Related Experiment Video
Updated: May 22, 2026
08:35
In Situ Immunofluorescent Staining of Autophagy in Muscle Stem Cells
Published on: June 12, 2017
Autophagy fuels tissue fibrogenesis
Virginia Hernández-Gea1, Scott L Friedman
1Division of Liver Diseases, Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA.
Autophagy
|May 24, 2012
Summary
Autophagy drives hepatic stellate cell (HSC) activation and fibrosis by releasing lipid droplets for energy. Inhibiting autophagy reduces lipid release, ATP levels, and liver fibrosis in vivo.
Area of Science:
- Cell Biology
- Liver Disease Pathophysiology
- Autophagy Research
Background:
- Hepatic stellate cell (HSC) activation is central to liver fibrosis.
- Lipid droplet (LD) release is a hallmark of HSC activation but its mechanism is unclear.
- Understanding HSC activation is crucial for treating liver fibrosis.
Purpose of the Study:
- To elucidate the mechanism behind lipid droplet release during HSC activation.
- To investigate the role of autophagy in HSC activation and hepatic fibrosis.
- To explore autophagy as a therapeutic target for fibrotic diseases.
Main Methods:
- Inhibition of the autophagic pathway in activated HSCs.
- Measurement of cellular ATP levels and LD release.
- Generation of HSC-specific Atg7 knockout mouse models.
- Assessment of liver injury and fibrosis in vivo.
- Analysis of fibrogenic cells from kidney and lung.
Main Results:
- Inhibiting autophagy in activated HSCs impairs LD release and decreases ATP levels.
- Mice with HSC-specific Atg7 deletion show reduced activation and liver fibrosis after injury.
- Autophagy is essential for LD metabolism and energy supply fueling HSC activation.
- Fibrogenic cells in other organs also depend on autophagy for scarring.
Conclusions:
- Autophagy is a critical regulator of lipid droplet metabolism and energy production in activated HSCs.
- Autophagy represents a novel therapeutic target for mitigating hepatic fibrosis.
- The findings extend to other fibrogenic cell types, suggesting a conserved role for autophagy in organ fibrosis.
Related Concept Videos
01:27Autophagy
Autophagy is a self-digesting process by which a cell protects itself from threats both within and outside the cell, ranging from abnormal proteins to invading bacteria. In this process, obsolete components of the cell and invading microbes are degraded by hydrolytic enzymes active in an acidic environment of the lysosomal lumen.
An autophagic pathway consists of a series of signaling events activated in response to diverse stress and physiological conditions such as food deprivation,...
An autophagic pathway consists of a series of signaling events activated in response to diverse stress and physiological conditions such as food deprivation,...
01:09Introduction to Fibroblasts
Rudolph Virchow discovered spindle-shaped cells called fibroblasts in 1858. Inactive fibroblasts, called fibrocytes, become activated by various stimuli, such as growth factors and inflammatory cytokines. Activated fibroblasts play a crucial role in wound healing, inflammation, formation of new blood vessels, and cancer progression. Uncontrolled activation of fibroblasts results in fibrosis, the excess deposition of fibrous tissue, which can lead to scarring and affect normal organs. This...
01:22Cellular Injury V: Apoptosis and Autophagy
Cells respond to damage and stress through highly coordinated processes that decide whether they survive or undergo controlled self-destruction. Two major pathways involved in this regulation are apoptosis, a type of programmed cell death, and autophagy, a survival mechanism that helps cells adapt to adverse conditions.ApoptosisApoptosis removes aged or injured cells to maintain tissue balance. During this process, the cell shrinks, chromatin condenses and fragments, and membrane-bound...
01:12Chronic Inflammation: Introduction
Chronic inflammation is a prolonged, dysregulated immune response that persists for weeks to years when the inciting stimulus is difficult to eradicate or when self‑antigens drive ongoing reactivity. Morphologically, it is defined by mononuclear cell infiltration, progressive tissue destruction, and concurrent attempts at healing via angiogenesis and fibrosis. Compared with acute inflammation, edema is less prominent while cellular infiltration predominates; triggers include persistent...
01:36Delivery Pathways to the Lysosome
Eukaryotic cells use different mechanisms to eliminate toxic waste obsolete and worn-out substances. Lysosomes play a pivotal role in this, and hence, these substances are carried to the lysosome from other parts of the cell and extracellular space through different pathways. The most elaborately studied pathways to the lysosome are the endocytic pathways.
Endocytosis
In endocytosis, the cell membrane takes up macromolecules and particles from the surrounding medium. Clathrin-mediated...
Endocytosis
In endocytosis, the cell membrane takes up macromolecules and particles from the surrounding medium. Clathrin-mediated...
01:24Cirrhosis II: Pathophysiology
Cirrhosis is a progressive chronic liver injury caused by prolonged inflammation, excessive fibrotic remodeling, and impaired regeneration. Over time, repeated hepatic insults disrupt the liver’s architecture and function, leading to reduced blood flow, impaired bile drainage, and diminished metabolic capacity.Pathophysiology of cirrhosisCirrhosis arises from three main responses to chronic liver damage: inflammation, immune activation, and hepatocyte death. These processes lead to structural...