Bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase, inhibits acidification and protein degradation in lysosomes of cultured cells.

Yoshimori, Tamotsu; Yamamoto, Akira; Moriyama, Yoshinori; Futai, Masamitsu; Tashiro, Yutaka

doi:10.1016/s0021-9258(19)47429-2

Cited by 1,188 publications

(317 citation statements)

References 26 publications

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“…BFA also abrogated the effect of BRD4780 on MUC1-fs clearance (Figure 6E). Second, inhibition of lysosomal degradation by Bafilomycin A (Yoshimori et al, 1991) resulted in a 170 kD MUC1-fs protein retained in late secretory compartments (trans-Golgi, late endosomes, and lysosomes) (Figures 6E and S5C). This 170 kD MUC1-fs protein was present but less abundant in control P cells at baseline, likely representing a fully O-glycosylated version of the protein (Apostolopoulos et al, 2015).…”

Section: Brd4780 Releases Muc1-fs From the Early Secretory Compartmentmentioning

confidence: 99%

Small Molecule Targets TMED9 and Promotes Lysosomal Degradation to Reverse Proteinopathy

Dvela‐Levitt

Kost‐Alimova

Emani

et al. 2019

Cell

147

129

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Intracellular accumulation of misfolded proteins causes toxic proteinopathies, diseases without targeted therapies. Mucin 1 kidney disease (MKD) results from a frameshift mutation in the MUC1 gene (MUC1-fs). Here, we show that MKD is a toxic proteinopathy. Intracellular MUC1-fs accumulation activated the ATF6 unfolded protein response (UPR) branch. We identified BRD4780, a small molecule that clears MUC1-fs from patient cells, from kidneys of knockin mice and from patient kidney organoids. MUC1-fs is trapped in TMED9 cargo receptor-containing vesicles of the early secretory pathway. BRD4780 binds TMED9, releases MUC1-fs, and reroutes it for lysosomal degradation, an effect phenocopied by TMED9 deletion. Our findings reveal BRD4780 as a promising lead for the treatment of MKD and other toxic proteinopathies. Generally, we elucidate a novel mechanism for the entrapment of misfolded proteins by cargo receptors and a strategy for their release and anterograde trafficking to the lysosome.(F) IF co-staining of distal tubule in MKD patient kidney organoid for MUC1-wt (red), MUC1-fs (green), E-cadherin (blue), and Na + /K + -ATPase (yellow). MUC1-fs localized intracellularly (middle) compared to apical MUC1-wt (left). (G) IF co-staining in P cells for MUC1-fs (green), MUC1-wt (red), and Hoechst (gray). MUC1-fs localized intracellularly (middle) compared to MUC1-wt on the plasma membrane (left). See also Figures S1, S2, and S3 and Table S1.

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Section: Brd4780 Releases Muc1-fs From the Early Secretory Compartmentmentioning

confidence: 99%

Small Molecule Targets TMED9 and Promotes Lysosomal Degradation to Reverse Proteinopathy

Dvela‐Levitt

Kost‐Alimova

Emani

et al. 2019

Cell

147

129

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“…To further elucidate the influences of CRT in promoting eYFP-ATZ degradation via ERAD, we used MG132, an inhibitor of the catalytic activity of the 26S proteasome subunit ( 40 ). To examine CRT's role in any autophagy component-mediated pathway we used bafilomycin A1, a specific inhibitor of the lysosomal vacuolar H + -ATPase ( 41 , 42 ). CRT KO, CNX KO (as controls), or corresponding WT cells were transfected with eYFP-ATZ.…”

