scholarly journals The Tumor-sensitive Calmodulin-like Protein Is a Specific Light Chain of Human Unconventional Myosin X

2001 ◽  
Vol 276 (15) ◽  
pp. 12182-12189 ◽  
Author(s):  
Michael S. Rogers ◽  
Emanuel E. Strehler
Keyword(s):  
Light Chain ◽  
Membrane Trafficking ◽  
Cell Periphery ◽  
Dependent Manner ◽  
Unconventional Myosin ◽  
Iq Motif ◽  
Cellular Processes ◽  
Cell Growth And Differentiation ◽  
Myosin X

Human calmodulin-like protein (CLP) is an epithelial-specific Ca2+-binding protein whose expression is strongly down-regulated in cancers. Like calmodulin, CLP is thought to regulate cellular processes via Ca2+-dependent interactions with specific target proteins. Using gel overlays, we identified a ∼210-kDa protein binding specifically and in a Ca2+-dependent manner to CLP, but not to calmodulin. Yeast two-hybrid screening yielded a CLP-interacting clone encoding the three light chain binding IQ motifs of human “unconventional” myosin X. Pull-down experiments showed CLP binding to the IQ domain to be direct and Ca2+-dependent. CLP interacted strongly with IQ motif 3 (Kd∼0.5 nm) as determined by surface plasmon resonance. Epitope-tagged myosin X was localized preferentially at the cell periphery in MCF-7 cells, and CLP colocalized with myosin X in these cells. Myosin X was able to coprecipitate CLP and, to a lesser extent, calmodulin from transfected COS-1 cells, indicating that CLP is a specific light chain of myosin Xin vivo. Because unconventional myosins participate in cellular processes ranging from membrane trafficking to signaling and cell motility, myosin X is an attractive CLP target. Altered myosin X regulation in (tumor) cells lacking CLP may have as yet unknown consequences for cell growth and differentiation.

Physical exercise increases autophagic signaling through ULK1 in human skeletal muscle

2015 ◽  
Vol 118 (8) ◽  
pp. 971-979 ◽  
Author(s):  
Andreas Buch Møller ◽  
Mikkel Holm Vendelbo ◽  
Britt Christensen ◽  
Berthil Forrest Clasen ◽  
Ann Mosegaard Bak ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Physical Exercise ◽  
Light Chain ◽  
Human Skeletal Muscle ◽  
Transgenic Animal ◽  
Dependent Manner ◽  
Healthy Humans ◽  
Transgenic Animal Models ◽  
Exercise Induced

Data from transgenic animal models suggest that exercise-induced autophagy is critical for adaptation to physical training, and that Unc-51 like kinase-1 (ULK1) serves as an important regulator of autophagy. Phosphorylation of ULK1 at Ser555 stimulates autophagy, whereas phosphorylation at Ser757 is inhibitory. To determine whether exercise regulates ULK1 phosphorylation in humans in vivo in a nutrient-dependent manner, we examined skeletal muscle biopsies from healthy humans after 1-h cycling exercise at 50% maximal O2 uptake on two occasions: 1) during a 36-h fast, and 2) during continuous glucose infusion at 0.2 kg/h. Physical exercise increased ULK1 phosphorylation at Ser555 and decreased lipidation of light chain 3B. ULK1 phosphorylation at Ser555 correlated positively with AMP-activated protein kinase-α Thr172 phosphorylation and negatively with light chain 3B lipidation. ULK1 phosphorylation at Ser757 was not affected by exercise. Fasting increased ULK1 and p62 protein expression, but did not affect exercise-induced ULK1 phosphorylation. These data demonstrate that autophagy signaling is activated in human skeletal muscle after 60 min of exercise, independently of nutritional status, and suggest that initiation of autophagy constitutes an important physiological response to exercise in humans.

scholarly journals The Ubiquitin Carboxyl Hydrolase BAP1 Forms a Ternary Complex with YY1 and HCF-1 and Is a Critical Regulator of Gene Expression

