scholarly journals SLC38A2 provides proline to fulfil unique synthetic demands arising during osteoblast differentiation and bone formation.

2022 ◽  
Author(s):  
Leyao Shen ◽  
Yilin Yu ◽  
Yunji Zhou ◽  
Shondra M Pruett-Miller ◽  
Guo-Fang Zhang ◽  
...  
Keyword(s):  
Amino Acid ◽  
Bone Formation ◽  
Osteoblast Differentiation ◽  
Genetic Ablation ◽  
Differentiated Cells ◽  
Neutral Amino Acid Transporter ◽  
Unique Protein ◽  
Associated Proteins ◽  
Bioinformatic Approach ◽  
Metabolomic Approach

Cellular differentiation is associated with the acquisition of a unique protein signature which is essential to attain the ultimate cellular function and activity of the differentiated cell. This is predicted to result in unique biosynthetic demands that arise during differentiation. Using a bioinformatic approach, we discovered osteoblast differentiation is associated with increased demand for the amino acid proline. When compared to other differentiated cells, osteoblast-associated proteins including RUNX2, OSX, OCN and COL1A1 are significantly enriched in proline. Using a genetic and metabolomic approach, we demonstrate that the neutral amino acid transporter SLC38A2 acts cell autonomously to provide proline to facilitate the efficient synthesis of proline-rich osteoblast proteins. Genetic ablation of SLC38A2 in osteoblasts limits both osteoblast differentiation and bone formation in mice. Mechanistically, proline is primarily incorporated into nascent protein with little metabolism observed. Collectively, these data highlight a requirement for proline in fulfilling the unique biosynthetic requirements that arise during osteoblast differentiation and bone formation.

scholarly journals SLC1A5 provides glutamine and asparagine necessary for bone development in mice

2021 ◽  
Author(s):  
Deepika Sharma ◽  
Yilin Yu ◽  
Leyao Shen ◽  
Guo-Fang Zhang ◽  
Courtney M. Karner
Keyword(s):  
Amino Acid ◽  
Osteoblast Differentiation ◽  
Bone Development ◽  
Essential Amino Acids ◽  
Amino Acid Production ◽  
Matrix Synthesis ◽  
Acid Biosynthesis ◽  
Intracellular Amino Acid ◽  
Metabolomic Approach ◽  
Asparagine Metabolism

Osteoblast differentiation is sequentially characterized by high rates of proliferation followed by increased protein and matrix synthesis, processes that require substantial amino acid acquisition and production. How osteoblasts obtain or maintain intracellular amino acid production is poorly understood. Here we identify Slc1a5 as a critical amino acid transporter during bone development. Using a genetic and metabolomic approach, we show Slc1a5 acts cell autonomously in osteoblasts to import glutamine and asparagine. Deleting Slc1a5 or reducing either glutamine or asparagine availability prevents protein synthesis and osteoblast differentiation. Mechanistically, glutamine and asparagine metabolism support amino acid biosynthesis. Thus, osteoblasts depend on Slc1a5 to provide glutamine and asparagine, which are subsequently used to produce non-essential amino acids and support osteoblast differentiation and bone development.

scholarly journals SLC1A5 provides glutamine and asparagine necessary for bone development in mice

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Deepika Sharma ◽  
Yilin Yu ◽  
Leyao Shen ◽  
Guo-Fang Zhang ◽  
Courtney M Karner
Keyword(s):  
Amino Acid ◽  
Osteoblast Differentiation ◽  
Bone Development ◽  
Essential Amino Acids ◽  
Amino Acid Production ◽  
Matrix Synthesis ◽  
Acid Biosynthesis ◽  
Intracellular Amino Acid ◽  
Regulate Protein ◽  
Metabolomic Approach

Osteoblast differentiation is sequentially characterized by high rates of proliferation followed by increased protein and matrix synthesis, processes that require substantial amino acid acquisition and production. How osteoblasts obtain or maintain intracellular amino acid production is poorly understood. Here we identify SLC1A5 as a critical amino acid transporter during bone development. Using a genetic and metabolomic approach, we show SLC1A5 acts cell autonomously to regulate protein synthesis and osteoblast differentiation. SLC1A5 provides both glutamine and asparagine which are essential for osteoblast differentiation. Mechanistically, glutamine and to a lesser extent asparagine support amino acid biosynthesis. Thus, osteoblasts depend on Slc1a5 to provide glutamine and asparagine, which are subsequently used to produce non-essential amino acids and support osteoblast differentiation and bone development.

scholarly journals Identification and Characterization of Inhibitors of a Neutral Amino Acid Transporter, SLC6A19, Using Two Functional Cell-Based Assays

2018 ◽  
Vol 24 (2) ◽  
pp. 111-120 ◽  
Author(s):  
Sanjay J. Danthi ◽  
Beirong Liang ◽  
Oanh Smicker ◽  
Benjamin Coupland ◽  
Jill Gregory ◽  
...  
Keyword(s):  
Amino Acid ◽  
High Throughput Screening ◽  
Amino Acid Transporter ◽  
Neutral Amino Acid ◽  
Imaging Plate ◽  
Acid Uptake ◽  
Functional Assays ◽  
Neutral Amino Acid Transporter ◽  
Acid Transporter ◽  
Pharmacologically Active

