2-Deoxy-D-glucose treatment changes the Golgi apparatus architecture without blocking synthesis of complex lipids

Renal tubular epithelial cells response to injury in acute kidney injury

Acute kidney injury (AKI) is a clinical syndrome characterized by a rapid and significant decrease in renal function that can arise from various etiologies, and is associated with high morbidity and mortality. The renal tubular epithelial cells (TECs) represent the central cell type affected by AKI, and their notable regenerative capacity is critical for the recovery of renal function in afflicted patients. The adaptive repair process initiated by surviving TECs following mild AKI facilitates full renal recovery. Conversely, when injury is severe or persistent, it allows the TECs to undergo pathological responses, abnormal adaptive repair and phenotypic transformation, which will lead to the development of renal fibrosis. Given the implications of TECs fate after injury in renal outcomes, a deeper understanding of these mechanisms is necessary to identify promising therapeutic targets and biomarkers of the repair process in the human kidney.

A novel nanoparticle fluorescent probe based on a water-soluble conjugated polymer for real-time monitoring of ATP fluctuation and configuration of the Golgi apparatus during the inhibition of glycolysis

BACKGROUND

Adenosine 5'-triphosphate (ATP) plays an important role in cell metabolism and has been regarded as an indicator of cell survival and damage. Golgi apparatus participates in the signal transduction processes of substance transport, ion homeostasis and stress when extracellular substances enter cells. Till now, there is no fluorescent probe for monitoring Golgi ATP level fluctuation and visualizing the configuration change of the Golgi apparatus during the inhibition of glycolysis.

RESULTS

Herein, we report the synthesis of a novel water-soluble cationic polythiophene derivative (PEMTEA) that can be employed as a fluorescent sensor for measuring ATP in the Golgi apparatus. PEMTEA self-assembles into PT-NP nanoparticles in aqueous solution with a diameter of approximately 2 nm. PT-NP displays high sensitivity and superb selectivity towards ATP with a detection limit of 90 nM and a linear detection range from 0 to 3.0 μM. The nanoparticles show low toxicity to HepG2 cells and good photostability in the Golgi apparatus. With the stimulation of Ca2+, PT-NP was practically applied to real-time monitor of endogenous ATP levels in the Golgi apparatus through fluorescence microscopy. Finally, we studied the relationship between the concentration of ATP and configuration of the Golgi apparatus during the inhibition of glycolysis using PT-NP.

SIGNIFICANCE

We have demonstrated that PT-NP can not only indicate the fluctuation and distribution of ATP in the Golgi apparatus, but also give the information of the configuration change of the Golgi apparatus at the single-cell level during the inhibition of glycolysis.

Lysosomal Sequestration Impairs the Activity of the Preclinical FGFR Inhibitor PD173074

Knowledge of intracellular pharmacokinetics of anticancer agents is imperative for understanding drug efficacy as well as intrinsic and acquired cellular resistance mechanisms. However, the factors driving subcellular drug distribution are complex and poorly understood. Here, we describe for the first time the intrinsic fluorescence properties of the fibroblast growth factor receptor inhibitor PD1703074 as well as utilization of this physicochemical feature to investigate intracellular accumulation and compartmentalization of this compound in human lung cancer cells. Cell-free PD173074 fluorescence, intracellular accumulation and distribution were investigated using analytical chemistry and molecular biology approaches. Analyses on a subcellular scale revealed selective drug accumulation in lysosomes. Coincubation with inhibitors of lysosomal acidification strongly enhanced PD173074-mediated fibroblast growth factor receptor (FGFR) inhibition and cytotoxicity. In conclusion, intrinsic fluorescence enables analysis of molecular factors influencing intracellular pharmacokinetics of PD173074. Lysosome-alkalinizing agents might represent candidates for rational combination treatment, preventing cancer cell-intrinsic PD173074 resistance based on lysosomal trapping.

Electron tomography-a tool for ultrastructural 3D visualization in cell biology and histology

Electron tomography (ET) was developed to overcome some of the problems associated reconstructing three-dimensional (3D) images from 2D election microscopy data from ultrathin slices. Virtual sections of semithin sample are obtained by incremental rotation of the target and this information is used to assemble a 3D image. Herein, we provide an instruction to ET including the physical principle, possibilities, and limitations. We review the development of innovative methods and highlight important investigations performed in our department and with our collaborators. ET has opened up the third dimension at the ultrastructural level and represents a milestone in structural molecular biology.

Role of the Golgi Apparatus in the Blood-Brain Barrier: Golgi Protection May Be a Targeted Therapy for Neurological Diseases

The blood-brain barrier (BBB) protects the brain from toxic material in the blood, provides nutrients for brain tissues, and screens harmful substances from the brain. The specific brain microvascular endothelial cells (BMVECs), tight junction between endothelial cells, and astrocytes ensure proper function of the central nervous system (CNS). Pathological factors disrupt the integrity of the BBB by destroying the normal function of endothelial cells and decreasing the production of tight junction proteins or the expression of proteins specifically localized on astrocytes. Interestingly, fragmentation of the Golgi apparatus is observed in neurological diseases and is involved in the destruction of the BBB function. The Golgi acts as a processing center in which proteins are transported after being processed in the endoplasmic reticulum. Besides reprocessing, classifying, and packaging proteins, the Golgi apparatus (GA) also acts as a signaling platform and calcium pool. In this review, we summarized the current literature on the potential relationship between the Golgi and endothelial cells, tight junction, and astrocytes. The normal function of the BBB is maintained as long as the normal function and morphology of the GA are not disturbed. Furthermore, we speculate that protecting the Golgi may be a novel therapeutic approach to protect the BBB and treat neurological diseases due to BBB dysfunction.

Golgi apparatus dis- and reorganizations studied with the aid of 2-deoxy-D-glucose and visualized by 3D-electron tomography

We studied Golgi apparatus disorganizations and reorganizations in human HepG2 hepatoblastoma cells by using the nonmetabolizable glucose analogue 2-deoxy-d-glucose (2DG) and analyzing the changes in Golgi stack architectures by 3D-electron tomography. Golgi stacks remodel in response to 2DG-treatment and are replaced by tubulo-glomerular Golgi bodies, from which mini-Golgi stacks emerge again after removal of 2DG. The Golgi stack changes correlate with the measured ATP-values. Our findings indicate that the classic Golgi stack architecture is impeded, while cells are under the influence of 2DG at constantly low ATP-levels, but the Golgi apparatus is maintained in forms of the Golgi bodies and Golgi stacks can be rebuilt as soon as 2DG is removed. The 3D-electron microscopic results highlight connecting regions that interlink membrane compartments in all phases of Golgi stack reorganizations and show that the compact Golgi bodies mainly consist of continuous intertwined tubules. Connections and continuities point to possible new transport pathways that could substitute for other modes of traffic. The changing architectures visualized in this work reflect Golgi stack dynamics that may be essential for basic cell physiologic and pathologic processes and help to learn, how cells respond to conditions of stress.