Development of AlissAID system targeting GFP or mCherry fusion protein.

Conditional control of target proteins using the auxin-inducible degron (AID) system provides a powerful tool for investigating protein function in eukaryotes. Here, we established an Affinity-linker based super-sensitive auxin-inducible degron (AlissAID) system in budding yeast by using a single domain antibody (a nanobody). In this system, target proteins fused with GFP or mCherry were degraded depending on a synthetic auxin, 5-Adamantyl-IAA (5-Ad-IAA). In AlissAID system, nanomolar concentration of 5-Ad-IAA induces target degradation, thus minimizing the side effects from chemical compounds. In addition, in AlissAID system, we observed few basal degradations which was observed in other AID systems including ssAID system. Furthermore, AlissAID based conditional knockdown cell lines are easily generated by using budding yeast GFP Clone Collection. Target protein, which has antigen recognition sites exposed in cytosol or nucleus, can be degraded by the AlissAID system. From these advantages, the AlissAID system would be an ideal protein-knockdown system in budding yeast cells.

Regulator of Awn Elongation 3, an E3 ubiquitin ligase, is responsible for loss of awns during African rice domestication.

Two species of rice have been independently domesticated from different ancestral wild species in Asia and Africa. Comparison of mutations that underlie phenotypic and physiological alterations associated with domestication traits in these species gives insights into the domestication history of rice in both regions. Asian cultivated rice, Oryza sativa, and African cultivated rice, Oryza glaberrima, have been modified and improved for common traits beneficial for humans, including erect plant architecture, nonshattering seeds, nonpigmented pericarp, and lack of awns. Independent mutations in orthologous genes associated with these traits have been documented in the two cultivated species. Contrary to this prevailing model, selection for awnlessness targeted different genes in O. sativa and O. glaberrima. We identify Regulator of Awn Elongation 3 (RAE3) a gene that encodes an E3 ubiquitin ligase and is responsible for the awnless phenotype only in O. glaberrima. A 48-bp deletion may disrupt the substrate recognition domain in RAE3 and diminish awn elongation. Sequencing analysis demonstrated low nucleotide diversity in a ~600-kb region around the derived rae3 allele on chromosome 6 in O. glaberrima compared with its wild progenitor. Identification of RAE3 sheds light on the molecular mechanism underlying awn development and provides an example of how selection on different genes can confer the same domestication phenotype in Asian and African rice.

Alpha-linolenic acid selectively inhibits the contraction of pig coronary arteries mediated through prostanoid TP receptors.

We examined the inhibitory effects of α-linolenic acid (ALA) on the contractions of pig coronary arteries. ALA concentration-dependently inhibited the contractions elicited by U46619 and prostaglandin F2α without affecting those elicited by 80 mM KCl, histamine, acetylcholine, and serotonin. ALA rightward shifted the concentration-response curve of U46619, and Schild plot analysis revealed that ALA competitively antagonized U46619. Furthermore, ALA inhibited the increase in intracellular Ca2+ concentration caused by TP receptor stimulation but not that caused by FP receptor stimulation. These results suggest that ALA behaves as a selective antagonist of TP receptors in coronary arteries.

Platelet-activating factor contracts guinea pig esophageal muscularis mucosae by stimulating extracellular Ca2+ influx through diltiazem-insensitive Ca2+ channels.

