeries such as extreme lateral interbody fusion. CONCLUSION: Laparoscopic repair for abdominal wall incisional hernia after spine surgery is safe and feasible.

7.
Arch Biochem Biophys ; 697: 108721, 2021 01 15.
Article in English | MEDLINE | ID: mdl-33307066

ABSTRACT

5-Aminolevulinic acid (ALA) is the rate-limiting intermediate in heme biosynthesis in vertebrate species; a reaction catalyzed by the mitochondrial ALA synthase 1 (ALAS1) enzyme. Previously we reported that knockdown of the ubiquitously expressed ALAS1 gene in mice disrupts normal glucose metabolism, attenuates mitochondrial function and results in a prediabetic like phenotype when animals pass 20-weeks of age (Saitoh et al., 2018). Contrary to our expectations, the cytosolic and mitochondrial heme content of ALAS1 heterozygous (A1+/-) mice were similar to WT animals. Therefore, we speculated that regulatory "free heme" may be reduced in an age dependent manner in A1+/- mice, but not total heme. Here, we examine free and total heme from the skeletal muscle and liver of WT and A1+/- mice using a modified acetone extraction method and examine the effects of aging on free heme by comparing the amounts at 8-12 weeks and 30-36 weeks of age, in addition to the mRNA abundance of ALAS1. We found an age-dependent reduction in free heme in the skeletal muscle and liver of A1+/- mice, while WT mice showed only a slight decrease in the liver. Total heme levels showed no significant difference between young and aged WT and A1+/- mice. ALAS1 mRNA levels showed an age-dependent reduction similar to that of free heme levels, indicating that ALAS1 mRNA expression levels are a major determinant for free heme levels. The free heme pools in skeletal muscle tissue were almost 2-fold larger than that of liver tissue, suggesting that the heme pool varies across different tissue types. The expression of heme oxygenase 1 (HO-1) mRNA, which is expressed proportionally to the amount of free heme, were similar to those of free heme levels. Taken together, this study demonstrates that the free heme pool differs across tissues, and that an age-dependent reduction in free heme levels is accelerated in mice heterozygous for ALAS1, which could account for the prediabetic phenotype and mitochondrial abnormality observed in these animals.


Subject(s)
Aging/metabolism , Heme/metabolism , Heterozygote , Liver/metabolism , Muscle, Skeletal/metabolism , Aging/genetics , Animals , Gene Expression Regulation/genetics , Kinetics , Mice , RNA, Messenger/genetics
8.
FASEB J ; 35(1): e21177, 2021 01.
Article in English | MEDLINE | ID: mdl-33205488

ABSTRACT

Enzymatic control of lipid homeostasis in the cell is a vital element in the complex organization of life. Phosphatidylserine (PS) is an essential anionic phospholipid of cell membranes, and conducts numerous roles for their structural and functional integrity. In mammalian cells, two distinct enzymes phosphatidylserine synthases-1 (PSS1) and -2 (PSS2) in the mitochondria-associated membrane (MAM) in the ER perform de novo synthesis of PS. It is based on base-exchange reactions of the preexisting dominant phospholipids phosphatidylcholine (PC) and phosphatidylethanolamine (PE). While PSS2 specifically catalyzes the reaction "PE â†’ PS," whether or not PSS1 is responsible for the same reaction along with the reaction "PC â†’ PS" remains unsettled despite its fundamental impact on the major stoichiometry. We propose here that a key but the only report that appeared to have put scientists on hold for decades in answering to this issue may be viewed consistently with other available research reports; PSS1 utilizes the two dominant phospholipid classes at a similar intrinsic rate. In this review, we discuss the issue in view of the current information for the enzyme machineries, membrane structure and dynamics, intracellular network of lipid transport, and PS synthesis in health and disease. Resolution of the pending issue is thus critical in advancing our understanding of roles of the essential anionic lipid in biology, health, and disease.


