Microarrays, antiobesity and the liver

Abstract

In this review, the microarray technology and especially oligonucleotide arrays are exemplified with a practical example taken from the perilipin-/- mice and using the dChip software, available for non-lucrative purposes. It was found that the liver of perilipin-/- mice was healthy and normal, even under high-fat diet when compared with the results published for the scd1-/- mice, which under high-fat diets had a darker liver, suggestive of hepatic steatosis. Scd1 is required for the biosynthesis of monounsaturated fatty acids and plays a key role in the hepatic synthesis of triglycerides and of very-low-density lipoproteins. Both models of obesity resistance share many similar phenotypic antiobesity features, however, the perilipin-/- mice had a significant downregulation of stearoyl CoA desaturases scd1 and scd2 in its white adipose tissue, but a normal level of both genes inside the liver, even under high-fat diet. Here, different microarray methodologies are discussed, and also some of the most recent discoveries and perspectives regarding the use of microarrays, with an emphasis on obesity gene expression, and a personal remark on my findings of increased expression for hemoglobin transcripts and other hemo related genes (hemo-like), and for leukocyte like (leuko-like) genes inside the white adipose tissue of the perilipin-/- mice. In conclusion, microarrays have much to offer in comparative studies such as those in antiobesity, and also they are methodologies adequate for new astounding molecular discoveries [free full text of this article Online].

Figure 1

Methodology used in the microarray fabrication and application in a practical experimental design.

Figure 2

Hierarchical clustering of the gene expression changes between tissues of plin^−/− (ko) vs. wild-type (wt) mice. Metabolic genes are upregulated in plin^−/− WAT, brown rectangle. Transcription related genes are downregulated in plin^−/− WAT, black rectangle, translation related genes appear below, after a short gap (not highlighted). Location of scd1, green rectangle and scd2, purple rectangle. The columns represent the organism and its tissues as labeled, and the rows represent the individual genes. A red color inside a cell in this figure represents upregulation, whereas a blue color in a cell represents downregulation. The clusters are grouped according to the intensity of expression for each particular transcript (dChip V 1.2). Symbols: wt, wild type (replicas); ko, knock out (replicas); WAT, white adipose tissue.