Related Experiment Video
Updated: Jun 8, 2026
11:36
In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones
Published on: July 25, 2019
Ubiquitin/SUMO modification regulates VHL protein stability and nucleocytoplasmic localization
Qiliang Cai1, Erle S Robertson
1Department of Microbiology and Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America.
Plos One
|September 17, 2010
Summary
The von Hippel-Lindau (VHL) protein
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- The von Hippel-Lindau (VHL) tumor suppressor protein is crucial for preventing cancer, particularly renal clear-cell carcinomas (RCC).
- VHL regulates hypoxia-inducible factor α (HIFα) degradation, but the post-translational modifications governing VHL activity remain largely uncharacterized.
- Previous research indicated PIASy ligase induces VHL SUMOylation at lysine 171.
Purpose of the Study:
- To investigate the ubiquitylation of VHL and its interplay with SUMOylation.
- To elucidate the impact of VHL post-translational modifications on its stability, localization, and tumor-suppressive function.
Main Methods:
- Investigated VHL ubiquitylation at lysine residues 171 and 196.
- Assessed the effect of PIASy on VHL ubiquitylation.
- Utilized VHL-SUMO1 and ubiquitin fusion proteins to examine localization.
- Performed site-directed mutagenesis (K171R, K196R) to assess functional consequences.
Main Results:
- VHL undergoes ubiquitylation at lysine 171 and 196, a process inhibited by PIASy.
- Ubiquitylated VHL localizes to the cytoplasm, while SUMOylated VHL shows increased stability and nuclear localization.
- Mutating lysine 171 and 196 to arginine abolished VHL's inhibitory effect on HIFα transcriptional activity and in vitro tube formation.
Conclusions:
- Post-translational modifications, including ubiquitylation and SUMOylation, are critical regulators of VHL protein stability and nucleocytoplasmic shuttling.
- Precise and dynamic regulation of VHL through protein modification is essential for its tumor suppressor functions.
Related Concept Videos
02:04Covalently Linked Protein Regulators
Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.
These groups modify specific amino acids in a protein.
02:58Regulated Protein Degradation
It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
02:58Regulated Protein Degradation
It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
01:23Regulation of Expression at Multiple Steps
The gene expression in cells is regulated at different stages: (i) transcription, (ii) RNA processing, (iii) RNA localization, and (iv) translation. Transcriptional regulation is mediated by regulatory proteins such as transcription factors, activators, or repressors—these control gene expression by initiating or inhibiting the transcription of genes. Once a precursor or pre-mRNA is produced, it undergoes post-transcriptional modification, including 5' capping, splicing, and the addition of a...
01:45Regulation of Nuclear Protein Sorting
Nuclear protein sorting regulates nucleus composition and gene expression, crucial for determining the fate of a eukaryotic cell. Hence, the entry and exit of molecules across the nuclear envelope is a tightly controlled process. Nuclear protein sorting can be inhibited by one of the following ways: 1) masking cargo signal sequences, 2) modifying the nuclear receptor's affinity for cargo, 3) controlling the nuclear pore size, 4) retaining the cargo during its transit to the cytosol or the...
02:30Histone Variants at the Centromere
Histone variants are the histone proteins with structural and sequence variations. These variants may be regarded as “mutant” forms that replace their canonical histone counterparts in the nucleosomes. Specific post-translational modifications on the histone variants enable further chromatin complexity and regulate tissue-specific gene expression. The most common histone variants are from histone H2A, H2B, and linker histone H1 families. However, several variants of histone H3 variants are also...