Defective Lipid Droplet-Lysosome Interaction Causes Fatty Liver Disease as Evidenced by Human Mutations in TMEM199 and CCDC115

BACKGROUND &amp; AIMS: Recently, novel inborn errors of metabolism were identified because of mutations in V-ATPase assembly factors TMEM199 and CCDC115. Patients are characterized by generalized protein glycosylation defects, hypercholesterolemia, and fatty liver disease. Here, we set out to characterize the lipid and fatty liver phenotype in human plasma, cell models, and a mouse model.METHODS AND RESULTS: Patients with TMEM199 and CCDC115 mutations displayed hyperlipidemia, characterized by increased levels of lipoproteins in the very low density lipoprotein range. HepG2 hepatoma cells, in which the expression of TMEM199 and CCDC115 was silenced, and induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells from patients with TMEM199 mutations showed markedly increased secretion of apolipoprotein B (apoB) compared with controls. A mouse model for TMEM199 deficiency with a CRISPR/Cas9-mediated knock-in of the human A7E mutation had marked hepatic steatosis on chow diet. Plasma N-glycans were hypogalactosylated, consistent with the patient phenotype, but no clear plasma lipid abnormalities were observed in the mouse model. In the siTMEM199 and siCCDC115 HepG2 hepatocyte models, increased numbers and size of lipid droplets were observed, including abnormally large lipid droplets, which colocalized with lysosomes. Excessive de novo lipogenesis, failing oxidative capacity, and elevated lipid uptake were not observed. Further investigation of lysosomal function revealed impaired acidification combined with impaired autophagic capacity.CONCLUSIONS: Our data suggest that the hyperchole-sterolemia in TMEM199 and CCDC115 deficiency is due to increased secretion of apoB-containing particles. This may in turn be secondary to the hepatic steatosis observed in these patients as well as in the mouse model. Mechanistically, we observed impaired lysosomal function characterized by reduced acidification, autophagy, and increased lysosomal lipid accumulation. These findings could explain the hepatic steatosis seen in patients and highlight the importance of lipophagy in fatty liver disease. Because this pathway remains understudied and its regulation is largely untargeted, further exploration of this pathway may offer novel strategies for therapeutic interventions to reduce lipotoxicity in fatty liver disease.</p

Beyond the Washington consensus: what do we mean?

This paper underscores the need to overcome the fundamental problems of the "Washington Consensus" that have not been entirely solved in its recent reformulations calling for a "second generation of reforms." Such problems are its narrow view of macroeconomic stability; its disregard for the role that policy interventions in the productive sector can play in inducing investment and accelerating growth; its tendency to subordinate social policies to economic policies; and, finally, its tendency to forget that it is citizens who should choose what economic and social institutions they prefer. The examination of the frustrating experience of Latin America under structural reforms provides the empirical backdrop for the analysis.macroeconomic stability, Washington Consensus,

Estudio de la morfolog\ueda y aclimataci\uf3n de plantas de Laelia eyermaniana Rchb. f. generadas in vitro

A morphological study of plantlets of Laelia eyermaniana Rchb.f. cultured in vitro was carried out. Histologic preparations were made to observe different stages from seed germination until ex vitro acclimatization of plantlets. Photomicrographs showed various transitional stages. Seven relative stages of development were identified and described: seed, non-photosynthetic protocorm, photosynthetic protocorm, differentiated protocorm, plantlets with leafs, plantlets with leaves and roots, and plantlets with leaves and two roots, as well as two transitory phases: somatic embryogenic mass (SEM) and protocorm-like bodies (PLBs) obtained by indirect somatic embryogenesis. Stomatal leaf density doubled under ex vitro conditions. This study contributes to the knowledge of morphological development of L. eyermaniana during in vitro culture and ex vitro acclimatization.En este trabajo se hizo un seguimiento morfológico de plantas de Laelia eyermaniana Rchb. f. obtenidas in vitro. Se realizaron preparaciones histológicas para observar diferentes etapas, desde la germinación hasta la aclimatación ex vitro. Las fotomicrografías de las preparaciones mostraron varios estadios transitorios. Se identificaron y describieron siete estadios relativos de desarrollo: semilla, protocormo no fotosintético, protocormo fotosintético, protocormo en diferenciación, plántula con hojas, plántulas con hojas y raíz, plántula con hojas y dos raíces. Así como también, dos fases transitorias: masa embrionaria somática (MES) y cuerpos parecidos a protocormos (PLBs) por sus siglas en inglés, obtenidos por embriogénesis somática indirecta. La densidad estomática en las hojas se duplicó bajo condiciones ex vitro. Este estudio contribuye al conocimiento del desarrollo morfológico de L. eyermaniana durante su cultivo in vitro y aclimatación ex vitro

Mutations in the V-ATPase Assembly Factor VMA21 Cause a Congenital Disorder of Glycosylation With Autophagic Liver Disease

Background and Aims Vacuolar H+-ATP complex (V-ATPase) is a multisubunit protein complex required for acidification of intracellular compartments. At least five different factors are known to be essential for its assembly in the endoplasmic reticulum (ER). Genetic defects in four of these V-ATPase assembly factors show overlapping clinical features, including steatotic liver disease and mild hypercholesterolemia. An exception is the assembly factor vacuolar ATPase assembly integral membrane protein (VMA21), whose X-linked mutations lead to autophagic myopathy. Approach and Results Here, we report pathogenic variants in VMA21 in male patients with abnormal protein glycosylation that result in mild cholestasis, chronic elevation of aminotransferases, elevation of (low-density lipoprotein) cholesterol and steatosis in hepatocytes. We also show that the VMA21 variants lead to V-ATPase misassembly and dysfunction. As a consequence, lysosomal acidification and degradation of phagocytosed materials are impaired, causing lipid droplet (LD) accumulation in autolysosomes. Moreover, VMA21 deficiency triggers ER stress and sequestration of unesterified cholesterol in lysosomes, thereby activating the sterol response element-binding protein-mediated cholesterol synthesis pathways. Conclusions Together, our data suggest that impaired lipophagy, ER stress, and increased cholesterol synthesis lead to LD accumulation and hepatic steatosis. V-ATPase assembly defects are thus a form of hereditary liver disease with implications for the pathogenesis of nonalcoholic fatty liver disease.Peer reviewe