Secretory Lysosomes
Secretory Lysosomes - Related Videos
16:01
Investigating Mast Cell Secretory Granules; from Biosynthesis to Exocytosis
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Cited by 9 •
2015
The goal of the present protocol was to develop a method that will allow functional genomic analyses of mast cell secretion. The protocol is based on quantitative assessment of the release of a fluorescent reporter gene cotrasfected with the gene of interest and real time analyses of the secretory granule's morphology.
01:31
Lysosomes
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2023
Lysosomes are membrane-enclosed spherical sacs derived from the Golgi apparatus. The most important function of the lysosome is degrading macromolecules and biological polymers that are released during membrane trafficking events such as the secretory, endocytic, autophagic, and phagocytic pathways. The degradation is carried out by several hydrolytic enzymes active in an acidic environment of the lysosomal lumen. These acid hydrolases are involved in cellular processes such as cell signaling,...
01:31
Lysosomes
0 Views •
2023
Lysosomes are membrane-enclosed spherical sacs derived from the Golgi apparatus. The most important function of the lysosome is degrading macromolecules and biological polymers that are released during membrane trafficking events such as the secretory, endocytic, autophagic, and phagocytic pathways. The degradation is carried out by several hydrolytic enzymes active in an acidic environment of the lysosomal lumen. These acid hydrolases are involved in cellular processes such as cell signaling,...
01:19
Secretory Phase
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2024
The secretory phase of the menstrual cycle, spanning from day 14 to 28 in a typical 28-day cycle, is a period of significant physiological changes in the female reproductive system. This phase commences immediately after ovulation and is characterized by the preparation of the endometrium for potential embryo implantation. Following ovulation, the corpus luteum, a temporary endocrine structure, produces progesterone and estrogens. These hormones stimulate the growth and coiling of endometrial...
03:34
An In Vitro Technique to Visualize Exocytosis of Secretory Granules in Mast Cells
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2025
This video demonstrates a technique to visualize exocytosis in mast cells. The cells are incubated with FITC-dextran — a fluorescent reporter — which is taken up by cells inside secretory granules (SGs), where the acidic pH quenches its fluorescence. Upon stimulation of granule exocytosis, the medium's higher pH induces reporter fluorescence inside the fused SGs, which is visualized using a fluorescence microscope.
FAQs
Cytosolic calcium acts as the stimulation-linked signal that initiates secretion. When calcium levels rise, secretory lysosomes are prompted to fuse with the plasma membrane, allowing their stored cargo to move outside the cell by exocytosis. This coupling gives the cell a rapid way to convert an intracellular signal into an extracellular response, rather than releasing material continuously.
An acidic lumen houses the hydrolytic enzymes responsible for lysosome-associated degradation, while some secretory lysosomes also contain specialized cargo. This internal organization supports two linked outcomes: material can be processed within the cell, and selected contents can later be delivered outside it. The lumen therefore connects cellular recycling with specialized communication or tissue functions.
Fusion with the plasma membrane is the key transition that exposes secretory lysosome cargo to the extracellular space. Before fusion, cargo remains enclosed within the organelle; after fusion, exocytosis releases it outside the cell. This mechanism links intracellular membrane trafficking to communication, defense, pigment release, and tissue maintenance without requiring separate systems for each role.
An investigation can compare stimulation, the resulting rise in cytosolic calcium, fusion with the plasma membrane, and release of cargo outside the cell. Examining these events in sequence helps organize the relationship between signaling, membrane fusion, and secretion. This framework also helps researchers connect cellular observations with defects in lysosomal storage or exocytosis.
In immune cells, regulated release from these organelles supports killing of target cells. The relevant sequence is stimulation, cytosolic calcium elevation, organelle fusion with the plasma membrane, and exocytosis of specialized cargo. Secretory lysosomes therefore connect intracellular storage and degradation machinery with host defense, showing how one trafficking pathway can produce a direct biological outcome.
Osteoclasts use secretory lysosome activity in bone remodeling, whereas melanocytes use it for pigment release. These examples show that the same general trafficking principle can be adapted to different cell-specific cargos and physiological tasks. Comparing the two systems helps biology researchers relate organelle behavior to tissue maintenance in bone and specialized cellular functions in pigmentation.
Defects in lysosomal storage or exocytosis can disrupt the balance between intracellular degradation and regulated release. Studying such defects helps identify whether problems arise from handling material within the organelle, responding to stimulation, fusing with the plasma membrane, or releasing cargo. This makes secretory lysosomes useful for connecting cell biology to disorders involving recycling or secretion.