scholarly journals Developmental changes in the utilization of citrulline by neonatal pigs

2020 ◽  
Vol 318 (1) ◽  
pp. F175-F182 ◽  
Author(s):  
Mahmoud A. Mohammad ◽  
Inka C. Didelija ◽  
Xioying Wang ◽  
Barbara Stoll ◽  
Douglas G. Burrin ◽  
...  
Keyword(s):  
Bolus Dose ◽  
Developmental Changes ◽  
Excess Capacity ◽  
Argininosuccinate Lyase ◽  
Viable Option ◽  
Neonatal Pigs ◽  
Plasma Citrulline ◽  
Argininosuccinate Synthase ◽  
Renal Expression

Developmental changes in the renal expression and activity of argininosuccinate synthase (ASS1) and argininosuccinate lyase (ASL), enzymes that use citrulline for the production of arginine, have been reported. Thus, the ability of neonates, and especially premature neonates, to produce arginine may be compromised. To determine the utilization of citrulline in vivo, we measured renal expression of ASS1 and ASL and conducted citrulline compartmental and noncompartmental kinetics using [15N]citrulline in pigs of five different ages (from 10 days preterm to 5 wk of age). The tracer was given in substrate amounts to also test the ability of neonatal pigs to use exogenous citrulline. Preterm and term pigs at birth had lower ASS1 and ASL expression than older animals, which was reflected in the longer half-life of citrulline in the neonatal groups. The production and utilization of citrulline by 1-wk-old pigs was greater than in pigs of other ages, including 5-wk-old animals. Plasma citrulline concentration was not able to capture these differences in citrulline production and utilization. In conclusion, the developmental changes in renal ASS1 and ASL gene expression are reflected in the ability of the pigs to use citrulline. However, it seems that there is an excess capacity to use citrulline at all ages, including during prematurity, since the bolus dose of tracer did not result in an increase in endogenous citrulline. Our results support the idea that citrulline supplementation in neonatal, including premature, pigs is a viable option to increase arginine availability.

scholarly journals The intestinal-renal axis for arginine synthesis is present and functional in the neonatal pig

2017 ◽  
Vol 313 (2) ◽  
pp. E233-E242 ◽  
Author(s):  
Juan C. Marini ◽  
Umang Agarwal ◽  
Jason L. Robinson ◽  
Yang Yuan ◽  
Inka C. Didelija ◽  
...  
Keyword(s):  
Small Intestine ◽  
Age Groups ◽  
Kidney Tissue ◽  
High Plasma ◽  
Neonatal Pigs ◽  
Plasma Citrulline ◽  
Young Pigs ◽  
Argininosuccinate Synthase ◽  
Neonatal Pig

The intestinal-renal axis for endogenous arginine synthesis is an interorgan process in which citrulline produced in the small intestine is utilized by the kidney for arginine synthesis. The function of this axis in neonates has been questioned because during this period the enzymes needed for arginine synthesis argininosuccinate synthase (ASS1) and lyase (ASL) are present in the gut. However, evidence of high plasma citrulline concentrations in neonates suggests otherwise. We quantified in vivo citrulline production in premature (10 days preterm), neonatal (7 days old), and young pigs (35 days old) using citrulline tracers. Neonatal pigs had higher fluxes (69 µmol·kg−1·h−1, P < 0.001) than premature and young pigs (43 and 45 µmol·kg−1·h−1, respectively). Plasma citrulline concentration was also greater in neonatal pigs than in the other age groups. We also determined the site of synthesis and utilization of citrulline in neonatal and young pigs by measuring organ balances across the gut and the kidney. Citrulline was released from the gut and utilized by the kidney in both neonatal and young pigs. The abundance and localization of the enzymes involved in the synthesis and utilization were determined in intestinal and kidney tissue. Despite the presence of ASS1 and ASL in the neonatal small intestine, the lack of colocalization with the enzymes that produce citrulline results in the release of citrulline by the PDV and its utilization by the kidney to produce arginine. In conclusion, the intestinal-renal axis for arginine synthesis is present in the neonatal pig.

scholarly journals ASS1 and ASL suppress growth in clear cell renal cell carcinoma via altered nitrogen metabolism

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Sanika Khare ◽  
Laura C. Kim ◽  
Graham Lobel ◽  
Paschalis-Thomas Doulias ◽  
Harry Ischiropoulos ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Renal Cell Carcinoma ◽  
Renal Cell ◽  
Clear Cell ◽  
Urea Cycle ◽  
Argininosuccinate Lyase ◽  
Cell Renal Cell Carcinoma ◽  
Argininosuccinate Synthase ◽  
Urea Cycle Enzymes

