Related Experiment Video

Updated: Jun 12, 2026

Heterokaryon Technique for Analysis of Cell Type-specific Localization
09:31

Heterokaryon Technique for Analysis of Cell Type-specific Localization

Published on: March 11, 2011

CCN5, a secreted protein, localizes to the nucleus

Kristina C Wiesman, Lan Wei, Cassandra Baughman

    Journal of Cell Communication and Signaling
    |June 10, 2010
    PubMed

    Insights

    CCN5, a growth factor, is found in the nucleus, challenging previous understanding of its function. Further research will explore how CCN5 enters the nucleus and its roles in different cellular locations.

    Area of Science:

    • Cell Biology
    • Molecular Biology
    • Biochemistry

    Background:

    • CCN5 is a CCN family member known to inhibit smooth muscle cell proliferation and migration.
    • CCN5 is typically found associated with the cell surface, characteristic of secreted matricellular proteins.
    • Immunohistochemical data suggested a potential nuclear localization for CCN5, contrary to its known extracellular functions.

    Purpose of the Study:

    • To experimentally confirm the presence and localization of CCN5 within the cell nucleus.
    • To investigate the mechanism of CCN5 nuclear transport.
    • To explore the functional implications of nuclear versus secreted CCN5.

    Main Methods:

    • Immunofluorescence and confocal imaging were used to visualize CCN5 localization.
    • Cell fractionation techniques were employed to isolate nuclear and cytoplasmic components.
    • Site-directed mutagenesis was performed on a putative nuclear localization signal (NLS).

    Main Results:

    • Four independent experimental methods confirmed the presence of CCN5 in the nucleus.
    • A single canonical NLS was identified in the von Willebrand factor C domain of CCN5.
    • Mutagenesis of the putative NLS did not abolish CCN5 nuclear localization in multiple cell types.

    Conclusions:

    • CCN5 is demonstrably present in the cell nucleus, expanding its known cellular roles.
    • The canonical NLS identified is not solely responsible for CCN5 nuclear import.
    • The mechanism and functional significance of nuclear CCN5 require further investigation.
    Keywords:
    CCN familyCCN5Matricellular proteinsNuclear localizationWISP-2

    More Related Videos

    Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay12:26

    Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

    Published on: May 3, 2018

    Immunofluorescence Analysis of Endogenous and Exogenous Centromere-kinetochore Proteins05:35

    Immunofluorescence Analysis of Endogenous and Exogenous Centromere-kinetochore Proteins

    Published on: March 3, 2016

    Related Concept Videos

    Nuclear Localization Signals and Import01:46

    Nuclear Localization Signals and Import

    Proteins targeted to the nucleus carry short stretches of amino acid sequences called the nuclear localization signal or NLS. Classical nuclear localization signals are of two types: monopartite and bipartite NLS. Monopartite classical NLS (cNLS) consists of a single cluster of 4-8 amino acids. Bipartite cNLS consists of two clusters of  2-3 amino acids and a 9-12 residue long proline-rich linker bridging the two clusters. Signal clusters are rich in positively charged amino acids such as...
    Regulation of Nuclear Protein Sorting01:45

    Regulation 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...
    Nuclear Protein Sorting01:34

    Nuclear Protein Sorting

    Nuclear protein sorting is the selective trafficking of histones, polymerases, gene regulatory proteins into the nucleus and exporting RNAs and ribosomes to the cytosol. It is a tightly controlled process that regulates gene expression within a cell.
    Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
    Nuclear Export01:42

    Nuclear Export

    The nucleus restricts several proteins within and allows others to pass. The restricted proteins possess a nuclear retention sequence or NRS, anchoring them to the nuclear lamins and preventing their transport to the cytosol. The non-restricted proteins, after their synthesis, are transported to their site of action, such as the cytosol or other organelles, with the help of nuclear export signals or NES.
    NES are of three types- the canonical 10-residue long leucine-rich signal and other...
    Chromatin Position Affects Gene Expression02:35

    Chromatin Position Affects Gene Expression

    Chromatin is the massive complex of DNA and proteins packaged inside the nucleus. The complexity of chromatin folding and how it is packaged inside the nucleus greatly influences  access to genetic information. Generally, the nucleus' periphery is considered transcriptionally repressive, while the cell's interior is considered a transcriptionally active area. 
    Topologically Associated Domains (TADs)
    The 3-dimensional positioning of chromatin in the nucleus influences the timing and level of...
    Additional Subnuclear Structures02:10

    Additional Subnuclear Structures

    The eukaryotic nucleus is a double membrane-bound organelle that contains nearly all of the cell’s genetic material in the form of chromosomes. It is rightly called the “brain” of the cell as it shoulders the responsibility of responding to various physiological processes, stress, altered metabolic conditions, and other cellular signals. 
    The nucleus contains many membrane-less subnuclear organelles or nuclear bodies, such as nucleoli, Cajal bodies, speckles, paraspeckles, etc. These nuclear...