(Nutrigenomics )

Introduction. Role of Macronutrients (fats, protein and

CHO) on genotype. Role of Micronutrients (minerals &

vitamins) on gene expression. Molecular Tools and Techniques

DIET AND GENOTYPE INTERACTIONS divined into two terms :

Nutrigenomics

Nutrigenetics

The study of the effects diet on the activity of individual`s genes and health

gene expression : the flow of genetic information from DNA to protein via RNA

Energy homeostasis

Energy homeostasis

Nutrient absorptionNutrient

absorption

Cell proliferation

Cell proliferation

Nutritional factors

Gene transcription

Transcription factors

(The genetic information)

(The “external” features)

Growth Immunity Normal maintenance of body function and

structure .

In addition to its role as an energy source and its effects on membrane lipid composition, dietary fat has profound effects on gene expression, leading to changes in metabolism, growth, and cell differentiation.

The effects of dietary fat on gene expression reflect an adaptive response to changes in the quantity and type of fat ingested.

In mammals, fatty acid regulated transcription factors include peroxisome proliferator–activated receptors

Lipogenic enzymes in liver decreased as result of feeding a diet containing 60 % linoleic acid.

Fatty acids stimulated the expression of adipocyte fatty acid binding protein (ap2) mRNA

In the 3T3 –L1 adipocyte cell line, arachidonic acid (n-6) decreased SCD1 m RNA stability in a dose depedent manner (80% maximum repression), as did linoleic acid.

Feeding high-energy diet to rats leads to early development of obesity and metabolic syndrome, apparently through an inability to cope with energy density of the diet.

Obesity is associated with increase in mRNA levels for the oxygenic neuropeptides, NPY (neuropeptides Y), Ag RP (Agouti Related Peptide) etc.

The effect of hyperglycemia on liver angiotensinogen (AGT) gene expression and found that hyperglycemia activated AGT gene expression in liver increased approximately 3 fold.

Glucose, the most abundant monosaccharide in nature, provides a very good example of how organisms have developed regulatory mechanisms to cope with a fluctuating level of nutrient supply.

In the pancreatic - cells, glucose is the primary physiological stimulus for the regulation of insulin synthesis and secretion.

In the liver, glucose, in the presence of insulin, induces expression of genes encoding glucose transporters and glycolytic and lipogenic enzymes, e.g. L-type pyruvate kinase (L-PK), acetyl-CoA carboxylase (ACC), and fatty acid synthase, and represses genes of the gluconeogenic pathway, such as the phosphoenolpyruvate carboxykinase gene.

RT-PCR is the most sensitive technique for mRNA detection and quantitation currently available.

commonly used techniques for quantifying mRNA levels.

• Measurement of mRNA in very small tissue samples.

Procedure:  Isolate RNA from cells/tissues RNA used as template for synthesis of complementary DNA (cDNA) PCR performed on the cDNA with gene specific primers Products can be analysed using Southern blotting/fluorescent

techniques to assess amplification levels. 

: Include1. Collect Samples.2. Isolate mRNA.3. Create Labelled DNA.4. Hybridization.5. Microarray Scanner.6. Analyze Data.

Microarray is a technique used to monitor and compare expression levels of multiple genes simultaneously.

GREEN – the healthy sample hybridized more than the diseased sample.

RED – the diseased/cancerous sample hybridized more than the nondiseased sample.

YELLOW - both samples hybridized equally to the target DNA.

BLACK - areas where neither sample hybridized to the target DNA.

By comparing the differences in gene expression between the two samples, we can understand more about the genomics of a disease.

Reporter systems allow study of eukaryotic gene expression and regulation

1-Differential gene expression leading to cells specialization

2-Level of regulation

Not all genes expressed at

the same time

o Genotyping is the process of determining differences in the genetic make-up (genotype) of an individual by examining the individual's DNA sequence using biological assays and comparing it to another individual's sequence or a reference sequence.

o Polymorphisms (different forms of a gene) may be present in coding and non-coding regions of a gene.

o Polymorphisms may influence gene regulation in response to nutrients

That’s all..……

Thank you!!!!