Related Experiment Video

Updated: Sep 20, 2025

Assessing Cellular Target Engagement by SHP2 PTPN11 Phosphatase Inhibitors
08:45

Assessing Cellular Target Engagement by SHP2 PTPN11 Phosphatase Inhibitors

Published on: July 17, 2020

6.3K

Regulation of the MDM2-p53 Nexus by a Nuclear Phosphoinositide and Small Heat Shock Protein Complex

Jeong Hyo Lee, Mo Chen, Tianmu Wen

    Biorxiv : the Preprint Server for Biology
    |May 23, 2025
    PubMed

    Insights

    Genotoxic stress activates PIPKIα, generating PIP2 that binds MDM2. This interaction regulates MDM2 stability and its interaction with p53, offering new cancer therapy strategies.

    Area of Science:

    • Molecular Biology
    • Cellular Biology
    • Biochemistry

    Background:

    • The tumor suppressor p53 is crucial for genome stability and frequently mutated in cancer.
    • p53 stability is regulated by its interaction with the MDM2 oncoprotein, a ubiquitin E3 ligase.
    • Nuclear phosphoinositides have recently been shown to bind and stabilize p53.

    Purpose of the Study:

    • To investigate the role of nuclear phosphoinositides in regulating MDM2 stability and function.
    • To elucidate the mechanism by which genotoxic stress affects the MDM2-p53 pathway.
    • To explore novel therapeutic strategies targeting the MDM2-p53 interaction in cancer.

    Main Methods:

    • Investigated the effect of genotoxic stress on type I phosphatidylinositol phosphate kinase (PIPKIα) and phosphatidylinositol 4,5-bisphosphate (PIP2) levels.
    • Analyzed the binding of PIPKIα and PIP2 to MDM2 following genotoxic stress.
    • Examined the differential recruitment of small heat shock proteins (sHSPs) like αB-crystallin (αBC) and HSP27 to the MDM2-PIP2 complex.
    • Assessed the impact of PIP2 binding on MDM2 stability, ubiquitination activity, and p53 interaction.

    Main Results:

    • Genotoxic stress induces nuclear PIPKIα and PIP2, which bind to MDM2.
    • PIP2 binding to MDM2 differentially regulates the recruitment of αBC and HSP27, acting as an on-off switch for MDM2.
    • This regulation affects MDM2 stability, downstream targets, ubiquitination activity, and interaction with p53.
    • sHSPs play active, selective roles in fine-tuning MDM2 function and the MDM2-p53 nexus.

    Conclusions:

    • Nuclear phosphoinositides confer specificity to the MDM2-PIP2-sHSPs association.
    • The differential engagement of sHSPs highlights their active role beyond passive chaperoning.
    • These findings present a novel therapeutic strategy for targeting the MDM2-p53 pathway in cancer.

    More Related Videos

    Purification of Ubiquitinated p53 Proteins from Mammalian Cells10:55

    Purification of Ubiquitinated p53 Proteins from Mammalian Cells

    Published on: March 21, 2022

    2.3K
    Yeast As a Chassis for Developing Functional Assays to Study Human P5314:57

    Yeast As a Chassis for Developing Functional Assays to Study Human P53

    Published on: August 4, 2019

    9.7K

    Related Concept Videos

    Abnormal Proliferation02:23

    Abnormal Proliferation

    Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the...
    4.6K
    Negative Regulator Molecules01:23

    Negative Regulator Molecules

    Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
    36.2K
    DNA Damage can Stall the Cell Cycle02:37

    DNA Damage can Stall the Cell Cycle

    In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
    9.3K
    Covalently Linked Protein Regulators02:04

    Covalently 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....
    7.5K
    PI3K/mTOR/AKT Signaling Pathway01:22

    PI3K/mTOR/AKT Signaling Pathway

    The mammalian target of rapamycin  (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1  (mTORC1) and mTOR complex 2  (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast,  mTORC2 consists of a...
    4.0K
    Regulation of the Unfolded Protein Response01:31

    Regulation of the Unfolded Protein Response

    Inositol-requiring kinase one or IRE1 is the most conserved eukaryotic unfolded protein response (UPR) receptor. It is a type I transmembrane protein kinase receptor with a distinctive site-specific RNase activity. As the binding mechanics of the misfolded proteins with the N-terminal domain of IRE-1 are unclear, three binding models — direct, indirect, and allosteric -- are proposed for receptor activation. Nevertheless, it is known that once a misfolded protein associates with IRE1, it...
    2.6K