Subject(s)
Homeostasis , Lipid Metabolism , Phosphatidylethanolamines/biosynthesis , Phosphatidylserines/biosynthesis , Animals , Humans , Mitochondrial Membranes/metabolism , Nitrogenous Group Transferases/metabolism
9.
J Clin Psychiatry ; 81(6)2020 10 06.
Article in English | MEDLINE | ID: mdl-33027560

ABSTRACT

OBJECTIVE: This study aimed to examine the effects of suvorexant on delirium prevention in a real-world setting. Previous studies have demonstrated the efficacy of suvorexant for delirium prevention in limited randomized clinical trial settings; however, its effectiveness in everyday clinical settings remains unknown. METHODS: A single-center, retrospective cohort study was conducted in the intensive care unit of an academic hospital. Patients (aged ≥ 3 years) admitted from January 2016 to December 2018 were eligible if they stayed in the intensive care unit for at least 72 hours. Suvorexant was prescribed by the attending physician for insomnia as part of everyday clinical practice. A Cox proportional hazards regression analysis was conducted on delirium-free survival for suvorexant users, adjusting for delirium-related covariates. As part of routine clinical practice, the Confusion Assessment Method for the Intensive Care Unit was used to detect the existence of delirium at least twice daily throughout the intensive care unit stay. RESULTS: There were 699 patients-84 suvorexant users and 615 suvorexant nonusers. Delirium was detected in 214 patients. Delirium prevalence was significantly lower in suvorexant users than in nonusers (17.9% vs 32.4%, respectively; P = .007). Cox regression analysis revealed a significantly lower hazard ratio (0.472; 95% CI, 0.268-0.832; P = .009) of delirium in suvorexant users than in nonusers. Trazodone also had a preventive effect on delirium (hazard ratio 0.345; 95% CI, 0.149-0.802; P = .013). CONCLUSIONS: The present study extends to real-world settings previous findings that suvorexant is effective for delirium prevention.


Subject(s)
Azepines/administration & dosage , Critical Care/statistics & numerical data , Delirium/prevention & control , Orexin Receptor Antagonists/administration & dosage , Outcome Assessment, Health Care/statistics & numerical data , Sleep Initiation and Maintenance Disorders/drug therapy , Triazoles/administration & dosage , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Critical Care/methods , Delirium/epidemiology , Female , Humans , Male , Middle Aged , Prevalence , Proportional Hazards Models , Retrospective Studies , Selective Serotonin Reuptake Inhibitors/pharmacology , Trazodone/pharmacology , Young Adult
10.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4807-4810, 2020 07.
Article in English | MEDLINE | ID: mdl-33019066

ABSTRACT

The human-machine interface (HMI) of a tractor cockpit includes not only the steering wheel and pedals, but also many levers and switches. According to a report from the National Agriculture and Food Research Organization of Japan, the HMI layout often differs from the operator's expectation. This gap between expectations and reality has led to operator errors and market complaints. However, few reports have ergonomically evaluated these arrangements. Our previous work showed that this gap can be evaluated by the amplitude of the P300 component of the event-related potentials (ERPs) for discrimination tasks by using a picture of the vehicle cockpit on the display. However, in real-world driving and operation situations, eye movements occur. In such cases, the eye-fixation related potential (EFRP) may be used. The EFRP appears at the end of a saccade, which is a rapid movement of the eyes between fixation points. Its positive component, called the lambda response, is reported to reflect the human attention level to visual targets. We hypothesize that if the HMI layout differs from the user's expectation, operation becomes difficult and the user's attention to the target during operation will be reduced. In order to confirm this hypothesis, an experiment was conducted during the actual operation of a tractor while changing the tiller switch position. The participants were 13 adult males with experience in tractor operations. The amplitude of the lambda wave was reduced when the switch position was different from the user's expectations, reflecting the decrease in attention caused by the increased difficulty of operating the tiller. We suggest that the amplitude of the lambda response can be used as the evaluation index for optimizing the switch position.


Subject(s)
Fixation, Ocular , Saccades , Adult , Agriculture , Eye Movements , Humans , Japan , Male
11.
Int J Surg Case Rep ; 75: 46-49, 2020.
Article in English | MEDLINE | ID: mdl-32919328

