1
|
Sah JP, Hao NTT, Han X, Tran TTT, McCarthy S, Oh Y, Yoon JK. Ectonucleotide pyrophosphatase 2 (ENPP2) plays a crucial role in myogenic differentiation through the regulation by WNT/β-Catenin signaling. Int J Biochem Cell Biol 2019; 118:105661. [PMID: 31805399 DOI: 10.1016/j.biocel.2019.105661] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 11/28/2019] [Accepted: 11/30/2019] [Indexed: 12/23/2022]
Abstract
Ectonucleotide pyrophosphate phosphodiesterase type II (ENPP2), also known as Autotaxin (ATX), is an enzyme present in blood circulation that converts lysophosphatidyl choline (LPC) to lysophosphatidic acid (LPA). While LPA has been demonstrated to play diverse roles in skeletal myogenesis, mainly through in vitro studies, the role of ENPP2 in skeletal myogenesis has not been determined. We previously found that Enpp2 is induced by a positive WNT/β-Catenin signaling regulator, R-spondin2 (RSPO2), in C2C12 myoblast cells. As RSPO2 promotes myogenic differentiation via the WNT/β-Catenin signaling pathway, we hypothesized that ENPP2 may act as a key mediator for the crosstalk between WNT and LPA signaling during myogenic differentiation. Herein, we found that ENPP2 function is essential for myogenic differentiation in C2C12 cells. Pharmacological ENPP2 inhibitors or RNAi-mediated Enpp2 gene knockdown severely impaired the myogenic differentiation, including the cell fusion process, whereas administration of the recombinant ENPP2 protein enhanced myogenic differentiation. Consistent with the in vitro results, mice lacking the Enpp2 gene showed a disrupted muscle regeneration after acute muscle injury. The size of newly regenerated myofibers in Enpp2 mutant muscle was significantly reduced compared with wild-type regenerated muscle. Modified expression patterns of myogenic markers in Enpp2 mutant muscle further emphasized the impaired muscle regeneration process. Finally, we convincingly demonstrate that the Enpp2 gene is a direct transcriptional target for WNT/β-Catenin signaling. Functional TCF/LEF1 binding sites within the upstream region of Enpp2 gene were identified by chromatin immunoprecipitation using anti-β-Catenin antibodies and reporter assay. Our study reveals that ENPP2 is regulated by WNT/β-Catenin signaling and plays a key positive role in myogenic differentiation.
Collapse
Affiliation(s)
- Jay Prakash Sah
- Soonchunhyang Institute of Medi-Bio Science, Soonchunhyang University, 25 Bongjeong-ro, Dongnam-gu, Cheonan-si, 31151, South Korea; Department of Integrated Biomedical Science, Soonchunhyang University, 25 Bongjeong-ro, Dongnam-gu, Cheonan-si, 31151, South Korea
| | - Nguyen Thi Thu Hao
- Soonchunhyang Institute of Medi-Bio Science, Soonchunhyang University, 25 Bongjeong-ro, Dongnam-gu, Cheonan-si, 31151, South Korea; Department of Integrated Biomedical Science, Soonchunhyang University, 25 Bongjeong-ro, Dongnam-gu, Cheonan-si, 31151, South Korea
| | - Xianghua Han
- Center for Molecular Medicine, Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME, 04074, USA
| | - Trinh Thi Tuyet Tran
- Soonchunhyang Institute of Medi-Bio Science, Soonchunhyang University, 25 Bongjeong-ro, Dongnam-gu, Cheonan-si, 31151, South Korea; Department of Integrated Biomedical Science, Soonchunhyang University, 25 Bongjeong-ro, Dongnam-gu, Cheonan-si, 31151, South Korea
| | - Sarah McCarthy
- Center for Molecular Medicine, Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME, 04074, USA
| | - Younjeong Oh
- Soonchunhyang Institute of Medi-Bio Science, Soonchunhyang University, 25 Bongjeong-ro, Dongnam-gu, Cheonan-si, 31151, South Korea
| | - Jeong Kyo Yoon
- Soonchunhyang Institute of Medi-Bio Science, Soonchunhyang University, 25 Bongjeong-ro, Dongnam-gu, Cheonan-si, 31151, South Korea; Department of Integrated Biomedical Science, Soonchunhyang University, 25 Bongjeong-ro, Dongnam-gu, Cheonan-si, 31151, South Korea.