2010 ◽  
Vol 30 (21) ◽  
pp. 5071-5085 ◽  
Author(s):  
Helen Yu ◽  
Nazar Mashtalir ◽  
Salima Daou ◽  
Ian Hammond-Martel ◽  
Julie Ross ◽  
...  
Keyword(s):  
Gene Expression ◽  
Ternary Complex ◽  
Transcriptional Control ◽  
Molecular Mechanisms ◽  
Mitochondrial Protein ◽  
Coiled Coil ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Rich Domain

ABSTRACT The candidate tumor suppressor BAP1 is a deubiquitinating enzyme (DUB) involved in the regulation of cell proliferation, although the molecular mechanisms governing its function remain poorly defined. BAP1 was recently shown to interact with and deubiquitinate the transcriptional regulator host cell factor 1 (HCF-1). Here we show that BAP1 assembles multiprotein complexes containing numerous transcription factors and cofactors, including HCF-1 and the transcription factor Yin Yang 1 (YY1). Through its coiled-coil motif, BAP1 directly interacts with the zinc fingers of YY1. Moreover, HCF-1 interacts with the middle region of YY1 encompassing the glycine-lysine-rich domain and is essential for the formation of a ternary complex with YY1 and BAP1 in vivo. BAP1 activates transcription in an enzymatic-activity-dependent manner and regulates the expression of a variety of genes involved in numerous cellular processes. We further show that BAP1 and HCF-1 are recruited by YY1 to the promoter of the cox7c gene, which encodes a mitochondrial protein used here as a model of BAP1-activated gene expression. Our findings (i) establish a direct link between BAP1 and the transcriptional control of genes regulating cell growth and proliferation and (ii) shed light on a novel mechanism of transcription regulation involving ubiquitin signaling.

Recombinant Rat Protein C: Comparative Studies of Structure, Function and Synthesis with Plasma Protein C

1994 ◽  
Vol 71 (01) ◽  
pp. 054-061 ◽  
Author(s):  
Mayumi Ono ◽  
Hiroyuki Fujiwara ◽  
Takaaki Okafuji ◽  
Tomoko Enjoh ◽  
Katsuhiko Nawa
Keyword(s):  
Heavy Chain ◽  
Light Chain ◽  
Protein C ◽  
Rat Hepatocytes ◽  
Rat Plasma ◽  
Chain Molecule ◽  
Dependent Manner ◽  
Single Chain

SummaryIn order to elucidate the role of protein C (PC) in the rat, we expressed, purified, and characterized recombinant rat PC. The purified recombinant rat PC was 70–90% two-chain (41 kDa heavy chain; 22 and 23 kDa light chain) and 10–30% single-chain (61 kDa). Amino acid analysis confirmed the presence of 10 moles of γ-carboxyglutamic acid residues per mol of protein. For comparison, plasma rat PC was purified from a barium citrate precipitate using similar method. Plasma rat PC was a two-chain form (41 kDa heavy chain; 22 kDa light chain) with no detectable single-chain nor 23 kDa light chain. For determination of the in vitro secreted species, primary cultured rat hepatocytes were incubated for 6 h with methionine-free MEM containing vitamin K1, aprotinin, and [35S]methionine. The supernatant was immunoprecipitated and analyzed by SDS-PAGE followed by autoradiography. Approximately 90% of the PC radioactivity migrated as a two-chain molecule. These results indicate that rat PC is secreted mainly as a two-chain molecule from the liver. PROTAC-activated forms of recombinant rat PC, plasma rat PC, and plasma human PC hydrolyzed the S-2366 chromogenic substrate at the same rate Recombinant rat PC was also activated by the thrombin-thrombomodulin complex at a rate similar to plasma lat PC. The anticoagulant activities of the three activated PCs were examined in rat plasma. Both recombinant and plasma rat PC prolonged the activated partial thromboplastin time in a dose-dependent manner, but plasma human PC was less effective. These results suggest that recombinant rat PC is applicable for in vivo thrombosis studies in the rat.

