scholarly journals PQLC2 recruits the C9orf72 complex to lysosomes in response to cationic amino acid starvation

2019 ◽  
Vol 219 (1) ◽  
Author(s):  
Joseph Amick ◽  
Arun Kumar Tharkeshwar ◽  
Gabriel Talaia ◽  
Shawn M. Ferguson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Starvation ◽  
Cationic Amino Acid Transporter ◽  
Cationic Amino Acid ◽  
Binding Partner ◽  
Sensing Mechanism ◽  
Cationic Amino Acids ◽  
Sense And Respond ◽  
Amino Acid Sensing

The C9orf72 protein is required for normal lysosome function. In support of such functions, C9orf72 forms a heterotrimeric complex with SMCR8 and WDR41 that is recruited to lysosomes when amino acids are scarce. These properties raise questions about the identity of the lysosomal binding partner of the C9orf72 complex and the amino acid–sensing mechanism that regulates C9orf72 complex abundance on lysosomes. We now demonstrate that an interaction with the lysosomal cationic amino acid transporter PQLC2 mediates C9orf72 complex recruitment to lysosomes. This is achieved through an interaction between PQLC2 and WDR41. The interaction between PQLC2 and the C9orf72 complex is negatively regulated by arginine, lysine, and histidine, the amino acids that PQLC2 transports across the membrane of lysosomes. These results define a new role for PQLC2 in the regulated recruitment of the C9orf72 complex to lysosomes and reveal a novel mechanism that allows cells to sense and respond to changes in the availability of cationic amino acids within lysosomes.

scholarly journals PQLC2 signals lysosomal cationic amino acid abundance to the C9orf72 complex

2019 ◽  
Author(s):  
Joseph Amick ◽  
Arun Kumar Tharkeshwar ◽  
Gabriel Talaia ◽  
Shawn M. Ferguson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Transporter ◽  
Cationic Amino Acid Transporter ◽  
Cationic Amino Acid ◽  
Binding Partner ◽  
Sensing Mechanism ◽  
Cationic Amino Acids ◽  
Sense And Respond ◽  
Amino Acid Sensing

AbstractThe C9orf72 protein is required for normal lysosome function. In support of such functions, C9orf72 forms a heterotrimeric complex with SMCR8 and WDR41 that is recruited to lysosomes when amino acids are scarce. These properties raise questions about the identity of the lysosomal binding partner of the C9orf72 complex and the amino acid sensing mechanism that regulates C9orf72 complex abundance on lysosomes. We now demonstrate that an interaction with the lysosomal cationic amino acid transporter PQLC2 mediates C9orf72 complex recruitment to lysosomes. This is achieved through an interaction between PQLC2 and WDR41. The interaction between PQLC2 and the C9orf72 complex is negatively regulated by arginine, lysine and histidine, amino acids that PQLC2 transports across the membrane of lysosomes. These results define a new role for PQLC2 in the regulated recruitment of the C9orf72 complex to lysosomes and reveal a novel mechanism that allows cells to sense and respond to changes in the availability of cationic amino acids within lysosomes.

Cis-inhibition and trans-stimulation of cationic amino acid transport in the perfused rat pancreas

1991 ◽  
Vol 261 (3) ◽  
pp. C506-C514 ◽  
Author(s):  
J. H. Sweiry ◽  
M. Munoz ◽  
G. E. Mann
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Maximum Velocity ◽  
Isobutyric Acid ◽  
Perfused Rat Pancreas ◽  
Cultured Fibroblasts ◽  
Rat Pancreas ◽  
Dual Isotope ◽  
Cationic Amino Acid ◽  
Cationic Amino Acids