Section: Resultsmentioning

confidence: 99%

Calreticulin enhances the secretory trafficking of a misfolded α-1-antitrypsin

Mohan

Yang

Dean

et al. 2020

Journal of Biological Chemistry

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Alpha-1-antitrypsin (AAT) regulates the activity of multiple proteases in the lungs and liver. A E342K mutant of AAT called ATZ forms polymers present at only low levels in the serum that induce intracellular protein inclusions, causing lung emphysema and liver cirrhosis. An understanding of factors that can reduce the intracellular accumulation of ATZ is of great interest. We now show that calreticulin (CRT), an endoplasmic reticulum (ER) glycoprotein chaperone, promotes the secretory trafficking of ATZ, enhancing the media to cell ratio. This effect is more pronounced for ATZ than with AAT, and is only partially dependent on the glycan-binding site of CRT, which is generally relevant to substrate recruitment and folding by CRT. The CRT-related chaperone calnexin (CNX) does not enhance ATZ secretory trafficking, despite the higher cellular abundance of CNX-ATZ complexes. CRT deficiency alters the distributions of ATZ-ER chaperone complexes, increasing ATZ-BiP binding and inclusion body formation, and reducing ATZ interactions with components required for ER-Golgi trafficking, coincident with reduced levels of the protein transport protein Sec31A in CRT-deficient cells. These findings indicate a novel role for CRT in promoting the secretory trafficking of a protein that forms polymers and large intracellular inclusions. Inefficient secretory trafficking of ATZ in the absence of CRT is coincident with enhanced accumulation of ER-derived ATZ inclusion bodies (IB). Further understanding of the factors that control the secretory trafficking of ATZ and their regulation by CRT could lead to new therapies for lung diseases linked to AAT deficiency.

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“…To determine whether this was due to an increase in the number of autophagosomes or a blockade in autophagic flux, 56 we used bafilomycin A1 (Baf), a lysosomal v-ATPase inhibitor that blocks lysosomal acidification. 57 Coincubation of WT neurons with GlcSph and Baf did not further increase LC3-II levels, suggesting that elevated LC3-II levels were due to a block in autophagic flux and not an increase in the number of autophagosomes (Figure 6A).…”

Section: Glcsph Induces An Autophagy Block That Is Reversed By Inhibitors Of Mtor and Acid Ceramidasementioning

confidence: 93%

Elevated Glucosylsphingosine in Gaucher Disease induced Pluripotent Stem Cell Neurons Deregulates Lysosomal Compartment through Mammalian Target of Rapamycin Complex 1

Srikanth

Jones

Kane

et al. 2021

Stem Cells Translational Medicine

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Gaucher disease (GD) is a lysosomal storage disorder caused by mutations in GBA1, the gene that encodes lysosomal β-glucocerebrosidase (GCase). Mild mutations in GBA1 cause type 1 non-neuronopathic GD, whereas severe mutations cause types 2 and 3 neuronopathic GD (nGD). GCase deficiency results in the accumulation of glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph). GlcSph is formed by deacylation of GlcCer by the lysosomal enzyme acid ceramidase. Brains from patients with nGD have high levels of GlcSph, a lipid believed to play an important role in nGD, but the mechanisms involved remain unclear. To identify these mechanisms, we used human induced pluripotent stem cell-derived neurons from nGD patients. We found that elevated levels of GlcSph activate mammalian target of rapamycin (mTOR) complex 1 (mTORC1), interfering with lysosomal biogenesis and autophagy, which were restored by incubation of nGD neurons with mTOR inhibitors. We also found that inhibition of acid ceramidase prevented both, mTOR hyperactivity and lysosomal dysfunction, suggesting that these alterations were caused by GlcSph accumulation in the mutant neurons. To directly determine whether GlcSph can cause mTOR hyperactivation, we incubated wild-type neurons with exogenous GlcSph. Remarkably, GlcSph treatment recapitulated the mTOR hyperactivation and lysosomal abnormalities in mutant neurons, which were prevented by coincubation of GlcSph with mTOR inhibitors. We conclude that elevated GlcSph activates an mTORC1-dependent pathogenic mechanism that is responsible for the lysosomal abnormalities of nGD neurons. We also identify acid ceramidase as essential to the pathogenesis of nGD, providing a new therapeutic target for treating GBA1-associated neurodegeneration.

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Bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase, inhibits acidification and protein degradation in lysosomes of cultured cells.

Cited by 1,188 publications

References 26 publications

Small Molecule Targets TMED9 and Promotes Lysosomal Degradation to Reverse Proteinopathy

Small Molecule Targets TMED9 and Promotes Lysosomal Degradation to Reverse Proteinopathy

Calreticulin enhances the secretory trafficking of a misfolded α-1-antitrypsin

Elevated Glucosylsphingosine in Gaucher Disease induced Pluripotent Stem Cell Neurons Deregulates Lysosomal Compartment through Mammalian Target of Rapamycin Complex 1

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