scholarly journals Regulating bacterial behavior within hydrogels of tunable viscoelasticity

2022 ◽  
Author(s):  
Shardul Bhusari ◽  
Shrikrishnan Sankaran ◽  
Aranzazu del Campo
Keyword(s):  
Mammalian Cells ◽  
Protein Production ◽  
3D Culture ◽  
Variable Degree ◽  
New Class ◽  
Hydrogel Network ◽  
Hydrogel Matrix ◽  
The Matrix ◽  
Living Organisms ◽  
And Function

Engineered living materials (ELMs) are a new class of materials in which living organisms incorporated into diffusive matrices uptake a fundamental role in material composition and function. Understanding how the spatial confinement in 3D affects the behavior of the embedded cells is crucial to design and predict ELM functions, regulate and minimize their environmental impact and facilitate their translation into applied materials. This study investigates the growth and metabolic activity of bacteria within an associative hydrogel network (Pluronic-based) with mechanical properties that can be tuned by introducing a variable degree of acrylate crosslinks. Individual bacteria distributed in the hydrogel matrix at low density form functional colonies whose size is controlled by the extent of permanent crosslinks. With increasing stiffness and decreasing plasticity of the matrix, a decrease in colony volumes and an increase in their sphericity is observed. Protein production surprisingly follows a different pattern with higher production yields occurring in networks with intermediate permanent crosslinking degrees. These results demonstrate that, bacterial mechanosensitivity can be used to control and regulate the composition and function of ELMs by thoughtful design of the encapsulating matrix, and by following design criteria with interesting similarities to those developed for 3D culture of mammalian cells.

scholarly journals Microengineering of Collagen Hydrogels Integrated into Microfluidic Devices for Perfusion Culture of Mammalian Cells

2021 ◽  
Vol 333 ◽  
pp. 07006
Author(s):  
Misaki Kato ◽  
Mayu Fukushi ◽  
Masumi Yamada ◽  
Rie Utoh ◽  
Minoru Seki
Keyword(s):  
Mammalian Cells ◽  
Three Dimensional ◽  
3D Culture ◽  
Perfusion Culture ◽  
Microfluidic Devices ◽  
Tubular Structures ◽  
Collagen Hydrogel ◽  
Hydrogel Matrix ◽  
Collagen Hydrogels ◽  
Micrometer Size

Collagen-based hydrogels are widely used for three-dimensional (3D) culture of mammalian cells because of their high cell-activating characteristis. However, techniques for preparing of cell-embedding collagen hydrogels with micrometer-size precision in perfusable, microfluidic devices have not been fully developed. In this study, we propose a facile strategy enabling microfabrication of collagen hydrogels in microfluidic devices. We used phosphate particle-embedding polydimethylsiloxane (PP-PDMS) as a gelation agent, which neutralizes the acidic collagen soltuion. The collagen solution near the surface of the PP-PDMS is selectively gelled. We fabricated micropatterns and tubular structures made of collagen hydrogel, both of which were used for perfusion culture of mammalian cells encapsulated in the hydrogel matrix. The presented approach would be applicable to various types of cell culture experiments.

scholarly journals Modulation of Innate Immune Toxicity by Silver Nanoparticle Exposure and the Preventive Effects of Pterostilbene

2021 ◽  
Vol 22 (5) ◽  
pp. 2536
Author(s):  
Rong-Jane Chen ◽  
Chiao-Ching Huang ◽  
Rosita Pranata ◽  
Yu-Hsuan Lee ◽  
Yu-Ying Chen ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Good Alternative ◽  
Innate Immune ◽  
Toxic Effects ◽  
Transgenic Zebrafish ◽  
Zebrafish Model ◽  
Cytokines And Chemokines ◽  
Living Organisms ◽  
And Function ◽  
Immune Toxicity