Platelet-activating factor (PAF) is expected to increase esophageal motility. However, to the best of our knowledge, this has not been examined. Thus, we investigated the contractile effects of PAF on guinea pig (GP) esophageal muscularis mucosae (EMM) and the extracellular Ca2+ influx pathways responsible. PAF (10-9-10-6 M) contracted EMM in a concentration-dependent manner. PAF (10-6 M)-induced contractions were almost completely suppressed by apafant (a PAF receptor antagonist, 3 × 10-5 M). In EMM strips, PAF receptor and PAF-synthesizing/degrading enzyme mRNAs were detected. PAF (10-6 M)-induced contractions were abolished by extracellular Ca2+ removal but were not affected by diltiazem [a voltage-dependent Ca2+ channel (VDCC) inhibitor, 10-5 M]. PAF (10-6 M)-induced contractions in the presence of diltiazem were significantly suppressed by LOE-908 [a receptor-operated Ca2+ channel (ROCC) inhibitor, 3 × 10-5 M], SKF-96365 [an ROCC and store-operated Ca2+ channel (SOCC) inhibitor, 3 × 10-5 M], and LOE-908 plus SKF-96365. Among the tested ROCC/SOCC-related mRNAs, Trpc3, Trpc6, and Trpv4/Orai1, Orai3, and Stim2 were abundantly expressed in EMM strips. These results indicate that PAF potently induces GP EMM contractions that are dependent on extracellular Ca2+ influx through ROCCs/SOCCs, and VDCCs are unlikely to be involved.

Inhibitory Actions of Antidepressants, Hypnotics, and Anxiolytics on Recombinant Human Acetylcholinesterase Activity.

Alzheimer's disease (AD) is accompanied by behavioral and psychological symptoms of dementia (BPSD), which is often alleviated by treatment with psychotropic drugs, such as antidepressants, hypnotics, and anxiolytics. If these drugs also inhibit acetylcholinesterase (AChE) activity, they may contribute to the suppression of AD progression by increasing brain acetylcholine concentrations. We tested the potential inhibitory effects of 31 antidepressants, 21 hypnotics, and 12 anxiolytics on recombinant human AChE (rhAChE) activity. At a concentration of 10-4 M, 22 antidepressants, 19 hypnotics, and 11 anxiolytics inhibited rhAChE activity by <20%, whereas nine antidepressants (clomipramine, amoxapine, setiptiline, nefazodone, paroxetine, sertraline, citalopram, escitalopram, and mirtazapine), two hypnotics (triazolam and brotizolam), and one anxiolytic (buspirone) inhibited rhAChE activity by ≥20%. Brotizolam (≥10-6 M) exhibited stronger inhibition of rhAChE activity than the other drugs, with its pIC50 value being 4.57 ± 0.02. The pIC50 values of the other drugs were <4, and they showed inhibitory activities toward rhAChE at the following concentrations: ≥3 × 10-6 M (sertraline and buspirone), ≥10-5 M (amoxapine, nefazodone, paroxetine, citalopram, escitalopram, mirtazapine, and triazolam), and ≥3 × 10-5 M (clomipramine and setiptiline). Among these drugs, only nefazodone inhibited rhAChE activity within the blood concentration range achievable at clinical doses. Therefore, nefazodone may not only improve the depressive symptoms of BPSD through its antidepressant actions but also slow the progression of cognitive symptoms of AD through its AChE inhibitory actions.

Platelet-activating factor (PAF) enhances guinea pig detrusor smooth muscle contractile activities by stimulating voltage-dependent Ca2+ channels and store-operated Ca2+ channels.

We investigated the extracellular Ca2+ influx pathways involved in platelet-activating factor (PAF)-enhanced guinea pig detrusor smooth muscle (DSM) contractile activities. One micromolar PAF-enhanced DSM contractile activities were completely inhibited by extracellular Ca2+ removal and strongly suppressed by voltage-dependent Ca2+ channel (VDCC) inhibitors. PAF-enhanced DSM contractile activities remaining in the presence of verapamil (10 µM) were not inhibited by LOE-908 (30 µM, an inhibitor of receptor-operated Ca2+ channels (ROCCs)), but were almost completely inhibited by SKF-96365 (30 µM, an inhibitor of store-operated Ca2+ channels (SOCCs) and ROCCs). These results suggest that VDCCs and SOCCs are responsible for PAF-enhanced DSM contractile activities.

Pharmacological study on the enhancing effects of U46619 on guinea pig urinary bladder smooth muscle contraction induced by acetylcholine and α,ß-methylene ATP and the possible involvement of protein kinase C.

