Sniffing Urine: #xBio

Apr 27 2014 Published by under EB2014

KidneySmells

"Sniffing out urine"

ol·fac·to·ry

 adjective äl-ˈfak-t(ə-)rē, ōl-

: of, relating to, or connected with the sense of smell

Full Definition of OLFACTORY

:  of or relating to the sense of smell
— ol·fac·to·ri·ly  adverb

Origin of OLFACTORY

Latin olfactorius, from olfacere to smell, from olēre to smell +facere to do — more at odordo

First Known Use: circa 1658

Elucidating the role of a renal proximal tubule-specific olfactory receptor

Blythe D. Shepard, Lydie Cheval, Alain Doucet, Jennifer L. Pluznick


Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD,Centre de Recherche des Cordeliers, Paris, France

Do kidneys “smell” proximal tubular fluid to guide urine production? Do our bean-like organs suffer when we eat asparagus? Can they sniff out toxins for elimination?
First, the short answer: No. We scientists named this class of seven transmembrane domain G protein-coupled chemosensors “olfactory” because they were first identified transmitting smell in the nose. Further studies have documented their presence in many organs where they sense the same sorts of chemicals and signal their presence to the cells in the tissue. Many in this receptor class are classified as orphans, meaning we do not know their ligand.

Ligand Receptor

What? Think of the ligand as the “key” that fits a specific receptor or “lock”. Once the key is in, it can open the lock and allow other things to happen.
This group examined one of these orphan receptors, Olfr1393, which is expressed widely in organs including the kidney. Microdissection experiments revealed that it localized to the proximal tubule and in all 3 segments. They screened a multitude of compounds as potential ligands, and they found that Olfr1393 detects pre-constrained cyclic molecules containing either a carbonyl or alcohol  group. No endogenous ligands have yet been identified. Other experiments reveal that these receptors localize to the apical (tubular-lumen) side of proximal tubular cells, so they will interact with ligand in the urinary space.
Thus, our kidneys smell our urine in progress.
On top of all of this work, these investigators have made a knock-out mouse that lacks this receptor completely in all organs. On standard chow and water, these mice have no basal perturbations in kidney function. So what is the function of our intrarenal nose?
Bottom line: we really don't know! If you prefer, only the kidneys' nose knows...{insert laughter for the pun}
In the meantime, remember that your kidneys may be able to smell that cabbage you're eating.
You can catch an oral presentation of this abstract on Monday, April 28, at 8:30 am in room 25 B of the San Diego Convention Center. It will be presented on the same date in poster format at 12:45 on board A456.

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