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Lysosomes

Lysosomes are the "waste-disposal" system of the cell digesting unwanted materials and cellular debris in the cytoplasm. They are membrane-enclosed organelles with an acidic interior (pH ~4.8) and can vary in size from 0.1 to 1.2 μm. Lysosomes house various hydrolytic enzymes responsible for digesting biopolymers such as proteins, peptides, nucleic acids, carbohydrates, and lipids. Nuclear genes control the synthesis of lysosomal hydrolases, and mutations in these genes can cause an array of inherited metabolic disorders due to defects in lysosomal enzyme functionality. These metabolic disorders are collectively known as lysosomal storage diseases. Defects to lysosomal hydrolytic enzymes result in the accumulation of macromolecules or monomeric compounds, contributing to abnormal signaling pathways, which ultimately lead to pathogenic disorders. In addition to breaking down polymers, lysosomes can fuse with other organelles to allow lysosomal hydrolytic enzymes to digest the organelle's contents and clear out damaged structures, a mechanism known as autophagy.

 

 

Lysosomal Labeling Dyes and Kits


LysoBrite™ dyes are a series of cell-permeable fluorescent dyes for imaging lysosomal morphology and localization and investigating the biosynthesis and pathogenesis of lysosomes in live cells. At nanomolar concentrations, LysoBrite™ dyes selectively target and accumulate within lysosomes and other acidic organelles via the lysosomal pH gradient. Upon entering lysosomes, the pH-sensitive fluorescence of LysoBrite™ dyes significantly enhances. The resulting signal can be measured using fluorescence imaging, high-content imaging, microplate fluorometry, or flow cytometry. LysoBrite™ Orange, LysoBrite™ Red, LysoBrite™ Deep Red, and LysoBrite™ NIR dyes have extremely high photostability and excellent cellular retention, making them useful for various studies, including cell adhesion, chemotaxis, multidrug resistance, cell viability, apoptosis, and cytotoxicity.

LysoBrite™ Dyes for Live Cell Lysosomal Imaging


LysoBrite™ dyes are available in spectral characteristics ranging from blue to near-infrared to accommodate multiplexing with other fluorescent probes or after fixation for co-localization studies if using fixable dye CytoFix™ Red Lysosomal Stain (Cat No. 23210). LysoBrite™ dyes are key components of Cell Navigator™ Lysosome Staining Kits made available separately here. Each kit provides sufficient materials for 500 tests.


Images of HeLa cells stained with AAT Bioquest's LysoBrite™ Green (Cat No. 22643) and ThermoFisher's LysoTracker® Green DND-26 in a Costar black wall/clear bottom 96-well microplate. Samples were continuously illuminated for 120 seconds, and the signals were compared before and after exposure using a Keyence fluorescence microscope.


Features of LysoBrite™ dyes:

  • Selectively accumulates inside lysosomes and other acidic organelles via the lysosomal pH gradient
  • pH-sensitive fluorescence for a more specific lysosomal staining
  • Photostable signal generation for extended imaging windows
  • Minimal cytotoxicity
  • It can be imaged without washing
  • Multiple wavelength options for multiplex analysis with other fluorescent probes
  • Suitable for both proliferating and non-proliferating cells, as well as cells in suspension and adherent cells
 

Table 1. Available LysoBrite™ dyes for labeling lysosomes in live cells.

Product name
Sample Type
Fixable
Ex (nm)
Em (nm)
Filter Set
Unit Size
Cat No.
Assay Kit No.
LysoBrite™ BlueLive CellsNo434480DAPI500 Tests2264222655
LysoBrite™ VLG26Live CellsNo405480Violet500 Tests 22651
LysoBrite™ GreenLive CellsNo501510FITC500 Tests2264322656
LysoBrite™ OrangeLive CellsNo543565TRITC500 Tests2264422657
LysoBrite™ Red DND-99Live CellsYes573592TRITC500 Tests22647 
LysoBrite™ RedLive CellsNo576596TRITC500 Tests2264522658
LysoBrite™ Deep RedLive CellsNo597619Texas Red500 Tests2264622659
LysoBrite™ NIRLive CellsNo636651Cy5500 Tests2264122652


CytoFix™ Red Fixable Lysosomal Stain


The enhanced cellular retention of CytoFix™ Red lysosomal stain preserves its lysosomal localized fluorescence even after the pH gradient is lost during fixation. The fluorescence signal generated by this dye is well-retained in the lysosome for at least one week, making it well-suited for long-term lysosomal tracking. CytoFix™ Red can be used with GFP-expressed cells, other fluorescent conjugates, or other organelle stains for multicolor analysis. It can be used for both suspension and adherent cells and readily adapted for a wide variety of fluorescence platforms.


The fluorescence images of HeLa cells stained with CytoFix™ LysoRed in a 96-well black-wall clear-bottom plate. The image was acquired before (Left) and after (Right) fixation with 4% formaldehyde solution for 20 minutes at RT. The cells were imaged using a fluorescence microscope with a Cy3/TRITC filter.


Features of CytoFix™ Red:

  • High lysosomal staining efficiency
  • Long retention after fixation (1 week or longer)
  • Labeling protocol with minimal hands-on time
 

Table 2. CytoFix™ Red fixable lysosomal stain

Product name
Sample Type
Fixable
Ex (nm)
Em (nm)
Filter Set
Unit Size
Cat No.
CytoFix™ Red Lysosomal StainLive CellsYes540590Cy3/TRITC500 Tests23210

 

Autophagy - Lysosomal Degradation Pathway


Autophagy is a natural and regulated lysosomal degradation pathway for cell viability, development, and homeostasis. This destructive mechanism of cells degrades and recycles unnecessary or dysfunctional cellular components. It achieves this through the sequestration of targeted cytoplasmic materials into double-membrane bound organelles known as autophagosomes. These autophagosomes later fuse with lysosomal organelles to have their contents digested and recycled by lysosomal enzymes. Autophagy serves as an adaptive mechanism to protect organisms against various pathologies. To investigate the role autophagy plays in cell homeostasis, imaging tools and assays have been developed to monitor autophagy functionality in response to cellular stress, microbial infection, and disease. Cell Meter™ Autophagy Fluorescence Imaging Kits utilizes our proprietary Autophagy Super Blue™ probe to selectively target and analyze autophagy activity.

Control
(DMEM Medium)

Autophagy Treatment
(1X HBSS buffer with 5% serum)


Autophagy Green™ labeled vesicles are induced by starvation in HeLa cells. HeLa cells were incubated in a regular DMEM medium (Control) or in 1X HBSS buffer with 5% serum (Autophagy Treatment) for 16 hours. Both control cells and starved cells were incubated with Autophagy Green™ working solution for 20 minutes in a 37°C, 5% CO2 incubator, and then washed 3 times with wash buffer. Cells were imaged immediately under a fluorescence microscope with a FITC channel (green). Cell nuclei were stained with Hoechst 33342 (Cat No. 17530).

 

Table 3. Cell Meter™ assay kits for measuring autophagy activity.

Product name
Sample Type
Ex (nm)
Em (nm)
Filter Set
Unit Size
Cat No.
Cell Meter™ Autophagy Fluorescence Imaging KitLive Cells360445DAPI200 Tests23001
Cell Meter™ Autophagy Assay Kit *Blue Fluorescence*Live Cells360445DAPI200 Tests23000
Cell Meter™ Autophagy Assay Kit *Green Fluorescence*Live Cells485525FITC200 Tests23002
Cell Meter™ Mitochondrial Autophagy Imaging Kit *Red Fluorescence*Live Cells540590Cy3/TRITC100 Tests22998

 

Product Ordering Information