Abstract
Skeletal myogenesis is coordinated by multiple signaling pathways that control cell adhesion/migration, survival and differentiation accompanied by muscle-specific gene expression. A cell surface protein Cdo is involved in cell contact-mediated promyogenic signals through activation of p38MAPK and AKT. Protein kinase C-related kinase 2 (PKN2/PRK2) is implicated in regulation of various biological processes, including cell migration, adhesion and death. It has been shown to interact with and inhibit AKT thereby inducing cell death. This led us to investigate the role of PKN2 in skeletal myogenesis and the crosstalk between PKN2 and Cdo. Like Cdo, PKN2 was upregulated in C2C12 myoblasts during differentiation and decreased in cells with Cdo depletion caused by shRNA or cultured on integrin-independent substratum. This decline of PKN2 levels resulted in diminished AKT activation during myoblast differentiation. Consistently, PKN2 overexpression-enhanced C2C12 myoblast differentiation, whereas PKN2-depletion impaired it, without affecting cell survival. PKN2 formed complexes with Cdo, APPL1 and AKT via its C-terminal region and this interaction appeared to be important for induction of AKT activity as well as myoblast differentiation. Furthermore, PKN2-enhanced MyoD-responsive reporter activities by mediating the recruitment of BAF60c and MyoD to the myogenin promoter. Taken together, PKN2 has a critical role in cell adhesion-mediated AKT activation during myoblast differentiation.
Highlights
For efficient regeneration of damaged tissues, stem cells need to respond properly to the extracellular cues to proliferate and to facilitate the differentiation process
Well-supported evidences have suggested that AKT signaling has important roles in myoblast differentiation[8,18,19] and insulin-like growth factor (IGF)-mediated myoblast survival, which is critically activated during myogenic differentiation.[20,21]
To investigate the function of PKN2 in skeletal myogenesis, C2C12 cells were grown to near-confluency (D0) and induced to differentiate for 3 days (D3), followed by immunoblotting
Summary
For efficient regeneration of damaged tissues, stem cells need to respond properly to the extracellular cues to proliferate and to facilitate the differentiation process. Received 09.5.16; revised 10.8.16; accepted 22.8.16; Edited by E Candi pathways,[24,25,26,27,28] such as cytoskeletal organization,[25] cell adhesion,[26] cell cycle control[27] as well as cell migration,[28] PKN2 appears to regulate cell–cell adhesion,[26] apical junction maturation in keratinocytes[29] and migration of astrocytes.[30] PKN2 can be cleaved by caspases at amino acid (AA) 700 and the resulting C-terminal fragment can interact and inhibit AKT during apoptosis in 293 and COS cells.[31] PKN2 is expressed ubiquitously in developing embryos,[32] its role in myogenesis is currently unclear. Considering the proposed role of PKN2 in cytoskeletal organization and cell adhesion signaling regulated by Rho GTPases and its interaction with AKT, prompt us to assess its role in myogenesis, especially in Cdo-mediated promyogenic pathway. PKN2 interacted with Cdo, APPL1 and AKT via its C-terminal region, and this interaction appeared to be important for AKT activation in myoblast differentiation thereby positively regulating myoblast differentiation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
