O.o um what?

Over the past few years biologists have developed several lines of evidence showing that one particular protein molecule inside cells plays an extraordinary variety of life-protecting roles, so much so that the molecule has been dubbed a “guardian angel.” The findings are leading to greater knowledge of how life works and to a deeper understanding of the root causes of cancer.

So pervasive is the molecule’s role that scientists in four areas of biology were on the trail of it, each field unaware, until recently, of the protein’s importance in the others.

Molecular biologists, for example, were trying to learn more about how cells repair the genetic damage that is routinely inflicted by radiation, chemicals and even body heat. In another area of research, cell biologists were trying to understand how cells govern the timing of when they divide. Other cell biologists wanted to know how cells carry out a natural process called “programmed cell death,” or apoptosis, in which a cell literally commits suicide. And, finally, cancer researchers were puzzled by the fact that at least half of all victims had tumors with mutations in one particular gene — so many that they called the gene a “tumor suppressor” on the grounds that when it was knocked out, a cell was predisposed to become cancerous. A Four-Team Effort.

Klotho (KL) is described as an anti-aging gene because mutation of Kl gene leads to multiple pre-mature aging phenotypes and shortens lifespan in mice. Growing evidence suggests that an increase in KL expression may be beneficial for age-related diseases such as arteriosclerosis and diabetes. It remains largely unknown, however, how Kl expression could be induced. Here we discovered novel molecular mechanism for induction of Kl expression with a small molecule ‘Compound H’, N-(2-chlorophenyl)-1 H-indole-3-caboxamide. Compound H was originally identified through a high-throughput screening of small molecules for identifying Kl inducers. However, how Compound H induces Kl expression has never been investigated. We found that Compound H increased Kl expression via demethylation in CpG islands of the Kl gene. The demethylation was accomplished by activating demethylases rather than inhibiting methylases. Due to demethylation, Compound H enhanced binding of transcription factors, Pax4 and Kid3, to the promoter of the Kl gene. Pax4 and Kid3 regulated Kl promoter activity positively and negatively, respectively. Thus, our results show that demethylation is an important molecular mechanism that mediates Compound H-induced Kl expression. Further investigation is warranted to determine whether Compound H demethylates the Kl gene in vivo and whether it can serve as a therapeutic agent for repressing or delaying the onset of age-related diseases.

Keywords: klotho, methylation, Pax4, Kid3, CpG island.

Pre-mature aging phenotypes were eminent in the klotho (Kl)-deficient mice, which have ~ 10 copies of a transgene integrated in the 5’ flanking region of the Kl gene disrupting its expression [1]. The klotho mice die around ~ 2 months of age after birth due to multiple aging-related organ failures [1]. Later, the role of KL in aging was confirmed by the reproduction of the same aging phenotypes in Kl knockout homozygous (Kl −/−) mice [2]. On the other hand, overexpression of KL extends lifespan by 20–30% [2, 3]. The protein products of Kl gene can be divided into two forms: membrane-integrated form of Kl and non-integrated form of Kl which includes secreted and soluble Kl (sKl). These two type of proteins are produced from the two transcripts that arise from a single kl gene due to alternative RNA splicing [4, 5].