PCSK9 is not secreted from mature differentiated intestinal cells
2021
Moreau, François | Thédrez, Aurélie | Garçon, Damien | Ayer, Audrey | Sotin, Thibaud | Dijk, Wieneke | Blanchard, Claire | Chadeuf, Gilliane | Arnaud, Lucie | Croyal, Mikaël | van Landeghem, Laurianne | Touvron, Melissa | Prieur, Xavier | Roubtsova, Anna | Seidah, Nabil | Prat, Annik | Cariou, Bertrand | Le May, Cedric | ITX - unité de recherche de l'institut du thorax (ITX) ; Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Nantes - UFR de Médecine et des Techniques Médicales (UFR MEDECINE) ; Université de Nantes (UN)-Université de Nantes (UN) | Université de Montréal (UdeM) | Centre Hospitalier Universitaire de Nantes = Nantes University Hospital (CHU Nantes) | North Carolina State University [Raleigh] (NC State) ; University of North Carolina System (UNC) | Centre de Recherche en Nutrition Humaine Ouest (CRNH Ouest) | ANR-16-CE14-0025,Int2PCSK9,Décrypter le rôle intracellulaire intestinal de PCSK9(2016) | ANR-16-RHUS-0007,CHOPIN,CHOPIN(2016)
International audience
Mostrar más [+] Menos [-]Inglés. Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes lysosomal degradation of the LDL receptor and is a key regulator of cholesterol metabolism. After the liver, the small intestine is the second organ that highly expresses PCSK9. However, the small intestine's ability to secrete PCSK9 remains a matter of debate. While liver-specific PCSK9-deficient mice present no PCSK9 in systemic blood, human intestinal Caco-2 cells can actively secrete PCSK9. This raises the possibility for active intestinal secretion via the portal blood. Here, we aimed to determine whether enterocytes can secrete PCSK9 using in vitro, ex vivo, and in vivo approaches. We first observed that PCSK9 secretion from Caco-2 cells was biphasic and dependent on Caco-2 maturation status. Transcriptional analysis suggested that this transient reduction in PCSK9 secretion might be due to loss of SREBP2-mediated transcription of PCSK9. Consistently, PCSK9 secretion was not detected ex vivo in human or mouse intestinal biopsies mounted in Ussing chambers. Finally, direct comparison of systemic versus portal blood PCSK9 concentrations in WT or liver-specific PCSK9-deficient mice confirmed the inability of the small intestine to secrete PCSK9 into the portal compartment. Altogether, our data demonstrate that mature enterocytes do not secrete PCSK9 and reinforce the central role of the liver in the regulation of the concentration of circulating PCSK9 and consequently of cellular LDL receptors.
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