Búsqueda de nuevos genes implicados en la etiopatogenia de los síndromes lipodistróficos infrecuentes

Las lipodistrofias son un grupo de enfermedades caracterizadas por la pérdida de tejido adiposo, asociadas a resistencia a la insulina y síndrome metabólico. En la lipodistrofia parcial familiar tipo 1 o síndrome de Köbberling, esta pérdida de grasa afecta a unas regiones (sobre todo extremidades inferiores), mientras en otras existe un acúmulo excesivo. Aunque está descrito como un síndrome de origen genético, el gen o genes causales no han sido descubiertos. Además de establecer una caracterización fenotípica y clínica detallada de la enfermedad, en la presente tesis se han encontrado, a raíz de estudios familiares, una serie de variantes genéticas que podrían estar ocasionando la aparición del cuadro

Does Seipin Play a Role in Oxidative Stress Protection and Peroxisome Biogenesis? New Insights from Human Brain Autopsies

Seipin is a widely expressed protein but with highest levels found in the brain and testes. Seipin function is not yet completely understood, therefore the aim of this study was to evaluate the expression of BSCL2 transcripts in the central nervous system (CNS) of humans and investigate the effect of their overexpression on a neuron model and their relationship with oxidative stress protection, as well as shed light on the pathogenic mechanisms of Celia’s Encephalopathy. We analyzed the expression of BSCL2 transcripts using real-time RT– PCR in samples across the brain regions of subjects who underwent necropsy and from a case with Celia’s Encephalopathy. The transcript encoding the long seipin isoform (BSCL2-203, 462 aa) is expressed primarily in the brain and its expression is inversely correlated with age in the temporal lobe, amygdala, and hypothalamus. Strong positive correlations were found between BSCL2 expression and some genes encoding protective enzymes against oxidative stress including SOD1 and SOD2, as well as peroxisome proliferator-activated receptor gamma (PPARG) in the amygdala. These results were experimentally corroborated by overexpressing BSCL2 transcripts in SH-SY5Y cells with lentiviral transduction and assessing their effects on neuron differentiated cells. Confocal microscopy studies showed that both seipin and PEX16 are closely expressed in the hypothalami of healthy human brains, and PEX16 was absent in the same region of the PELD case. We hypothesize that seipin has specific CNS functions and may play a role in peroxisome biogenesis.This work was supported by the Instituto de Salud Carlos III and the European Regional Development Fund, FEDER (grants number PI10/02873 and PI13/00314), by the Consellería de Industria, Xunta de Galicia (grants number 10PXIB208013PR and ED341b2017/19), and by Fundación Mutua Madrileña (Call 2015)S

Inflammatory myopathy in the context of an unusual overlapping laminopathy

Laminopathies are genetic disorders associated with alterations in nuclear envelope proteins, known as lamins. The LMNA gene encodes lamins A and C, and LMNA mutations have been linked to diseases involving fat (type 2 familial partial lipodystrophy [FPLD2]), muscle (type 2 Emery–Dreifuss muscular dystrophy [EDMD2], type 1B limb-girdle muscular dystrophy [LGMD1B], and dilated cardiomyopathy), nerves (type 2B1 Charcot–Marie–Tooth disease), and premature aging syndromes. Moreover, overlapping syndromes have been reported. This study aimed to determine the genetic basis of an overlapping syndrome in a patient with heart disease, myopathy, and features of lipodystrophy, combined with severe metabolic syndrome. We evaluated a 54-year-old woman with rheumatoid arthritis, chronic hypercortisolism (endogenous and exogenous), and a history of cured adrenal Cushing syndrome. The patient presented with a complex disorder, including metabolic syndrome associated with mild partial lipodystrophy (Köbberling-like); mild hypertrophic cardiomyopathy, with Wolff–Parkinson– White syndrome and atrial fibrillation; and limb-girdle inflammatory myopathy. Mutational analysis of the LMNA gene showed a heterozygous c.1634G>A (p.R545H) variant in exon 10 of LMNA. This variant has previously been independently associated with FPLD2, EDMD2, LGMD1B, and heart disease. We describe a new, LMNA-associated, complex overlapping syndrome in which fat, muscle, and cardiac disturbances are related to a p.R545H variant.This work was funded by the Instituto de Salud Carlos III (grant number: PI081449) and the European Regional Development Fund, FEDER. In addition, SRG was awarded a Research Fellowship granted by the Asociación Española de Familiares y Afectados de Lipodistrofias (AELIP)S

Skipped BSCL2 Transcript in Celia’s Encephalopathy (PELD): New Insights on Fatty Acids Involvement, Senescence and Adipogenesis

