PMID- 30774622
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20210208
IS  - 1664-2392 (Print)
IS  - 1664-2392 (Electronic)
IS  - 1664-2392 (Linking)
VI  - 10
DP  - 2019
TI  - Chaperone-Mediated Autophagy Upregulation Rescues Megalin Expression and 
      Localization in Cystinotic Proximal Tubule Cells.
PG  - 21
LID - 10.3389/fendo.2019.00021 [doi]
LID - 21
AB  - Cystinosis is a lysosomal storage disorder caused by defects in CTNS, the gene 
      that encodes the lysosomal cystine transporter cystinosin. Patients with 
      nephropathic cystinosis are characterized by endocrine defects, defective 
      proximal tubule cell (PTC) function, the development of Fanconi syndrome and, 
      eventually, end-stage renal disease. Kidney disease is developed despite the use 
      of cysteamine, a drug that decreases lysosomal cystine overload but fails to 
      correct overload-independent defects. Chaperone-mediated autophagy (CMA), a 
      selective form of autophagy, is defective in cystinotic mouse fibroblasts, and 
      treatment with cysteamine is unable to correct CMA defects in vivo, but whether 
      the vesicular trafficking mechanisms that lead to defective CMA in cystinosis are 
      manifested in human PTCs is not currently known and whether PTC-specific 
      mechanisms are corrected upon CMA upregulation remains to be elucidated. Here, 
      using CRISPR-Cas9 technology, we develop a new human PTC line with defective 
      cystinosin expression (CTNS-KO PTCs). We show that the expression and 
      localization of the CMA receptor, LAMP2A, is defective in CTNS-KO PTCs. The 
      expression of the lipidated form of LC3B, a marker for another form of autophagy 
      (macroautophagy), is decreased in CTNS-KO PTCs indicating decreased autophagosome 
      numbers under basal conditions. However, the autophagic flux is functional, as 
      measured by induction by starvation or by blockage using the v-ATPase inhibitor 
      bafilomycin A, and by degradation of the macroautophagy substrate SQSTM1 under 
      starvation and proteasome-inhibited conditions. Previous studies showed that 
      LAMP2A accumulates in Rab11-positive vesicles in cystinotic cells. Here, we show 
      defective Rab11 expression, localization and trafficking in CTNS-KO PTCs as 
      determined by confocal microscopy, immunoblotting and TIRFM. We also show that 
      both Rab11 expression and trafficking in cystinotic PTCs are rescued by the 
      upregulation of CMA using small-molecule CMA activators. Cystinotic PTCs are 
      characterized by PTC de-differentiation accompanied by loss of the endocytic 
      receptor megalin, and megalin recycling is regulated by Rab11. Here we show that 
      megalin plasma membrane localization is defective in CTNS-KO PTCs and its 
      expression is rescued by treatment with CMA activators. Altogether, our data 
      support that CMA upregulation has the potential to improve PTC function in 
      cystinosis.
FAU - Zhang, Jinzhong
AU  - Zhang J
AD  - Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 
      United States.
FAU - He, Jing
AU  - He J
AD  - Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 
      United States.
FAU - Johnson, Jennifer L
AU  - Johnson JL
AD  - Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 
      United States.
FAU - Rahman, Farhana
AU  - Rahman F
AD  - Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 
      United States.
FAU - Gavathiotis, Evripidis
AU  - Gavathiotis E
AD  - Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 
      United States.
FAU - Cuervo, Ana Maria
AU  - Cuervo AM
AD  - Department of Developmental and Molecular Biology, Albert Einstein College of 
      Medicine, Bronx, NY, United States.
FAU - Catz, Sergio D
AU  - Catz SD
AD  - Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 
      United States.
LA  - eng
GR  - R01 HL088256/HL/NHLBI NIH HHS/United States
GR  - R01 DK110162/DK/NIDDK NIH HHS/United States
GR  - R37 AG021904/AG/NIA NIH HHS/United States
GR  - R01 AR070837/AR/NIAMS NIH HHS/United States
GR  - P30 AG038072/AG/NIA NIH HHS/United States
GR  - R21 EY028642/EY/NEI NIH HHS/United States
GR  - P01 AG031782/AG/NIA NIH HHS/United States
PT  - Journal Article
DEP - 20190201
PL  - Switzerland
TA  - Front Endocrinol (Lausanne)
JT  - Frontiers in endocrinology
JID - 101555782
PMC - PMC6367655
OTO - NOTNLM
OT  - LAMP2A
OT  - Rab 11 GTPase
OT  - chaperone-mediated autophagy (CMA)
OT  - cystinosis
OT  - fanconi syndrome
OT  - lysosomal storage disorder (LSD)
OT  - megalin
OT  - vesicular trafficking
EDAT- 2019/02/19 06:00
MHDA- 2019/02/19 06:01
PMCR- 2019/01/01
CRDT- 2019/02/19 06:00
PHST- 2018/10/10 00:00 [received]
PHST- 2019/01/14 00:00 [accepted]
PHST- 2019/02/19 06:00 [entrez]
PHST- 2019/02/19 06:00 [pubmed]
PHST- 2019/02/19 06:01 [medline]
PHST- 2019/01/01 00:00 [pmc-release]
AID - 10.3389/fendo.2019.00021 [doi]
PST - epublish
SO  - Front Endocrinol (Lausanne). 2019 Feb 1;10:21. doi: 10.3389/fendo.2019.00021. 
      eCollection 2019.