Transport of cationic amino acids in the isolated perfused rat pancreas was studied using dual-isotope dilution techniques. At 50 microM substrate concentration, unidirectional tracer uptakes for L-arginine (56 +/- 1%), L-lysine (49 +/- 2%), and L-ornithine (44 +/- 3%) were followed by rapid tracer efflux. In the presence of Na+, influx of L-arginine [Michaelis constant (Km) = 1.74 +/- 0.15 mM, maximum velocity (Vmax) = 1.97 +/- 0.07 mumol.min-1.g-1] and L-lysine (Km = 2.48 +/- 0.17 mM, Vmax = 2.42 +/- 0.08 mumol.min-1.g-1) was mediated by a common transport system, sensitive to cis-inhibition by L-ornithine, 2,4-L-diaminobutyric acid, D-lysine, and D-arginine. Substrates for system A [alpha-(methylamino)isobutyric acid] and an anionic carrier (L-aspartate) were poor cis-inhibitors of L-arginine entry. Removal of Na+ resulted in a 40% reduction in cationic amino acid influx. After cell loading (20 min), L-[3H]-lysine cleared predominantly from a slowly exchanging pool with a rate constant of 5.97 +/- 0.67 min. An influx/efflux permeability ratio of 14.5 +/- 1.6 was determined, and efflux of L-lysine was trans-stimulated by vascular challenges with cationic or large neutral amino acids. The specificity, relative Na+ independence, and exchange properties of this saturable cationic amino acid transporter in the pancreatic epithelium resemble those reported for system y+ in cultured fibroblasts and hepatocytes.

Transporters for Cationic Amino Acids in Animal Cells: Discovery, Structure, and Function

1998 ◽  
Vol 78 (2) ◽  
pp. 487-545 ◽  
Author(s):  
R. DEVÉS ◽  
C. A. R. BOYD
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Structure And Function ◽  
Xenopus Laevis Oocytes ◽  
Amino Acid Transporters ◽  
Cdna Clones ◽  
Animal Cells ◽  
Cationic Amino Acid ◽  
Cationic Amino Acids ◽  
And Function

Devés, R., and C. A. R. Boyd. Transporters for Cationic Amino Acids in Animal Cells: Discovery, Structure, and Function. Physiol. Rev. 78: 487–545, 1998. — The structure and function of the four cationic amino acid transporters identified in animal cells are discussed. The systems differ in specificity, cation dependence, and physiological role. One of them, system y+, is selective for cationic amino acids, whereas the others (B0,+, b0,+, and y+L) also accept neutral amino acids. In recent years, cDNA clones related to these activities have been isolated. Thus two families of proteins have been identified: 1) CAT or cationic amino acid transporters and 2) BAT or broad-scope transport proteins. In the CAT family, three genes encode for four different isoforms [CAT-1, CAT-2A, CAT-2(B) and CAT-3]; these are ∼70-kDa proteins with multiple transmembrane segments ( 12 – 14 ), and despite their structural similarity, they differ in tissue distribution, kinetics, and regulatory properties. System y+is the expression of the activity of CAT transporters. The BAT family includes two isoforms (rBAT and 4F2hc); these are 59- to 78-kDa proteins with one to four membrane-spanning segments, and it has been proposed that these proteins act as transport regulators. The expression of rBAT and 4F2hc induces system b0,+and system y+L activity in Xenopus laevis oocytes, respectively. The roles of these transporters in nutrition, endocrinology, nitric oxide biology, and immunology, as well as in the genetic diseases cystinuria and lysinuric protein intolerance, are reviewed. Experimental strategies, which can be used in the kinetic characterization of coexpressed transporters, are also discussed.

scholarly journals Coordinated Action of Multiple Transporters in the Acquisition of Essential Cationic Amino Acids by the Intracellular Parasite Toxoplasma gondii

2021 ◽  
Author(s):  
Stephen J Fairweather ◽  
Esther Rajendran ◽  
Martin Blume ◽  
Kiran Javed ◽  
Birte Steinhoefel ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Toxoplasma Gondii ◽  
Large Family ◽  
Essential Amino Acids ◽  
Amino Acid Transporters ◽  
Cationic Amino Acid ◽  
Intracellular Parasites ◽  
Cationic Amino Acids ◽  
High Concentrations

