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. 1999 Apr;19(2):297–300. doi: 10.1023/A:1006989530148

Localization of Transforming Growth Factor β in Association with Neuromuscular Junctions in Adult Human Muscle

M Toepfer 1, P Fischer 1, A Abicht 1, H Lochmüller 1, D Pongratz 1, W Müller-Felber 1
PMCID: PMC11545652  PMID: 10081612

Abstract

Transforming growth factors-β 1, 2, and 3 are known for their regulatory function in embryogenesis, fibrogenesis, and tissue repair of different cell types. A trophic function of TGF-β subclasses for motoneurons has been shown in vitro. TGF-β 1 is a potent survival factor for cultured embryonic rat motoneurons. In addition, TGF-β 1 stimulates proliferation of rat Schwann cells. Recently, TGF-β 2 has been reported to be associated with the subsynaptic nuclei of mature rat neuromuscular junctions. In this study, we investigated the expression of TGF-β 1, 2, and 3 at neuromuscular junctions in skeletal muscle of 11 adults without neuromuscular disease. On muscle biopsies, neuromuscular junctions were depicted by acetylcholine esterase reaction and acetylcholine receptor antibodies. TGF-β 1, 2, and 3 were stained immunohistochemically with monoclonal antibodies. Some muscle fibers showed low levels of inhomogeneous immunoreactivity for both TGF-β 1 and TGF-β 3. Intense immunoreactivity of TGF-β 1 and 3 was shown at the postsynaptic area of neuromuscular junctions. TGF-β 2 was expressed in the same subcellular distribution, but less strongly. In conclusion, the colocalization of TGF-β with neuromuscular junctions may suggest a significant function in neuromuscular communication.

Keywords: transforming growth factor β, neuromuscular junctions, acetylcholine receptor, motoneuron

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