We examined whether U46619 (a prostanoid TP receptor agonist) could enhance the contractions of guinea pig urinary bladder smooth muscle (UBSM) in response to acetylcholine (ACh) and an ATP analog (α,ß-methylene ATP (αß-MeATP)) through stimulation of the UBSM TP receptor and whether protein kinase C (PKC) is involved. U46619 (10-7 M) markedly enhanced UBSM contractions induced by electrical field stimulation and ACh/αß-MeATP (3 × 10-6 M each), the potentiation of which was completely suppressed by SQ 29,548 (a TP receptor antagonist, 6 × 10-7 M). PKC inhibitors did not attenuate the ACh-induced contractions enhanced by U46619 although they partly suppressed the U46619-enhanced, αß-MeATP-induced contractions. While phorbol 12-myristate 13-acetate (PMA, a PKC activator, 10-6 M) did not enhance ACh-induced contractions, it enhanced αß-MeATP-induced contractions, an effect that was completely suppressed by PKC inhibitors. αß-MeATP-induced contractions, both with and without U46619 enhancement, were strongly inhibited by diltiazem. U46619/PMA enhanced 50 mM KCl-induced contractions, the potentiation of which was partly/completely attenuated by PKC inhibitors. These findings suggest that U46619 potentiates parasympathetic nerve-associated UBSM contractions by stimulating UBSM TP receptors. PKC-increased Ca2+ influx through voltage-dependent Ca2+ channels may partially play a role in purinergic receptor-mediated UBSM contractions enhanced by TP receptor stimulation.

Pharmacological Studies on the Ca2+ Influx Pathways in Platelet-Activating Factor (PAF)-Induced Mouse Urinary Bladder Smooth Muscle Contraction.

Platelet-activating factor (PAF) not only acts as a mediator of platelet aggregation, inflammation, and allergy responses but also as a constrictor of various smooth muscle (SM) tissues, including gastrointestinal, tracheal/bronchial, and pregnancy uterine SMs. Previously, we reported that PAF induces basal tension increase (BTI) and oscillatory contraction (OC) in mouse urinary bladder SM (UBSM). In this study, we examined the Ca2+ influx pathways involved in PAF-induced BTI and OC in the mouse UBSM. PAF (10-6 M) induced BTI and OC in mouse UBSM. However, the PAF-induced BTI and OC were completely suppressed by extracellular Ca2+ removal. PAF-induced BTI and OC frequencies were markedly suppressed by voltage-dependent Ca2+ channel (VDCC) inhibitors (verapamil (10-5 M), diltiazem (10-5 M), and nifedipine (10-7 M)). However, these VDCC inhibitors had a minor effect on the PAF-induced OC amplitude. The PAF-induced OC amplitude in the presence of verapamil (10-5 M) was strongly suppressed by SKF-96365 (3 × 10-5 M), an inhibitor of receptor-operated Ca2+ channel (ROCC) and store-operated Ca2+ channel (SOCC), but not by LOE-908 (3 × 10-5 M) (an inhibitor of ROCC). Overall, PAF-induced BTI and OC in mouse UBSM depend on Ca2+ influx and the main Ca2+ influx pathways in PAF-induced BTI and OC may be VDCC and SOCC. Of note, VDCC may be involved in PAF-induced BTI and OC frequency, and SOCC might be involved in PAF-induced OC amplitude.

Dimethyl Sulfoxide Enhances Acetylcholine-Induced Contractions in Rat Urinary Bladder Smooth Muscle by Inhibiting Acetylcholinesterase Activities.