Intracellular parasites of the phylum Apicomplexa are dependent on the scavenging of essential amino acids from their hosts. We previously identified a large family of apicomplexan-specific plasma membrane-localized amino acid transporters, the ApiATs, and showed that the Toxoplasma gondii transporter TgApiAT1 functions in the selective uptake of arginine. TgApiAT1 is essential for parasite virulence, but dispensable for parasite growth in medium containing high concentrations of arginine, indicating the presence of at least one other arginine transporter. Here we identify TgApiAT6-1 as the second arginine transporter. Using a combination of parasite assays and heterologous characterisation of TgApiAT6-1 in Xenopus laevis oocytes, we demonstrate that TgApiAT6-1 is a general cationic amino acid transporter that mediates both the high-affinity uptake of lysine and the low-affinity uptake of arginine. TgApiAT6-1 is the primary lysine transporter in the disease-causing tachyzoite stage of T. gondii and is essential for parasite proliferation. We demonstrate that the uptake of cationic amino acids by TgApiAT6-1 is "trans-stimulated" by cationic and neutral amino acids and is likely promoted by an inwardly negative membrane potential. These findings demonstrate that T. gondii has evolved overlapping transport mechanisms for the uptake of essential cationic amino acids, and we draw together our findings into a comprehensive model that highlights the finely-tuned, regulated processes that mediate cationic amino acid scavenging by these intracellular parasites.

scholarly journals Coordinated action of multiple transporters in the acquisition of essential cationic amino acids by the intracellular parasite Toxoplasma gondii

2021 ◽  
Vol 17 (8) ◽  
pp. e1009835
Author(s):  
Stephen J. Fairweather ◽  
Esther Rajendran ◽  
Martin Blume ◽  
Kiran Javed ◽  
Birte Steinhöfel ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Toxoplasma Gondii ◽  
Large Family ◽  
Essential Amino Acids ◽  
Amino Acid Transporters ◽  
Cationic Amino Acid ◽  
Intracellular Parasites ◽  
Cationic Amino Acids ◽  
High Concentrations

Intracellular parasites of the phylum Apicomplexa are dependent on the scavenging of essential amino acids from their hosts. We previously identified a large family of apicomplexan-specific plasma membrane-localized amino acid transporters, the ApiATs, and showed that the Toxoplasma gondii transporter TgApiAT1 functions in the selective uptake of arginine. TgApiAT1 is essential for parasite virulence, but dispensable for parasite growth in medium containing high concentrations of arginine, indicating the presence of at least one other arginine transporter. Here we identify TgApiAT6-1 as the second arginine transporter. Using a combination of parasite assays and heterologous characterisation of TgApiAT6-1 in Xenopus laevis oocytes, we demonstrate that TgApiAT6-1 is a general cationic amino acid transporter that mediates both the high-affinity uptake of lysine and the low-affinity uptake of arginine. TgApiAT6-1 is the primary lysine transporter in the disease-causing tachyzoite stage of T. gondii and is essential for parasite proliferation. We demonstrate that the uptake of cationic amino acids by TgApiAT6-1 is ‘trans-stimulated’ by cationic and neutral amino acids and is likely promoted by an inwardly negative membrane potential. These findings demonstrate that T. gondii has evolved overlapping transport mechanisms for the uptake of essential cationic amino acids, and we draw together our findings into a comprehensive model that highlights the finely-tuned, regulated processes that mediate cationic amino acid scavenging by these intracellular parasites.

scholarly journals l-Arginine and Cationic Amino Acid Transporter 2B Regulate Growth and Survival of Leishmania amazonensis Amastigotes in Macrophages

2007 ◽  
Vol 75 (6) ◽  
pp. 2802-2810 ◽  
Author(s):  
Nanchaya Wanasen ◽  
Carol L. MacLeod ◽  
Lesley G. Ellies ◽  
Lynn Soong
Keyword(s):  
Amino Acid ◽  
Amino Acid Transporter ◽  
Parasite Growth ◽  
Leishmania Amazonensis ◽  
Growth Enhancement ◽  
Cationic Amino Acid Transporter ◽  
Cationic Amino Acid ◽  
Arginine Transport ◽  
Ifn Γ ◽  
Acid Transporter

