The role of L-type amino acid transporter 1 (Slc7a5) during in vitro myogenesis

Abstract

Satellite cells are required for muscle regeneration, remodeling, and repair through their activation, proliferation, and differentiation; however, how dietary factors regulate this process remains poorly understood. The L-Type amino acid transporter 1 (LAT1) transports amino acids, such as leucine, into mature myofibers, which then stimulates protein synthesis and anabolic signaling. However, whether LAT1 is expressed on myoblasts and is involved in regulating myogenesis is unknown. The aim of this study was to characterize the expression and functional relevance of LAT1 during different stages of myogenesis and in response to growth and atrophic conditions in vitro. We determined that LAT1 is expressed by C2C12 and human primary myoblasts, and its gene expression is lower during differentiation (p<0.05). Pharmacological inhibition and genetic knockdown of LAT1 impaired myoblast viability, differentiation, and fusion (all p<0.05). LAT1 protein content in C2C12 myoblasts was not significantly altered in response to different leucine concentrations in cell culture media or in two in vitro atrophy models. However, LAT1 content was decreased in myotubes under atrophic conditions in vitro (p<0.05). These findings indicate that LAT1 is stable throughout myogenesis and in response to several in vitro conditions that induce muscle remodeling. Further, amino acid transport through LAT1 is required for normal myogenesis in vitro.

PPARβ/δ Agonism with GW501516 Increases Myotube PGC-1α Content and Reduces BCAA Media Content Independent of Changes in BCAA Catabolic Enzyme Expression

“…This example of LAT1 dispensability has been shown in gastrocnemius of LAT1-knockout mice that exhibit increased LAT2 mRNA expression ( Slc7a8 ) and do not display altered intra-gastrocnemius leucine content following a fed state (and display elevated leucine content under a fasting state) [ 55 ]. Our findings seem to agree with other experiments showing LAT1 abundance is not dependent on cell culture media leucine content in myocytes [ 56 ], nor dependent on dietary protein within skeletal muscle [ 57 ]. Together, our study provides a first level of evidence suggesting PPAR β / δ agonism with GW may upregulate BCAA metabolism.…”

LncRNA XLOC_015548 affects the proliferation and differentiation of myoblasts via the MAPK signaling pathway

“…At present, it is believed that the regulation mechanism of cell fusion is mainly related to the adhesion molecules and membrane protein structures on the cell membrane, such as P4-ATPase flippase subunit CDC50A and L-type amino acid transporter 1 (LAT1). [39][40][41] As one of the characteristics of skeletal myogenic differentiation, the fusion of individual myocytes into multinucleated mature myotubes has also been shown to be regulated by genetic mechanisms distinct from myogenic differentiation. Some studies have found that small open reading frames (sORF) exist in lncRNA, and the sORF-encoded micropeptide may be related to cell fusion.…”

The association between the amino acid transporter LAT1, tumor immunometabolic and proliferative features and menopausal status in breast cancer

“…Therefore, we elected to focus the current study on the expression of LAT1, which transports large amino acids including leucine, isoleucine, valine, phenylalanine, methionine, tyrosine, histidine, and tryptophan into the cell, and its relationships with body weight, tumor cell proliferation, and immune infiltration. Prior literature indicates that LAT1 is involved in protein synthesis [ 40 , 41 ] and mTORC1 activity [ 42 , 43 ], and may also modulate the anti-tumor immune response [ 44 – 47 ]. Overexpression of LAT1 has been observed in a plethora of tumor types ranging from lung to endometrial to liver, but fewer studies of the relationship between LAT1 and breast cancer exist [ 48 ].…”