Two Pore Channel 2 (TPC2) Inhibits Autophagosomal-Lysosomal Fusion by Alkalinizing Lysosomal pH

Lǚ, Yingying; Hao, Bai Xia; Graeff, Richard; Wong, Connie W.M.; Wu, Wu Tian; Yue, Jianbo

doi:10.1074/jbc.m113.484253

Cited by 89 publications

(78 citation statements)

References 82 publications

(97 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Vacuolin-1 alkalinized lysosomal pH and decreased lysosomal Ca 2C content We then explored the mechanisms underlying vacuolin-1-induced autophagy arrest. As lysosomal pH is essential for the fusion 36 and lysosomes were enlarged by vacuolin-1 treatment, [33][34][35] we examined whether vacuolin-1 affects lysosomal pH in these enlarged lysosomes. We first applied LysoSensor Green DND-189 (pK a D »5.2) to qualitatively measure lysosomal pH.…”

Section: Vacuolin-1 Inhibited Autophagosome-lysosome Fusion In Hela Cmentioning

confidence: 99%

Vacuolin-1 potently and reversibly inhibits autophagosome-lysosome fusion by activating RAB5A

et al. 2014

Self Cite

View full text Add to dashboard Cite

-l-phenylalanine 2-naphthylamide; LAMP1, lysosomal-associated membrane protein 1; Leup, leupeptin; MAP1LC3, microtubule-associated protein 1 light chain 3;MTOR, mechanistic target of rapamycin; RFP, red fluorescent protein; tfLC3, tandem fluorescence-tagged LC3.Autophagy is a catabolic lysosomal degradation process essential for cellular homeostasis and cell survival. Dysfunctional autophagy has been associated with a wide range of human diseases, e.g., cancer and neurodegenerative diseases. A large number of small molecules that modulate autophagy have been widely used to dissect this process and some of them, e.g., chloroquine (CQ), might be ultimately applied to treat a variety of autophagy-associated human diseases. Here we found that vacuolin-1 potently and reversibly inhibited the fusion between autophagosomes and lysosomes in mammalian cells, thereby inducing the accumulation of autophagosomes. Interestingly, vacuolin-1 was less toxic but at least 10-fold more potent in inhibiting autophagy compared with CQ. Vacuolin-1 treatment also blocked the fusion between endosomes and lysosomes, resulting in a defect in general endosomal-lysosomal degradation. Treatment of cells with vacuolin-1 alkalinized lysosomal pH and decreased lysosomal Ca 2C content. Besides marginally inhibiting vacuolar ATPase activity, vacuolin-1 treatment markedly activated RAB5A GTPase activity. Expression of a dominant negative mutant of RAB5A or RAB5A knockdown significantly inhibited vacuolin-1-induced autophagosome-lysosome fusion blockage, whereas expression of a constitutive active form of RAB5A suppressed autophagosome-lysosome fusion. These data suggest that vacuolin-1 activates RAB5A to block autophagosome-lysosome fusion. Vacuolin-1 and its analogs present a novel class of drug that can potently and reversibly modulate autophagy. IntroductionAmong 3 types of autophagy, including microautophagy, chaperone-mediated autophagy, and macroautophagy, in mammals, macroautophagy (hereafter referred as autophagy) is the most common type. Autophagy is an evolutionarily conserved catabolic degradation cellular process in which misfolded proteins or damaged organelles are first sequestered by a doublemembrane vesicle, called an autophagosome. Autophagosomes then fuse with lysosomes to form autolysosomes, inside which the sequestered contents are digested by lysosomal enzymes and recycled to maintain cellular homeostasis. Autophagy can also be markedly induced by a wide variety of stresses, e.g., nutrient starvation, infection, and aging, for cell survival. Dysfunctional autophagy has been associated with wide ranges of human diseases, e.g., cancer and neurodegenerative diseases. [1][2][3][4][5][6] Basal autophagy activity is essential for cell homeostasis, and it is tightly controlled by a complicated interplay among several key machineries, including ULK1 or ULK2 complexes and the class III phosphatidylinositol-3 kinase complexes. The MTOR (mechanistic target of rapamycin) Ser/Thr kinase suppresses autophagy by inhibiting the ULK1/2 comple...

show abstract

Section: Vacuolin-1 Inhibited Autophagosome-lysosome Fusion In Hela Cmentioning

confidence: 99%

Vacuolin-1 potently and reversibly inhibits autophagosome-lysosome fusion by activating RAB5A

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

“…This group postulated that this overexpression of TPC2, through NAADP and Ca 2C pathway, could alkalinize lysosomal pH and prevent the recruitment of Rab7 (an important protein involved in late endocytic membrane traffic regulation); therefore, the fusion between the lysosome and the autophagosome would be inhibited. 37 However, TPC2 K D or treatment of cells with Ned-19, an NAADP antagonist, reversed this process and markedly reduced the accumulation of autophagosomes. 37 Later, in 2014, Lin et al 38 showed that TPC2 contributed to autophagy through the regulation of the protein homeostasis in skeletal muscle: TPC2 KO mice muscles showed atrophy compared to WT mice, which resulted from a harmful increase of autophagosomes accumulation during autophagy induced by energy deprivation and chloroquine, suggesting that these effects could be mediated by a change in pH or a reduced activity of the lysosomal proteases.…”