Dimethyl sulfoxide (DMSO) has been used not only as an experimental solvent, but also as a therapeutic agent for interstitial cystitis. The therapeutic effects of DMSO on interstitial cystitis are presumed to involve anti-inflammatory and analgesic effects. However, the effects of DMSO on urinary bladder smooth muscle (UBSM) have not been fully investigated. Thus, in this study, we investigated the effects of DMSO on rat UBSM contractions, and these effects were compared with those of acetone, which has a structure in which the sulfur of DMSO is replaced with carbon. DMSO (0.5-5%) enhanced acetylcholine (ACh)-induced contractions, whereas acetone (3 and 5%) suppressed them. Additionally, DMSO (5%) suppressed carbachol-induced contractions. DMSO/acetone (0.5-5%) inhibited 80 mM KCl-induced contractions in a concentration-dependent manner; however, the inhibitory effects of DMSO were weaker than those of acetone. The enhancing/suppressing effects of DMSO and acetone were almost completely abolished by wash out. DMSO and acetone (0.5-5%) inhibited recombinant human acetylcholinesterase (rhAChE) activity in a concentration-dependent manner. At 0.5 and 1%, the inhibitory effects of DMSO on rhAChE activity were more potent than those of acetone. These findings suggest that DMSO can enhance ACh-induced UBSM contractions and promote urinary bladder motility by inhibiting acetylcholinesterase (AChE), although DMSO also inhibits Ca2+ influx-mediated UBSM contractions. In addition, the sulfur atom in DMSO might play an important role in its enhancing effect on ACh-induced contractions by inhibiting AChE, as acetone did not enhance these contractions.

Phenylephrine-Induced Contraction in Guinea Pig Thoracic Aorta Is Triggered by Stimulation of α1L-Adrenoceptors Functionally Coupled with Store-Operated Ca2+ Channels and Voltage-Dependent Ca2+ Channels.

We examined whether the α1L-adrenoceptor (AR), which shows low affinity (pA2 < 9) for prazosin (an α1-AR antagonist) and high affinity (pA2 ≈ 10) for tamsulosin/silodosin (α1A-AR antagonists), is involved in phenylephrine-induced contractions in the guinea pig (GP) thoracic aorta (TA). Intracellular signaling induced by α1L-AR activation was also examined by focusing on Ca2+ influx pathways. Tension changes of endothelium-denuded TAs were isometrically recorded and mRNA encoding α-ARs/Ca2+ channels and their related molecules were measured using RT-quantitative PCR. Phenylephrine-induced contractions were competitively inhibited by prazosin/tamsulosin, and their pA2 value were calculated to be 8.53/9.74, respectively. These contractions were also inhibited by silodosin concentration-dependently. However, the inhibition was not competitive fashion with the apparent pA2 value being 9.48. In contrast, phenylephrine-induced contractions were not substantially suppressed by L-765314 (an α1B-AR antagonist), BMY 7378 (an α1D-AR antagonist), yohimbine, and idazoxan (α2-AR antagonists). Phenylephrine-induced contractions were markedly inhibited by YM-254890 (a Gq protein inhibitor) or removal of extracellular Ca2+, and partially inhibited by verapamil (a voltage-dependent Ca2+ channel (VDCC) inhibitor). The residual contractions in the presence of verapamil were slightly inhibited by LOE 908 (a receptor-operated Ca2+ channel (ROCC) inhibitor) and strongly inhibited by SKF-96365 (a store-operated Ca2+ channel (SOCC) and ROCC inhibitor). Among the mRNA encoding α-ARs/SOCC-related molecules, α1A-AR (Adra1a)/Orai3, Orai1, and Stim2 were abundant in this tissue. In conclusion, phenylephrine-induced contractions in the GP TA can be triggered by stimulation of Gq protein-coupled α1L-AR, followed by activation of SOCCs and VDCCs.

Effects of NP-1815-PX, a P2X4 Receptor Antagonist, on Contractions in Guinea Pig Tracheal and Bronchial Smooth Muscles.

