IFT88 interacts with polycystin 2 to regulate mechanosensitive hedgehog signaling in mandibular condylar chondrocytes

Abstract

<h3>Objective</h3><p>This study aimed to explore whether intraflagellar <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/mitochondrial-membrane-transport-protein" title="Learn more about transport protein from ScienceDirect's AI-generated Topic Pages">transport protein</a> 88 (IFT88) was associated with <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/polycystin-2" title="Learn more about polycystin 2 from ScienceDirect's AI-generated Topic Pages">polycystin 2</a> during <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/mechanotransduction" title="Learn more about mechanotransduction from ScienceDirect's AI-generated Topic Pages">mechanotransduction</a> of mandibular condylar <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/chondrocyte" title="Learn more about chondrocytes from ScienceDirect's AI-generated Topic Pages">chondrocytes</a>.</p><h3>Methods</h3><p>Rat mandibular condylar <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/chondrocyte" title="Learn more about chondrocytes from ScienceDirect's AI-generated Topic Pages">chondrocytes</a> isolated from the condylar bone-cartilage junction were subjected to cyclic tensile strain (0.1 Hz, 10% elongation). Overexpression of IFT88 was achieved by lentiviral vector-mediated transfection. Knockdown of IFT88 and <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/polycystin-2" title="Learn more about polycystin 2 from ScienceDirect's AI-generated Topic Pages">polycystin 2</a> was achieved by <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/small-interfering-rna" title="Learn more about small interfering RNA from ScienceDirect's AI-generated Topic Pages">small interfering RNA</a> (siRNA). The prevalence and length of cilia were reflected by <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/immunofluorescence" title="Learn more about immunofluorescence from ScienceDirect's AI-generated Topic Pages">immunofluorescence</a> staining. The activities of <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/hedgehog-signaling" title="Learn more about hedgehog signaling from ScienceDirect's AI-generated Topic Pages">hedgehog signaling</a> were evaluated by <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/western-blot" title="Learn more about western blot analysis from ScienceDirect's AI-generated Topic Pages">western blot analysis</a>. The interaction between polycystin 2 and IFT88 was evaluated by conducting a co-immunoprecipitation (co-IP) assay.</p><h3>Results</h3><p>Overexpression of IFT88 increased the length of cilia. Protein levels of polycystin 2, Indian hedgehog (Ihh), <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/protein-patched-1" title="Learn more about Patched 1 from ScienceDirect's AI-generated Topic Pages">Patched 1</a> (Ptch1), Smoothened (Smo), and Glioma-associated oncogene homolog 1 (Gli1) were elevated in IFT88-overexpressing mandibular condylar chondrocytes under cyclic tensile strain. Knockdown of the protein level of IFT88 reduced the prevalence and length of cilia, and protein levels of polycystin 2, Ihh, Ptch1, Smo, and Gli1. A co-IP assay showed that IFT88 formed a complex with polycystin 2 under cyclic tensile strain. Knockdown of polycystin 2 decreased the protein levels of IFT88, Ihh, Ptch1, Smo, and Gli1 in mandibular condylar chondrocytes following cyclic tensile strain.</p><h3>Conclusion</h3><p>These findings highlight the vital role of an interaction between IFT88 and polycystin 2 in mechanosensitive <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/hedgehog-signaling" title="Learn more about hedgehog signaling from ScienceDirect's AI-generated Topic Pages">hedgehog signaling</a> in mandibular condylar chondrocytes following cyclic tensile strain, which suggest that therapies regulating polycystin 2 may be considered for the disorders of <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/temporomandibular-joint" title="Learn more about temporomandibular joints from ScienceDirect's AI-generated Topic Pages">temporomandibular joints</a>.</p>