Related Experiment Videos
PNRC2 is a 16 kDa coactivator that interacts with nuclear receptors through an SH3-binding motif
1Division of Immunology, Beckman Research Institute of the City of Hope, 1450 East Duarte Road, Duarte, CA 91010, USA.
Abstract:
PNRC2 (proline-rich nuclear receptor co-regulatory protein 2) was identified using mouse steroidogenic factor 1 (SF1) as bait in a yeast two-hybrid screening of a human mammary gland cDNA expression library. PNRC2 is an unusual coactivator in that it is the smallest coactivator identified so far, with a molecular weight of 16 kDa, and interacts with nuclear receptors using a proline-rich sequence. In yeast two-hybrid assays PNRC2 interacted with orphan receptors SF1 and estrogen receptor-related receptor alpha1 in a ligand-independent manner. PNRC2 was also found to interact with the ligand-binding domains of estrogen receptor, glucocorticoid receptor, progesterone receptor, thyroid receptor, retinoic acid receptor and retinoid X receptor in a ligand-dependent manner. A functional activation function 2 domain is required for nuclear receptors to interact with PNRC2. Using the yeast two-hybrid assay, the region amino acids 85-139 was found to be responsible for the interaction with nuclear receptors. This region contains an SH3 domain-binding motif (SEPPSPS) and an NR box-like sequence (LKTLL). A mutagenesis study has shown that the SH3 domain-binding motif is important for PNRC2 to interact with all the nuclear receptors tested. Our results reveal that PNRC2 has a structure and function similar to PNRC, a previously characterized coactivator. These two proteins represent a new type of nuclear receptor co-regulatory proteins.
Insights
Proline-rich nuclear receptor co-regulatory protein 2 (PNRC2) is a small coactivator that interacts with various nuclear receptors. Its SH3 domain-binding motif is crucial for these interactions, revealing a new class of co-regulatory proteins.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Nuclear receptors are key regulators of gene expression.
- Coactivators modulate nuclear receptor activity.
- PNRC2 is a newly identified coactivator with unique structural features.
Purpose of the Study:
- To identify and characterize PNRC2, a novel coactivator.
- To elucidate the interaction mechanism between PNRC2 and nuclear receptors.
- To determine the functional domains of PNRC2 involved in nuclear receptor binding.
Main Methods:
- Yeast two-hybrid screening using mouse steroidogenic factor 1 (SF1).
- Interaction assays with various nuclear receptors (ligand-dependent and independent).
- Mutagenesis studies to identify critical interaction motifs.
Main Results:
- PNRC2, a 16 kDa coactivator, was identified.
- PNRC2 interacts with SF1 and estrogen receptor-related receptor alpha1 ligand-independently.
- PNRC2 interacts with multiple nuclear receptors (ER, GR, PR, TR, RAR, RXR) ligand-dependently via its amino acids 85-139 region.
- An SH3 domain-binding motif (SEPPSPS) is essential for PNRC2-nuclear receptor interactions.
Conclusions:
- PNRC2 represents a novel class of small nuclear receptor coactivators.
- The SH3 domain-binding motif is critical for PNRC2's coactivator function.
- PNRC2 shares functional similarities with PNRC, suggesting a conserved co-regulatory mechanism.