| |
Collapse
|
2
|
Matheny RW, Abdalla MN, Geddis AV, Leandry LA, Lynch CM. Skeletal muscle PI3K p110β regulates expression of AMP-activated protein kinase. Biochem Biophys Res Commun 2016; 482:1420-1426. [PMID: 27965101 DOI: 10.1016/j.bbrc.2016.12.051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 12/07/2016] [Indexed: 11/29/2022]
Abstract
Skeletal muscle metabolic homeostasis is maintained through numerous biochemical and physiological processes. Two principal molecular regulators of skeletal muscle metabolism include AMP-activated protein kinase (AMPK) and phosphatidylinositol 3-kinase (PI3K); however, PI3K exists as multiple isoforms, and specific metabolic actions of each isoform have not yet been fully elucidated in skeletal muscle. Given this lack of knowledge, we performed a series of experiments to define the extent to which PI3K p110β mediated expression and (or) activation of AMPK in skeletal muscle. To determine the effect of p110β inhibition on AMPK expression and phosphorylation in cultured cells, C2C12 myoblasts were treated with a pharmacological inhibitor of p110β (TGX-221), siRNA against p110β, or overexpression of kinase-dead p110β. Expression and phosphorylation of AMPK were unaffected in myoblasts treated with TGX-221 or expressing kinase-dead p110β. However, expressions of total and phosphorylated AMPK at T172 were reduced in myoblasts treated with p110β siRNA. When normalized to expression of total AMPK, phosphorylation of AMPK S485/491 was elevated in p110β-deficient myoblasts. Similar results were observed in tibialis anterior muscle from mice with conditional deletion of p110β (p110β-mKO mice). Analysis of AMPK transcript expression revealed decreased expression of Prkaa2 in p110β-deficient myoblasts and in p110β-mKO muscle. Loss of p110β had no effect on oligomycin-stimulated phosphorylation of AMPK or phosphorylated Acetyl-CoA carboxylase (ACC), although oligomycin-induced AMPK and ACC phosphorylation were increased in p110β-deficient myoblasts compared to oligomycin-stimulated control myoblasts when normalized to levels of total AMPK or ACC. Overall, these results suggest that p110β positively regulates expression of AMPK in cultured myoblasts and in skeletal muscle in vivo; moreover, despite the reduced abundance of AMPK in p110β-deficient myoblasts, loss of p110β does not appear to impair AMPK activation following stimulus. These findings thus reveal a novel role for p110β in mediating skeletal muscle metabolic signaling.
Collapse
Affiliation(s)
- Ronald W Matheny
- Military Performance Division, US Army Research Institute of Environmental Medicine, 10 General Greene Ave, Building 42, Natick, MA, 01760, USA.
| | - Mary N Abdalla
- Military Performance Division, US Army Research Institute of Environmental Medicine, 10 General Greene Ave, Building 42, Natick, MA, 01760, USA
| | - Alyssa V Geddis
- Military Performance Division, US Army Research Institute of Environmental Medicine, 10 General Greene Ave, Building 42, Natick, MA, 01760, USA
| | - Luis A Leandry
- Military Performance Division, US Army Research Institute of Environmental Medicine, 10 General Greene Ave, Building 42, Natick, MA, 01760, USA
| | - Christine M Lynch
- Military Performance Division, US Army Research Institute of Environmental Medicine, 10 General Greene Ave, Building 42, Natick, MA, 01760, USA
| |
Collapse
|
4
|
Abstract
Phosphoinositide 3-OH kinase (PI3K) regulates a number of developmental and physiologic processes in skeletal muscle; however, the contributions of individual PI3K p110 catalytic subunits to these processes are not well-defined. To address this question, we investigated the role of the 110-kDa PI3K catalytic subunit β (p110β) in myogenesis and metabolism. In C2C12 cells, pharmacological inhibition of p110β delayed differentiation. We next generated mice with conditional deletion of p110β in skeletal muscle (p110β muscle knockout [p110β-mKO] mice). While young p110β-mKO mice possessed a lower quadriceps mass and exhibited less strength than control littermates, no differences in muscle mass or strength were observed between genotypes in old mice. However, old p110β-mKO mice were less glucose tolerant than old control mice. Overexpression of p110β accelerated differentiation in C2C12 cells and primary human myoblasts through an Akt-dependent mechanism, while expression of kinase-inactive p110β had the opposite effect. p110β overexpression was unable to promote myoblast differentiation under conditions of p110α inhibition, but expression of p110α was able to promote differentiation under conditions of p110β inhibition. These findings reveal a role for p110β during myogenesis and demonstrate that long-term reduction of skeletal muscle p110β impairs whole-body glucose tolerance without affecting skeletal muscle size or strength in old mice.
Collapse
|