ABSTRACT

INTRODUCTION: Cryptorchidism or undescended testis is the most common disorder of male children, which is often diagnosed and treated during childhood. Adult patients with cryptorchidism are uncommon. Herein we report the case of adult inguinal hernia with cryptorchidism successfully treated by laparoscopic surgery simultaneously. PRESENTATION OF CASE: We report a case of 68 year-old-man who was admitted to our hospital with a complaint of bulge and pain in the right groin area from 2 weeks before. CT or MRI revealed a right inguinal hernia and an undescended testis in the right inguinal canal. He was diagnosed with right inguinal hernia accompanied by cryptorchidism. Laparoscopic transabdominal preperitoneal repair (TAPP) and orchiectomy were performed simultaneously. Postoperative period was uneventful and he was discharged home on the 1st postoperative day. Pathological examination of the specimen was reported as atrophic testis with no malignancy. There has been no recurrence during a follow-up. DISCUSSION: To our Knowledge, the case report of adult inguinal hernia with cryptorchidism treated by laparoscopic surgery is rare. All cases recommended the feasibility of laparoscopic surgery. CONCLUSION: Adult inguinal hernia with cryptorchidism is a rare condition. TAPP and simultaneous laparoscopic orchiectomy for inguinal hernia with cryptorchidism were safe and feasible. It could be the first surgical option for the treatment of such adult patients.

12.
Sci Rep ; 9(1): 17235, 2019 11 21.
Article in English | MEDLINE | ID: mdl-31754246

ABSTRACT

Ribosome biogenesis is essential for maintaining basic cellular activities although its mechanism is not fully understood. Inhibitor of growth 4 (ING4) is a member of ING family while its cellular functions remain controversial. Here, we identified several nucleolar proteins as novel ING4 interacting proteins. ING4 localized in the nucleus with strong accumulation in the nucleolus through its plant homeodomain, which is known to interact with histone trimethylated H3K4, commonly present in the promoter of active genes. ING4 deficient cells exhibited slower proliferation and the alteration in nucleolar structure with reduced rRNA transcription, which was rescued by exogenous expression of GFP-ING4 to the similar levels of wild type cells. In the ING4 deficient cells, histone H3K9 acetylation and the key rRNA transcription factor UBF at the promoter of rDNA were reduced, both of which were also recovered by exogenous GFP-ING4 expression. Thus, ING4 could positively regulate rRNA transcription through modulation of histone modifications at the rDNA promoter.


Subject(s)
Cell Cycle Proteins/genetics , Homeodomain Proteins/genetics , RNA, Ribosomal/genetics , Tumor Suppressor Proteins/genetics , Acetylation , Cell Line, Tumor , Cell Nucleus/genetics , DNA, Ribosomal/genetics , HeLa Cells , Histones/genetics , Humans , Promoter Regions, Genetic/genetics , Transcription, Genetic/genetics
13.
Geriatr Gerontol Int ; 19(11): 1108-1111, 2019 Nov.
Article in English | MEDLINE | ID: mdl-31746525

ABSTRACT

AIM: In Japan, the number of older patients with cancer has been increasing. Assessment of performance status, cognitive function and social background is necessary for the treatment of older patients. The aims of the present study were: (i) to establish an evaluation system using electronic medical records; and (ii) to distinguish older patients as fit versus vulnerable or frail according to a geriatric assessment (GA) system score. METHODS: We incorporated GA tools in our electronic medical records system and carried out comprehensive assessments for patients with newly diagnosed lung cancer aged ≥65 years. The decision about primary treatment followed consultation with the clinical team and was not guided by GA scores. Subsequent treatment and outcomes were recorded. RESULTS: A total of 100 patients had completed GA. The average age was 75 years (range 65-94 years). Regarding GA results, 63% were positive on the Comprehensive Geriatric Assessment 7, 39% on the Vulnerable Elderly Survey-13 and 84% on the Geriatric 8. The percentage of vulnerable patients (positive on all three GA) was significantly higher in the non-standard therapy group (n = 19) than in the standard therapy group (n = 81; 78.9% vs 21.0%, P < 0.001). Among vulnerable patients who received standard therapy, 47% discontinued chemotherapy as a result of toxicity. Even if a patient was considered vulnerable based on GA scores, chemotherapy is possibly safe for those with EGFR mutations. CONCLUSIONS: We confirmed the feasibility of this system. During decision-making for older patients with cancer, a combination of GA helps prevent undertreatment or overtreatment. Geriatr Gerontol Int 2019; 19: 1108-1111.