Administration of a P2X4 receptor antagonist to asthma model mice improved asthma symptoms, suggesting that P2X4 receptor antagonists may be new therapeutics for asthma. However, the effects of these antagonists on tracheal/bronchial smooth muscle (TSM and BSM) have not been investigated. This study examined the effects of NP-1815-PX, a selective P2X4 receptor antagonist, on guinea pig TSM and BSM contractions. In epithelium-intact TSM, NP-1815-PX (10-5 M) strongly suppressed ATP-induced contractions. ATP-induced contractions were strongly suppressed by indomethacin (3 × 10-6 M) and ONO-8130 (a prostanoid EP1 receptor antagonist, 10-7 M). ATP-induced contractions were partially suppressed by SQ 29,548 (a prostanoid TP receptor antagonist, 3 × 10-7 M), although the difference was not significant. In contrast, ATP-induced contractions were not affected by AL 8810 (a prostanoid FP receptor antagonist, 10-5 M) or L-798,106 (a prostanoid EP3 receptor antagonist, 10-8 M). NP-1815-PX (10-5-10-4 M) strongly suppressed U46619 (a TP receptor agonist)- and prostaglandin F2α (PGF2α)-induced epithelium-denuded TSM and BSM contractions, which were largely inhibited by SQ 29,548. Additionally, NP-1815-PX (10-5-10-4 M) strongly suppressed the U46619-induced increase in intracellular Ca2+ concentrations in human TP receptor-expressing cells. However, NP-1815-PX (10-4 M) did not substantially inhibit the TSM/BSM contractions induced by carbachol, histamine, neurokinin A, or 50 mM KCl. These findings indicate that NP-1815-PX inhibits guinea pig TSM and BSM contractions mediated through the TP receptor, in addition to the P2X4 receptor, whose stimulation mainly induces EP1 receptor-related mechanisms. Thus, these findings support the usefulness of NP-1815-PX as a therapeutic drug for asthma.

Docosahexaenoic Acid Selectively Suppresses U46619- and PGF2α-Induced Contractions in Guinea Pig Tracheal Smooth Muscles.

We investigated the potential inhibitory effects of docosahexaenoic acid (DHA) on the contractions of guinea pig tracheal smooth muscles in response to U46619 (a thromboxane A2 (TXA2) mimetic) and prostaglandin F2α (PGF2α) to examine whether this n-3 polyunsaturated fatty acid suppresses prostanoid-induced tracheal contractions. DHA (3 × 10-5 M) significantly suppressed tracheal contractions elicited by lower concentrations of U46619 (10-8 M) and PGF2α (5 × 10-7 M) (vs. control), although it did not suppress the contractions induced by higher concentrations (U46619: 10-7 M; PGF2α: 10-5 M). Supporting these findings, DHA (4 × 10-5 M/6 × 10-5 M) shifted the concentration-response curves for U46619 (10-9-10-6 M) and PGF2α (10-8-10-5 M) to the right. However, the slope of the regression line in the Schild plot of DHA vs. U46619/PGF2α was larger than unity. The tracheal contractions induced by U46619 (10-8 M) and PGF2α (5 × 10-7 M) were significantly suppressed by the prostanoid TP receptor antagonist SQ 29,548 (10-6 M) (vs. ethanol-treated). In contrast, DHA (4 × 10-5 M) did not show significant inhibitory effects on the contractions induced by acetylcholine (10-8-10-4 M), histamine (10-8-10-4 M), and leukotriene D4 (10-11-10-7 M) (vs. ethanol-treated). These findings indicate that DHA selectively suppresses tracheal contractions induced by U46619 and PGF2α. Therefore, DHA may be a useful therapeutic agent against asthma associated with tracheal/bronchial hyper-constriction caused by prostanoids including TXA2 and PGF2α.

The Rim101 pathway mediates adaptation to external alkalization and altered lipid asymmetry: hypothesis describing the detection of distinct stresses by the Rim21 sensor protein.

Yeast cells adapt to alkaline conditions by activating the Rim101 alkali-responsive pathway. Rim21 acts as a sensor in the Rim101 pathway and detects extracellular alkalization. Interestingly, Rim21 is also known to be activated by alterations involving the lipid asymmetry of the plasma membrane. In this study, we briefly summarize the mechanism of activation and the signal transduction cascade of the Rim101 pathway and propose a hypothesis on how Rim21 is able to detect distinct signals, particularly external alkalization, and altered lipid asymmetry. We found that external alkalization can suppress transbilayer movements of phospholipids between the two leaflets of the plasma membrane, which may lead to the disturbance of the lipid asymmetry of the plasma membrane. Therefore, we propose that external alteration is at least partly sensed by Rim21 through alterations in lipid asymmetry. Understanding this activation mechanism could greatly contribute to drug development against fungal infections.