The interaction of IQGAPs with calmodulin-like proteins

2011 ◽  
Vol 39 (2) ◽  
pp. 694-699 ◽  
Author(s):  
Sevvel Pathmanathan ◽  
Elaine Hamilton ◽  
Erwan Atcheson ◽  
David J. Timson
Keyword(s):  
Protein Interactions ◽  
Light Chain ◽  
Protein Protein Interactions ◽  
Iq Motif ◽  
Calcium Dependent ◽  
Essential Light Chain ◽  
Cellular Processes ◽  
Wide Range ◽  
Related Proteins ◽  
Do So

Since their identification over 15 years ago, the IQGAP (IQ-motif-containing GTPase-activating protein) family of proteins have been implicated in a wide range of cellular processes, including cytoskeletal reorganization, cell–cell adhesion, cytokinesis and apoptosis. These processes rely on protein–protein interactions, and understanding these (and how they influence one another) is critical in determining how the IQGAPs function. A key group of interactions is with calmodulin and the structurally related proteins myosin essential light chain and S100B. These interactions occur primarily through a series of IQ motifs, which are α-helical segments of the protein located towards the middle of the primary sequence. The three human IQGAP isoforms (IQGAP1, IQGAP2 and IQGAP3) all have four IQ motifs. However, these have different affinities for calmodulin, myosin light chain and S100B. Whereas all four IQ motifs of IQGAP1 interact with calmodulin in the presence of calcium, only the last two do so in the absence of calcium. IQ1 (the first IQ motif) interacts with the myosin essential light chain Mlc1sa and the first two undergo a calcium-dependent interaction with S100B. The significance of the interaction between Mlc1sa and IQGAP1 in mammals is unknown. However, a similar interaction involving the Saccharomyces cerevisiae IQGAP-like protein Iqg1p is involved in cytokinesis, leading to speculation that there may be a similar role in mammals.

Effect of thyroid state on cardiac myosin P-light chain phosphorylation during exercise

1990 ◽  
Vol 69 (1) ◽  
pp. 313-320 ◽  
Author(s):  
D. P. Fitzsimons ◽  
P. W. Bodell ◽  
R. E. Herrick ◽  
K. M. Baldwin
Keyword(s):  
Light Chain ◽  
Myocardial Function ◽  
Fold Increase ◽  
Cardiac Myosin ◽  
Thyroid State ◽  
Cellular Processes ◽  
Myosin Light Chain 2 ◽  
Normal Controls ◽  
Rest And Exercise

This study ascertained the effects of thyroid deficiency (TD) and hyperthyroidism (H) on in vivo cardiovascular functional capacity in the context of cardiac myosin light chain 2 phosphorylation [P-LC(P)], a proposed modulator of myocardial function, at rest and during exercise. Compared with normal controls (NC), Ca2(+)-regulated myofibril adenosinetriphosphatase was reduced by 39% in TD and increased by 9% in H rats. This response was associated with a 20-fold increase in the V3 isoform and an 11% increase in the V1 isoform in TD and H rats, respectively. Submaximal treadmill exercise elicited significant elevations in all myocardial functional indexes examined in H rats compared with the NC group, whereas the opposite occurred for the TD group. Despite the marked contrast in cardiac function among the three groups, intrinsic levels of P-LC(P) were similar at rest among the groups and were significantly reduced in both TD and H groups relative to controls during exercise. These data suggest that although thyroid state exerts a profound impact on intrinsic myocardial functional state, it exerts little control over cellular processes regulating P-LC(P) during rest and exercise.

scholarly journals Myo1c Binds Phosphoinositides through a Putative Pleckstrin Homology Domain

2006 ◽  
Vol 17 (11) ◽  
pp. 4856-4865 ◽  
Author(s):  
David E. Hokanson ◽  
Joseph M. Laakso ◽  
Tianming Lin ◽  
David Sept ◽  
E. Michael Ostap
Keyword(s):  
Binding Site ◽  
Membrane Trafficking ◽  
Cellular Localization ◽  
Membrane Binding ◽  
Pleckstrin Homology Domain ◽  
Dependent Manner ◽  
Ph Domain ◽  
Pleckstrin Homology

