scholarly journals Caveolins and cavins in the trafficking, maturation, and degradation of caveolae: implications for cell physiology

2017 ◽  
Vol 312 (4) ◽  
pp. C459-C477 ◽  
Author(s):  
Anna R. Busija ◽  
Hemal H. Patel ◽  
Paul A. Insel
Keyword(s):  
Protein Interactions ◽  
Conformational Stability ◽  
Cell Physiology ◽  
Adapter Proteins ◽  
Scaffolding Proteins ◽  
Protein Protein Interactions ◽  
Outer Coat ◽  
Ligand Affinity ◽  
Cellular Changes ◽  
Raft Domains

Caveolins (Cavs) are ~20 kDa scaffolding proteins that assemble as oligomeric complexes in lipid raft domains to form caveolae, flask-shaped plasma membrane (PM) invaginations. Caveolae (“little caves”) require lipid-lipid, protein-lipid, and protein-protein interactions that can modulate the localization, conformational stability, ligand affinity, effector specificity, and other functions of proteins that are partners of Cavs. Cavs are assembled into small oligomers in the endoplasmic reticulum (ER), transported to the Golgi for assembly with cholesterol and other oligomers, and then exported to the PM as an intact coat complex. At the PM, cavins, ~50 kDa adapter proteins, oligomerize into an outer coat complex that remodels the membrane into caveolae. The structure of caveolae protects their contents (i.e., lipids and proteins) from degradation. Cellular changes, including signal transduction effects, can destabilize caveolae and produce cavin dissociation, restructuring of Cav oligomers, ubiquitination, internalization, and degradation. In this review, we provide a perspective of the life cycle (biogenesis, degradation), composition, and physiologic roles of Cavs and caveolae and identify unanswered questions regarding the roles of Cavs and cavins in caveolae and in regulating cell physiology.1

Probing the 14-3-3 Isoform-Specificity Profile of Interactions Stabilized by Fusicoccin A

2020 ◽  
Author(s):  
James Frederich ◽  
Ananya Sengupta ◽  
Josue Liriano ◽  
Ewa A. Bienkiewicz ◽  
Brian G. Miller
Keyword(s):  
Protein Interactions ◽  
Neurological Diseases ◽  
Adapter Proteins ◽  
Protein Protein Interactions ◽  
Specific Expression ◽  
Individual Client ◽  
Isoform Specificity ◽  
Fusicoccin A

Fusicoccin A (FC) is a fungal phytotoxin that stabilizes protein–protein interactions (PPIs) between 14-3-3 adapter proteins and their phosphoprotein interaction partners. In recent years, FC has emerged as an important chemical probe of human 14-3-3 PPIs implicated in cancer and neurological diseases. These previous studies have established the structural requirements for FC-induced stabilization of 14-3-3·client phosphoprotein complexes; however, the effect of different 14-3-3 isoforms on FC activity has not been systematically explored. This is a relevant question for the continued development of FC variants because there are seven distinct isoforms of 14-3-3 in humans. Despite their remarkable sequence and structural similarities, a growing body of experimental evidence supports both tissue-specific expression of 14-3-3 isoforms and isoform-specific functions <i>in vivo</i>. Herein, we report the isoform-specificity profile of FC <i>in vitro</i>using recombinant human 14-3-3 isoforms and a focused library of fluorescein-labeled hexaphosphopeptides mimicking the C-terminal 14-3-3 recognition domains of client phosphoproteins targeted by FC in cell culture. Our results reveal modest isoform preferences for individual client phospholigands and demonstrate that FC differentially stabilizes PPIs involving 14-3-3s. Together, these data provide strong motivation for the development of non-natural FC variants with enhanced selectivity for individual 14-3-3 isoforms.

