The ceramide transporter and the Goodpasture antigen binding protein: one protein--one function?
The Goodpasture antigen-binding protein (GPBP) and its splice variant the ceramide transporter (CERT) are multifunctional proteins that have been found to play important roles in brain development and biology. However, the function of GPBP and CERT is controversial because of their involvement in two apparently unrelated research fields: GPBP was initially isolated as a protein associated with collagen IV in patients with the autoimmune disease Goodpasture syndrome. Subsequently, a splice variant lacking a serine-rich domain of 26 amino acids (GPBPDelta26) was found to mediate the cytosolic transport of ceramide and was therefore (re)named CERT. The two splice forms likely carry out different functions in specific sub-cellular localizations. Selective GPBP knockdown induces extensive apoptosis and tissue loss in the brain of zebrafish. GPBP/GPBPDelta26 knock-out mice die as a result of structural and functional defects in endoplasmic reticulum and mitochondria. Because both mitochondria and ceramide play an important role in many biological events that regulate neuronal differentiation, cellular senescence, proliferation and cell death, we propose that GPBP and CERT are pivotal in neurodegenerative processes. In this review, we discuss the current state of knowledge on GPBP and CERT, including the molecular and biochemical characterization of GPBP in the field of autoimmunity as well as the fundamental research on CERT in ceramide transport, biosynthesis, localization, metabolism and cell homeostasis.
Department of Neuroscience, School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands.
Chiara
C
Mencarelli
Mario
M
Losen
Caroline
C
Hammels
Jochen
J
De Vry
Matthijs K C
MK
Hesselink
Harry W M
HW
Steinbusch
Marc H
MH
De Baets
Pilar
P
Martínez-Martínez
D000818:Animals; D001324:Autoantigens / Q000378:metabolism; D002490:Central Nervous System / Q000378:metabolism; D024141:Collagen Type IV / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D019636:Neurodegenerative Diseases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000145:classification* / Q000502:physiology*; D019154:Protein Splicing / Q000235:genetics
D001324:Autoantigens; D024141:Collagen Type IV; C057112:type IV collagen alpha3 chain; C119090:CERT1 protein, human; D017346:Protein Serine-Threonine Kinases