REGULATION OF PANCREATIC PDX1 AND DOWNSTREAM TARGET GENES AFTER EXPOSURE TO PROTEIN RESTRICTION DURING DIFFERENT WINDOWS OF PANCREATIC DEVELOPMENT
Date of Award
Master of Science
Dr. Edith Arany
Protein restriction (low protein, LP) during fetal and neonatal life has been shown in our laboratory to alter the normal development of the pancreas, resulting in predisposition to glucose intolerance and striking gender differences in key insulin signaling molecules. The objectives of this study were to examine the overall expression of Pdxl and its downstream target genes in young and adult rats (d21and d l 30) and to investigate the intrinsic molecular mechanisms that may be involved in the differentiation and function of P-cells when an insult such as dietary protein content is changed during different periods of early development.
Pregnant Wistar rats given control diet (C, 20% protein) or low protein diet (LP, 8% protein) were separated into four groups: C group (fed with C diet all life), LP1 group (fed with LP diet all life), LP2 group (fed with LP diet during gestation and lactation and C diet after weaning) and LP3 group (fed with LP diet during gestation only, and C diet thereafter). Eight mothers were used per group. Offspring from each mother, one male and one female, were sacrificed at d21 and at dl30 and their pancreata were collected. RNA was extracted and analyzed by quantitative real time PCR (qRT-PCR) and protein analysis was performed by Western blot.
Data obtained from qRT-PCR showed that Pdxl gene expression did not change in males in all LP groups as compared to control group at d21. At dl30, the C group showed a significant increase in Pdxl gene expression as compared to C group of d21 age group. Interestingly, LP groups did not show such significant changes over time as compared to d21 C group. When the levels of Pdxl gene expression in LP groups at d130 were compared to the C group at the same age, it appears that the expression of the gene and protein was
significantly decreased (p<0.05) suggesting an inhibition of the age-dependent increase in Pdxl in male rats by LP diet treatment. On the other hand, protein abundance of downstream target genes including insulin, glucokinase (GK) and GLUT2 did not change in male offspring within LP groups compared with C at d21. At d l 30; however, insulin gene and protein were also significantly decreased in LP1 and LP3 males compared to C, but did not change in LP2. Other downstream target genes including GLUT2 gene and protein levels were significantly decreased in LP3 group only, while GK did not change in all groups compared to control at dl30. We also observed that in females Pdxl expression and protein and its downstream target gene did not change by LP treatments at d21 or dl30. Intra- peritoneal glucose tolerance test (IGTT) also showed a significant impairment in males of the LP3 group. Therefore, we examined the morphometry of the pancreas in the LP3 males, which showed that (3-cell mass, (%) islet area and (%) (3-cells area were significantly decreased in this group compared to the control.
The presented data show that nutritional imbalance correlates with changes in Pdxl transcription factor gene expression patterns that can alter (3-cell development. It also contributes to further understanding of the molecular basis of fetal programming. This could provide a unique opportunity to develop new strategies for treatment of chronic diseases such as diabetes mellitus in the future.
Abuzgaia, Awatif, "REGULATION OF PANCREATIC PDX1 AND DOWNSTREAM TARGET GENES AFTER EXPOSURE TO PROTEIN RESTRICTION DURING DIFFERENT WINDOWS OF PANCREATIC DEVELOPMENT" (2011). Digitized Theses. 3492.