Silver nanoparticles pose a potential risk to ecosystems and living organisms due to their widespread use in various fields and subsequent gradual release into the environment. Only a few studies have investigated the effects of silver nanoparticles (AgNPs) toxicity on immunological functions. Furthermore, these toxic effects have not been fully explored. Recent studies have indicated that zebrafish are considered a good alternative model for testing toxicity and for evaluating immunological toxicity. Therefore, the purpose of this study was to investigate the toxicity effects of AgNPs on innate immunity using a zebrafish model and to investigate whether the natural compound pterostilbene (PTE) could provide protection against AgNPs-induced immunotoxicity. Wild type and neutrophil- and macrophage-transgenic zebrafish lines were used in the experiments. The results indicated that the exposure to AgNPs induced toxic effects including death, malformation and the innate immune toxicity of zebrafish. In addition, AgNPs affect the number and function of neutrophils and macrophages. The expression of immune-related cytokines and chemokines was also affected. Notably, the addition of PTE could activate immune cells and promote their accumulation in injured areas in zebrafish, thereby reducing the damage caused by AgNPs. In conclusion, AgNPs may induce innate immune toxicity and PTE could ameliorate this toxicity.

scholarly journals Brain Long Noncoding RNAs: Multitask Regulators of Neuronal Differentiation and Function

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3951
Author(s):  
Sarva Keihani ◽  
Verena Kluever ◽  
Eugenio F. Fornasiero
Keyword(s):  
Neuronal Differentiation ◽  
Neuronal Excitability ◽  
Noncoding Rnas ◽  
Long Noncoding Rnas ◽  
Regulatory Mechanisms ◽  
Control Robustness ◽  
Living Organisms ◽  
And Function ◽  
Regulatory Functions ◽  
Neuronal Physiology

The extraordinary cellular diversity and the complex connections established within different cells types render the nervous system of vertebrates one of the most sophisticated tissues found in living organisms. Such complexity is ensured by numerous regulatory mechanisms that provide tight spatiotemporal control, robustness and reliability. While the unusual abundance of long noncoding RNAs (lncRNAs) in nervous tissues was traditionally puzzling, it is becoming clear that these molecules have genuine regulatory functions in the brain and they are essential for neuronal physiology. The canonical view of RNA as predominantly a ‘coding molecule’ has been largely surpassed, together with the conception that lncRNAs only represent ‘waste material’ produced by cells as a side effect of pervasive transcription. Here we review a growing body of evidence showing that lncRNAs play key roles in several regulatory mechanisms of neurons and other brain cells. In particular, neuronal lncRNAs are crucial for orchestrating neurogenesis, for tuning neuronal differentiation and for the exact calibration of neuronal excitability. Moreover, their diversity and the association to neurodegenerative diseases render them particularly interesting as putative biomarkers for brain disease. Overall, we foresee that in the future a more systematic scrutiny of lncRNA functions will be instrumental for an exhaustive understanding of neuronal pathophysiology.

scholarly journals Targeting Senescent Cells to Counter Aging and Aging-Related Conditions

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 818-818
Author(s):  
Nathan LeBrasseur
Keyword(s):  
Human Populations ◽  
Geriatric Syndromes ◽  
Preclinical Models ◽  
Pharmacological Agents ◽  
New Class ◽  
Age Related ◽  
Selective Elimination ◽  
Early Phase Clinical Trials ◽  
And Function ◽  
State Of The Science

Abstract In response to various forms of age-associated damage, cells can enter a state of senescence. Senescent cells can compromise the health and function of a tissue, and their accumulation with advancing age is believed to contribute to age-related diseases and geriatric syndromes. In preclinical models (i.e., mice), selective elimination of senescent cells through either genetic approaches or a new class of pharmacological agents, termed “senolytics”, has been show to effectively delay, prevent, or reverse the onset and/or progression of pulmonary disease, osteoporosis, atherosclerosis, diabetes, cognitive decline, and several other conditions. Thus, considerable efforts are underway to optimize pharmacological strategies and test their effectiveness in human populations. This seminar will highlight the state-of-the-science of senolytic drugs, and the opportunities and challenges for early phase clinical trials in humans.

scholarly journals ADP-Ribosylation Factor (ARF) Interaction Is Not Sufficient for Yeast GGA Protein Function or Localization

2002 ◽  
Vol 13 (9) ◽  
pp. 3078-3095 ◽  
Author(s):  
Annette L. Boman ◽  
Paul D. Salo ◽  
Melissa J. Hauglund ◽  
Nicole L. Strand ◽  
Shelly J. Rensink ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Mammalian Cells ◽  
Fluorescent Protein ◽  
Protein Localization ◽  
Carboxypeptidase Y ◽  
Minor Role ◽  
Temperature Sensitive ◽  
Adp Ribosylation ◽  
And Function ◽  
Adp Ribosylation Factor