Myo1c is a member of the myosin superfamily that binds phosphatidylinositol-4,5-bisphosphate (PIP2), links the actin cytoskeleton to cellular membranes and plays roles in mechano-signal transduction and membrane trafficking. We located and characterized two distinct membrane binding sites within the regulatory and tail domains of this myosin. By sequence, secondary structure, and ab initio computational analyses, we identified a phosphoinositide binding site in the tail to be a putative pleckstrin homology (PH) domain. Point mutations of residues known to be essential for polyphosphoinositide binding in previously characterized PH domains inhibit myo1c binding to PIP2 in vitro, disrupt in vivo membrane binding, and disrupt cellular localization. The extended sequence of this binding site is conserved within other myosin-I isoforms, suggesting they contain this putative PH domain. We also characterized a previously identified membrane binding site within the IQ motifs in the regulatory domain. This region is not phosphoinositide specific, but it binds anionic phospholipids in a calcium-dependent manner. However, this site is not essential for in vivo membrane binding.

scholarly journals Increased extracellular signal regulated kinases phosphorylation in the adrenal gland in response to chronic ACTH treatment

2007 ◽  
Vol 192 (3) ◽  
pp. 647-658 ◽  
Author(s):  
Jorge G Ferreira ◽  
Célia D Cruz ◽  
Delminda Neves ◽  
Duarte Pignatelli
Keyword(s):  
Cell Proliferation ◽  
Mek Inhibitor ◽  
Nuclear Antigen ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Extracellular Signal ◽  
Extracellular Stimuli ◽  
Corticosterone Release

ACTH released from the pituitary acts through activation of cAMP/PKA in adrenocortical cells stimulating steroidogenesis. Although ACTH was originally thought to have anti-proliferative effects on the adrenal, recently it has been described that it could also have proliferative effects acting through other signalling cascades. This is also relevant in humans given the increased levels of ACTH occurring together with adrenal cortex hyperplasia observed in Cushing’s disease and possibly in other situations such as chronic stress. One of the signalling pathways regulating cell proliferation is the extracellular signal regulated kinase (ERKs) pathway. ERKs are members of the MAPK family of cascades. They are activated by extracellular stimuli such as growth factors and mitogens, become phosphorylated through MEK1/2 and regulate a diversity of cellular processes such as proliferation and differentiation. Until now, no study addressed the effects of chronic ACTH administration on the activation of ERKs in vivo. Using rats submitted to different ACTH dosages as well as variable durations, we determined if ACTH induced ERKs activation and by establishing a parallelism with proliferating cell nuclear antigen (PCNA) expression, we aimed to demonstrate a role of ACTH-induced ERKs activation in cell proliferation. Blood was collected for hormonal analysis and the role of ACTH-induced ERKs activation in the stimulation of steroidogenesis was also studied. We confirmed that ACTH increased adrenal weight and corticosterone levels when compared with control or dexamethasone-treated animals. We also demonstrated that ACTH increases ERKs activation and PCNA expression in a time- and dose-dependent manner. When ERKs activation was blocked by the use of a specific MEK inhibitor (PD98059), there was a decrease in ACTH-induced corticosterone release and PCNA expression. We conclude that chronic ACTH induces ERKs activation and that this plays an important role in the induction of cell proliferation as well as steroidogenesis.

scholarly journals Identification of 3′ UTR motifs required for mRNA localization to myelin sheaths in vivo

PLoS Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. e3001053
Author(s):  
Katie M. Yergert ◽  
Caleb A. Doll ◽  
Rebecca O’Rouke ◽  
Jacob H. Hines ◽  
Bruce Appel
Keyword(s):  
Mrna Localization ◽  
Dependent Manner ◽  
Global Regulator ◽  
Local Protein Synthesis ◽  
Consensus Sequences ◽  
Cellular Processes ◽  
Myelin Sheaths ◽  
Growth Zones ◽  
Local Protein

