scholarly journals TORC1 regulates vacuole membrane composition through ubiquitin- and ESCRT-dependent microautophagy

2020 ◽  
Vol 219 (3) ◽  
Author(s):  
Xi Yang ◽  
Weichao Zhang ◽  
Xin Wen ◽  
Patrick J. Bulinski ◽  
Dominic A. Chomchai ◽  
...  
Keyword(s):  
Amino Acids ◽  
Membrane Proteins ◽  
Signaling Cascade ◽  
Complex Relationship ◽  
Membrane Composition ◽  
Down Regulation ◽  
Cellular Adaptation ◽  
Vacuole Membrane ◽  
Lysosome Biogenesis ◽  
Vacuole Biogenesis

Cellular adaptation in response to nutrient limitation requires the induction of autophagy and lysosome biogenesis for the efficient recycling of macromolecules. Here, we discovered that starvation and TORC1 inactivation not only lead to the up-regulation of autophagy and vacuole proteins involved in recycling but also result in the down-regulation of many vacuole membrane proteins to supply amino acids as part of a vacuole remodeling process. Down-regulation of vacuole membrane proteins is initiated by ubiquitination, which is accomplished by the coordination of multiple E3 ubiquitin ligases, including Rsp5, the Dsc complex, and a newly characterized E3 ligase, Pib1. The Dsc complex is negatively regulated by TORC1 through the Rim15-Ume6 signaling cascade. After ubiquitination, vacuole membrane proteins are sorted into the lumen for degradation by ESCRT-dependent microautophagy. Thus, our study uncovered a complex relationship between TORC1 inactivation and vacuole biogenesis.

scholarly journals TORC1 regulates vacuole membrane composition through ubiquitin- and ESCRT-dependent microautophagy

2019 ◽  
Author(s):  
Xi Yang ◽  
Weichao Zhang ◽  
Xin Wen ◽  
Patrick J. Bulinski ◽  
Dominic A. Chomchai ◽  
...  
Keyword(s):  
Amino Acids ◽  
Membrane Proteins ◽  
Nutrient Limitation ◽  
Signaling Cascade ◽  
Complex Relationship ◽  
Membrane Composition ◽  
Cellular Adaptation ◽  
Vacuole Membrane ◽  
Lysosome Biogenesis ◽  
Vacuole Biogenesis

AbstractCellular adaptation in response to nutrient limitation requires the induction of autophagy and lysosome biogenesis for the efficient recycling of macromolecules. Here, we discovered that starvation and TORC1 inactivation not only lead to the upregulation of autophagy and vacuole proteins involved in recycling, but also result in the downregulation of many vacuole membrane proteins to supply amino acids as part of a vacuole remodeling process. Downregulation of vacuole membrane proteins is initiated by ubiquitination, which is accomplished by the coordination of multiple E3 ubiquitin ligases, including Rsp5, the Dsc complex, and a newly characterized E3 ligase, Pib1. The Dsc complex is negatively regulated by TORC1 through the Rim15-Ume6 signaling cascade. After ubiquitination, vacuole membrane proteins are sorted into the lumen for degradation by ESCRT-dependent microautophagy. Thus, our study uncovered a complex relationship between TORC1 inactivation and vacuole biogenesis.

scholarly journals ESCRT, not intralumenal fragments, sorts ubiquitinated vacuole membrane proteins for degradation

2021 ◽  
Vol 220 (8) ◽  
Author(s):  
Xi Yang ◽  
Lucas Reist ◽  
Dominic A. Chomchai ◽  
Liang Chen ◽  
Felichi Mae Arines ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Degradation Process ◽  
Nutrient Sensing ◽  
Imaging Method ◽  
Membrane Composition ◽  
Vacuole Membrane ◽  
Internalization Mechanism ◽  
Vacuole Fusion ◽  
Competing Models

