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Waters LR, Ahsan FM, Ten Hoeve J, Hong JS, Kim DNH, Minasyan A, Braas D, Graeber TG, Zangle TA, Teitell MA. Ampk regulates IgD expression but not energy stress with B cell activation. Sci Rep 2019; 9:8176. [PMID: 31160601 PMCID: PMC6546716 DOI: 10.1038/s41598-019-43985-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 04/28/2019] [Indexed: 12/25/2022] Open
Abstract
Ampk is an energy gatekeeper that responds to decreases in ATP by inhibiting energy-consuming anabolic processes and promoting energy-generating catabolic processes. Recently, we showed that Lkb1, an understudied kinase in B lymphocytes and a major upstream kinase for Ampk, had critical and unexpected roles in activating naïve B cells and in germinal center formation. Therefore, we examined whether Lkb1 activities during B cell activation depend on Ampk and report surprising Ampk activation with in vitro B cell stimulation in the absence of energy stress, coupled to rapid biomass accumulation. Despite Ampk activation and a controlling role for Lkb1 in B cell activation, Ampk knockout did not significantly affect B cell activation, differentiation, nutrient dynamics, gene expression, or humoral immune responses. Instead, Ampk loss specifically repressed the transcriptional expression of IgD and its regulator, Zfp318. Results also reveal that early activation of Ampk by phenformin treatment impairs germinal center formation but does not significantly alter antibody responses. Combined, the data show an unexpectedly specific role for Ampk in the regulation of IgD expression during B cell activation.
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Affiliation(s)
- Lynnea R Waters
- Molecular Biology Interdepartmental Program, UCLA, Los Angeles, CA, 90095, USA
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, CA, 90095, USA
| | - Fasih M Ahsan
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, CA, 90095, USA
| | - Johanna Ten Hoeve
- Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, CA, 90095, USA
- UCLA Metabolomics Center, UCLA, Los Angeles, CA, 90095, USA
- Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, 90095, USA
| | - Jason S Hong
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, CA, 90095, USA
| | - Diane N H Kim
- Department of Bioengineering, UCLA, Los Angeles, CA, 90095, USA
| | - Aspram Minasyan
- Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, CA, 90095, USA
- Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, 90095, USA
| | - Daniel Braas
- Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, CA, 90095, USA
- UCLA Metabolomics Center, UCLA, Los Angeles, CA, 90095, USA
- Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, 90095, USA
| | - Thomas G Graeber
- Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, CA, 90095, USA
- UCLA Metabolomics Center, UCLA, Los Angeles, CA, 90095, USA
- Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, 90095, USA
- Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, CA, 90095, USA
- California NanoSystems Institute, UCLA, Los Angeles, CA, 90095, USA
- Broad Stem Cell Research Center, UCLA, Los Angeles, CA, 90095, USA
| | - Thomas A Zangle
- Department of Chemical Engineering, University of Utah, Salt Lake City, UT, 84112, USA
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, 84112, USA
| | - Michael A Teitell
- Molecular Biology Interdepartmental Program, UCLA, Los Angeles, CA, 90095, USA.
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, CA, 90095, USA.
- Department of Bioengineering, UCLA, Los Angeles, CA, 90095, USA.
- Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, CA, 90095, USA.
- California NanoSystems Institute, UCLA, Los Angeles, CA, 90095, USA.
- Broad Stem Cell Research Center, UCLA, Los Angeles, CA, 90095, USA.
- Department of Pediatrics, UCLA, Los Angeles, CA, 90095, USA.
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Shan T, Zhang P, Xiong Y, Wang Y, Kuang S. Lkb1 deletion upregulates Pax7 expression through activating Notch signaling pathway in myoblasts. Int J Biochem Cell Biol 2016; 76:31-8. [PMID: 27131604 DOI: 10.1016/j.biocel.2016.04.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 03/19/2016] [Accepted: 04/26/2016] [Indexed: 11/28/2022]
Abstract
Satellite cells play crucial roles in mediating the growth, maintenance, and repair of postnatal skeletal muscle. Activated satellite cells (myoblasts) can divide symmetrically or asymmetrically to generate progenies that self-renewal, proliferate or differentiate. Pax7 is a defining marker of quiescent and activated satellite cells, but not differentiated myoblast. We demonstrate here that deletion of Lkb1 upregulates Pax7 expression in myoblasts and inhibits asymmetric divisions that generate differentiating progenies. Furthermore, we find that Lkb1 activates the Notch signaling pathway, which subsequently increases Pax7 expression and promotes self-renewal and proliferation while inhibiting differentiation. Mechanistic studies reveal that Lkb1 regulates Notch activation through AMPK-mTOR pathway in myoblasts. Together, these results establish a key role of Lkb1 in regulating myoblast division and cell fates choices.
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Affiliation(s)
- Tizhong Shan
- Department of Animal Science, Zhejiang University, Hangzhou, Zhejiang 310058, China; Department of Animal Science, Purdue University, West Lafayette, IN 47907, USA.
| | - Pengpeng Zhang
- Department of Animal Science, Purdue University, West Lafayette, IN 47907, USA
| | - Yan Xiong
- Department of Animal Science, Purdue University, West Lafayette, IN 47907, USA
| | - Yizhen Wang
- Department of Animal Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Shihuan Kuang
- Department of Animal Science, Purdue University, West Lafayette, IN 47907, USA; Purdue University Center for Cancer Research, West Lafayette, IN 47907, USA.
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