ABSTRACT Leishmania spp. are obligate intracellular parasites, requiring a suitable microenvironment for their growth within host cells. We previously reported that the growth of Leishmania amazonensis amastigotes in murine macrophages (Mφs) was enhanced in the presence of gamma interferon (IFN-γ), a Th1 cytokine normally associated with classical Mφ activation and killing of intracellular pathogens. In this study, we provided several lines of evidence suggesting that IFN-γ-mediated parasite growth enhancement was associated with l-arginine transport via mouse cationic amino acid transporter 2B (mCAT-2B). (i) mRNA expression of Slc7A2, the gene encoding for mCAT-2B, as well as l-arginine transport was increased in IFN-γ-treated Mφs. (ii) Supplementation of l-arginine in Mφ cultures increased parasite growth. (iii) Parasite growth enhancement in wild-type Mφs was inhibited in the presence of nonmetabolized l-arginine analogues. (iv) IFN-γ-mediated parasite growth was absent in Mφs derived from mCAT-2B-deficient mice. Although we detected a clear upregulation of mCAT-2B and l-arginine transport, no measurable iNOS or arginase activities were observed in IFN-γ-treated, infected Mφs. Together, these data suggest an involvement of a novel l-arginine usage independent of iNOS and arginase activities during IFN-γ-mediated parasite growth enhancement. A possible role of mCAT-2B in supplying l-arginine directly to the parasites for their proliferation is discussed.

Cationic Amino Acid Transporter-1 (CAT-1) Promotes Fibroblast-Like Synoviocytes Proliferation and Cytokine Secretion by Taking Up L-Arginine in Rheumatoid Arthritis

2021 ◽  
Author(s):  
Ying Lu ◽  
Chongbo Hao ◽  
Shanshan Yu ◽  
Zuan Ma ◽  
Xuelian Fu ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Amino Acid ◽  
Synovial Fluid ◽  
Culture Conditions ◽  
Cytokine Secretion ◽  
Cationic Amino Acid Transporter ◽  
Cationic Amino Acid ◽  
The Relationship ◽  
Fibroblast Like Synoviocytes

Abstract Background: Abnormal proliferation of fibroblast-like synoviocytes (FLSs) in the synovial lining layer is the primary cause of synovial hyperplasia and joint destruction in rheumatoid arthritis (RA). Currently, the relationship between metabolic abnormalities and FLS proliferation is a new focus of investigation. However, little is known regarding the relationship between amino acid metabolism and RA. Methods: The concentrations of amino acids and cytokines in the synovial fluid of RA (n=9) and osteoarthritis (OA,n=9) were detected by LC-MS/MS and CBA assay, respectively. The mRNA and protein expression of CAT-1 were determined in FLSs isolated from RA and OA patients by real-time PCR and western blotting. MTT assay, cell cycle, apoptosis, invasion and cytokine secretion were determined in FLSs knocked down of CAT-1 using siRNA or treated with D-arginine under normoxic and hypoxic culture conditions. A mouse collagen-induced arthritis (CIA) model was applied to test the therapeutic potential of blocking the uptake of L-arginine in vivo.Results: L-arginine was upregulated in the synovial fluid of RA patients and was positively correlated with elevation of the cytokines IL-1β, IL-6 and IL-8. Further examination demonstrated that cationic amino acid transporter-1 (CAT-1) was the primary transporter for L-arginine and was overexpressed on RA FLSs compared to OA FLSs. Moreover, knockdown of CAT-1 using siRNA or inhibition of L-arginine uptake using D-arginine significantly suppressed L-arginine metabolism, cell proliferation, migration and cytokine secretion in RA FLSs under normoxic and hypoxic culture conditions in vitro but increased cell apoptosis in a dose-dependent manner. Meanwhile, in vivo assays revealed that an L-arginine-free diet or blocking the uptake of L-arginine using D-arginine suppressed arthritis progression in CIA mice. Conclusion: CAT-1 is upregulated and promotes FLS proliferation by taking up L-arginine, thereby promoting RA progression.

