DNA methylation and cancer (*gasp*)...

Lets start off with the basics...what is DNA methylation? As if you don't already know?!? DNA methylation is the biological process by which a methyl group, which is an organic functional group with the formula CH3, is added to DNA nucleotide. Through DNA methylation, a methyl group can be attached to a carbon atom on cytosine or to a nitrogen atom on adenine. The addition of a methyl group to these nucleotides can serve many important biological purposes, such as suppressing potentially harmful viral genetic information that is present in the human genome.

Now that we understand the fundamental info, I can explain what the article is about. Basically, this article talks about DNA methylation and how cancer can be involved in the process.

The enzyme involved in this process is DNA methyltransferase, which catalyzes the transfer of a methyl group from S-adenosyl-methionine to cytosine residues to form 5-methylcytosine, a modified base that is found mostly at CpG sites in the genome. CpG islands are found near promoters in vertebrates and plants. In different types of tumors, abnormal or accidental methylation of CpG islands in the promoter region has been observed for many cancer-related genes resulting in the silencing of their expression. However, the reason why abnormal hypermethylation takes place is not known. The genes involved include tumor suppressor genes, genes that suppress metastasis and angiogenesis, and genes that repair DNA suggesting that epigenetics plays an important role in tumorigenesis.

Article:

DNA methylation and cancer

New Discovery of Gene Regulation in Mammals!

As you may have read from the title this article talks about a new type of gene regulation. Researchers at the University of California, Santa Cruz (UCSC), have discovered a type of gene regulation never before observed in mammals. The UCSC researchers discovered a ribozyme (RNA enzyme or catalytic RNA) that controls the activity of an important family of genes in several different species. A ribozyme is an RNA molecule that catalyzes a chemical reaction.

A newly discovered role for the hammerhead ribozyme was found embedded within certain genes in mice, rats, horses, platypuses, and other mammals as well. The genes are involved in the immune response and bone metabolism. Monika Martick, a UCSC postdoctoral researcher and first author of the Nature paper says, "the unique thing about these ribozymes is that they control the expression of the genes they're embedded in."

In the genes studied by Martick and coauthor Lucas Horan, a graduate student in molecular, cell, and developmental biology at UCSC, the messenger RNA contains sequences that assemble to form an active hammerhead ribozyme. The hammerhead ribozyme is able to divide itself in two because it is a self-cleaving molecule. By preventing protein translation, this self-cleaving action in the messenger RNAs effectively turns off the genes. Most likely, another mechanism exists to turn on the genes by stopping the self-cleaving action of the ribozyme. However, the UCSC researchers are still searching for such a mechanism, but they assume it is out there, somewhere.

Article:

New Mode Of Gene Regulation Discovered In Mammals

Chapter 13: Useful Materials

As always I love posting videos from Mr. Anderson because he explains stuff so well. It's like having a personal teacher at your finger tips! Anyways, this video is about the regulation of genes in both prokaryotes and eukaryotes. He also talks about operons, which are clusters of genes under transcriptional control of one promoter in bacterial cells. Another thing he explains is the importance of transcription factors in eukaryotic gene expression. Overall, this video is quite helpful...but I mean lets be honest, all of his videos are helpful (am I right or am I right?).

This video is a NDSU Virtual Cell Animation that talks about lac operon. Is it just me or do these videos creep you out too? The music at the beginning of each video is quite creepy and mysterious. But I'm not here to talk about creepy music, I'm here to talk about this awesome video. The video explains lac operon, which is an operon required for the transport and metabolism of lactose in Escherichia coli and some other bacteria. It consists of three adjacent structural genes, lacZ, lacY and lacA. The lac operon is regulated by several factors including the availability of glucose and of lactose. If lactose is absent, the gene is turned off; if lactose is present, the gene is turned on. In the absence of lactose, a repressor protein (made by the lacI gene) binds to the operator region upstream of the lacZ, lacY and lacA genes and prevents the lactose utilization gene from being transcribed.