Swim-exercised mice show a decreased level of protein O-GlcNAcylation and expression of O-GlcNAc transferase in heart

2011 ◽  
Vol 111 (1) ◽  
pp. 157-162 ◽  
Author(s):  
Darrell D. Belke
Keyword(s):  
Protein Interactions ◽  
Contractile Function ◽  
Cell Physiology ◽  
Protein Protein Interactions ◽  
Training Exercise ◽  
General Protein ◽  
Exercise Induced ◽  
Glcnac Transferase ◽  
The Impact ◽  
Physiological Hypertrophy

Swim-training exercise in mice leads to cardiac remodeling associated with an improvement in contractile function. Protein O-linked N-acetylglucosamine ( O-GlcNAcylation) is a posttranslational modification of serine and threonine residues capable of altering protein-protein interactions affecting gene transcription, cell signaling pathways, and general cell physiology. Increased levels of protein O-GlcNAcylation in the heart have been associated with pathological conditions such as diabetes, ischemia, and hypertrophic heart failure. In contrast, the impact of physiological exercise on protein O-GlcNAcylation in the heart is currently unknown. Swim-training exercise in mice was associated with the development of a physiological hypertrophy characterized by an improvement in contractile function relative to sedentary mice. General protein O-GlcNAcylation was significantly decreased in swim-exercised mice. This effect was mirrored in the level of O-GlcNAcylation of individual proteins such as SP1. The decrease in protein O-GlcNAcylation was associated with a decrease in the expression of O-GlcNAc transferase (OGT) and glutamine-fructose amidotransferase (GFAT) 2 mRNA. O-GlcNAcase (OGA) activity was actually lower in swim-trained than sedentary hearts, suggesting that it did not contribute to the decreased protein O-GlcNAcylation. Thus it appears that exercise-induced physiological hypertrophy is associated with a decrease in protein O-GlcNAcylation, which could potentially contribute to changes in gene expression and other physiological changes associated with exercise.

scholarly journals ATP and Tri-Polyphosphate (TPP) Suppress Protein Aggregate Growth by a Supercharging Mechanism

Biomedicines ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1646
Author(s):  
Jordan Bye ◽  
Kiah Murray ◽  
Robin Curtis
Keyword(s):  
Protein Interactions ◽  
Electrostatic Interactions ◽  
Colloidal Stability ◽  
Conformational Stability ◽  
Kinetic Studies ◽  
Structural Factors ◽  
Protein Protein Interactions ◽  
Protein Aggregate ◽  
Aggregate Growth

A common strategy to increase aggregation resistance is through rational mutagenesis to supercharge proteins, which leads to high colloidal stability, but often has the undesirable effect of lowering conformational stability. We show this trade-off can be overcome by using small multivalent polyphosphate ions, adenosine triphosphate (ATP) and tripolyphosphate (TPP) as excipients. These ions are equally effective at suppressing aggregation of ovalbumin and bovine serum albumin (BSA) upon thermal stress as monitored by dynamic and static light scattering. Monomer loss kinetic studies, combined with measurements of native state protein–protein interactions and ζ-potentials, indicate the ions reduce aggregate growth by increasing the protein colloidal stability through binding and overcharging the protein. Out of three additional proteins studied, ribonuclease A (RNaseA), α-chymotrypsinogen (α-Cgn), and lysozyme, we only observed a reduction in aggregate growth for RNaseA, although overcharging by the poly-phosphate ions still occurs for lysozyme and α-Cgn. Because the salts do not alter protein conformational stability, using them as excipients could be a promising strategy for stabilizing biopharmaceuticals once the protein structural factors that determine whether multivalent ion binding will increase colloidal stability are better elucidated. Our findings also have biological implications. Recently, it has been proposed that ATP also plays an important role in maintaining intracellular biological condensates and preventing protein aggregation in densely packed cellular environments. We expect electrostatic interactions are a significant factor in determining the stabilizing ability of ATP towards maintaining proteins in non-dispersed states in vivo.

scholarly journals Probing the 14-3-3 Isoform-Specificity Profile of Interactions Stabilized by Fusicoccin A

