scholarly journals Biphasic regulation of glutamine consumption by WNT during osteoblast differentiation

2020 ◽  
pp. jcs.251645
Author(s):  
Leyao Shen ◽  
Deepika Sharma ◽  
Yilin Yu ◽  
Fanxin Long ◽  
Courtney Karner
Keyword(s):  
Cell Biology ◽  
Osteoblast Differentiation ◽  
Amino Acid Transporters ◽  
Matrix Synthesis ◽  
Glutamine Transport ◽  
Glutamine Consumption ◽  
A Cell ◽  
Mtorc1 Pathway ◽  
Dependent Pathway ◽  
Glutamine Uptake

Osteoblasts are the principal bone forming cells. As such, osteoblasts have enhanced demand for amino acids to sustain high rates of matrix synthesis associated with bone formation. The precise systems utilized by osteoblasts to meet these synthetic demands are not well understood. WNT signaling is known to rapidly stimulate glutamine uptake during osteoblast differentiation. Using a cell biology approach, we identified two amino acid transporters, Slc7a7 and Slc1a5, as the primary transporters of glutamine in response to WNT. Slc1a5 mediates the majority of glutamine uptake, whereas Slc7a7 mediates the rapid increase in glutamine uptake in response to WNT. Mechanistically, WNT signals through the canonical/β-catenin dependent pathway to rapidly induce Slc7a7 expression. Conversely, Slc1a5 expression is regulated by the transcription factor ATF4 downstream of the mTORC1 pathway. Targeting either Slc1a5 or Slc7a7 using shRNA reduced WNT induced glutamine uptake and prevented osteoblast differentiation. Collectively these data highlight the critical nature of glutamine transport for WNT induced osteoblast differentiation.

scholarly journals A cell-penetrating whole molecule antibody targeting intracellular HBx suppresses hepatitis B virus via TRIM21-dependent pathway

Theranostics ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 549-562 ◽  
Author(s):  
Jun-Fang Zhang ◽  
Hua-Long Xiong ◽  
Jia-Li Cao ◽  
Shao-Juan Wang ◽  
Xue-Ran Guo ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
B Virus ◽  
Cell Penetrating ◽  
A Cell ◽  
Antibody Targeting ◽  
Dependent Pathway

scholarly journals e-Book on plant virus infection—a cell biology perspective

2013 ◽  
Vol 4 ◽  
Author(s):  
Jean-François Laliberté ◽  
Peter Moffett ◽  
Hélène Sanfaçon ◽  
Aiming Wang ◽  
Richard S. Nelson ◽  
...  
Keyword(s):  
Virus Infection ◽  
Cell Biology ◽  
Plant Virus ◽  
A Cell

(A) Cell biology of epithelia

1991 ◽  
Vol 7 (3) ◽  
pp. 313-338 ◽  
Author(s):  
Martin Mackay ◽  
Ian Williamson ◽  
John Hastewell
Keyword(s):  
Cell Biology ◽  
A Cell

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 Intra-S-Phase Checkpoint Activation by Direct CDK2 Inhibition

2004 ◽  
Vol 24 (14) ◽  
pp. 6268-6277 ◽  
Author(s):  
Yonghong Zhu ◽  
Carmen Alvarez ◽  
Ronald Doll ◽  
Hirokazu Kurata ◽  
Xiao Min Schebye ◽  
...  
Keyword(s):  
Genomic Stability ◽  
S Phase ◽  
Cell Cycle Checkpoints ◽  
Minichromosome Maintenance ◽  
Checkpoint Activation ◽  
Cdk2 Activity ◽  
A Cell ◽  
Dependent Pathway ◽  
Number Of Cells ◽  
S Phase Checkpoint

ABSTRACT To ensure proper progression through a cell cycle, checkpoints have evolved to play a surveillance role in maintaining genomic integrity. In this study, we demonstrate that loss of CDK2 activity activates an intra-S-phase checkpoint. CDK2 inhibition triggers a p53-p21 response via ATM- and ATR-dependent p53 phosphorylation at serine 15. Phosphorylation of other ATM and ATR downstream substrates, such as H2AX, NBS1, CHK1, and CHK2 is also increased. We show that during S phase when CDK2 activity is inhibited, there is an unexpected loading of the minichromosome maintenance complex onto chromatin. In addition, there is an increased number of cells with more than 4N DNA content, detected in the absence of p53, suggesting that rereplication can occur as a result of CDK2 disruption. Our findings identify an important role for CDK2 in the maintenance of genomic stability, acting via an ATM- and ATR-dependent pathway.

Characterization of l-glutamine transport by a human neuroblastoma cell line

2002 ◽  
Vol 282 (6) ◽  
pp. C1246-C1253 ◽  
Author(s):  
Masafumi Wasa ◽  
Hong-Sheng Wang ◽  
Akira Okada
Keyword(s):  
Cell Line ◽  
Neuroblastoma Cell ◽  
Neuroblastoma Cell Line ◽  
Human Neuroblastoma Cell ◽  
Human Neuroblastoma ◽  
Uptake Kinetic ◽  
Human Neuroblastoma Cell Line ◽  
Glutamine Transport ◽  
Glutamine Deprivation ◽  
Glutamine Uptake