Rapid turnover of transcription factor Rim101 confirms a flexible adaptation mechanism against environmental stress in Saccharomyces cerevisiae.

Saccharomyces cerevisiae cells activate the Rim101 pathway to adapt to alkaline and salt stresses. On activation of this pathway, the transcription factor Rim101 undergoes proteolytic activation and regulates the expression of responsive genes. We found Rim101 to be a short-lived protein with a half-life of approximately 15 min. Its rapid turnover was supposedly mediated by the ubiquitin-proteasome system. Excess accumulation of the processed active Rim101 through its over-expression conferred tolerance to both alkaline and salt stresses in yeast cells; in contrast, it had detrimental effects under cadmium stress condition. Cadmium ion inhibited proteolytic activation of Rim101, implying reciprocal interaction between the Rim101 pathway and cadmium stress. Our results showed yeast cells to be equipped with two protective systems to prevent overaccumulation of the processed active Rim101; Rim101 processing is inhibited when Rim101 level is high, and turnover of processed Rim101 is accelerated when it is abundant. Collectively, the results confirmed the flexible aspect of stress response in yeast cell; the cells not only prevent excess activation of one stress-responsive pathway but also facilitate its attenuation to cope with other environmental stresses.

Docosahexaenoic Acid and Eicosapentaenoic Acid Inhibit the Contractile Responses of the Guinea Pig Lower Gastrointestinal Tract.

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are n-3 polyunsaturated fatty acids (PUFAs), and are abundant in fish oil. These n-3 PUFAs have been reported to improve the lower gastrointestinal (LGI) disorders such as ulcerative colitis and Crohn's disease through their anti-inflammatory effects. However, there are few studies on the effect of n-3 PUFAs on motility of the LGI tract, such as the ileum and colon, the parts frequently affected by these inflammatory disorders. To elucidate the effects of DHA and EPA on the LGI tract motility, we performed comparative evaluation of their effects and linoleic acid (LA), an n-6 PUFA, on contractions in the ileal and colonic longitudinal smooth muscles (LSMs) isolated from guinea pigs. In the ileal and colonic LSMs, DHA and EPA (3 × 10-5 M each) significantly inhibited contractions induced by acetylcholine (ACh), histamine, and prostaglandin (PG) F2α (vs. control), and these effects are stronger than that of LA (3 × 10-5 M). In the colonic LSMs, DHA and EPA also significantly inhibited contractions induced by PGD2 (vs. control). In addition, DHA and EPA significantly inhibited CaCl2-induced ileal and colonic LSM contractions in Ca2+-free 80 mM-KCl solution (vs. control). Any ileal and colonic LSM contractions induced by ACh, histamine, PGF2α, and CaCl2 were completely suppressed by verapamil (10-5 M), a voltage-gated/dependent Ca2+ channel (VGCC/VDCC) inhibitor. These findings suggest that DHA and EPA could improve the abnormal contractile functions of the LGI tract associated with inflammatory diseases, partly through inhibition of VGCC/VDCC-dependent ileal and colonic LSM contractions.

Inhibitory Effects of Antipsychotics on the Contractile Response to Acetylcholine in Rat Urinary Bladder Smooth Muscles.

