Project Number: 6250-51000-043-00
Project Type: Appropriated

Start Date: May 21, 2004
End Date: Apr 30, 2009

Objective:
Establish the role of critical nutritional, endocrine and genetic factors on growth, development and function of mammalian cells, tissues and organs. Determine metabolic fate and regulatory role of essential amino acids, especially methionine and cysteine, in intestinal epithelial cells in neonates. Determine the regulatory role of branched-chain amino acids, especially leucine, and glucose on activation of cellular protein synthesis signaling mechanisms in neonates. Determine the molecular function of vitamin A in vascular development and embryonic hematopoiesis and the key signaling molecules involved. Determine how maternal gestational malnutrition affects glucocorticoid status, growth factor expression and satellite cell proliferation in skeletal muscle and whether these factors contribute to postnatal growth impairment of offspring. Determine the impact of glutamine, simple sugars, soluble fiber, and probiotics on intestinal sensory, motor and immune function in infants and children. Understand the role of obestatin and GPR39 gene receptor which will increase our knowledge about critical development of obesity and type II diabetes in human.

Approach:
These objectives will be accomplished by quantifying the metabolism of isotopic labeled sulfur amino acids when given enterally and parenterally to neonatal piglets in vivo and in cultured intestinal epithelial cells in vitro. The in vivo rates and cellular localization of sulfur amino acid metabolism via transmethylation into homocysteine, transsulfuration into cysteine and incorporation into glutathione will be quantified. The fractional rates of tissue protein synthesis and the activation and/or protein-protein interaction of nutrient signaling proteins will be determined in tissues from neonatal piglets infused with amino acids and glucose to achieve levels within the fasting to fed range. Modulators of cellular nutrient signaling (rapamycin, LY294002 and AICAR) will be infused to distinguish the specificity of key signaling pathways. Endodermal differentiation and subsequent induction of endothelial cell growth, maturation, and vessel assembly will be characterized in retinoic acid deficient embryos cultured in the presence and absence of endodermally derived signals. The production of hematopoietic cells from mesodermal progenitors and the expression of specific target genes will be measured in normal and mutant cultured embryos in response to retinoic acid sufficiency and deficiency. Protein synthesis, growth factor expression, satellite cell cycle activity, rDNA transcription, and rRNA abundance will be measured in skeletal muscle of offspring from dams subjected to manipulation of nutrition and glucocorticoid status during gestation. Bowel motor and sensory patterns, stool transit time, permeability, and fecal calprotectin will be measured in children randomized and stratified by age to receive in a double blind fashion either fiber psyllium, probiotic, or glucose for four weeks. Children with bowel pain that do not respond to treatment will be placed on a lactose, sorbitol, fructose restricted diet and reassessed for intestinal functional endpoints. Infection rate and duration of hospitalization will be measured in preterm infants fed glutamine-supplemented or placebo formulas. Implement a series of experiments utilizing the mouse model and analysis of the hypothalamus in order to understand GPR39 gene function.