2020 ◽  
Author(s):  
James Frederich ◽  
Ananya Sengupta ◽  
Josue Liriano ◽  
Ewa A. Bienkiewicz ◽  
Brian G. Miller
Keyword(s):  
Protein Interactions ◽  
Neurological Diseases ◽  
Adapter Proteins ◽  
Protein Protein Interactions ◽  
Specific Expression ◽  
Individual Client ◽  
Isoform Specificity ◽  
Fusicoccin A

Fusicoccin A (FC) is a fungal phytotoxin that stabilizes protein–protein interactions (PPIs) between 14-3-3 adapter proteins and their phosphoprotein interaction partners. In recent years, FC has emerged as an important chemical probe of human 14-3-3 PPIs implicated in cancer and neurological diseases. These previous studies have established the structural requirements for FC-induced stabilization of 14-3-3·client phosphoprotein complexes; however, the effect of different 14-3-3 isoforms on FC activity has not been systematically explored. This is a relevant question for the continued development of FC variants because there are seven distinct isoforms of 14-3-3 in humans. Despite their remarkable sequence and structural similarities, a growing body of experimental evidence supports both tissue-specific expression of 14-3-3 isoforms and isoform-specific functions <i>in vivo</i>. Herein, we report the isoform-specificity profile of FC <i>in vitro</i>using recombinant human 14-3-3 isoforms and a focused library of fluorescein-labeled hexaphosphopeptides mimicking the C-terminal 14-3-3 recognition domains of client phosphoproteins targeted by FC in cell culture. Our results reveal modest isoform preferences for individual client phospholigands and demonstrate that FC differentially stabilizes PPIs involving 14-3-3s. Together, these data provide strong motivation for the development of non-natural FC variants with enhanced selectivity for individual 14-3-3 isoforms.

Probing the 14-3-3 Isoform-Specificity Profile of Interactions Stabilized by Fusicoccin A

2020 ◽  
Author(s):  
James Frederich ◽  
Ananya Sengupta ◽  
Josue Liriano ◽  
Ewa A. Bienkiewicz ◽  
Brian G. Miller
Keyword(s):  
Protein Interactions ◽  
Neurological Diseases ◽  
Adapter Proteins ◽  
Protein Protein Interactions ◽  
Specific Expression ◽  
Individual Client ◽  
Isoform Specificity ◽  
Fusicoccin A

Fusicoccin A (FC) is a fungal phytotoxin that stabilizes protein–protein interactions (PPIs) between 14-3-3 adapter proteins and their phosphoprotein interaction partners. In recent years, FC has emerged as an important chemical probe of human 14-3-3 PPIs implicated in cancer and neurological diseases. These previous studies have established the structural requirements for FC-induced stabilization of 14-3-3·client phosphoprotein complexes; however, the effect of different 14-3-3 isoforms on FC activity has not been systematically explored. This is a relevant question for the continued development of FC variants because there are seven distinct isoforms of 14-3-3 in humans. Despite their remarkable sequence and structural similarities, a growing body of experimental evidence supports both tissue-specific expression of 14-3-3 isoforms and isoform-specific functions <i>in vivo</i>. Herein, we report the isoform-specificity profile of FC <i>in vitro</i>using recombinant human 14-3-3 isoforms and a focused library of fluorescein-labeled hexaphosphopeptides mimicking the C-terminal 14-3-3 recognition domains of client phosphoproteins targeted by FC in cell culture. Our results reveal modest isoform preferences for individual client phospholigands and demonstrate that FC differentially stabilizes PPIs involving 14-3-3s. Together, these data provide strong motivation for the development of non-natural FC variants with enhanced selectivity for individual 14-3-3 isoforms.

scholarly journals Targeting epigenetic protein–protein interactions with small-molecule inhibitors