Abstract Background Kidney cancer is a common adult malignancy in the USA. Clear cell renal cell carcinoma (ccRCC), the predominant subtype of kidney cancer, is characterized by widespread metabolic changes. Urea metabolism is one such altered pathway in ccRCC. The aim of this study was to elucidate the contributions of urea cycle enzymes, argininosuccinate synthase 1 (ASS1), and argininosuccinate lyase (ASL) towards ccRCC progression. Methods We employed a combination of computational, genetic, and metabolomic tools along with in vivo animal models to establish a tumor-suppressive role for ASS1 and ASL in ccRCC. Results We show that the mRNA and protein expression of urea cycle enzymes ASS1 and ASL are reduced in ccRCC tumors when compared to the normal kidney. Furthermore, the loss of ASL in HK-2 cells (immortalized renal epithelial cells) promotes growth in 2D and 3D growth assays, while combined re-expression of ASS1 and ASL in ccRCC cell lines suppresses growth in 2D, 3D, and in vivo xenograft models. We establish that this suppression is dependent on their enzymatic activity. Finally, we demonstrate that conservation of cellular aspartate, regulation of nitric oxide synthesis, and pyrimidine production play pivotal roles in ASS1+ASL-mediated growth suppression in ccRCC. Conclusions ccRCC tumors downregulate the components of the urea cycle including the enzymes argininosuccinate synthase 1 (ASS1) and argininosuccinate lyase (ASL). These cytosolic enzymes lie at a critical metabolic hub in the cell and are involved in aspartate catabolism and arginine and nitric oxide biosynthesis. Loss of ASS1 and ASL helps cells redirect aspartate towards pyrimidine synthesis and support enhanced proliferation. Additionally, reduced levels of ASS1 and ASL might help regulate nitric oxide (NO) generation and mitigate its cytotoxic effects. Overall, our work adds to the understanding of urea cycle enzymes in a context-independent of ureagenesis, their role in ccRCC progression, and uncovers novel potential metabolic vulnerabilities in ccRCC.

Arginine synthesis in enterocytes of neonatal pigs

1995 ◽  
Vol 269 (3) ◽  
pp. R621-R629 ◽  
Author(s):  
G. Wu ◽  
D. A. Knabe
Keyword(s):  
Amino Acid ◽  
Essential Amino Acid ◽  
Developmental Change ◽  
Postnatal Growth ◽  
Arginase Activity ◽  
Developmental Changes ◽  
Argininosuccinate Lyase ◽  
Neonatal Pigs ◽  
Hydrolysis Of ◽  
In Cells

Arginine is deficient in porcine colostrum and milk, and yet the piglet has a particularly high requirement for this essential amino acid for rapid postnatal growth. To explain this paradox, arginine synthesis was quantified in enterocytes from newborn (0-day-old) and 2- to 7-day-old suckling pigs. Arginine was found to be synthesized from glutamine in 0- to 7-day-old pig enterocytes, but the rates of arginine synthesis were three- to fourfold greater in 0- to 2-day-old pigs than in 7-day-old pigs. To elucidate the developmental change of the intestinal arginine synthesis, the metabolism of glutamine to citrulline, the conversion of citrulline to arginine, and the activities of the enzymes involved were measured. The rates of metabolism of glutamine to citrulline were 2.5- to 3.5-fold greater in enterocytes from 0- to 2-day-old pigs than in cells from 7-day-old pigs, as were the rates of conversion of citrulline to arginine. The activities of all enzymes that synthesize arginine from glutamine, except pyrroline-5-carboxylate synthase and argininosuccinate lyase (ASL), increased in enterocytes from 2-day-old pigs compared with 0-day-old pigs. The activities of all these enzymes decreased by approximately 75% in 7-day-old pigs compared with 2-day-old pigs. Arginase activity was negligible in enterocytes from 0- to 7-day-old pigs, thus minimizing intestinal hydrolysis of newly synthesized arginine and maximizing the endogenous provision of arginine. The results of this study demonstrate the presence of arginine-synthesizing enzymes and their developmental changes in postnatal pig enterocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Developmental Changes in Release Properties of the CA3-CA1 Glutamate Synapse in Rat Hippocampus

2004 ◽  
Vol 92 (5) ◽  
pp. 2714-2724 ◽  
Author(s):  
P. Wasling ◽  
E. Hanse ◽  
B. Gustafsson
Keyword(s):  
Developmental Change ◽  
Hippocampal Slices ◽  
Nmda Receptor Antagonist ◽  
Developmental Changes ◽  
Excitatory Postsynaptic Potential ◽  
Paired Pulse ◽  
Mk 801 ◽  
Release Probability ◽  
The Individual