Golgi-localized γ-ear homology domain, ADP-ribosylation factor (ARF)-binding proteins (GGAs) facilitate distinct steps of post-Golgi traffic. Human and yeast GGA proteins are only ∼25% identical, but all GGA proteins have four similar domains based on function and sequence homology. GGA proteins are most conserved in the region that interacts with ARF proteins. To analyze the role of ARF in GGA protein localization and function, we performed mutational analyses of both human and yeast GGAs. To our surprise, yeast and human GGAs differ in their requirement for ARF interaction. We describe a point mutation in both yeast and mammalian GGA proteins that eliminates binding to ARFs. In mammalian cells, this mutation disrupts the localization of human GGA proteins. Yeast Gga function was studied using an assay for carboxypeptidase Y missorting and synthetic temperature-sensitive lethality between GGAs andVPS27. Based on these assays, we conclude that non-Arf-binding yeast Gga mutants can function normally in membrane trafficking. Using green fluorescent protein-tagged Gga1p, we show that Arf interaction is not required for Gga localization to the Golgi. Truncation analysis of Gga1p and Gga2p suggests that the N-terminal VHS domain and C-terminal hinge and ear domains play significant roles in yeast Gga protein localization and function. Together, our data suggest that yeast Gga proteins function to assemble a protein complex at the late Golgi to initiate proper sorting and transport of specific cargo. Whereas mammalian GGAs must interact with ARF to localize to and function at the Golgi, interaction between yeast Ggas and Arf plays a minor role in Gga localization and function.

scholarly journals Proteomic profiling of the mitochondrial ribosome identifies Atp25 as a composite mitochondrial precursor protein

2016 ◽  
Vol 27 (20) ◽  
pp. 3031-3039 ◽  
Author(s):  
Michael W. Woellhaf ◽  
Frederik Sommer ◽  
Michael Schroda ◽  
Johannes M. Herrmann
Keyword(s):  
Precursor Protein ◽  
Ribosomal Biogenesis ◽  
Proteomic Profiling ◽  
Mitochondrial Translation ◽  
Bacterial Ribosome ◽  
Mitochondrial Ribosome ◽  
Translation Apparatus ◽  
The Matrix ◽  
Processing Peptidase ◽  
And Function

Whereas the structure and function of cytosolic ribosomes are well characterized, we only have a limited understanding of the mitochondrial translation apparatus. Using SILAC-based proteomic profiling, we identified 13 proteins that cofractionated with the mitochondrial ribosome, most of which play a role in translation or ribosomal biogenesis. One of these proteins is a homologue of the bacterial ribosome-silencing factor (Rsf). This protein is generated from the composite precursor protein Atp25 upon internal cleavage by the matrix processing peptidase MPP, and in this respect, it differs from all other characterized mitochondrial proteins of baker’s yeast. We observed that cytosolic expression of Rsf, but not of noncleaved Atp25 protein, is toxic. Our results suggest that eukaryotic cells face the challenge of avoiding negative interference from the biogenesis of their two distinct translation machineries.

scholarly journals Secreted CXCL12 (SDF-1) forms dimers under physiological conditions

2012 ◽  
Vol 442 (2) ◽  
pp. 433-442 ◽  
Author(s):  
Paramita Ray ◽  
Sarah A. Lewin ◽  
Laura Anne Mihalko ◽  
Sasha-Cai Lesher-Perez ◽  
Shuichi Takayama ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Extracellular Space ◽  
Mammalian Cells ◽  
Cell Signalling ◽  
Xenograft Model ◽  
Physiological Conditions ◽  
Cxc Chemokine ◽  
Chemokine Ligand ◽  
Chemokine Cxcl12 ◽  
And Function