Subject(s)
Frailty/complications , Frailty/diagnosis , Geriatric Assessment/methods , Lung Neoplasms/complications , Aged , Aged, 80 and over , Electronic Health Records , Female , Humans , Male , Prospective Studies
14.
Life Sci Alliance ; 2(4)2019 08.
Article in English | MEDLINE | ID: mdl-31434794

ABSTRACT

Lipid homeostasis is crucial in human health. Barth syndrome (BTHS), a life-threatening disease typically diagnosed with cardiomyopathy and neutropenia, is caused by mutations in the mitochondrial transacylase tafazzin. By high-resolution 31P nuclear magnetic resonance (NMR) with cryoprobe technology, recently we found a dramatic loss of choline plasmalogen in the tafazzin-knockdown (TAZ-KD) mouse heart, besides observing characteristic cardiolipin (CL) alterations in BTHS. In inner mitochondrial membrane where tafazzin locates, CL and diacyl phosphatidylethanolamine are known to be essential via lipid-protein interactions reflecting their cone shape for integrity of respiratory chain supercomplexes and cristae ultrastructure. Here, we investigate the TAZ-KD brain, liver, kidney, and lymphoblast from patients compared with controls. We identified common yet markedly cell type-dependent losses of ethanolamine plasmalogen as the dominant plasmalogen class therein. Tafazzin function thus critically relates to homeostasis of plasmalogen, which in the ethanolamine class has conceivably analogous and more potent molecular functions in mitochondria than diacyl phosphatidylethanolamine. The present discussion of a loss of plasmalogen-protein interaction applies to other diseases with mitochondrial plasmalogen loss and aberrant forms of this organelle, including Alzheimer's disease.


Subject(s)
Mitochondria/metabolism , Plasmalogens/metabolism , Acyltransferases , Animals , Barth Syndrome/genetics , Barth Syndrome/physiopathology , Cardiolipins/metabolism , Cardiomyopathies/metabolism , Female , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Mitochondrial Membranes/metabolism , Plasmalogens/physiology , Transcription Factors/metabolism
15.
J Bacteriol ; 201(14)2019 07 15.
Article in English | MEDLINE | ID: mdl-31036727

ABSTRACT

The rare actinomycete Actinoplanes missouriensis produces terminal sporangia containing a few hundred flagellated spores. After release from the sporangia, the spores swim rapidly in aquatic environments as zoospores. The zoospores stop swimming and begin to germinate in niches for vegetative growth. Here, we report the characterization and functional analysis of zoospore type IV pili in A. missouriensis The pilus gene (pil) cluster, consisting of three apparently σFliA-dependent transcriptional units, is activated during sporangium formation similarly to the flagellar gene cluster, indicating that the zoospore has not only flagella but also pili. With a new method in which zoospores were fixed with glutaraldehyde to prevent pilus retraction, zoospore pili were observed relatively easily using transmission electron microscopy, showing 6 ± 3 pili per zoospore (n = 37 piliated zoospores) and a length of 0.62 ± 0.35 µm (n = 206), via observation of fliC-deleted, nonflagellated zoospores. No pili were observed in the zoospores of a prepilin-encoding pilA deletion (ΔpilA) mutant. In addition, the deletion of pilT, which encodes an ATPase predicted to be involved in pilus retraction, substantially reduced the frequency of pilus retraction. Several adhesion experiments using wild-type and ΔpilA zoospores indicated that the zoospore pili are required for the sufficient adhesion of zoospores to hydrophobic solid surfaces. Many zoospore-forming rare actinomycetes conserve the pil cluster, which indicates that the zoospore pili yield an evolutionary benefit in the adhesion of zoospores to hydrophobic materials as footholds for germination in their mycelial growth.IMPORTANCE Bacterial zoospores are interesting cells in that their physiological state changes dynamically: they are dormant in sporangia, show temporary mobility after awakening, and finally stop swimming to germinate in niches for vegetative growth. However, the cellular biology of a zoospore remains largely unknown. This study describes unprecedented zoospore type IV pili in the rare actinomycete Actinoplanes missouriensis Similar to the case for the usual bacterial type IV pili, zoospore pili appeared to be retractable. Our findings that the zoospore pili have a functional role in the adhesion of zoospores to hydrophobic solid surfaces and that the zoospores use both pili and flagella properly according to their different purposes provide an important insight into the cellular biology of the zoospore.