Developmental changes in release probability ( Pr) and paired–pulse plasticity at CA3-CA1 glutamate synapses in hippocampal slices of neonatal rats were examined using field excitatory postsynaptic potential (EPSP) recordings. Paired-pulse facilitation (PPF) at these synapses was, on average, absent in the first postnatal week but emerged and became successively larger during the second postnatal week. This developmental increase in PPF was associated with a reduction in Pr, as indicated by the slower progressive block of the N-methyl-d-aspartate (NMDA) EPSP by the noncompetitive NMDA receptor antagonist MK-801. This developmental reduction in Pr was not homogenous among the synapses. As shown by the MK-801 analysis, the Pr heterogeneity observed among adult CA3-CA1 synapses is present already during the first postnatal week, and the developmental Pr reduction was found to be largely selective for synapses with higher Pr values, leaving Pr of the vast majority of the synapses essentially unaffected. A reduction in Pves, the release probability of the individual vesicle, possibly caused by reduction in Ca2+ influx, seems to explain the reduction in Pr. In vivo injection of tetanus toxin at the end of the first postnatal week did not prevent the increase in PPF, indicating that this developmental change in release is not critically dependent on normal neural activity during the second postnatal week.

scholarly journals Recapitulate development to promote axonal regeneration: good or bad approach?

2006 ◽  
Vol 361 (1473) ◽  
pp. 1565-1574 ◽  
Author(s):  
Marie T Filbin
Keyword(s):  
Spinal Cord ◽  
Axonal Regeneration ◽  
Molecular Level ◽  
Signal Transduction Pathway ◽  
Developmental Changes ◽  
Transduction Pathway ◽  
The Past ◽  
Brain And Spinal Cord ◽  
The Brain

In the past decade there has been an explosion in our understanding, at the molecular level, of why axons in the adult, mammalian central nervous system (CNS) do not spontaneously regenerate while their younger counterparts do. Now a number of inhibitors of axonal regeneration have been described, some of the receptors they interact with to transduce the inhibitory signal are known, as are some of the steps in the signal transduction pathway that is responsible for inhibition. In addition, developmental changes in the environment and in the neurons themselves are also now better understood. This knowledge in turn reveals novel, putative sites for drug development and therapeutic intervention after injury to the brain and spinal cord. The challenge now is to determine which of these putative treatments are the most effective and if they would be better applied in combination rather than alone. In this review I will summarize what we have learnt about these molecules and how they signal. Importantly, I will also describe approches that have been shown to block inhibitors and encourage regeneration in vivo . I will also speculate on what the differences are between the neonatal and adult CNS that allow the former to regenerate and the latter not to.

scholarly journals The abundance and activation of mTORC1 regulators in skeletal muscle of neonatal pigs are modulated by insulin, amino acids, and age

2010 ◽  
Vol 109 (5) ◽  
pp. 1448-1454 ◽  
Author(s):  
Agus Suryawan ◽  
Teresa A. Davis
Keyword(s):  
Skeletal Muscle ◽  
Mammalian Target Of Rapamycin ◽  
Developmentally Regulated ◽  
Fk506 Binding Protein ◽  
Neonatal Pigs ◽  
Cell Culture Systems ◽  
Mtorc1 Signaling ◽  
Phospholipase D1 ◽  
Vacuolar Protein

Mammalian target of rapamycin complex 1 (mTORC1) signaling is crucial for the regulation of protein synthesis. Most of known mTORC1 regulators have been isolated and characterized using cell culture systems, and the physiological roles of these regulators have not been fully tested in vivo. Previously we demonstrated that the insulin (INS) and amino acid (AA)-induced activation of mTORC1 is developmentally regulated in skeletal muscle (Suryawan A et al. Am J Physiol Endocrinol Metab 293: E1597–E1605, 2007). The present study aimed to characterize in more detail the effects of the postprandial rise in INS and AA on the activation and abundance of mTORC1 regulators in muscle and how this is modified by development. Overnight fasted 6- and 26-day-old pigs were studied during 1) euinsulinemic-euglycemic-euaminoacidemic conditions (control), 2) euinsulinemic-euglycemic-hyperaminoacidemic clamps (AA), and 3) hyperinsulinemic-euglycemic-euaminoacidemic clamps (INS). INS, but not AA, enhanced the PRAS40 phosphorylation, and this effect was greater in 6- than in 26-day old pigs. Phospholipase D1 (PLD1) abundance and phosphorylation, and the association of PLD1 with Ras homolog enriched in brain (Rheb), were greater in the younger pigs. Neither INS, AA, nor age altered the abundance of Rheb, vacuolar protein sorting 34 (Vps34), or FK506-binding protein 38 (FKBP38). Although INS and AA had no effect, the abundance of ras-related GTP binding B (RagB) and the association of RagB with Raptor were greater in 6- than in 26-day-old pigs. Neither INS, AA, nor age altered AMPK-induced phosphorylation of Raptor. Our results suggest that the enhanced activation of mTORC1 in muscle of neonatal pigs is in part due to regulation by PRAS40, PLD1, and the Rag GTPases.