The lysosome (or vacuole in fungi and plants) is an essential organelle for nutrient sensing and cellular homeostasis. In response to environmental stresses such as starvation, the yeast vacuole can adjust its membrane composition by selectively internalizing membrane proteins into the lumen for degradation. Regarding the selective internalization mechanism, two competing models have been proposed. One model suggests that the ESCRT machinery is responsible for the sorting. In contrast, the ESCRT-independent intralumenal fragment (ILF) pathway proposes that the fragment generated by homotypic vacuole fusion is responsible for the sorting. Here, we applied a microfluidics-based imaging method to capture the complete degradation process in vivo. Combining live-cell imaging with a synchronized ubiquitination system, we demonstrated that ILF cargoes are not degraded through intralumenal fragments. Instead, ESCRTs function on the vacuole membrane to sort them into the lumen for degradation. We further discussed challenges in reconstituting vacuole membrane protein degradation.

Sustained endotoxemia leads to marked down-regulation of early steps in the insulin-signaling cascade

2001 ◽  
Vol 29 (4) ◽  
pp. 839-846 ◽  
Author(s):  
Karen C. McCowen ◽  
Pei Ra Ling ◽  
Annamaria Ciccarone ◽  
Yilei Mao ◽  
Jesse C. Chow ◽  
...  
Keyword(s):  
Insulin Signaling ◽  
Signaling Cascade ◽  
Down Regulation

scholarly journals Monitoring mitochondrial translation by pulse SILAC

2021 ◽  
Author(s):  
Koshi Imami ◽  
Matthias Selbach ◽  
Yasushi Ishihama
Keyword(s):  
Oxidative Stress ◽  
Amino Acids ◽  
Membrane Proteins ◽  
Translational Regulation ◽  
Isotope Labeling ◽  
Protein Complexes ◽  
Complex Iii ◽  
Mitochondrial Translation ◽  
Mitochondrial Ribosomes ◽  
Hydrophobic Nature

SummaryMitochondrial ribosomes are specialized to translate the 13 membrane proteins encoded in the mitochondrial genome, but it is challenging to quantify mitochondrial translation products due to their hydrophobic nature. Here, we introduce a proteomic method that combines biochemical isolation of mitochondria with pulse stable isotope labeling by amino acids in cell culture (pSILAC). Our method provides the highest protein coverage (quantifying 12 out of the 13 inner-membrane proteins; average 2-fold improvement over previous studies) with the shortest measurement time. We applied this method to uncover the global picture of (post)translational regulation of both mitochondrial- and nuclear-encoded proteins involved in the assembly of protein complexes that mediate oxidative phosphorylation (OXPHOS). The results allow us to infer the assembly order of complex components and/or partners, as exemplified by complex III. This method should be applicable to study mitochondrial translation programs in many contexts, including oxidative stress and mitochondrial disease.

51 Effects of modulating early luteal phase progestin concentration on endometrial function in early pregnant mares

2019 ◽  
Vol 31 (1) ◽  
pp. 151
Author(s):  
C. Aurich ◽  
T. Beyer ◽  
D. Scarlet
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Progesterone Receptor ◽  
Luteal Phase ◽  
Free Amino ◽  
Progesterone Receptors ◽  
Wilcoxon Test ◽  
Down Regulation ◽  
Once Daily ◽  
Endometrial Epithelium