The clinical applications of antipsychotics for symptoms unrelated to schizophrenia, such as behavioral and psychological symptoms, in patients with Alzheimer's disease, and the likelihood of doctors prescribing antipsychotics for elderly people are increasing. In elderly people, drug-induced and aging-associated urinary disorders are likely to occur. The most significant factor causing drug-induced urinary disorders is a decrease in urinary bladder smooth muscle (UBSM) contraction induced by the anticholinergic action of therapeutics. However, the anticholinergic action-associated inhibitory effects of antipsychotics on UBSM contraction have not been sufficiently assessed. In this study, we examined 26 clinically available antipsychotics to determine the extent to which they inhibit acetylcholine (ACh)-induced contraction in rat UBSM to predict the drugs that should not be used by elderly people to avoid urinary disorders. Of the 26 antipsychotics, six (chlorpromazine, levomepromazine (phenothiazines), zotepine (a thiepine), olanzapine, quetiapine, clozapine (multi-acting receptor targeted antipsychotics (MARTAs))) competitively inhibited ACh-induced contractions at concentrations corresponding to clinically significant doses. Further, 11 antipsychotics (perphenazine, fluphenazine, prochlorperazine (phenothiazines), haloperidol, bromperidol, timiperone, spiperone (butyrophenones), pimozide (a diphenylbutylpiperidine), perospirone, blonanserin (serotonin-dopamine antagonists; SDAs), and asenapine (a MARTA)) significantly suppressed ACh-induced contraction; however, suppression occurred at concentrations substantially exceeding clinically achievable blood levels. The remaining nine antipsychotics (pipamperone (a butyrophenone), sulpiride, sultopride, tiapride, nemonapride (benzamides), risperidone, paliperidone (SDAs), aripiprazole, and brexpiprazole (dopamine partial agonists)) did not inhibit ACh-induced contractions at concentrations up to 10-5 M. These findings suggest that chlorpromazine, levomepromazine, zotepine, olanzapine, quetiapine, and clozapine should be avoided by elderly people with urinary disorders.

N-glycosylation of Rim21 at an Unconventional Site Fine-tunes Its Behavior in the Plasma Membrane.

The polytopic plasma membrane protein Rim21 senses both the elevation of ambient pH and alterations in plasma membrane lipid asymmetry in the Rim101 pathway in budding yeast. Rim21 is known to undergo N-glycosylation, but the site and function of the glycosylation modification is not known. Using a systematic mutation analysis, we found that Rim21 is N-glycosylated at an unconventional motif located in the N-terminal extracellular region. The Rim21 mutant protein that failed to receive N-glycosylation showed prolonged protein lifetime compared to that of WT Rim21 protein. Although both the WT and mutant Rim21 localized to the plasma membrane, they exhibited different biochemical fractionation profiles. The mutant Rim21, but not WT Rim21, was mainly fractionated into the heavy membrane fraction. Further, compared to WT Rim21, mutant Rim21 was more easily solubilized with digitonin but was conversely more resistant to solubilization with Triton X-100. Despite these different biochemical properties from WT Rim21, mutant Rim21 protein could still activate the Rim101 pathway in response to external alkalization. Collectively, N-glycosylation of Rim21 is not indispensable for its activity as a sensor protein, but modulates the residence of Rim21 protein to some microdomains within the plasma membrane with distinct lipid conditions, thereby affecting its turnover.Key words: plasma membrane, lipid asymmetry, N-linked glycosylation, microdomain, Saccharomyces cerevisiae.

Effects of Catecholamine Metabolites on Beta-Adrenoceptor-Mediated Relaxation of Smooth Muscle: Evaluation in Mouse and Guinea-Pig Trachea and Rat Aorta.

The ß-adrenoceptor (ß-AR)-mediated pharmacological effects of catecholamine (CA) metabolites are not well known. We examined the effects of seven CA metabolites on smooth muscle relaxation in mouse and guinea pig (GP) tracheas and rat thoracic aorta. Among them, metadrenaline (MA) significantly relaxed GP trachea (ß2-AR dominant), even in the presence of clorgiline, a monoamine oxidase-A inhibitor. In mouse trachea (ß1-AR dominant), normetadrenaline (NMA) and MA (10-4 M each) apparently did not affect isoprenaline (ISO)-induced relaxation, but significantly inhibited it in the presence of clorgiline. ISO-induced relaxation was also unaffected by 3,4-dihydroxyphenylglycol (DHPG) (10-4 M), but significant suppression was observed with the addition of 3,5-dinitrocatechol, a catechol-O-methyltransferase inhibitor. In GP trachea, NMA, MA, 3,4-dihydroxymandelic acid (DOMA), and DHPG (10-4 M each) significantly augmented ISO-induced relaxation. However, in the presence of clorgiline plus 3,5-dinitrocatechol, both NMA and MA (10-4 M) significantly suppressed ISO-induced relaxation. DHPG (10-4 M) also significantly suppressed ISO-induced relaxation in the presence of 3,5-dinitrocatechol. In rat thoracic aorta, DHPG (10-4 M) significantly suppressed relaxation induced by CGP-12177 A (a ß3-AR partial agonist) in the presence of 3,5-dinitrocatechol plus propranolol. Our findings indicate that 1) MA may possess ß2-AR agonistic action; 2) NMA and MA augment ß2-AR-mediated tracheal relaxation in the absence of CA metabolic inhibitors, though themselves possessing ß1-, ß2-AR antagonistic action (ß2 > ß1); 3) DHPG exhibits ß1-, ß2-, ß3-AR antagonistic action, and this is particularly marked for ß3-AR. Our observations may help explain some of the pathologies associated with pheochromocytoma, which is characterized by increased CA metabolite levels.