scholarly journals In vivo renal arginine release is impaired throughout development of chronic kidney disease

2010 ◽  
Vol 298 (1) ◽  
pp. F95-F102 ◽  
Author(s):  
Gin-Fu Chen ◽  
Chris Baylis
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Renal Plasma Flow ◽  
Severe Injury ◽  
Normal Kidney ◽  
Plasma Citrulline ◽  
Renal Ablation ◽  
Early Injury ◽  
Production Increase

The kidney is a major site of arginine synthesis where citrulline is converted to arginine via argininosuccinate synthase (ASS) and lyase (ASL). The rate-limiting step in arginine synthesis by the normal kidney is the rate of citrulline delivery and uptake to the renal cortex. We tested whether with chronic kidney disease (CKD) renal arginine synthesis may be compromised. Using the renal ablation/infarction (A/I) injury model, we measured renal citrulline delivery and uptake as well as arginine release at early, moderate, and severe stages of CKD vs. healthy controls. The renal plasma flow (RPF) and arterial-renal venous difference was measured at baseline and during citrulline infusion. Citrulline delivery was reduced at all stages of disease due to marked reductions in RPF and despite moderately increased plasma citrulline. Early after A/I, the kidney demonstrated a compensatory increase in citrulline uptake while at moderate and severe injury baseline citrulline uptake fell. At all stages of CKD, renal arginine release was markedly reduced. Citrulline infusion increased plasma citrulline in all groups, resulting in increased renal delivery vs. baseline. In healthy kidneys and early injury, citrulline uptake increased with the infusion, but only in the normal kidney did arginine production increase in parallel with the increased citrulline uptake. At moderate and severe injury, there was no increase in citrulline uptake or arginine production. The fall in arginine production in A/I was due to an early loss of ASS and ASL conversion of citrulline, which combined with a later reduction in citrulline uptake.

Abstract P301: Renal Expression of Collectrin (TMEM27) is Downregulated During Angiotensin II-induced Hypertension

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Sylvia Cechova ◽  
Pei-Lun Chu ◽  
Joseph Gigliotti ◽  
Thu H Le
Keyword(s):  
Angiotensin Ii ◽  
Catalytic Domain ◽  
Collecting Duct ◽  
Amino Acid Transporters ◽  
Ang Ii ◽  
Salt Loading ◽  
Transmembrane Glycoprotein ◽  
First Time ◽  
Renal Expression

Collectrin ( Tmem27 ) is transmembrane glycoprotein with homology to ACE-2, but lacks any catalytic domain. It plays a key role as a chaperone of amino acid transporters, and is abundantly expressed in the kidney in the proximal tubules and collecting duct. Deletion of collectrin in the mouse results in hypertension (HTN) at baseline and augmented salt-sensitivity that are associated with decreased renal nitric oxide and increased superoxide levels. During high salt diet, renal expression of collectrin is upregulated, suggesting an adaptive homeostatic response to salt loading. Here, we queried whether the expression of collectrin is regulated by angiotensin II (Ang II). Wild-type 129S6 mice were made hypertensive with Ang II osmotic minipump @ 600 ng/kg/min x 2 weeks, and were compared to age-matched untreated WT 129 mice. Shown in Fig. 1 , renal mRNA expression of collectrin is significantly reduced after 2 weeks of Ang II (Panel A). Immunostaining shows collectrin protein level is also significantly diminished to near undetectable level (Panel B). We show for the first time that Ang II regulates the expression of collectrin, suggesting that the action of Ang II on blood pressure may be mediated, in part, through the downregulation of collectrin. Further studies are needed to determine the effect of AT 1 and AT 2 receptor signaling on renal expression of collectrin during Ang II-HTN in vivo.

Formaldehyde cross-linking and immunoprecipitation demonstrate developmental changes in H1 association with transcriptionally active genes

1991 ◽  
Vol 11 (3) ◽  
pp. 1729-1733
Author(s):  
P C Dedon ◽  
J A Soults ◽  
C D Allis ◽  
M A Gorovsky
Keyword(s):  
Transcriptional Activity ◽  
Inverse Correlation ◽  
Dna Interaction ◽  
Histone H1 ◽  
Developmental Changes ◽  
Cross Linking ◽  
Developmental States ◽  
Logarithmic Growth ◽  
Active Genes

The in vivo association of histone H1 with specific genes in Tetrahymena thermophila was studied by using a simplified cross-linking and immunoprecipitation technique. Four genes were analyzed whose activities vary in three different developmental states (logarithmic growth, starvation, and conjugation). Hybridization of the immunoprecipitated DNA to cloned probes showed an inverse correlation between the level of immunoprecipitation with H1 antiserum and transcriptional activity. This represents the first demonstration of an alteration in histone H1-DNA interaction associated with developmental changes in transcriptional activity.

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