This study characterized the Na+-dependent transport of l-glutamine by a human neuroblastoma cell line, SK-N-SH. The Na+-dependent component represented >95% of the total glutamine uptake. Kinetic studies showed a single saturable high-affinity carrier with a Michaelis constant ( K m) of 163 ± 23 μM and a maximum transport velocity ( V max) of 13,713 ± 803 pmol · mg protein−1 · min−1. Glutamine uptake was markedly inhibited in the presence of l-alanine,l-asparagine, and l-serine. Li+ did not substitute for Na+. These data show thatl-glutamine is predominantly taken up through system ASC. Glutamine deprivation resulted in the decrease of glutamine transport by a mechanism that decreased V max without affecting K m. The expression of the system ASC subtype ASCT2 decreased in the glutamine-deprived group, whereas glutamine deprivation did not induce changes in system ASC subtype ASCT1 mRNA expression. Adaptive increases in Na+-dependent glutamate, Na+-dependent 2-(methylamino)isobutyric acid, and Na+-independent leucine transport were observed under glutamine-deprived conditions, which were completely blocked by actinomycin D and cycloheximide. These mechanisms may allow cells to survive and even grow under nutrient-deprived conditions.

scholarly journals Teaching Real Data Interpretation with Models (TRIM): Analysis of Student Dialogue in a Large-Enrollment Cell and Developmental Biology Course

2016 ◽  
Vol 15 (2) ◽  
pp. ar17 ◽  
Author(s):  
Patricia Zagallo ◽  
Shanice Meddleton ◽  
Molly S. Bolger
Keyword(s):  
Cell Biology ◽  
Biological Significance ◽  
Real Data ◽  
Data Interpretation ◽  
Biological Data ◽  
Scientific Practices ◽  
Student Dialogue ◽  
Audio Recordings ◽  
A Cell ◽  
Large Enrollment

We present our design for a cell biology course to integrate content with scientific practices, specifically data interpretation and model-based reasoning. A 2-yr research project within this course allowed us to understand how students interpret authentic biological data in this setting. Through analysis of written work, we measured the extent to which students’ data interpretations were valid and/or generative. By analyzing small-group audio recordings during in-class activities, we demonstrated how students used instructor-provided models to build and refine data interpretations. Often, students used models to broaden the scope of data interpretations, tying conclusions to a biological significance. Coding analysis revealed several strategies and challenges that were common among students in this collaborative setting. Spontaneous argumentation was present in 82% of transcripts, suggesting that data interpretation using models may be a way to elicit this important disciplinary practice. Argumentation dialogue included frequent co-construction of claims backed by evidence from data. Other common strategies included collaborative decoding of data representations and noticing data patterns before making interpretive claims. Focusing on irrelevant data patterns was the most common challenge. Our findings provide evidence to support the feasibility of supporting students’ data-interpretation skills within a large lecture course.

scholarly journals Design and interpretation of cell trajectory assays

2013 ◽  
Vol 10 (88) ◽  
pp. 20130630 ◽  
Author(s):  
Lucie G. Bowden ◽  
Matthew J. Simpson ◽  
Ruth E. Baker
Keyword(s):  
Cell Biology ◽  
Time Interval ◽  
Short Time Interval ◽  
Trajectory Data ◽  
Time Intervals ◽  
Different Types ◽  
Long Time ◽  
A Cell ◽  
Cell Trajectory ◽  
Short Time

Cell trajectory data are often reported in the experimental cell biology literature to distinguish between different types of cell migration. Unfortunately, there is no accepted protocol for designing or interpreting such experiments and this makes it difficult to quantitatively compare different published datasets and to understand how changes in experimental design influence our ability to interpret different experiments. Here, we use an individual-based mathematical model to simulate the key features of a cell trajectory experiment. This shows that our ability to correctly interpret trajectory data is extremely sensitive to the geometry and timing of the experiment, the degree of motility bias and the number of experimental replicates. We show that cell trajectory experiments produce data that are most reliable when the experiment is performed in a quasi-one-dimensional geometry with a large number of identically prepared experiments conducted over a relatively short time-interval rather than a few trajectories recorded over particularly long time-intervals.

scholarly journals Preconditioned Cell Array Optimized for a Three-Dimensional Culture of Hepatocytes

2009 ◽  
Vol 18 (5-6) ◽  
pp. 677-682 ◽  
Author(s):  
Yoshitaka Miyamoto ◽  
Takeshi Ikeya ◽  
Shin Enosawa
Keyword(s):  
Cell Biology ◽  
Culture Medium ◽  
Biological Activities ◽  
Three Dimensional ◽  
Rat Hepatocytes ◽  
Cell Array ◽  
Cell Arrays ◽  
A Cell ◽  
Three Dimensional Culture ◽  
Hepatocyte Spheroids

Three-dimensional culture procedures have attracted attention in various fields of cell biology. A newly developed cell array assisted in the formation of hepatocyte spheroids by two innovations: 1) micropatterning by a hydrophilic polymer, and 2) the use of bovine carotid artery-derived HH cells as feeder cells. The former contributes to the standardization of the spheroid size and the latter to the maintenance of the spheroids. We created a way to provide a ready-to-use cell array by cryopreservation of an HH feeder cell cultured array. After inoculation of HH cells on the cell array, the culture medium was replaced by freezing medium containing dimethyl sulfoxide. Thereafter, the array was frozen and stored in a −80°C deep freezer. At the start of the hepatocyte culture, the cryopreserved HH cell array was thawed by adding warmed (37°C) culture medium. The morphology and biological activities of the cryopreserved HH cells were intact, as confirmed by phase contrast microscopy and functional staining with calcein and formazan. The rat hepatocytes formed perfect spheroids on the cryopreserved HH cell array without any differences from those on the freshly prepared HH cell array. The CYP3A drug metabolism activities of the hepatocytes were well maintained on the cryopreserved and fresh cell arrays. The present protocol greatly shortened the time and labor required to prepare a cell array for culturing hepatocytes.

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