Section: Autophagymentioning

confidence: 98%

“…37 However, TPC2 K D or treatment of cells with Ned-19, an NAADP antagonist, reversed this process and markedly reduced the accumulation of autophagosomes. 37 Later, in 2014, Lin et al 38 showed that TPC2 contributed to autophagy through the regulation of the protein homeostasis in skeletal muscle: TPC2 KO mice muscles showed atrophy compared to WT mice, which resulted from a harmful increase of autophagosomes accumulation during autophagy induced by energy deprivation and chloroquine, suggesting that these effects could be mediated by a change in pH or a reduced activity of the lysosomal proteases. 38 It has also been observed an association between mTOR and TPC2 in skeletal muscle: the absence of TPC2 prevents reactivation of mTOR during prolonged deprivation, suggesting that there is a relationship between both, and that no proper termination of autophagy occurs in those conditions.…”

Section: Autophagymentioning

confidence: 98%

“…Today it is known that TPCs have a role not only in ion signaling but also in intracellular vesicle trafficking, [18][19][20] participating in a wide range of pathophysiological processes; that is why in the last years TPCs have received an increased attention from the main journals in the field, and they have been related to the regulation of many biological functions at different levels, including pancreatic b-cell function, 21,22 thermogenesis, 23 nutrient sensing, 6 endolysosomal transport and functions, 19,20 exocytosis, 24,25 cytokinesis, 26 fertilization and embryogenesis, 27 cell differentiation, [28][29][30][31] angiogenesis, 32 endothelium activation mediated by histamine, 33 smooth muscle contraction, 34 autophagy, [35][36][37][38][39][40] skin pigmentation, 41 or even to the Ebola virus infection mechanism. 42 As well, recent studies have suggested their possible implication in the pathogenesis of Alzheimer disease, 36 46 Thus, TPCs have become attractive therapeutic targets, although it is necessary to go deeper into their main functions and mechanisms of action not only to clinically relevant compounds could be designed but also to understand the pathophysiology of an increased wide range of diseases related to TPCs function/dysfunction.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Two-pore channels (TPCs): Novel voltage-gated ion channels with pleiotropic functions

Feijóo‐Bandín¹,

García-Vence²,

García-Rúa³

et al. 2016

Channels

View full text Add to dashboard Cite

Two-pore channels (TPC1-3) comprise a subfamily of the eukaryotic voltage-gated ion channels (VGICs) superfamily that are mainly expressed in acidic stores in plants and animals. TPCS are widespread across the animal kingdom, with primates, mice and rats lacking TPC3, and mainly act as Ca C and Na C channels, although it was also suggested that they could be permeable to other ions. Nowadays, TPCs have been related to the development of different diseases, including Parkinsons disease, obesity or myocardial ischemia. Due to this, their study has raised the interest of the scientific community to try to understand their mechanism of action in order to be able to develop an efficient drug that could regulate TPCs activity. In this review, we will provide an updated view regarding TPCs structure, function and activation, as well as their role in different pathophysiological processes.

show abstract

“…It is known that TPCs have recently emerging as the targets for NAADP, which are crucial for appropriate basal and induced autophagic flux in cardiomyocytes [50]. For instance, overexpression of TPC2 in vitro suppressed autophagosomal-lysosomal fusion, thereby resulting in the decreasing levels of LC3-II and p62 and the accumulation of autophagosomes, suggesting that inhibition of autophagy progression by TPC2 [39] [41]. Thus, NAADP and its receptors (TRPMLs or TPCs) in lysosome may play crucial roles in lysosomal functions and subsequent autophagy events.…”

Section: The Negative Regulation Of Cd38 In Autophagymentioning

confidence: 99%

Dual Roles of CD38 in Autophagy

Wang¹,

Song²,

Wu³

et al. 2017

View full text Add to dashboard Cite

CD38 is a versatile, ubiquitously expressed protein that was identified as a multifunctional enzyme. Recently, cumulating evidence has suggested that CD38 is involved in autophagy, which is an evolutionarily conserved lysosomal degradation and recycling system. Acting as a enzyme, CD38 utilizes nicotinamide adenine dinucleotide phosphate (NADP) to synthesize nicotinic acid adenine dinucleotide phosphate (NAADP), which acts as a key messenger for Ca 2+ -mobilizing in lysosome by targeting two-pore channels (TPCs) or transient receptor potential mucolipins (TRPMLs). Multiple studies have indicated that CD38 is involved in autophagy by modulating intracellular Ca 2+ signaling. However, the control of autophagy by CD38 signaling is the subject of two contrary views. The autophagosomes trafficking and fusion with lysosomes to form autolysosomes are crucial steps in autophagy. On the one hand, the available evidence indicates that lysosome trafficking and fusion to autophagosomes is positively modulated by CD38. On the other hand, overexpression of TPC2, which is positively modulated by CD38, was shown to promote the accumulation of autophagosomes, thus suppress autophagy. This review will reveal the interesting contrary dual roles of CD38 in autophagy, and critical insight into the molecular mechanisms of CD38 in autophagy regulation.

show abstract

Two Pore Channel 2 (TPC2) Inhibits Autophagosomal-Lysosomal Fusion by Alkalinizing Lysosomal pH

Cited by 89 publications

References 82 publications

Vacuolin-1 potently and reversibly inhibits autophagosome-lysosome fusion by activating RAB5A

Vacuolin-1 potently and reversibly inhibits autophagosome-lysosome fusion by activating RAB5A

Two-pore channels (TPCs): Novel voltage-gated ion channels with pleiotropic functions

Dual Roles of CD38 in Autophagy

Contact Info

Product

Resources

About