2020 ◽  
Vol 12 (14) ◽  
pp. 1305-1326 ◽  
Author(s):  
Brian M Linhares ◽  
Jolanta Grembecka ◽  
Tomasz Cierpicki
Keyword(s):  
Small Molecules ◽  
Small Molecule ◽  
Protein Interactions ◽  
Small Molecule Inhibitors ◽  
Chemical Space ◽  
Scaffolding Proteins ◽  
Protein Protein Interactions ◽  
Post Translational Modifications ◽  
Inhibitor Development ◽  
Interdisciplinary Approaches

Epigenetic protein–protein interactions (PPIs) play essential roles in regulating gene expression, and their dysregulations have been implicated in many diseases. These PPIs are comprised of reader domains recognizing post-translational modifications on histone proteins, and of scaffolding proteins that maintain integrities of epigenetic complexes. Targeting PPIs have become focuses for development of small-molecule inhibitors and anticancer therapeutics. Here we summarize efforts to develop small-molecule inhibitors targeting common epigenetic PPI domains. Potent small molecules have been reported for many domains, yet small domains that recognize methylated lysine side chains on histones are challenging in inhibitor development. We posit that the development of potent inhibitors for difficult-to-prosecute epigenetic PPIs may be achieved by interdisciplinary approaches and extensive explorations of chemical space.

scholarly journals Proteome-scale amino-acid resolution footprinting of protein-binding sites in the intrinsically disordered regions of the human proteome

2021 ◽  
Author(s):  
Caroline Benz ◽  
Muhammad Ali ◽  
Izabella Krystkowiak ◽  
Leandro Simonetti ◽  
Ahmed Sayadi ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Interactions ◽  
Human Proteome ◽  
Cell Physiology ◽  
Protein Protein Interactions ◽  
Linear Motif ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Wide Range ◽  
Disordered Regions

Specific protein-protein interactions are central to all processes that underlie cell physiology. Numerous studies using a wide range of experimental approaches have identified tens of thousands of human protein-protein interactions. However, many interactions remain to be discovered, and low affinity, conditional and cell type-specific interactions are likely to be disproportionately under-represented. Moreover, for most known protein-protein interactions the binding regions remain uncharacterized. We previously developed proteomic peptide phage display (ProP-PD), a method for simultaneous proteome-scale identification of short linear motif (SLiM)-mediated interactions and footprinting of the binding region with amino acid resolution. Here, we describe the second-generation human disorderome (HD2), an optimized ProP-PD library that tiles all disordered regions of the human proteome and allows the screening of ~1,000,000 overlapping peptides in a single binding assay. We define guidelines for how to process, filter and rank the results and provide PepTools, a toolkit for annotation and analysis of identified hits. We uncovered 2,161 interaction pairs for 35 known SLiM-binding domains and confirmed a subset of 38 interactions by biophysical or cell-based assays. Finally, we show how the amino acid resolution binding site information can be used to pinpoint functionally important disease mutations and phosphorylation events in intrinsically disordered regions of the human proteome. The HD2 ProP-PD library paired with PepTools represents a powerful pipeline for unbiased proteome-wide discovery of SLiM-based interactions.

scholarly journals Interactions of invadopodia scaffold protein TKS4 with intersectin family proteins

2019 ◽  
Vol 25 ◽  
pp. 126-130
Author(s):  
S. V. Kropyvko ◽  
T. A. Gryaznova ◽  
A. V. Rynditch
Keyword(s):  
Protein Interactions ◽  
Protein Complexes ◽  
Cancer Cell Line ◽  
Adaptor Proteins ◽  
Metastatic Potential ◽  
Adapter Proteins ◽  
Protein Protein Interactions ◽  
Membrane Structures ◽  
Active Forms Of Oxygen