Subject(s)
Actinoplanes/genetics , Fimbriae Proteins/metabolism , Fimbriae, Bacterial/metabolism , Spores, Bacterial/physiology , Actinoplanes/physiology , Fimbriae Proteins/genetics , Fimbriae, Bacterial/genetics , Gene Expression Regulation, Bacterial , Spores, Bacterial/genetics
16.
Intern Med ; 58(13): 1865-1870, 2019 Jul 01.
Article in English | MEDLINE | ID: mdl-30918185

ABSTRACT

An unconscious 55-year-old man with a history of neurofibromatosis type 1 (NF1) was transported to the emergency department and was diagnosed with acute renal failure owing to a large bladder tumor. A submucosal tumor was also identified in the duodenum. The patient was diagnosed with a primary gastrointestinal stromal tumor (GIST) of the bladder and duodenum. After six cycles of regorafenib therapy, 18F-fluorodeoxyglucose accumulation in the duodenal GIST on positron emission tomography-computed tomography (PET-CT) showed a partial metabolic response. Currently, no standard drug therapy for unresectable or relapsed NF1-associated GIST has been established. Regorafenib may thus be considered as and appropriate initial therapy.


Subject(s)
Duodenum/pathology , Enzyme Inhibitors/therapeutic use , Gastrointestinal Stromal Tumors/drug therapy , Gastrointestinal Stromal Tumors/pathology , Neurofibromatosis 1/pathology , Phenylurea Compounds/therapeutic use , Pyridines/therapeutic use , Urinary Bladder Neoplasms/pathology , Gastrointestinal Stromal Tumors/diagnostic imaging , Gastrointestinal Stromal Tumors/physiopathology , Humans , Male , Middle Aged , Neurofibromatosis 1/diagnostic imaging , Neurofibromatosis 1/etiology , Positron Emission Tomography Computed Tomography , Treatment Outcome
17.
Bio Protoc ; 9(24): e3458, 2019 Dec 20.
Article in English | MEDLINE | ID: mdl-33654953

ABSTRACT

Spherical zoospores of a rare actinomycete, Actinoplanes missouriensis, adhere to various hydrophobic solid surfaces by means of type IV pili. The purpose of this protocol is to provide detailed descriptions of the preparation of A. missouriensis zoospores and an assay for the adhesion of the zoospores to solid surfaces. This adhesion assay, which measures numbers of zoospores that adhered to the dish surface and swimming zoospores in a tunnel chamber by using a phase-contrast microscope, can also be used for swimming cells of other microorganisms.

18.
J Biol Chem ; 293(46): 17780-17791, 2018 11 16.
Article in English | MEDLINE | ID: mdl-30237168

ABSTRACT

Signaling events at membranes are often mediated by membrane lipid composition or membrane physical properties. These membrane properties could act either by favoring the membrane binding of downstream effectors or by modulating their activity. Several proteins can sense/generate membrane physical curvature (i.e. shape). However, the modulation of the activity of enzymes by a membrane's shape has not yet been reported. Here, using a cell-free assay with purified diacylglycerol kinase ϵ (DGKϵ) and liposomes, we studied the activity and acyl-chain specificity of an enzyme of the phosphatidylinositol (PI) cycle, DGKϵ. By systematically varying the model membrane lipid composition and physical properties, we found that DGKϵ has low activity and lacks acyl-chain specificity in locally flat membranes, regardless of the lipid composition. On the other hand, these enzyme properties were greatly enhanced in membrane structures with a negative Gaussian curvature. We also found that this is not a consequence of preferential binding of the enzyme to those structures, but rather is due to a curvature-mediated allosteric regulation of DGKϵ activity and acyl-chain specificity. Moreover, in a fine-tuned interplay between the enzyme and the membrane, DGKϵ favored the formation of structures with greater Gaussian curvature. DGKϵ does not bear a regulatory domain, and these findings reveal the importance of membrane curvature in regulating DGKϵ activity and acyl-chain specificity. Hence, this study highlights that a hierarchic coupling of membrane physical property and lipid composition synergistically regulates membrane signaling events. We propose that this regulatory mechanism of membrane-associated enzyme activity is likely more common than is currently appreciated.


