scholarly journals Plant Sterol Clustering Correlates with Membrane Microdomains as Revealed by Optical and Computational Microscopy

Membranes ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 747
Author(s):  
Ling Tang ◽  
Yang Li ◽  
Cheng Zhong ◽  
Xin Deng ◽  
Xiaohua Wang
Keyword(s):  
State Of The Art ◽  
Membrane Microdomains ◽  
Fluorescence Lifetime Imaging ◽  
Complex Environment ◽  
Specific Lipids ◽  
Lifetime Imaging ◽  
Liquid Ordered ◽  
Dynamics Simulations ◽  
Plant Plasma Membrane

Local inhomogeneities in lipid composition play a crucial role in the regulation of signal transduction and membrane traffic. This is particularly the case for plant plasma membrane, which is enriched in specific lipids, such as free and conjugated forms of phytosterols and typical phytosphingolipids. Nevertheless, most evidence for microdomains in cells remains indirect, and the nature of membrane inhomogeneities has been difficult to characterize. We used a new push–pull pyrene probe and fluorescence lifetime imaging microscopy (FLIM) combined with all-atom multiscale molecular dynamics simulations to provide a detailed view on the interaction between phospholipids and phytosterol and the effect of modulating cellular phytosterols on membrane-associated microdomains and phase separation formation. Our understanding of the organization principles of biomembranes is limited mainly by the challenge to measure distributions and interactions of lipids and proteins within the complex environment of living cells. Comparing phospholipids/phytosterol compositions typical of liquid-disordered (Ld) and liquid-ordered (Lo) domains, we furthermore show that phytosterols play crucial roles in membrane homeostasis. The simulation work highlights how state-of-the-art modeling alleviates some of the prior concerns and how unrefuted discoveries can be made through a computational microscope. Altogether, our results support the role of phytosterols in the lateral structuring of the PM of plant cells and suggest that they are key compounds for the formation of plant PM microdomains and the lipid-ordered phase.

scholarly journals The biochemical resolving power of fluorescence lifetime imaging

2021 ◽  
Author(s):  
Andrew L. Trinh ◽  
Alessandro Esposito
Keyword(s):  
Fluorescence Lifetime ◽  
Resolving Power ◽  
Fluorescence Lifetime Imaging ◽  
Time Resolved ◽  
Instrument Response Function ◽  
Lifetime Imaging ◽  
Use Of Time ◽  
Single Living Cells ◽  
Microscopy Techniques

AbstractA deeper understanding of spatial resolution in microscopy fostered a technological revolution that is now permitting us to investigate the structure of the cell with nanometer resolution. Although fluorescence microscopy techniques enable scientists to investigate both the structure and biochemistry of the cell, the biochemical resolving power of a microscope is a physical quantity that is not well-defined or studied. To overcome this limitation, we carried out a theoretical investigation of the biochemical resolving power in fluorescence lifetime imaging microscopy, one of the most effective tools to investigate biochemistry in single living cells. With the theoretical analysis of information theory and Monte Carlo simulations, we describe how the ‘biochemical resolving power’ in time-resolved sensing depends on instrument specifications. We unravel common misunderstandings on the role of the instrument response function and provide theoretical insights that have significant practical implications in the design and use of time-resolved instrumentation.

scholarly journals TIP60 governs the auto-ubiquitination of UHRF1 through USP7 dissociation from the UHRF1/USP7 complex

2020 ◽  
Author(s):  
Tanveer Ahmad ◽  
Waseem Ashraf ◽  
Abdulkhaleg Ibrahim ◽  
Liliyana Zaayter ◽  
Christian D. Muller ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Ring Finger ◽  
Fluorescence Lifetime Imaging ◽  
Cellular Functions ◽  
Apoptotic Pathway ◽  
Cellular Processes ◽  
Lifetime Imaging ◽  
Damage Repair ◽  
Microscopy Techniques

Abstract Background: The epigenetic regulator UHRF1 (Ubiquitin-like, containing PHD and RING finger domains 1) plays an essential role in faithful transmission of DNA methylation during replication. It has tumorogenesis potential and is overexpressed in cancers. TIP60 (Tat interactive protein, 60 kDa) is an important partner of UHRF1, ensuring various cellular processes through its acetyltransferase activity. TIP60 is believed to exert a tumor suppressive role partly explained by its down-regulation in many cancers. Both proteins participate in various cellular functions such as chromatin remodeling, cell cycle, DNA damage repair and regulation of protein stability.Methods: Immunoprecipitation and confocal microscopy techniques were performed to study the ubiquitination of UHRF1 and USP-UHRF1 association. Fluorescence lifetime imaging microscopy (FLIM) technique was performed to analyze the interaction between UHRF1 and ubiquitin inside the nucleus. Western blotting was used to assess the effect of TIP60 overexpression on p73, pro- and anti-apoptotic proteins. TIP60-mediated apoptosis in HeLa cells was investigated by flow cytometry. Results were statistically analyzed using Graphpad prism.Results: Herein, our goal was to investigate the role and mechanism of TIP60 in the regulation of UHRF1 expression. Our results showed that TIP60 overexpression down-regulated UHRF1 and DNMT1 (DNA methyltransferase 1) expressions. TIP60 interfered with USP7-UHRF1 association and induced degradation of UHRF1 in an auto-ubiquitination dependent pathway. Moreover, TIP60 activated the p73-mediated apoptotic pathway.Conclusion: Taken together, our data suggest that the tumor suppressor role of TIP60 is mediated by its regulation to UHRF1.