Myelin is a specialized membrane produced by oligodendrocytes that insulates and supports axons. Oligodendrocytes extend numerous cellular processes, as projections of the plasma membrane, and simultaneously wrap multiple layers of myelin membrane around target axons. Notably, myelin sheaths originating from the same oligodendrocyte are variable in size, suggesting local mechanisms regulate myelin sheath growth. Purified myelin contains ribosomes and hundreds of mRNAs, supporting a model that mRNA localization and local protein synthesis regulate sheath growth and maturation. However, the mechanisms by which mRNAs are selectively enriched in myelin sheaths are unclear. To investigate how mRNAs are targeted to myelin sheaths, we tested the hypothesis that transcripts are selected for myelin enrichment through consensus sequences in the 3′ untranslated region (3′ UTR). Using methods to visualize mRNA in living zebrafish larvae, we identified candidate 3′ UTRs that were sufficient to localize mRNA to sheaths and enriched near growth zones of nascent membrane. We bioinformatically identified motifs common in 3′ UTRs from 3 myelin-enriched transcripts and determined that these motifs are required and sufficient in a context-dependent manner for mRNA transport to myelin sheaths. Finally, we show that 1 motif is highly enriched in the myelin transcriptome, suggesting that this sequence is a global regulator of mRNA localization during developmental myelination.

scholarly journals Mechanochemical feedback and control of endocytosis and membrane tension

2017 ◽  
Author(s):  
Joseph Jose Thottacherry ◽  
Anita Joanna Kosmalska ◽  
Alberto Elosegui-Artola ◽  
Susav Pradhan ◽  
Sumit Sharma ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Feedback Loop ◽  
Negative Feedback Loop ◽  
Dependent Manner ◽  
Homeostatic Regulation ◽  
Membrane Tension ◽  
Cellular Processes ◽  
Tightly Coupled ◽  
And Control

AbstractPlasma membrane tension is an important factor that regulates many key cellular processes. Membrane trafficking is tightly coupled to membrane tension and can modulate the latter by addition or removal of the membrane. However, the cellular pathway(s) involved in these processes are poorly understood. Here we find that, among a number of endocytic processes operating simultaneously at the cell surface, a dynamin and clathrin-independent pathway, the CLIC/GEEC (CG) pathway, is rapidly and specifically upregulated upon reduction of tension. On the other hand, inhibition of the CG pathway results in lower membrane tension, while up regulation significantly enhances membrane tension. We find that vinculin, a well-studied mechanotransducer, mediates the tension-dependent regulation of the CG pathway. Vinculin negatively regulates a key CG pathway regulator, GBF1, at the plasma membrane in a tension dependent manner. Thus, the CG pathway operates in a negative feedback loop with membrane tension which leads to a homeostatic regulation of membrane tension.

Annexins – insights from knockout mice

2016 ◽  
Vol 397 (10) ◽  
pp. 1031-1053 ◽  
Author(s):  
Thomas Grewal ◽  
Sundeep J. Wason ◽  
Carlos Enrich ◽  
Carles Rentero
Keyword(s):  
Mouse Models ◽  
Membrane Trafficking ◽  
Membrane Binding ◽  
Dependent Manner ◽  
Binding Characteristics ◽  
Binding Behavior ◽  
Interaction Partners ◽  
Health And Disease ◽  
Underlying Mechanisms

AbstractAnnexins are a highly conserved protein family that bind to phospholipids in a calcium (Ca2+) – dependent manner. Studies with purified annexins, as well as overexpression and knockdown approaches identified multiple functions predominantly linked to their dynamic and reversible membrane binding behavior. However, most annexins are found at multiple locations and interact with numerous proteins. Furthermore, similar membrane binding characteristics, overlapping localizations and shared interaction partners have complicated identification of their precise functions. To gain insight into annexin functionin vivo, mouse models deficient of annexin A1 (AnxA1), A2, A4, A5, A6 and A7 have been generated. Interestingly, with the exception of one study, all mice strains lacking one or even two annexins are viable and develop normally. This suggested redundancy within annexins, but examining these knockout (KO) strains under stress conditions revealed striking phenotypes, identifying underlying mechanisms specific for individual annexins, often supporting Ca2+homeostasis and membrane transport as central for annexin biology. Conversely, mice lacking AnxA1 or A2 show extracellular functions relevant in health and disease that appear independent of membrane trafficking or Ca2+signaling. This review will summarize the mechanistic insights gained from studies utilizing mouse models lacking members of the annexin family.

Sign in / Sign up

Export Citation Format

Share Document