Subject(s)
Diacylglycerol Kinase/chemistry , Liposomes/chemistry , Phosphatidylinositols/chemistry , Animals , Cell Line , Cholesterol/chemistry , Diglycerides/chemistry , Enzyme Assays , Humans , Membrane Fusion , Micelles , Molecular Structure , Phosphatidylcholines/chemistry , Phosphatidylethanolamines/chemistry , Phosphatidylserines/chemistry , Spodoptera , Surface Properties
19.
Biochemistry ; 57(14): 2162-2175, 2018 04 10.
Article in English | MEDLINE | ID: mdl-29557170

ABSTRACT

Tafazzin is the mitochondrial enzyme that catalyzes transacylation between a phospholipid and a lysophospholipid in remodeling. Mutations in tafazzin cause Barth syndrome, a potentially life-threatening disease with the major symptom being cardiomyopathy. In the tafazzin-deficient heart, cardiolipin (CL) acyl chains become abnormally heterogeneous unlike those in the normal heart with a single dominant linoleoyl species, tetralinoleoyl CL. In addition, the amount of CL decreases and monolysocardiolipin (MLCL) accumulates. Here we determine using high-resolution 31P nuclear magnetic resonance with cryoprobe technology the fundamental phospholipid composition, including the major but oxidation-labile plasmalogens, in the tafazzin-knockdown (TAZ-KD) mouse heart as a model of Barth syndrome. In addition to confirming a lower level of CL (6.4 ± 0.1 → 2.0 ± 0.4 mol % of the total phospholipid) and accumulation of MLCL (not detected → 3.3 ± 0.5 mol %) in the TAZ-KD, we found a substantial reduction in the level of plasmenylcholine (30.8 ± 2.8 → 18.1 ± 3.1 mol %), the most abundant phospholipid in the control wild type. A quantitative Western blot revealed that while the level of peroxisomes, where early steps of plasmalogen synthesis take place, was normal in the TAZ-KD model, expression of Far1 as a rate-determining enzyme in plasmalogen synthesis was dramatically upregulated by 8.3 (±1.6)-fold to accelerate the synthesis in response to the reduced level of plasmalogen. We confirmed lyso-plasmenylcholine or plasmenylcholine is a substrate of purified tafazzin for transacylation with CL or MLCL, respectively. Our results suggest that plasmenylcholine, abundant in linoleoyl species, is important in remodeling CL in the heart. Tafazzin deficiency thus has a major impact on the cardiac plasmenylcholine level and thereby its functions.


Subject(s)
Barth Syndrome/metabolism , Mitochondria, Heart/metabolism , Mitochondrial Proteins/metabolism , Plasmalogens/biosynthesis , Transcription Factors/deficiency , Acylation , Acyltransferases , Animals , Barth Syndrome/genetics , Barth Syndrome/pathology , Disease Models, Animal , Mice , Mice, Transgenic , Mitochondria, Heart/genetics , Mitochondrial Proteins/genetics , Plasmalogens/genetics , Transcription Factors/metabolism
20.
J Biol Chem ; 292(20): 8436-8446, 2017 05 19.
Article in English | MEDLINE | ID: mdl-28373282

ABSTRACT

Metformin is the first-line drug in the treatment of type 2 diabetes. In addition to its hypoglycemic effect, metformin has an anti-inflammatory function, but the precise mechanism promoting this activity remains unclear. High mobility group box 1 (HMGB1) is an alarmin that is released from necrotic cells and induces inflammatory responses by its cytokine-like activity and is, therefore, a target of anti-inflammatory therapies. Here we identified HMGB1 as a novel metformin-binding protein by affinity purification using a biotinylated metformin analogue. Metformin directly bound to the C-terminal acidic tail of HMGB1. Both in vitro and in vivo, metformin inhibited inflammatory responses induced by full-length HMGB1 but not by HMGB1 lacking the acidic tail. In an acetaminophen-induced acute liver injury model in which HMGB1 released from injured cells exacerbates the initial injury, metformin effectively reduced liver injury and had no additional inhibitory effects when the extracellular HMGB1 was blocked by anti-HMGB1-neutralizing antibody. In summary, we report for the first time that metformin suppresses inflammation by inhibiting the extracellular activity of HMGB1. Because HMGB1 plays a major role in inflammation, our results suggest possible new ways to manage HMGB1-induced inflammation.


Subject(s)
HMGB1 Protein/antagonists & inhibitors , HMGB1 Protein/metabolism , Metformin/pharmacokinetics , Animals , Antibodies, Neutralizing/chemistry , Antibodies, Neutralizing/pharmacology , Humans , Inflammation/drug therapy , Inflammation/metabolism , Metformin/pharmacology , Mice , Protein Binding , Protein Domains , RAW 264.7 Cells
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