Progesterone prepares the endometrium for pregnancy. This requires down-regulation of progesterone receptors in the endometrial epithelium as a prerequisite for the expression of pregnancy-associated proteins. We investigated effects of modulated peripheral progestin concentration in early luteal phase mares on endometrial function on Day 14 of pregnancy. Genitally healthy oestrous mares (n=8; age 4 to 14 years) were inseminated until ovulation and treated with either altrenogest (0.044mg kg−1 once daily orally) on Days 5 to 10 after ovulation (ALT), cloprostenol (125mg once daily intramuscularly) on Days 0 to 3 after ovulation (CLO) or left untreated (CON). The ALT and CLO treatments were chosen to increase and decrease total peripheral progestin concentration, respectively. Each treatment was given to every mare in consecutive cycles at random order. On Day 14 after ovulation, endometrial fluid was collected with a cotton roll (Salivette, Sarstedt, Germany) inserted into the uterus and an endometrial biopsy for immunohistological examination was collected. In endometrial fluid, free amino acid concentrations were analysed by ion exchange liquid chromatography with an amino acid analyser (Institut Kuhlmann, Analytik-Zentrum Ludwigshafen, Germany). Cell nuclei staining positive for the progesterone receptor were determined in the luminar and glandular epithelium as well as in the stroma. Statistical analysis was performed by non-parametric Friedman test with subsequent Wilcoxon test. Values are given as mean±standard error of mean. Pregnancy rate was 0.6±0.1 (13 cycles/8 pregnancies), 1.0±0 (8 cycles/8 pregnancies), and 0.7±0.1 (11 cycles/8 pregnancies) in CON, ALT, and CLO cycles, respectively (P=0.062). Conceptus size between Days 10 and 14 did not differ among treatments. The percentage of luminal epithelial cells staining positive for progesterone receptor differed among treatments (CON 72.8±4.1, ALT 70.7±4.7, and CLO 84.1±1.9%; P<0.05) and was higher in CLO than in ALT and CON cycles (P<0.05). Free amino acids glutamic acid and glycine were most abundant in endometrial fluid, but their concentrations did not differ among treatments. The concentrations of the amino acids isoleucine (CON 0.17±0.03, CLO 0.14±0.02, and ALT 0.23±0.04 µmol) and lysine (CON 0.27±0.08, CLO 0.18±0.05, and ALT 0.44±0.13 µmol) were influenced by treatment (P<0.05) and lower in CLO than in ALT and CON cycles. In conclusion, impaired luteal function due to CLO treatment during the early luteal phase of pregnant mares delayed down-regulation of progesterone receptors in the endometrial epithelium on Day 14. This influenced endometrial function as reflected in lower concentrations of the amino acids lysine and isoleucine in endometrial secretions.

scholarly journals A new family of integral membrane proteins involved in transport of aromatic amino acids in Escherichia coli.

1991 ◽  
Vol 173 (10) ◽  
pp. 3231-3234 ◽  
Author(s):  
J P Sarsero ◽  
P J Wookey ◽  
P Gollnick ◽  
C Yanofsky ◽  
A J Pittard
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Membrane Proteins ◽  
Aromatic Amino Acids ◽  
Integral Membrane Proteins ◽  
New Family

scholarly journals Role of the Transmembrane Domain and Flanking Amino Acids in Internalization and Down-regulation of the Insulin Receptor

1995 ◽  
Vol 270 (7) ◽  
pp. 3115-3122 ◽  
Author(s):  
Kazunori Yamada ◽  
Jean-Louis Carpentier ◽  
Bentley Cheatham ◽  
Edison Goncalves ◽  
Steven E. Shoelson ◽  
...  
Keyword(s):  
Amino Acids ◽  
Insulin Receptor ◽  
Transmembrane Domain ◽  
Down Regulation

scholarly journals Negatively charged amino acids in the stalk region of membrane proteins reduce ectodomain shedding

2020 ◽  
Vol 295 (35) ◽  
pp. 12343-12352 ◽  
Author(s):  
Ryo Iwagishi ◽  
Rika Tanaka ◽  
Munenosuke Seto ◽  
Tomoyo Takagi ◽  
Naoko Norioka ◽  
...  
Keyword(s):  
Amino Acids ◽  
Membrane Proteins ◽  
Molecular Mechanisms ◽  
Alternative Exon ◽  
Ectodomain Shedding ◽  
Post Translational Modification ◽  
Charged Amino Acids ◽  
Juxtamembrane Region ◽  
Protein Variants ◽  
Variant Protein