scholarly journals Mitochondrial pH Nanosensors for Metabolic Profiling of Breast Cancer Cell Lines

2020 ◽  
Vol 21 (10) ◽  
pp. 3731
Author(s):  
Consuelo Ripoll ◽  
Mar Roldan ◽  
Rafael Contreras-Montoya ◽  
Juan J. Diaz-Mochon ◽  
Miguel Martin ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cell ◽  
Breast Cancer Cell ◽  
Breast Cancer Cell Lines ◽  
Main Role ◽  
Fluorescence Lifetime Imaging ◽  
Lifetime Imaging ◽  
Transport Chain ◽  
Alternative Routes

The main role of mitochondria, as pivotal organelles for cellular metabolism, is the production of energy (ATP) through an oxidative phosphorylation system. During this process, the electron transport chain creates a proton gradient that drives the synthesis of ATP. One of the main features of tumoral cells is their altered metabolism, providing alternative routes to enhance proliferation and survival. Hence, it is of utmost importance to understand the relationship between mitochondrial pH, tumoral metabolism, and cancer. In this manuscript, we develop a highly specific nanosensor to accurately measure the intramitochondrial pH using fluorescence lifetime imaging microscopy (FLIM). Importantly, we have applied this nanosensor to establish differences that may be hallmarks of different metabolic pathways in breast cancer cell models, leading to the characterization of different metabophenotypes.

scholarly journals An Overview of CMOS Photodetectors Utilizing Current-Assistance for Swift and Efficient Photo-Carrier Detection

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4576
Author(s):  
Gobinath Jegannathan ◽  
Volodymyr Seliuchenko ◽  
Thomas Van den Dries ◽  
Thomas Lapauw ◽  
Sven Boulanger ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Fluorescence Lifetime ◽  
3D Imaging ◽  
Review Paper ◽  
State Of The Art ◽  
Fluorescence Lifetime Imaging ◽  
Optical Receivers ◽  
Lifetime Imaging ◽  
Drift Field ◽  
Base Mechanism

This review paper presents an assortment of research on a family of photodetectors which use the same base mechanism, current assistance, for the operation. Current assistance is used to create a drift field in the semiconductor, more specifically silicon, in order to improve the bandwidth and the quantum efficiency. Based on the detector and application, the drift field can be static or modulated. Applications include 3D imaging (both direct and indirect time-of-flight), optical receivers and fluorescence lifetime imaging. This work discusses the current-assistance principle, the various photodetectors using this principle and a comparison is made with other state-of-the-art photodetectors used for the same application.

Visualization of Cutaneous Distribution of Minocycline of a Topical Gel in Human Facial Skin with Two-Photon Excited Fluorescence Lifetime Imaging Microscopy (FLIM) and Phasor Analysis

2017 ◽  
Vol 1 ◽  
pp. s57
Author(s):  
Sinyoung Jeong ◽  
Maiko Hermsmeier ◽  
Sam Osseiran ◽  
Akira Yamamoto ◽  
Usha Nagavarapu ◽  
...  
Keyword(s):  
Fluorescence Lifetime ◽  
Fluorescence Lifetime Imaging Microscopy ◽  
Fluorescence Lifetime Imaging ◽  
Facial Skin ◽  
Topical Gel ◽  
Two Photon ◽  
Lifetime Imaging ◽  
Phasor Analysis

Abstract Not AvailableStudy supported by BioPharmX.

The Role of Hydrophobicity in the Stability and pH-Switchability of (RXDX)4 and Coumarin-RXDX Conjugate β-Sheets

2020 ◽  
Author(s):  
Ryan Weber ◽  
Martin McCullagh
Keyword(s):  
Biological Imaging ◽  
Ph Sensing ◽  
Hydrophobic Residue ◽  
Ideal Candidate ◽  
Self Assembling ◽  
Sensing Applications ◽  
Β Sheets ◽  
The Stability ◽  
Dynamics Simulations

<p>pH-switchable, self-assembling materials are of interest in biological imaging and sensing applications. Here we propose that combining the pH-switchability of RXDX (X=Ala, Val, Leu, Ile, Phe) peptides and the optical properties of coumarin creates an ideal candidate for these materials. This suggestion is tested with a thorough set of all-atom molecular dynamics simulations. We first investigate the dependence of pH-switchabiliy on the identity of the hydrophobic residue, X, in the bare (RXDX)<sub>4</sub> systems. Increasing the hydrophobicity stabilizes the fiber which, in turn, reduces the pH-switchabilty of the system. This behavior is found to be somewhat transferable to systems in which a single hydrophobic residue is replaced with a coumarin containing amino acid. In this case, conjugates with X=Ala are found to be unstable and both pHs while conjugates with X=Val, Leu, Ile and Phe are found to form stable β-sheets at least at neutral pH. The (RFDF)<sub>4</sub>-coumarin conjugate is found to have the largest relative entropy value of 0.884 +/- 0.001 between neutral and acidic coumarin ordering distributions. Thus, we posit that coumarin-(RFDF)<sub>4</sub> containing peptide sequences are ideal candidates for pH-sensing bioelectronic materials.</p>

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