SLC6A19 (B0AT1) is a neutral amino acid transporter, the loss of function of which results in Hartnup disease. SLC6A19 is also believed to have an important role in amino acid homeostasis, diabetes, and weight control. A small-molecule inhibitor of human SLC6A19 (hSLC6A19) was identified using two functional cell-based assays: a fluorescence imaging plate reader (FLIPR) membrane potential (FMP) assay and a stable isotope-labeled neutral amino acid uptake assay. A diverse collection of 3440 pharmacologically active compounds from the Microsource Spectrum and Tocriscreen collections were tested at 10 µM in both assays using MDCK cells stably expressing hSLC6A19 and its obligatory subunit, TMEM27. Compounds that inhibited SLC6A19 activity in both assays were further confirmed for activity and selectivity and characterized for potency in functional assays against hSLC6A19 and related transporters. A single compound, cinromide, was found to robustly, selectively, and reproducibly inhibit SLC6A19 in all functional assays. Structurally related analogs of cinromide were tested to demonstrate structure–activity relationship (SAR). The assays described here are suitable for carrying out high-throughput screening campaigns to identify modulators of SLC6A19.

Conditional knockout of the PDK‐1 gene in osteoblasts affects osteoblast differentiation and bone formation

2020 ◽  
Author(s):  
Yiguang Bai ◽  
Qiong Zhang ◽  
Qiaoling Chen ◽  
Quan Zhou ◽  
Yanan Zhang ◽  
...  
Keyword(s):  
Bone Formation ◽  
Osteoblast Differentiation ◽  
Conditional Knockout

scholarly journals SLPI is a critical mediator that controls PTH-induced bone formation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Akito Morimoto ◽  
Junichi Kikuta ◽  
Keizo Nishikawa ◽  
Takao Sudo ◽  
Maki Uenaka ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Bone Formation ◽  
Protease Inhibitor ◽  
Bone Metabolism ◽  
Serine Protease ◽  
Serine Protease Inhibitor ◽  
Secretory Leukocyte Protease Inhibitor ◽  
Bone Imaging ◽  
Genetic Ablation

AbstractOsteoclastic bone resorption and osteoblastic bone formation/replenishment are closely coupled in bone metabolism. Anabolic parathyroid hormone (PTH), which is commonly used for treating osteoporosis, shifts the balance from osteoclastic to osteoblastic, although it is unclear how these cells are coordinately regulated by PTH. Here, we identify a serine protease inhibitor, secretory leukocyte protease inhibitor (SLPI), as a critical mediator that is involved in the PTH-mediated shift to the osteoblastic phase. Slpi is highly upregulated in osteoblasts by PTH, while genetic ablation of Slpi severely impairs PTH-induced bone formation. Slpi induction in osteoblasts enhances its differentiation, and increases osteoblast–osteoclast contact, thereby suppressing osteoclastic function. Intravital bone imaging reveals that the PTH-mediated association between osteoblasts and osteoclasts is disrupted in the absence of SLPI. Collectively, these results demonstrate that SLPI regulates the communication between osteoblasts and osteoclasts to promote PTH-induced bone anabolism.

scholarly journals Neutral amino acid transporter ASCT2 displays substrate-induced Na+ exchange and a substrate-gated anion conductance

2000 ◽  
Vol 346 (3) ◽  
pp. 705-710 ◽  
Author(s):  
Angelika BRÖER ◽  
Carsten WAGNER ◽  
Florian LANG ◽  
Stefan BRÖER
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Anion Channel ◽  
Amino Acid Transporter ◽  
Neutral Amino Acid ◽  
Xenopus Laevis Oocytes ◽  
Anion Conductance ◽  
Neutral Amino Acid Transporter ◽  
Inward Currents ◽  
Acid Transporter

The neutral amino acid transporter ASCT2 mediates electroneutral obligatory antiport but at the same time requires Na+ for its function. To elucidate the mechanism, ASCT2 was expressed in Xenopus laevis oocytes and transport was analysed by flux studies and two-electrode voltage clamp recordings. Flux studies with 22NaCl indicated that the uptake of one molecule of glutamine or alanine is accompanied by the uptake of four to seven Na+ ions. Similarly to the transport of amino acids, the Na+ uptake was mediated by an obligatory Na+ exchange mechanism that depended on the presence of amino acids but was not stoichiometrically coupled to the amino acid transport. Other cations could not replace Na+ in this transport mechanism. When NaCl was replaced by NaSCN in the transport buffer, the superfusion of oocytes with amino acid substrates resulted in large inward currents, indicating the presence of a substrate-gated anion channel in the ASCT2 transporter. The Km for glutamine derived from these experiments is in good agreement with the Km derived from flux studies; it varied between 40 and 90 μM at holding potentials of -60 and -20 mV respectively. The permeability of the substrate-gated anion conductance decreased in the order SCN- NO3- > I- > Cl- and also required the presence of Na+.

The SLC1 high-affinity glutamate and neutral amino acid transporter family

2013 ◽  
Vol 34 (2-3) ◽  
pp. 108-120 ◽  
Author(s):  
Yoshikatsu Kanai ◽  
Benjamin Clémençon ◽  
Alexandre Simonin ◽  
Michele Leuenberger ◽  
Martin Lochner ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Transporter ◽  
Neutral Amino Acid ◽  
High Affinity ◽  
Neutral Amino Acid Transporter ◽  
Transporter Family ◽  
Acid Transporter
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