Ectodomain shedding is a post-translational modification mechanism by which the entire extracellular domain of membrane proteins is liberated through juxtamembrane processing. Because shedding rapidly and irreversibly alters the characteristics of cells, this process is properly regulated. However, the molecular mechanisms governing the propensity of membrane proteins to shedding are largely unknown. Here, we present evidence that negatively charged amino acids within the stalk region, an unstructured juxtamembrane region at which shedding occurs, contribute to shedding susceptibility. We show that two activated leukocyte cell adhesion molecule (ALCAM) protein variants produced by alternative splicing have different susceptibilities to ADAM metallopeptidase domain 17 (ADAM17)-mediated shedding. Of note, the inclusion of a stalk region encoded by a 39-bp-long alternative exon conferred shedding resistance. We found that this alternative exon encodes a large proportion of negatively charged amino acids, which we demonstrate are indispensable for conferring the shedding resistance. We also show that the introduction of negatively charged amino acids into the stalk region of shedding-susceptible ALCAM variant protein attenuates its shedding. Furthermore, we observed that negatively charged amino acids residing in the stalk region of Erb-B2 receptor tyrosine kinase 4 (ERBB4) are indispensable for its shedding resistance. Collectively, our results indicate that negatively charged amino acids within the stalk region interfere with the shedding of multiple membrane proteins. We conclude that the composition of the stalk region determines the shedding susceptibility of membrane proteins.

Down-regulation of neutrophil functions by the ELR+CXC chemokine platelet basic protein

Blood ◽  
2000 ◽  
Vol 96 (9) ◽  
pp. 2965-2972 ◽  
Author(s):  
Jan E. Ehlert ◽  
Andreas Ludwig ◽  
Tobias A. Grimm ◽  
Buko Lindner ◽  
Hans-Dieter Flad ◽  
...  
Keyword(s):  
Amino Acids ◽  
Binding Sites ◽  
Chemokine Receptors ◽  
Cell Activation ◽  
Basic Protein ◽  
Cathepsin G ◽  
Terminal Part ◽  
Down Regulation ◽  
Cxc Chemokine ◽  
Continuous Accumulation

Abstract The platelet-derived neutrophil-activating peptide 2 (NAP-2, 70 amino acids) belongs to the ELR+ CXC subfamily of chemokines. Similar to other members of this group, such as IL-8, NAP-2 activates chemotaxis and degranulation in neutrophils (polymorphonuclear [PMN]) through chemokine receptors CXCR-1 and CXCR-2. However, platelets do not secrete NAP-2 as an active chemokine but as the C-terminal part of several precursors that lack PMN-stimulating capacity. As we have previously shown, PMN themselves may liberate NAP-2 from the precursor connective tissue-activating peptide III (CTAP-III, 85 amino acids) by proteolysis. Instead of inducing cell activation, continuous accumulation of the chemokine in the surroundings of the processing cells results in the down-regulation of specific surface-expressed NAP-2 binding sites and in the desensitization of chemokine-induced PMN degranulation. Thus, NAP-2 precursors may be regarded as indirect mediators of functional desensitization in neutrophils. In the current study we investigated the biologic impact of another major NAP-2 precursor, the platelet basic protein (PBP, 94 amino acids). We show that PBP is considerably more potent than CTAP-III to desensitize degranulation and chemotaxis in neutrophils. We present data suggesting that the high desensitizing capacity of PBP is based on its enhanced proteolytic cleavage into NAP-2 by neutrophil-expressed cathepsin G and that it involves efficient down-regulation of surface-expressed CXCR-2 while CXCR-1 is hardly affected. Correspondingly, we found PBP and, less potently, CTAP-III to inhibit CXCR-2– but not CXCR-1– dependent chemotaxis of neutrophils toward NAP-2. Altogether our findings demonstrate that the anti-inflammatory capacity of NAP-2 is governed by the species of its precursors.

scholarly journals Analysis of the interactions of sulfur-containing amino acids in membrane proteins

2016 ◽  
Vol 25 (8) ◽  
pp. 1517-1524 ◽  
Author(s):  
José C. Gómez-Tamayo ◽  
Arnau Cordomí ◽  
Mireia Olivella ◽  
Eduardo Mayol ◽  
Daniel Fourmy ◽  
...  
Keyword(s):  
Amino Acids ◽  
Membrane Proteins ◽  
Sulfur Containing
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