RESUMO
Although most mammalian fatty acids (FAs) are straight-chain, there also exist branched-chain FAs such as iso- and anteiso-FAs, especially in the meibomian glands. Meibum lipids, which are secreted from the meibomian glands and are important for dry eye prevention, contain abundant branched-chain lipids, such as cholesteryl esters and wax esters with chain-lengths of ≥C21 (very-long-chain; VLC). However, the exact tissue distribution of branched-chain lipids or the enzymes involved in the production of branched-chain VLCFAs has remained poorly understood. Here, we revealed that FA elongases ELOVL1, ELOVL3, and ELOVL7, of the seven mammalian ELOVL isozymes, elongated saturated branched-chain acyl-CoAs. ELOVL3 was highly active toward iso-C17:0 and anteiso-C17:0 acyl-CoAs and elongated them up to iso-C23:0 and anteiso-C25:0 acyl-CoAs, respectively. ELOVL1 elongated both iso- and anteiso-C23:0 acyl-CoAs to C25:0 acyl-CoAs. By establishing a liquid chromatography-tandem mass spectrometry method capable of separating branched- and straight-chain lipids, we showed that essentially all of the cholesteryl esters and 88% of the wax esters in the mouse meibomian glands are branched. In Elovl1 mutant mice, the levels of ≥C24:0 branched-chain cholesteryl esters and ≥C25:0 branched-chain wax esters were decreased, indicating that ELOVL1 indeed elongates branched-chain VLC acyl-CoAs in vivo. In addition, substantial amounts of ceramides containing branched-chain FAs were present in the skin, meibomian glands, and liver. Our findings provide new insights into the molecular mechanisms that create FA and lipid diversity.
Assuntos
Acil Coenzima A/metabolismo , Aminoácidos de Cadeia Ramificada/metabolismo , Elongases de Ácidos Graxos/metabolismo , Glândulas Tarsais/metabolismo , Aciltransferases/genética , Aciltransferases/metabolismo , Aldeído Oxirredutases/genética , Aldeído Oxirredutases/metabolismo , Aminoácidos de Cadeia Ramificada/classificação , Animais , Ceramidas/classificação , Ceramidas/metabolismo , Ésteres do Colesterol/classificação , Ésteres do Colesterol/metabolismo , Elongases de Ácidos Graxos/genética , Regulação da Expressão Gênica , Células HEK293 , Humanos , Lipidômica/métodos , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pele/metabolismo , Esterol O-Aciltransferase/genética , Esterol O-Aciltransferase/metabolismo , Especificidade por SubstratoRESUMO
La desnutrición que se observa en enfermedades hepáticas crónicas en niños se asocia a un aumento de requerimientos por gasto calórico elevado. La historia clínica incluye un recordatorio de alimentación, evaluación clínica, antropometría. Los niños con colestasis deben recibir una dieta hipercalórica. Es fundamental garantizar el aporte calórico calculado completo y la alimentación enteral. Se debe garantizar un crecimiento adecuado en un niño en lista de espera para trasplante. Los niños con enfermedades metabólicas requieren el uso de fórmulas comerciales especiales.
Malnutrition seen in chronic liver disease in children is associated with increased requirements for high caloric expenditure. The medical history includes a reminder of food, clinical evaluation, anthropometry. Children with cholestasis should receive a high calorie diet. It is essential to ensure complete and estimated calorie enteral feeding. It must ensure adequate growth in a child on the waiting list for transplantation. Children with metabolic diseases require the use of special comercial formulations.