Chemokine CXCL12 (CXC chemokine ligand 12) signalling through CXCR (CXC chemokine receptor) 4 and CXCR7 has essential functions in development and underlies diseases including cancer, atherosclerosis and autoimmunity. Chemokines may form homodimers that regulate receptor binding and signalling, but previous studies with synthetic CXCL12 have produced conflicting evidence for homodimerization. We used bioluminescence imaging with GL (Gaussia luciferase) fusions to investigate dimerization of CXCL12 secreted from mammalian cells. Using column chromatography and GL complementation, we established that CXCL12 was secreted from mammalian cells as both monomers and dimers. Secreted CXCL12 also formed homodimers in the extracellular space. Monomeric CXCL12 preferentially activated CXCR4 signalling through Gαi and Akt, whereas dimeric CXCL12 more effectively promoted recruitment of β-arrestin 2 to CXCR4 and chemotaxis of CXCR4-expressing breast cancer cells. We also showed that CXCR7 preferentially sequestered monomeric CXCL12 from the extracellular space and had minimal effects on dimeric CXCL12 in cell-based assays and an orthotopic tumour xenograft model of human breast cancer. These studies establish that CXCL12 secreted from mammalian cells forms homodimers under physiological conditions. Since monomeric and dimeric CXCL12 have distinct effects on cell signalling and function, our results have important implications for ongoing efforts to target CXCL12 pathways for therapy.

E3 ligase CHIP and Hsc70 regulate Kv1.5 protein expression and function in mammalian cells

2015 ◽  
Vol 86 ◽  
pp. 138-146 ◽  
Author(s):  
Peili Li ◽  
Yasutaka Kurata ◽  
Nani Maharani ◽  
Endang Mahati ◽  
Katsumi Higaki ◽  
...  
Keyword(s):  
Protein Expression ◽  
Mammalian Cells ◽  
E3 Ligase ◽  
And Function

Oxidative protein folding in the mammalian endoplasmic reticulum

2004 ◽  
Vol 32 (5) ◽  
pp. 655-658 ◽  
Author(s):  
C.E. Jessop ◽  
S. Chakravarthi ◽  
R.H. Watkins ◽  
N.J. Bulleid
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Redox State ◽  
Structure And Function ◽  
Reduced Form ◽  
Secretory Proteins ◽  
Oxidative Protein Folding ◽  
Disulphide Bonds ◽  
And Function ◽  
Substrate Proteins

Native disulphide bonds are essential for the structure and function of many membrane and secretory proteins. Disulphide bonds are formed, reduced and isomerized in the endoplasmic reticulum of mammalian cells by a family of oxidoreductases, which includes protein disulphide isomerase (PDI), ERp57, ERp72, P5 and PDIR. This review will discuss how these enzymes are maintained in either an oxidized redox state that allows them to form disulphide bonds in substrate proteins or a reduced form that allows them to perform isomerization and reduction reactions, how these opposing pathways may co-exist within the same compartment and why so many oxidoreductases exist when PDI alone can perform all three of these functions.

scholarly journals Proteolytic Events of Wound-Healing — Coordinated Interactions Among Matrix Metalloproteinases (MMPs), Integrins, and Extracellular Matrix Molecules

2001 ◽  
Vol 12 (5) ◽  
pp. 373-398 ◽  
Author(s):  
Bjorn Steffensen ◽  
Lari Häkkinen ◽  
Hannu Larjava
Keyword(s):  
Extracellular Matrix ◽  
Wound Healing ◽  
Matrix Metalloproteinases ◽  
Wound Repair ◽  
Enzyme Activation ◽  
Processing Enzymes ◽  
The Matrix ◽  
Signaling Receptors ◽  
State Of Rest ◽  
And Function

During wound-healing, cells are required to migrate rapidly into the wound site via a proteolytically generated pathway in the provisional matrix, to produce new extracellular matrix, and, subsequently, to remodel the newly formed tissue matrix during the maturation phase. Two classes of molecules cooperate closely to achieve this goal, namely, the matrix adhesion and signaling receptors, the integrins, and matrix-degrading and -processing enzymes, the matrix metalloproteinases (MMPs). There is now substantial experimental evidence that blocking key molecules of either group will prevent or seriously delay wound-healing. It has been known for some time now that cell adhesion by means of the integrins regulates the expression of MMPs. In addition, certain MMPs can bind to integrins or other receptors on the cell surface involved in enzyme activation, thereby providing a mechanism for localized matrix degradation. By proteolytically modifying the existing matrix molecules, the MMPs can then induce changes in cell behavior and function from a state of rest to migration. During wound repair, the expression of integrins and MMPs is simultaneously up-regulated. This review will focus on those aspects of the extensive knowledge of fibroblast and keratinocyte MMPs and integrins in biological processes that relate to wound-healing.

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