Multiple pathways for cationic amino acid transport in rat thyroid epithelial cell line PC Cl3

2005 ◽  
Vol 288 (2) ◽  
pp. C290-C303 ◽  
Author(s):  
Tiziano Verri ◽  
Cinzia Dimitri ◽  
Sonia Treglia ◽  
Fabio Storelli ◽  
Stefania De Micheli ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Cell Line ◽  
Amino Acid Transport ◽  
Transport Systems ◽  
Residual Fraction ◽  
Acid Transport ◽  
Thyroid Cells ◽  
Cationic Amino Acid ◽  
Rat Thyroid

Information regarding cationic amino acid transport systems in thyroid is limited to Northern blot detection of y+LAT1 mRNA in the mouse. This study investigated cationic amino acid transport in PC cell line clone 3 (PC Cl3 cells), a thyroid follicular cell line derived from a normal Fisher rat retaining many features of normal differentiated follicular thyroid cells. We provide evidence that in PC Cl3 cells plasmalemmal transport of cationic amino acids is Na+ independent and occurs, besides diffusion, with the contribution of high-affinity, carrier-mediated processes. Carrier-mediated transport is via y+, y+L, and b0,+ systems, as assessed by l-arginine uptake and kinetics, inhibition of l-arginine transport by N-ethylmaleimide and neutral amino acids, and l-cystine transport studies. y+L and y+ systems account for the highest transport rate (with y+L > y+) and b0,+ for a residual fraction of the transport. Uptake data correlate to expression of the genes encoding for CAT-1, CAT-2B, 4F2hc, y+LAT1, y+LAT2, rBAT, and b0,+AT, an expression profile that is also shown by the rat thyroid gland. In PC Cl3 cells cationic amino acid uptake is under TSH and/or cAMP control (with transport increasing with increasing TSH concentration), and upregulation of CAT-1, CAT-2B, 4F2hc/y+LAT1, and rBAT/b0,+AT occurs at the mRNA level under TSH stimulation. Our results provide the first description of an expression pattern of cationic amino acid transport systems in thyroid cells. Furthermore, we provide evidence that extracellular l-arginine is a crucial requirement for normal PC Cl3 cell growth and that long-term l-arginine deprivation negatively influences CAT-2B expression, as it correlates to reduction of CAT-2B mRNA levels.

Single amino acid substitution of rat MRP2 results in acquired transport activity for taurocholate

2001 ◽  
Vol 281 (4) ◽  
pp. G1034-G1043 ◽  
Author(s):  
Kousei Ito ◽  
Hiroshi Suzuki ◽  
Yuichi Sugiyama
Keyword(s):  
Amino Acids ◽  
Multidrug Resistance ◽  
Amino Acid ◽  
Membrane Vesicles ◽  
Single Amino Acid ◽  
Sf9 Cells ◽  
Transport Activity ◽  
Wild Type ◽  
Cationic Amino Acids ◽  
The Difference

Multidrug resistance-associated protein 3 (MRP3), unlike other MRPs, transports taurocholate (TC). The difference in TC transport activity between rat MRP2 and MRP3 was studied, focusing on the cationic amino acids in the transmembrane domains. For analysis, transport into membrane vesicles from Sf9 cells expressing wild-type and mutated MRP2 was examined. Substitution of Arg at position 586 with Leu and Ile and substitution of Arg at position 1096 with Lys, Leu, and Met resulted in the acquisition of TC transport activity, while retaining transport activity for glutathione and glucuronide conjugates. Substitution of Leu at position 1084 of rat MRP3 (which corresponds to Arg-1096 in rat MRP2) with Lys, but not with Val or Met, resulted in the loss of transport activity for TC and glucuronide conjugates. These results suggest that the presence of the cationic charge at Arg-586 and Arg-1096 in rat MRP2 prevents the transport of TC, whereas the presence of neutral amino acids at the corresponding position of rat MRP3 is required for the transport of substrates.

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