This is topic 880nM...another finding! (RXR) in forum Medical Questions at LymeNet Flash.


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Posted by Marnie (Member # 773) on :
 
As I stated in another post, it appears the WFL makes more rhodopsin, but that is unlike the rhodopsin WE, humans, make.

Repeating:

"Here, we show that unlike vertebrate rhodopsin, amphioxus rhodopsin

***is still able to bind the agonist (helper) all-trans-retinal.***"

Rhodopsin, has two components called 11-cis retinal and opsin. Retinal is a light-sensitive derivative of vitamin A, and opsin is a protein molecule.

When light strikes the retina, a retinal molecule may absorb a photon, promoting it into an excited electronic state...In other words, the 11-cis retinal is transformed into the all-trans retinal.

Again, rhodopsin in the WFL can bind all trans retinal (ATRA).

Now...while researching this morning, I came across this:

First, a primer:

There are two families of retinoid receptors:

retinoic acid receptors (RAR)
retinoid X receptors (RXR)

Now...watch for the mention of 880nM:

"ATRA (all trans retinal) administered to rats at 30 mg/kg/day should produce plasma concentrations that preferentially activate RAR (Ki = 17-19 nM)

over ***RXR (Ki = 290-880 nM)***

(Zhang et al., 1996 )."

So...does 880nM activate RXR?

If the the rhodopsin in the lizard is capable of binding all trans retinoic acid which binds to RXR...

What happens then?

It may effect our liver functioning:

"As a class, these ligands exerted profound effects on hepatic microsomal metabolic enzyme levels.

Those with RAR activity *decreased hepatic cytochrome P450* (CYP or P450) levels and in vitro metabolism of the compound of pretreatment,

whereas those exerting predominantly RXR activity increased these parameters."

There are 3 forms of RXR:

Retinoid X receptor alpha (RXR-alpha), also known as NR2B1 (nuclear receptor subfamily 2, group B, member 1) is a nuclear receptor encoded by the RXRA gene.

Retinoid X receptors (RXRs) and retinoic acid receptors (RARs), are nuclear receptors that mediate the biological effects of retinoids by their involvement in retinoic acid-mediated gene activation.

These receptors exert their action by binding, as homodimers or heterodimers, to specific sequences in the promoters of target genes and regulating their transcription.

The protein encoded by this gene is a member of

the steroid and thyroid hormone receptor

superfamily of transcriptional regulators.


Retinoid X receptor beta (RXR-beta), also known as NR2B2 (nuclear receptor subfamily 2, group B, member 2) is a nuclear receptor encoded by the RXRB gene.[1]

This gene encodes a member of the retinoid X receptor (RXR) family of nuclear receptors which are involved in mediating the effects of retinoic acid (RA).

This receptor forms homodimers with the retinoic acid,

thyroid hormone, and vitamin D receptors,

increasing both DNA binding and transcriptional function on their respective response elements.

The gene lies within the major histocompatibility complex (MHC) class II region on chromosome 6.

An alternatively spliced transcript variant has been described, but its full length sequence has not been determined.[1]

Retinoic acid receptor gamma (RXR-gamma), also known as NR2B3 (nuclear receptor subfamily 2, group B, member 3) is a nuclear receptor encoded by the RXRG gene.[1]

This gene encodes a member of the retinoid X receptor (RXR) family of nuclear receptors which are involved in mediating the antiproliferative effects of retinoic acid (RA).

This receptor forms homodimers with the retinoic acid, thyroid hormone, and vitamin D receptors, increasing both DNA binding and transcriptional function on their respective response elements.

This gene is expressed at significantly lower levels in non-small cell lung cancer cells. Alternate transcriptional splice variants, encoding different isoforms, have been characterized.[1]

Important?

CONCLUSION: RXR-selective retinoids can potentiate the antiproliferative and apoptotic responses of breast cancer cell lines to PPAR ligands.
PMID: 15318936
 
Posted by oyvey (Member # 11581) on :
 
Hi,

Thank you for posting this.

Can you please clarify one of the terms for me?

Is a WFL a wide flood lamp, a source of light?


Thanks,
 
Posted by clairenotes (Member # 10392) on :
 
WFL - Western Fence Lizard

Claire
 
Posted by seekhelp (Member # 15067) on :
 
I wish I could comprehend one thing you write in these posts! They're just above me I guess. [Smile]
 
Posted by lymie_in_md (Member # 14197) on :
 
seekhelp it really isn't for you to understand, or me. it is a message in a bottle to scientist, doctors, healers in general. it is to let them know to start pushing the light.

Nice post Marnie!
 
Posted by Keebler (Member # 12673) on :
 
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Yes, while it's still a lot to comprehend, I have often wondered about that lizard.


-
 
Posted by bejoy (Member # 11129) on :
 
I'm going to go lizard hunting. I want to just hold one of these little guys in my hands, and look into it's wee little eyes. It holds the answer, if we can figure out the right question.
 


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