This article has nothing........

[Don]

This article has absolutely nothing to do with either tanning or the science of UV. So why am I posting it? Because the "lead author" is my son Steve (who will get his PhD on May 12th) and his proud father just couldn't resist "bragging" about his son having a paper published in the prestigious scientific journal Endocrinology.

Luteinizing Hormone Receptors Translocate to Plasma Membrane Microdomains after Binding of Human Chorionic Gonadotropin

Steven M. L. Smith, Ying Lei, Jingjing Liu, Mary E. Cahill, Guy M. Hagen, B. George Barisas and Deborah A. Roess


Department of Biomedical Sciences (S.M.L.S., M.E.C., D.A.R.), Cell and Molecular Biology Program (Y.L., J.L.), and Department of Chemistry (G.M.H., B.G.B.), Colorado State University, Fort Collins, Colorado 80523

Receptor-mediated signal transduction by G protein-coupled receptors can involve redistribution of plasma membrane receptors into membrane structures that are characterized by insolubility in Triton X-100 and low buoyant density in sucrose gradients. Here we describe the translocation of wild-type (wt) rat LH receptors (LHR-wt) from the bulk membrane into membrane microdomains (rafts) after the binding of human chorionic gonadotropin (hCG). In sucrose gradient ultracentrifugation of plasma membranes from cells stably expressing FLAG-tagged LHR-wt, receptors were located in high-density membrane fractions before binding of hormone and in low-density fractions after hCG treatment. Receptor translocation to low-density sucrose fractions did not occur when cells were pretreated with 1% methyl-ß-cyclodextrin, which reduces membrane cholesterol and disrupts rafts. Single-particle tracking of individual FLAG-LHR-wt receptors showed that hCG-treated receptors become confined in small compartments with a diameter of 86 ± 36 nm, significantly smaller than 230 ± 79 nm diameter regions accessed by the untreated receptor. Receptors were no longer confined in these small compartments after disruption of rafts by methyl-ß-cyclodextrin, a treatment that also decreased levels of cAMP in response to hCG. Finally, translocation of LHR into rafts required a functional hormone-receptor complex but did not occur after extensive receptor cross-linking that elevated cAMP levels. Thus, retention of LHR in rafts or small membrane compartments is a characteristic of functional, hormone-occupied LHR-wt. Although raft translocation was not essential for cAMP production, it may be necessary for optimizing hormone-mediated signaling.

[Parrot Head]

Don, can you tell us in laymans terms what the article said? I bet the buttons on your shirt are popping off. It's a major acheivment and congratulations to all.

[Don]

I'll try.

First of all, Steve's group is involved in "basic" research trying to unravel the process of "cellular signalling" - i.e., how cells "talk" to each other.

So let's look at the cellular signalling process in terms of tanning.

When UVR strikes the body, an estimated 10,000 signalling events takes place instantaneously, i.e., within milliseconds. One of the most important cellular signalling events is the conversion of the vitamin D-effective photon "energy" found in UVR into the vitamin D (25-OH) that is necessary for optimal health. This process operates exactly like what Steve's abstract describes except that instead of the LH (leutenizing hormone) receptors involved in reproduction, we have the vitamin D receptors involved in vitamin D metabolism.

cAPM (i.e., cyclic AMP) is "key" to any and all signalling events. How cAMP "energy" passes from one cell to another cell has been a "mystery" that Steve's group has helped to clarify over the past few years. They were among the first to describe "lipid rafts" i.e., "domains" that are involved in conducting the "signal" through the cell membrane. [Note: To show you how "fast" things change in research today, when they first started working on lipid rafts several years ago, the task was to "prove" that they really existed. Today, thanks in part to their work, no one doubts their existance and everyone is now trying to determine how lipid rafts help cells to communicate with each other. Once the "pathway" of cellular signalling is identified (and understood) the "holy grail" is to find ways to either improve the process and/or use it more effectively.]

For instance, today I found a fantastic article talking about vitamin D receptors (and lipid rafts) and the way the German researchers were trying to use this knowledge to develop vitamin D "analogs" that would be as safe and effective as UVR-induced vitamin D.

As an example of how basic research data can be used, here is a "mystery" involving the tanning process that might be resolved using the basic cellular signalling/lipid raft information found in Steve's paper.

Why doesn't the body "recognize" in "real time" that it has had too much UVR exposure and "warn" us to get out of the sun before we suffer skin damage?

The "answer" to that question requires idenifiying the erythema (sunburning) "pathway" and finding out whether or not the "receptors" involved can be "taught" to let us know when we have had enough UVR.

The "bottom line" is that "cellular signalling" (and the important role that lipid rafts play) is one of the "new frontiers" of research. Understanding the role of reproductive receptors (i.e., LH/FSH, etc) cellular signalling has led to the advances in helping "infertile" women conceive; understanding the role of insulin receptors is leading to new treatments for diabetes; understanding the role of various receptors is leading to new treatments for various forms of cancer; and we haven't even scatched the surface regarding the 10,000 signalling events (all involving receptors) that take place when UVR strikes the skin.

After you have read the above, I DARE YOU to try not to think about all of the "signalling events" taking place the next time you tan-LOL.

[Parrot Head]

Very interesting. I understand the process a little bit better now. Thanks for taking the time to explain it to me. PS Don. I know that you were in Texas awhile back to meter and test the Mastersun. Matt has benn telling me that the Mastersun out-meters the Matrix. Can you supply me with some comparing numbers? Have you done these comparisons on all the major players in the hp market? ie--how does it compare to say the Magic 636 w/mug. I know we are not comparing apples to apples here, but am I going to be happy with Mastersun?