Lipocalin-2 (LCN-2) is a novel myokine that reduces lipid accumulation and induces lipolysis in adipocytes
Introduction LCN-2 is an acute phase protein, first identified as an adipokine secreted by adipose tissue. Contradictory experimental results show that LCN-2 is involved in pro- and anti-inflammatory states and can both increase and decrease insulin resistance. However, whilst the Lipocalin-2 prote...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English |
| Published: |
2023
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| Online Access: | https://eprints.nottingham.ac.uk/74736/ |
| _version_ | 1848800878262222848 |
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| author | Alsolami, Areej |
| author_facet | Alsolami, Areej |
| author_sort | Alsolami, Areej |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | Introduction
LCN-2 is an acute phase protein, first identified as an adipokine secreted by adipose tissue. Contradictory experimental results show that LCN-2 is involved in pro- and anti-inflammatory states and can both increase and decrease insulin resistance. However, whilst the Lipocalin-2 protein is widely expressed in several tissues/cells, its expression has been poorly studied in skeletal muscle. Experiments in FRAME lab have demonstrated that the mRNA expression of LCN-2 is increased after exercise post 3-hr in vivo in 3 partipiants out of 6, and therefore its role in skeletal muscle following exercise needs to be investigated. We hypothesise that LCN-2 is a novel potential myokine, acting post exercise in an endocrine fashion that affects lipid metabolism.
Methods
Primary human myotubes were isolated from healthy volunteers and cultured to study LCN-2 expression and secretion in response to EPS stimulation and AICAR treatment. The lentiviral inducible vector pINDUCER20 was used to enable inducible overexpression of LCN-2 in human primary myotubes. Lastly, adipocytes were exposed to conditioned media (CM) derived from human myotubes that overexpress LCN-2 to study the crosstalk between muscle and adipose tissue.
Results
We found that LCN-2 mRNA expression was significantly upregulated in a time- dependant manner (2 h, 4 h, 16 h) by EPS (p<0.0001; 6-fold post-16 hr) and protein was secreted by human myotubes in response to 16 h of EPS (p<0.0001; 43% increase). Moreover, the level of LCN-2 secretion by myotubes increased in response to AICAR treatment for 48 h (p<0.0001; 3-fold increae). Lipid accumulation in adipocytes (3T3L-1) reduced significantly post-48 h when adipocytes (3T3L-1) were exposed to 50% CM derived from human myotubes that overexpress LCN-2 (p<0.0001; 3-fold). Moreover, a significant increase in release of glycerol (nmol/mg of cell protein) post48 h occurred when exposed to human myotube CM (p<0.001; 2- fold). Additionally, we found that ATGL protein was upregulated in response to LCN-2 containing conditioned medium (p<0.0001; ~ 4-fold).
Conclusion
We conclude that LCN-2 is a novel exercise-induced myokine that appears to induce lipolysis and decrease lipid accumulation in adipocytes. |
| first_indexed | 2025-11-14T20:58:33Z |
| format | Thesis (University of Nottingham only) |
| id | nottingham-74736 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T20:58:33Z |
| publishDate | 2023 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-747362023-11-06T13:40:15Z https://eprints.nottingham.ac.uk/74736/ Lipocalin-2 (LCN-2) is a novel myokine that reduces lipid accumulation and induces lipolysis in adipocytes Alsolami, Areej Introduction LCN-2 is an acute phase protein, first identified as an adipokine secreted by adipose tissue. Contradictory experimental results show that LCN-2 is involved in pro- and anti-inflammatory states and can both increase and decrease insulin resistance. However, whilst the Lipocalin-2 protein is widely expressed in several tissues/cells, its expression has been poorly studied in skeletal muscle. Experiments in FRAME lab have demonstrated that the mRNA expression of LCN-2 is increased after exercise post 3-hr in vivo in 3 partipiants out of 6, and therefore its role in skeletal muscle following exercise needs to be investigated. We hypothesise that LCN-2 is a novel potential myokine, acting post exercise in an endocrine fashion that affects lipid metabolism. Methods Primary human myotubes were isolated from healthy volunteers and cultured to study LCN-2 expression and secretion in response to EPS stimulation and AICAR treatment. The lentiviral inducible vector pINDUCER20 was used to enable inducible overexpression of LCN-2 in human primary myotubes. Lastly, adipocytes were exposed to conditioned media (CM) derived from human myotubes that overexpress LCN-2 to study the crosstalk between muscle and adipose tissue. Results We found that LCN-2 mRNA expression was significantly upregulated in a time- dependant manner (2 h, 4 h, 16 h) by EPS (p<0.0001; 6-fold post-16 hr) and protein was secreted by human myotubes in response to 16 h of EPS (p<0.0001; 43% increase). Moreover, the level of LCN-2 secretion by myotubes increased in response to AICAR treatment for 48 h (p<0.0001; 3-fold increae). Lipid accumulation in adipocytes (3T3L-1) reduced significantly post-48 h when adipocytes (3T3L-1) were exposed to 50% CM derived from human myotubes that overexpress LCN-2 (p<0.0001; 3-fold). Moreover, a significant increase in release of glycerol (nmol/mg of cell protein) post48 h occurred when exposed to human myotube CM (p<0.001; 2- fold). Additionally, we found that ATGL protein was upregulated in response to LCN-2 containing conditioned medium (p<0.0001; ~ 4-fold). Conclusion We conclude that LCN-2 is a novel exercise-induced myokine that appears to induce lipolysis and decrease lipid accumulation in adipocytes. 2023-10-15 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en cc_by https://eprints.nottingham.ac.uk/74736/1/Lipocalin%202%20PhD%20thesis%20August%202023%20%28Final%29.pdf Alsolami, Areej (2023) Lipocalin-2 (LCN-2) is a novel myokine that reduces lipid accumulation and induces lipolysis in adipocytes. PhD thesis, University of Nottingham. Adipose tissue; EPS; Exercise; Lipid accumulation; Lipid metabolism; Lipocalin-2 (LCN-2); Lipolysis; Muscle contraction; Myokines; Skeletal muscle |
| spellingShingle | Adipose tissue; EPS; Exercise; Lipid accumulation; Lipid metabolism; Lipocalin-2 (LCN-2); Lipolysis; Muscle contraction; Myokines; Skeletal muscle Alsolami, Areej Lipocalin-2 (LCN-2) is a novel myokine that reduces lipid accumulation and induces lipolysis in adipocytes |
| title | Lipocalin-2 (LCN-2) is a novel myokine that reduces lipid accumulation and induces lipolysis in adipocytes |
| title_full | Lipocalin-2 (LCN-2) is a novel myokine that reduces lipid accumulation and induces lipolysis in adipocytes |
| title_fullStr | Lipocalin-2 (LCN-2) is a novel myokine that reduces lipid accumulation and induces lipolysis in adipocytes |
| title_full_unstemmed | Lipocalin-2 (LCN-2) is a novel myokine that reduces lipid accumulation and induces lipolysis in adipocytes |
| title_short | Lipocalin-2 (LCN-2) is a novel myokine that reduces lipid accumulation and induces lipolysis in adipocytes |
| title_sort | lipocalin-2 (lcn-2) is a novel myokine that reduces lipid accumulation and induces lipolysis in adipocytes |
| topic | Adipose tissue; EPS; Exercise; Lipid accumulation; Lipid metabolism; Lipocalin-2 (LCN-2); Lipolysis; Muscle contraction; Myokines; Skeletal muscle |
| url | https://eprints.nottingham.ac.uk/74736/ |