137 Filaggrin knock-out in keratinocytes indicates a functional role in skin barrier formation

The epidermis-specific lipid acylceramide plays a pivotal role in the formation of the permeability barrier in the skin; abrogation of its synthesis causes the skin disorder ichthyosis. However, the acylceramide synthetic pathway has not yet been fully elucidated: Namely, the acyl-CoA synthetase (ACS) involved in this pathway remains to be identified. Here, we hypothesized it to be encoded by FATP4/ACSVL4, the causative gene of ichthyosis prematurity syndrome (IPS). In vitro experiments revealed that FATP4 exhibits ACS activity toward an ω-hydroxy fatty acid (FA), an intermediate of the acylceramide synthetic pathway. Fatp4 knockout (KO) mice exhibited severe skin barrier dysfunction and morphological abnormalities in the epidermis. The total amount of acylceramide in Fatp4 KO mice was reduced to ∼10% of wild-type mice. Decreased levels and shortening of chain lengths were observed in the saturated, nonacylated ceramides. FA levels were not decreased in the epidermis of Fatp4 KO mice. The expression levels of the FA elongase Elovl1 were reduced in Fatp4 KO epidermis, partly accounting for the reduction and shortening of saturated, nonacylated ceramides. A decrease in acylceramide levels was also observed in human keratinocytes with FATP4 knockdown. From these results, we conclude that skin barrier dysfunction observed in IPS patients and Fatp4 KO mice is caused mainly by reduced acylceramide production. Our findings further elucidate the molecular mechanism governing acylceramide synthesis and IPS pathology.

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Skin Barrier Formation: The Membrane Folding Model

Journal of Investigative Dermatology ◽

10.1046/j.0022-202x.2001.01445.x ◽

2001 ◽

Vol 117 (4) ◽

pp. 823-829 ◽

Cited By ~ 74

Author(s):

Lars Norlén

Keyword(s):

Skin Barrier ◽

Folding Model ◽

Barrier Formation

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Prion Protein (PrP) Knock-Out Mice Show Altered Iron Metabolism: A Functional Role for PrP in Iron Uptake and Transport

PLoS ONE ◽

10.1371/journal.pone.0006115 ◽

2009 ◽

Vol 4 (7) ◽

pp. e6115 ◽

Cited By ~ 55

Author(s):

Ajay Singh ◽

Qingzhong Kong ◽

Xiu Luo ◽

Robert B. Petersen ◽

Howard Meyerson ◽

...

Keyword(s):

Prion Protein ◽

Iron Metabolism ◽

Iron Uptake ◽

Functional Role ◽

Knock Out ◽

Knock Out Mice ◽

Uptake And Transport

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Functional role of respiratory supercomplexes in mice: segmentation of the Qpool and SCAF1

10.1101/826115 ◽

2019 ◽

Author(s):

Enrique Calvo ◽

Sara Cogliati ◽

Pablo Hernansanz-Agustín ◽

Marta Loureiro-López ◽

Adela Guarás ◽

...

Keyword(s):

Quantitative Data ◽

Functional Role ◽

Physiological Role ◽

Oxidative Capacity ◽

Wild Type ◽

Knock Out ◽

Transport Chain ◽

Native Gel ◽

Blue Native

SummaryMitochondrial respiratory complexes assemble into different forms of supercomplexes (SC). In particular, SC III2+IV require the SCAF1 protein. However, the structural role of this factor in the formation of the respirasome (I+III2+IV) and the physiological role of SCs are controversial. Here, we study C57BL/6J mice harbouring either non-functional SCAF1, the full knock-out for SCAF1 or the wild-type version of the protein and found a growth and exercise phenotype due to the lack of functional SCAF1. By combining quantitative data-independent proteomics, high resolution 2D Blue Native Gel Electrophoresis and functional analysis of enriched respirasome fractions, we show that SCAF1 confers structural attachment between III2 and IV within the respirasome, increases NADH-dependent respiration and reduces ROS production. Furthermore, through the expression of AOX in cells and mice we confirm that CI-CIII superassembly segments the CoQ in two pools and modulates CI-NADH oxidative capacity. These data demonstrate that SC assembly, regulated by SCAF1, modulates the functionality of the electron transport chain.

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