Regulation of muscle growth by multiple ligands signaling through activin type II receptors
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Authors: Lee, SJ; Reed, LA; Davies, MV; Girgenrath, S; Goad, MEP; Tomkinson, KN; Wright, JF; Barker, C; Ehrmantraut, G; Holmstrom, J; Trowell, B; Gertz, B; Jiang, MS; Sebald, SM; Matzuk, M; Li, E; Liang, LF; Quattlebaum, E; Stotish, RL; Wolfman, NM
Abstract
Myostatin is a secreted protein that normally functions as a negative regulator of muscle growth. Agents capable of blocking the myostatin signaling pathway could have important applications for treating human muscle degenerative diseases as well as for enhancing livestock production. Here we describe a potent myostatin inhibitor, a soluble form of the activin type IIB receptor (ACVR2B), which can cause dramatic increases in muscle mass (up to 60% in 2 weeks) when injected into wild-type mice. Furthermore, we show that the effect of the soluble receptor is attenuated but not eliminated in Mstn(-/-) mice, suggesting that at least one other ligand in addition to myostatin normally functions to limit muscle growth. Finally, we provide genetic evidence that these ligands signal through both activin type II receptors, ACVR2 and ACVR2B, to regulate muscle growth in vivo.
Familial transposition of the great arteries caused by multiple mutations in laterality genes
HEART
Authors: De Luca, Alessandro; Sarkozy, Anna; Consoli, Federica; Ferese, Rosangela; Guida, Valentina; Dentici, Maria Lisa; Mingarelli, Rita; Bellacchio, Emanuele; Tuo, Giulia; Limongelli, Giuseppe; Digilio, Maria Cristina; Marino, Bruno; Dallapiccola, Bruno
Abstract
Background The pathogenesis of transposition of the great arteries (TGA) is still largely unknown. In general, TGA is not associated with the more common genetic disorders nor with extracardiac anomalies, whereas it can be found in individuals with lateralisation defects, heterotaxy and asplenia syndrome (right isomerism). Objective To analyse genes previously associated with heterotaxy in order to assess mutations in familial TGA unassociated with other features of laterality defects. Methods Probands of seven families with isolated TGA and a family history of concordant or discordant congenital heart disease were screened for mutations in the ZIC3, ACVR2B, LEFTYA, CFC1, NODAL, FOXH1, GDF1, CRELD1, GATA4 and NKX2.5 genes. Results Mutation analysis allowed the identification of three sequence variations in two out of seven TGA probands. A FOXH1 (Pro21Ser) missense variant was found in a proband who was also heterozogous for an amino acid substitution (Gly17Cys) in the ZIC3 gene. This ZIC3 variant was also found in another family member with a second sequence variation (Val150lle) in the NKX2.5 gene homeodomain who was affected by multiple ventricular septal defects. A second proband was found to harbour a splice site variant (IVS2-1G -> C) in the NODAL gene. Conclusions The present study provides evidence that some cases of familial TGA are caused by mutations in laterality genes and therefore are part of the same disease spectrum of heterotaxy syndrome, and argues for an oligogenic or complex mode of inheritance in these pedigrees.