Transportin 3 (TNPO3) is a nuclear carrier for serine/arginine-rich proteins which are essential for mRNA splicingand metabolism. Mutations in the TNPO3 gene result in a protein with an extended C-terminal domain, leadingto the onset of LGMDD2, a rare form of limb girdle muscular dystrophy. To investigate the role of TNPO3 inskeletal muscle and the pathogenic mechanism underlying LGMDD2, we develped both in vitro and in vivo modelsof the disease. The in vitro model was established using the C2C12 cell line, transfected with plasmids encodingeither the wild-type (WT) or mutated (MUT) human TNPO3 (hTNPO3). For the in vivo model, we microinjectedzebrafish (Danio rerio) embryos with mRNAs encoding WT or MUT hTNPO3. We analyzed the expression patterns ofmyogenesis-related genes, muscle-specific genes, myomiRNA and genes strictly related to the disease. These analyseswere complemented by protein expression studies, morphological assessments in both models, and behavioral assaysto validate the LGMDD2 zebrafish model. Our results demonstrate a key role for TNPO3 in regulating myogenesis inboth models and reveal that the TNPO3 mutation disrupts normal myogenic commitment, supporting its contributionto LGMDD2 pathogenesis. Overall, this study represents a significant advance in understanding the role of TNPO3in skeletal muscle biology and the molecular basis of LGMDD2.
Novel insights into the molecular mechanisms of LGMDD2: role of TNPO3 in experimental cell and zebrafish models
Altieri, MT;Sabbioni, G.;D'Aversa, E.;Breveglieri, G.;Gatto, E.;Bertolucci, C.;Borgatti, M.;
2025
Abstract
Transportin 3 (TNPO3) is a nuclear carrier for serine/arginine-rich proteins which are essential for mRNA splicingand metabolism. Mutations in the TNPO3 gene result in a protein with an extended C-terminal domain, leadingto the onset of LGMDD2, a rare form of limb girdle muscular dystrophy. To investigate the role of TNPO3 inskeletal muscle and the pathogenic mechanism underlying LGMDD2, we develped both in vitro and in vivo modelsof the disease. The in vitro model was established using the C2C12 cell line, transfected with plasmids encodingeither the wild-type (WT) or mutated (MUT) human TNPO3 (hTNPO3). For the in vivo model, we microinjectedzebrafish (Danio rerio) embryos with mRNAs encoding WT or MUT hTNPO3. We analyzed the expression patterns ofmyogenesis-related genes, muscle-specific genes, myomiRNA and genes strictly related to the disease. These analyseswere complemented by protein expression studies, morphological assessments in both models, and behavioral assaysto validate the LGMDD2 zebrafish model. Our results demonstrate a key role for TNPO3 in regulating myogenesis inboth models and reveal that the TNPO3 mutation disrupts normal myogenic commitment, supporting its contributionto LGMDD2 pathogenesis. Overall, this study represents a significant advance in understanding the role of TNPO3in skeletal muscle biology and the molecular basis of LGMDD2.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