Sustainable Effects of Distigmine Bromide on Urinary Bladder Contractile Function.

Distigmine bromide (distigmine) is a reversible carbamate cholinesterase (ChE) inhibitor that is used to treat myasthenia gravis. In Japan, it is also used as a remedy for urination disorder (underactive bladder). The most distinctive pharmacological feature of distigmine is its long-lasting action compared to that of other ChE inhibitors. In animals and humans, distigmine was reported to inhibit acetylcholinesterase (AChE) and improve myasthenia gravis for an extended period. Few studies have examined the sustainability of this enhancing effect on the contractile function of urinary bladder smooth muscle. In addition, the cause of this long-lasting feature remains unclear. In this review, we present our findings for the long-lasting feature of distigmine on isolated urinary bladder contraction and in vivo urinary function of guinea pig. We also present our results on the mechanism of its long-lasting sustainability using recombinant human AChE.

Pharmacological Characteristics of Anxiolytics on Acetylcholine-Induced Contractions in Rat Detrusor Smooth Muscle.

INTRODUCTION: Benzodiazepine anxiolytics are believed to cause urination disorders due to their anticholinergic effects. OBJECTIVE: This study was carried out to investigate the potential inhibitory effects of 15 clinically available anxiolytics in Japan on acetylcholine (ACh)-induced contractions in rat detrusor smooth muscle (DSM) to predict whether these anxiolytics could induce urination disorders. METHODS: -Effects of anxiolytics on contractions induced by ACh and 80 mmol/L KCl solution in rat DSM and effects of anxiolytics on specific binding of [N-methyl-3H]scopolamine ([3H]NMS) in mouse cerebral cortex were investigated. RESULTS AND CONCLUSIONS: ACh-induced contractions in rat DSM were inhibited by clotiazepam and diazepam (benzodiazepine anxiolytics) at concentrations that were clinically relevant. These contractions were also significantly inhibited by paroxetine, escitalopram (selective serotonin reuptake inhibitors -[SSRIs]), and hydroxyzine (a histamine H1 receptor antagonist), albeit at concentrations that substantially exceeded clinically achievable blood levels. At a concentration of 10-5 mol/L, paroxetine, escitalopram, and hydroxyzine inhibited 80 mmol/L high-KCl solution-induced rat DSM contractions but not clotiazepam and diazepam. Paroxetine, escitalopram, and hydroxyzine also inhibited specific binding of [3H]NMS in mouse cerebral cortex but clotiazepam and diazepam did not. In contrast to the effects of the abovementioned anxiolytics, ACh-induced contractions were not significantly affected by tofisopam, alprazolam, lorazepam, bromazepam, oxazolam, chlordiazepoxide, clonazepam, ethyl loflazepate (benzodiazepine anxiolytics), fluvoxamine (an SSRI), or tandospirone (a serotonin 5-HT1A receptor agonist). These findings suggest that most clinically used anxiolytics are not likely to result in anticholinergic-induced urination disorders within their clinically achievable blood concentration ranges. However, clotiazepam and diazepam may induce urination disorders within their clinical dose ranges via nonanticholinergic inhibition of DSM contractility.