Objective PELD (Progressive Encephalopathy with or without Lipodystrophy or Celia’s Encephalopathy) is a fatal and rare neurodegenerative syndrome associated with the BSCL2 mutation c.985C>T, that results in an aberrant transcript without the exon 7 (Celia seipin). The aim of this study was to evaluate both the process of cellular senescence and the effect of unsaturated fatty acids on preadipocytes from a homozygous c.985C>T patient. Also, the role of aberrant seipin isoform on adipogenesis was studied in adipose-derived human mesenchymal stem cells. Material and methods Cellular senescence was evaluated using β-galactosidase staining of preadipocytes obtained from a homozygous c.985C>T patient. Moreover, these cells were cultured during 24 hours with Intralipid, a soybean oil-based commercial lipid emulsion. The expression of the different BSCL2 transcripts was measured by qPCR. Adipose-derived human mesenchymal stem cells were differentiated to a fat lineage using StemPRO adipogenesis kit, and the expression of BSCL2 transcripts and several adipogenesis-related genes was measured by qPCR. Results the treatment of preadipocytes with unsaturated fatty acids significantly reduced the expression of the BSCL2 transcript without exon 7 by 34 to 63%. On the other hand, at least in preadipocytes, this mutation does not disturb cellular senescence rate. Finally, during adipocyte differentiation of adipose-derived human mesenchymal stem cells, the expression of adipogenic genes (PPARG, LPIN1, and LPL) increased significantly over 14 days, and noteworthy is that the BSCL2 transcript without exon 7 was differentially expressed by 332 to 723% when compared to day 0, suggesting an underlying role in adipogenesis. Conclusions our results suggest that Celia seipin is probably playing an underestimated role in adipocyte maturation, but not in senescence, and its expression can be modified by exogenous factors as fatty acidsThis work was supported by the Instituto de Salud Carlos III and the European Regional Development Fund, FEDER (grants number PI10/02873 and PI13/00314, http://www.isciii.es/), ISCIII/PI13/00314/Cofinanciado FEDER and by the Consellería de Industria, Xunta de Galicia (grant number 10PXIB208013PR, http://www.xunta.es/). SRG was awarded a Research Fellowship, granted by the Asociación Española de Familiares y Afectados de Lipodistrofias (AELIP, http://www.aelip.org/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscriptS

Recombinant human leptin treatment in genetic lipodystrophic syndromes: the long-term Spanish experience

Lipodystrophies are a group of diseases mainly characterized by a loss of adipose tissue and frequently associated with insulin resistance, hypertriglyceridemia, and hepatic steatosis. In uncommon lipodystrophies, these complications frequently are difficult to control with conventional therapeutic approaches. This retrospective study addressed the effectiveness of recombinant methionyl leptin (metreleptin) for improving glucose metabolism, lipid profile, and hepatic steatosis in patients with genetic lipodystrophic syndromes. We studied nine patients (five females and four males) with genetic lipodystrophies [seven with Berardinelli-Seip syndrome, one with atypical progeroid syndrome, and one with type 2 familial partial lipodystrophy (FPLD)]. Six patients were children under age 9 years, and all patients had baseline triglycerides levels >2.26 mmol/L and hepatic steatosis; six had poorly controlled diabetes mellitus. Metreleptin was self-administered subcutaneously daily at a final dose that ranged between 0.05 and 0.24 mg/(kg day) [median: 0.08 mg/(kg day)] according to the body weight. The duration of treatment ranged from 9 months to 5 years, 9 months (median: 3 years). Plasma glucose, hemoglobin A1c (Hb A1c), lipid profile, plasma insulin and leptin, and hepatic enzymes were evaluated at baseline and at least every 6 months. Except for the patient with FPLD, metreleptin replacement significantly improved metabolic control (Hb A1c: from 10.4 to 7.1 %, p < 0.05). Plasma triglycerides were reduced 76 % on average, and hepatic enzymes decreased more than 65 %. This study extends knowledge about metreleptin replacement in genetic lipodystrophies, bearing out its effectiveness for long periods of time

Percentage of change in expression of <i>BSCL2</i> transcripts and adipogenic genes.

<p>Percentage of change in expression of <i>BSCL2</i> transcripts and adipogenic genes referred to day 0, (a) <i>BSCL2</i> with exon 7 (b) <i>BSCL2</i> without exon 7 (c) <i>PPARG</i>, (d) <i>LPIN1</i>, (e) <i>LPL</i>, in ADSCs (differentiated over 14 days into adipocytes) normalized to the <i>18S</i> gene. All samples were analyzed in duplicate, n = 4, *:P<0.05.</p

Relative expression and percentage of change in expression of <i>BSCL2</i> transcripts after Intralipid treatment.

<p>(a) Percentage of change referred to the relative expression of <i>BSCL2</i> transcripts with exon 7 and (b) without exon 7, in WT and index case preadipocytes, normalized to the <i>RNA polymerase II</i> gene. White bar: WT; black bar: index case. All samples were analyzed in duplicate, n = 4, *:P<0.05.</p