Three-dimensional imaging in myotonic dystrophy type 1

Altres ajuts: The research of G. Nogales-Gadea, A. Ramos-Fransi, and A. Lucia is funded by Instituto de Salud Carlos III and cofinanced by Fondos FEDER. G. Nogales-Gadea is supported by a Miguel Servet research contract and by a Trampoline Grant #21108 from AFM Telethon. A. Ballester-Lopez is funded by an FI Agaur fellowship and Generalitat de Catalunya. E. Koehorst is funded by the La Caixa Foundation (ID 100010434), fellowship code LCF/BQ/IN18/11660019, cofunded by the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 713673. I. Linares-Pardo is funded by CP14/00032 and SGR 1520 (GRC) Generalitat de Catalunya. J. Núñez-Manchón was funded by AFM Telethon Trampoline Grant #21108. G. Lucente was supported by a Rio Hortega contract. J. Chojnacki is supported by European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant . The funding bodies had no role in the design of the study and collection, analysis, and interpretation of data.We aimed to determine whether 3D imaging reconstruction allows identifying molecular:clinical associations in myotonic dystrophy type 1 (DM1). We obtained myoblasts from 6 patients with DM1 and 6 controls. We measured cytosine-thymine-guanine (CTG) expansion and detected RNA foci and muscleblind like 1 (MBNL1) through 3D reconstruction. We studied dystrophia myotonica protein kinase (DMPK) expression and splicing alterations of MBNL1, insulin receptor, and sarcoplasmic reticulum Ca(2+)-ATPase 1. Three-dimensional analysis showed that RNA foci (nuclear and/or cytoplasmic) were present in 45%-100% of DM1-derived myoblasts we studied (range: 0-6 foci per cell). RNA foci represented <0.6% of the total myoblast nuclear volume. CTG expansion size was associated with the number of RNA foci per myoblast (r = 0.876 [95% confidence interval 0.222-0.986]) as well as with the number of cytoplasmic RNA foci (r = 0.943 [0.559-0.994]). Although MBNL1 colocalized with RNA foci in all DM1 myoblast cell lines, colocalization only accounted for 1% of total MBNL1 expression, with the absence of DM1 alternative splicing patterns. The number of RNA foci was associated with DMPK expression (r = 0.967 [0.079-0.999]). On the other hand, the number of cytoplasmic RNA foci was correlated with the age at disease onset (r = −0.818 [−0.979 to 0.019]). CTG expansion size modulates RNA foci number in myoblasts derived from patients with DM1. MBNL1 sequestration plays only a minor role in the pathobiology of the disease in these cells. Higher number of cytoplasmic RNA foci is related to an early onset of the disease, a finding that should be corroborated in future studies

Identification of an alternative triglyceride biosynthesis pathway

Triacylglycerols (TAGs) are the main source of stored energy in the body, providing an important substrate pool for mitochondrial beta-oxidation. Imbalances in the amount of TAGs are associated with obesity, cardiac disease and various other pathologies 1,2. In humans, TAGs are synthesized from excess, coenzyme A-conjugated fatty acids by diacylglycerol O-acyltransferases (DGAT1 and DGAT2) 3. In other organisms, this activity is complemented by additional enzymes 4, but whether such alternative pathways exist in humans remains unknown. Here we disrupt the DGAT pathway in haploid human cells and use iterative genetics to reveal an unrelated TAG-synthesizing system composed of a protein we called DIESL (also known as TMEM68, an acyltransferase of previously unknown function) and its regulator TMX1. Mechanistically, TMX1 binds to and controls DIESL at the endoplasmic reticulum, and loss of TMX1 leads to the unconstrained formation of DIESL-dependent lipid droplets. DIESL is an autonomous TAG synthase, and expression of human DIESL in Escherichia coli endows this organism with the ability to synthesize TAG. Although both DIESL and the DGATs function as diacylglycerol acyltransferases, they contribute to the cellular TAG pool under specific conditions. Functionally, DIESL synthesizes TAG at the expense of membrane phospholipids and maintains mitochondrial function during periods of extracellular lipid starvation. In mice, DIESL deficiency impedes rapid postnatal growth and affects energy homeostasis during changes in nutrient availability. We have therefore identified an alternative TAG biosynthetic pathway driven by DIESL under potent control by TMX1. </p

Three-dimensional imaging in myotonic dystrophy type 1

Altres ajuts: The research of G. Nogales-Gadea, A. Ramos-Fransi, and A. Lucia is funded by Instituto de Salud Carlos III and cofinanced by Fondos FEDER. G. Nogales-Gadea is supported by a Miguel Servet research contract and by a Trampoline Grant #21108 from AFM Telethon. A. Ballester-Lopez is funded by an FI Agaur fellowship and Generalitat de Catalunya. E. Koehorst is funded by the La Caixa Foundation (ID 100010434), fellowship code LCF/BQ/IN18/11660019, cofunded by the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 713673. I. Linares-Pardo is funded by CP14/00032 and SGR 1520 (GRC) Generalitat de Catalunya. J. Núñez-Manchón was funded by AFM Telethon Trampoline Grant #21108. G. Lucente was supported by a Rio Hortega contract. J. Chojnacki is supported by European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant . The funding bodies had no role in the design of the study and collection, analysis, and interpretation of data.We aimed to determine whether 3D imaging reconstruction allows identifying molecular:clinical associations in myotonic dystrophy type 1 (DM1). We obtained myoblasts from 6 patients with DM1 and 6 controls. We measured cytosine-thymine-guanine (CTG) expansion and detected RNA foci and muscleblind like 1 (MBNL1) through 3D reconstruction. We studied dystrophia myotonica protein kinase (DMPK) expression and splicing alterations of MBNL1, insulin receptor, and sarcoplasmic reticulum Ca(2+)-ATPase 1. Three-dimensional analysis showed that RNA foci (nuclear and/or cytoplasmic) were present in 45%-100% of DM1-derived myoblasts we studied (range: 0-6 foci per cell). RNA foci represented <0.6% of the total myoblast nuclear volume. CTG expansion size was associated with the number of RNA foci per myoblast (r = 0.876 [95% confidence interval 0.222-0.986]) as well as with the number of cytoplasmic RNA foci (r = 0.943 [0.559-0.994]). Although MBNL1 colocalized with RNA foci in all DM1 myoblast cell lines, colocalization only accounted for 1% of total MBNL1 expression, with the absence of DM1 alternative splicing patterns. The number of RNA foci was associated with DMPK expression (r = 0.967 [0.079-0.999]). On the other hand, the number of cytoplasmic RNA foci was correlated with the age at disease onset (r = −0.818 [−0.979 to 0.019]). CTG expansion size modulates RNA foci number in myoblasts derived from patients with DM1. MBNL1 sequestration plays only a minor role in the pathobiology of the disease in these cells. Higher number of cytoplasmic RNA foci is related to an early onset of the disease, a finding that should be corroborated in future studies