Aim. TKS4 is one of the key proteins of invadopodies, specialized membrane structures that provide invasiveness and metastatic potential of malignant cells. This protein is a substrate for the tyrosine kinase SRC, which is involved in the formation of the membrane bends, affects cellular production of active forms of oxygen, interacts with membrane metallоproteinases causing degradation of the extracellular matrix, but its role in invasive structures has not yet been fully understood. Further study of molecular components of invadopodies and their specific interactions provides better understanding of mechanisms of cellular invasion. Methods. Protein-protein interactions were identified by in vitro precipitation of protein complexes using GST-fused proteins and co-immunoprecipitation. Results. Adapter proteins ITSN1 and ITSN2 are new partners of TKS4. Interactions between intersectins and TKS4 are mediated by the SH3A, SH3C and SH3E domains of ITSN1 or ITSN2. TKS4 phosphorylation on tyrosine residues does not affect interactions between TKS4 and intersectins. Conclusions. In this study, we have showed that TKS4 interacts with endocytic adaptor proteins of the intersectin family, ITSN1 and ITSN2. We have also demonstrated that TKS4 and ITSN1 can form a complex in invasive MDA-MB-231 breast cancer cell line. Keywords: TKS4, ITSN1, ITSN2, protein-protein interactions.

scholarly journals The interaction of verprolin WIRE with the adapter proteins family intersectin

2019 ◽  
Vol 17 (1) ◽  
pp. 3-7
Author(s):  
S. V. Kropyvko ◽  
A. V. Rynditch
Keyword(s):  
Actin Cytoskeleton ◽  
Protein Interactions ◽  
Adapter Proteins ◽  
Protein Protein Interactions ◽  
Sh3 Domains ◽  
Invasion And Migration ◽  
The Family ◽  
Cellular Signal ◽  
And Migration ◽  
Cytoskeleton Rearrangements

Aim. WIRE is a scafold protein that regulates actin cytoskeleton rearrangements and the formation of actin enriched membrane processes responsible for invasion and migration. ITSN1 and ITSN2 are representatives of the family of intersectins who participate in the reorganization of the actin cytoskeleton, as well as in other processes, such as endo/enzocytosis, cellular signal transduction, etc. As these proteins participate in the same processes, we checked their interaction with each other. Methods. Protein-protein interactions were identified using the GST pull-down method. Results. We showed that the SH3 domains of ITSN1 and ITSN2 interact with WIRE, and found that while WIRE is in a complex with endogenous actin. Conclusions. ITSN1 and ITSN2 interact with WIRE, which is located in a complex with endogenous actin. Keywords: WIRE, ITSN1 and ITSN2, actin.

scholarly journals Hypothesized diprotomeric enzyme complex supported by stochastic modelling of palytoxin-induced Na/K pump channels

2018 ◽  
Vol 5 (3) ◽  
pp. 172155 ◽  
Author(s):  
Gabriel D. Vilallonga ◽  
Antônio-Carlos G. de Almeida ◽  
Kelison T. Ribeiro ◽  
Sergio V. A. Campos ◽  
Antônio M. Rodrigues
Keyword(s):  
Protein Interactions ◽  
Single Channel ◽  
Stochastic Modelling ◽  
Reaction Rates ◽  
Cell Physiology ◽  
Protein Protein Interactions ◽  
Conformational Substates ◽  
Pumping System ◽  
Electrophysiological Recordings ◽  
Probabilistic Queries

The sodium–potassium pump (Na + /K + pump) is crucial for cell physiology. Despite great advances in the understanding of this ionic pumping system, its mechanism is not completely understood. We propose the use of a statistical model checker to investigate palytoxin (PTX)-induced Na + /K + pump channels. We modelled a system of reactions representing transitions between the conformational substates of the channel with parameters, concentrations of the substates and reaction rates extracted from simulations reported in the literature, based on electrophysiological recordings in a whole-cell configuration. The model was implemented using the UPPAAL-SMC platform. Comparing simulations and probabilistic queries from stochastic system semantics with experimental data, it was possible to propose additional reactions to reproduce the single-channel dynamic. The probabilistic analyses and simulations suggest that the PTX-induced Na + /K + pump channel functions as a diprotomeric complex in which protein–protein interactions increase the affinity of the Na + /K + pump for PTX.

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