Dysregulated autophagy contributes to podocyte damage in Fabry's disease

TY - JOUR

T1 - Dysregulated autophagy contributes to podocyte damage in Fabry's disease

AU - Liebau, Max C

AU - Braun, Fabian

AU - Höpker, Katja

AU - Weitbrecht, Claudia

AU - Bartels, Valerie

AU - Müller, Roman-Ulrich

AU - Brodesser, Susanne

AU - Saleem, Moin A

AU - Benzing, Thomas

AU - Schermer, Bernhard

AU - Cybulla, Markus

AU - Kurschat, Christine E

PY - 2013

Y1 - 2013

N2 - Fabry's disease results from an inborn error of glycosphingolipid metabolism that is due to deficiency of the lysosomal hydrolase α-galactosidase A. This X-linked defect results in the accumulation of enzyme substrates with terminally α-glycosidically bound galactose, mainly the neutral glycosphingolipid Globotriaosylceramide (Gb3) in various tissues, including the kidneys. Although end-stage renal disease is one of the most common causes of death in hemizygous males with Fabry's disease, the pathophysiology leading to proteinuria, hematuria, hypertension, and kidney failure is not well understood. Histological studies suggest that the accumulation of Gb3 in podocytes plays an important role in the pathogenesis of glomerular damage. However, due to the lack of appropriate animal or cellular models, podocyte damage in Fabry's disease could not be directly studied yet. As murine models are insufficient, a human model is needed. Here, we developed a human podocyte model of Fabry's disease by combining RNA interference technology with lentiviral transduction of human podocytes. Knockdown of α-galactosidase A expression resulted in diminished enzymatic activity and slowly progressive accumulation of intracellular Gb3. Interestingly, these changes were accompanied by an increase in autophagosomes as indicated by an increased abundance of LC3-II and a loss of mTOR kinase activity, a negative regulator of the autophagic machinery. These data suggest that dysregulated autophagy in α-galactosidase A-deficient podocytes may be the result of deficient mTOR kinase activity. This finding links the lysosomal enzymatic defect in Fabry's disease to deregulated autophagy pathways and provides a promising new direction for further studies on the pathomechanism of glomerular injury in Fabry patients.

AB - Fabry's disease results from an inborn error of glycosphingolipid metabolism that is due to deficiency of the lysosomal hydrolase α-galactosidase A. This X-linked defect results in the accumulation of enzyme substrates with terminally α-glycosidically bound galactose, mainly the neutral glycosphingolipid Globotriaosylceramide (Gb3) in various tissues, including the kidneys. Although end-stage renal disease is one of the most common causes of death in hemizygous males with Fabry's disease, the pathophysiology leading to proteinuria, hematuria, hypertension, and kidney failure is not well understood. Histological studies suggest that the accumulation of Gb3 in podocytes plays an important role in the pathogenesis of glomerular damage. However, due to the lack of appropriate animal or cellular models, podocyte damage in Fabry's disease could not be directly studied yet. As murine models are insufficient, a human model is needed. Here, we developed a human podocyte model of Fabry's disease by combining RNA interference technology with lentiviral transduction of human podocytes. Knockdown of α-galactosidase A expression resulted in diminished enzymatic activity and slowly progressive accumulation of intracellular Gb3. Interestingly, these changes were accompanied by an increase in autophagosomes as indicated by an increased abundance of LC3-II and a loss of mTOR kinase activity, a negative regulator of the autophagic machinery. These data suggest that dysregulated autophagy in α-galactosidase A-deficient podocytes may be the result of deficient mTOR kinase activity. This finding links the lysosomal enzymatic defect in Fabry's disease to deregulated autophagy pathways and provides a promising new direction for further studies on the pathomechanism of glomerular injury in Fabry patients.

KW - Autophagy

KW - DNA Primers

KW - Fabry Disease

KW - Fluorescent Antibody Technique

KW - Gene Knockdown Techniques

KW - HEK293 Cells

KW - Humans

KW - In Situ Nick-End Labeling

KW - Luciferases

KW - Macrolides

KW - Male

KW - Models, Biological

KW - Podocytes

KW - RNA Interference

KW - Real-Time Polymerase Chain Reaction

KW - Sirolimus

KW - TOR Serine-Threonine Kinases

KW - Trihexosylceramides

KW - alpha-Galactosidase

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

U2 - 10.1371/journal.pone.0063506

DO - 10.1371/journal.pone.0063506

M3 - SCORING: Journal article

C2 - 23691056

VL - 8

SP - e63506

JO - PLOS ONE

JF - PLOS ONE

SN - 1932-6203

IS - 5

ER -