Talk:Ceramide

Role in apoptosis ?, and effect on "lipid rafts"

This page is heavily biased in favour of Ceramide having a role in apoptosis. Ceramide's role in apoptosis is still not fully accepted by mainstream scientists working in apoptosis, despite certain authors (particularly from Kolesnick's group) pushing their idea insistently.

There is plenty of research showing a role of ceramide in apoptosis induced by MANY different stimuli. I would like to know who are these 'mainstream scientists' who don't accept the role of ceramide.The above comment reads like an unsubstantiated attack on Kolesnick's group. J-P T 03:55, 7 April 2006 (UTC)

http://www.nature.com/nm/journal/v14/n4/abs/nm1748.html - worth mentioning? —Preceding unsigned comment added by 84.74.94.117 (talk) 20:35, 20 October 2008 (UTC)

I believe that evidence for ceramide involvement in apoptosis is substantial (cause or effect??), but this entry is not encyclopedic. Also, what do you mean that "[lipid] rafts can cross the entire lipid bilayer?" The point of that statement is not obvious, and the idea that lipid rafts cluster signal transduction proteins is accepted, but I do not know of evidence suggesting that ceramide regulates the presence or absence of lipid rafts- thats a little questionable to me. Certainly you can artifically remove them, but thats not what really happens in vivo. [BP] —Preceding unsigned comment added by 130.219.235.232 (talk) 21:55, 1 February 2009 (UTC)

An additional problem regarding this subject is the over-use of the term "lipid raft" as generic membrane platforms. As they were initially proposed by Simons (Simons K & Ikonen E 1997 Nature) lipid rafts were only to be enriched in cholesterol and sphingolipids. Ceramide is reportedly able to form (at least, in vitro), segregated domains which actually tend to displace cholesterol (Megha & London E 2004 JBC) (Chiantia S 2006 Biophys J) (Sot J et al 2008 FEBS Lett). These platforms would also be detergent resistant membranes (DRM), so again another common mistake is to consider DRM as "raft fractions" (Lichtenberg D et al 2005 Trends Biochem Sci). However, further studies reveal that a very high contents of cholesterol, these domains can solubilize (Castro BM 2009 JBC) (Busto JV et al 2010 Biophys J) or even form another kind of structure accomodating both ceramide an cholesterol (Busto JV et al 2014 Biophys J). Other useful references on ceramide-cholesterol dynamics: (Scheffer L et al 2005 Biophys J) (Fidorra M et al 2006 Biophys J) (Silva LC et al 2009 Biophys J).

As for in vivo experiments, ceramide enriched domains have been detected on red blood cell membranes upon cell death-inducing stress (Montes LR et al 2008 Biochemistry), and the apoptotic effect of ceramide has been reported since the late 80s - early 90s (Review: Hannun YA 1996 Science), interacting with proapoptotic Bcl2 family proteins (Lee H et al 2011 Plos One) (Chipuk JE et al 2012 Cell) (Review: Basanez G et al 2012 Plos Biol). The possibility of sphingolipid-enriched membrane platforms without cholesterol (therefore "non-raft" platforms) presence has also been reported in vivo (Frisz JF et al 2013 JBC, Frisz JF et al 2013 PNAS). Even some anticancer therapies are based on ceramide metabolism (or ceramide delivery) (Review: Morad SAF & Cabot MC 2013 Nat Rev Cancer). Other sphingolipids like ceramide-1-phosphate are reported to have an opposite effect (Review: Gomez-Munoz A et al 2010 Adv Exp Med Biol). Other results also suggest a relationship between ceramide and cholesterol, in accordance to in vitro experiments (Martinez-Abundis E et al 2009 FEBS J).

Finally, please also take into account that the effects of ceramides depend on their structure (number of carbons and unsaturations in the N-acyl chain) due to changes in the properties of the lipids (Jimenez-Rojo N et al 2014 BBA) (Pinto SN et al 2014 J Lipid Res) (Review: Hannun YA & Obeid LM 2011 JBC), but long chain saturated ceramides ~16C have reportedly effects on membrane permeation (Montes LR et al 2002 JBC) (Siskind LJ et al 2002 JBC), while ceramide-induced lipid transbilayer/interleaflet ("flip-flop") motion has also been described in vitro (Contreras XF 2003 JBC), and some mechanisms have been proposed regarding these processes (like the "ceramide channels"). It is accepted that these "special" biophysical properties of ceramide are probably related to their in vivo effects, but how this happens is not yet a fully understood issue. This recent review can also be of help regarding the properties of ceramides: Castro BM et al 2014 Prog Lipid Res. I hope all this information helps to improve the article. 159.92.184.204 (talk) 12:34, 2 July 2014 (UTC)

Isn't ceramide also supposed to have a role in insulin resistance? Well, I guess it probably has a role in a lot of things but there's not really space to put everything in... 30.3.11 —Preceding unsigned comment added by 130.130.37.12 (talk) 07:19, 30 March 2011 (UTC)

Role in cosmetics

I'd like to know how Ceramides are useful in hair conditioners and skin lotions. There are many brands out there that now market themselves has containing Ceramides. --Navstar 19:16, 22 August 2006 (UTC)

I came to the article hoping for some of the same. Disappointed that it is nearly 9 years later and still no information, so I have added a new but brief section and hope that somebody more able will be able to expand upon it. 99bonk (talk) 22:17, 29 January 2015 (UTC)

The article now mentions Wheat ceramides for skin. There is at least Rice ceramides also and Rice may be better: <spam link removed> "Tom is a lifelong nutrition enthusiast". So he is not university professor or similar, but that page looks useful to me anyway. 91.155.24.127 (talk) 19:33, 8 September 2017 (UTC)

"Ceramide Channels"

Although the increase in membrane permeability by the effect of ceramide has been described and widely accepted (http://www.ncbi.nlm.nih.gov/pubmed/11796726 or http://www.ncbi.nlm.nih.gov/pubmed/20178791 for a general review), the presence of "ceramide channels" as a mechanism for this phenomena is not yet colectively accepted, in fact, almost every publication that mentions this subject comes from a common source (M. Colombini), so in order to keep the most careful enciclopedic neutrality of the article it would be worth noting that there is still controversy among biophysicists around this specific subject. — Preceding unsigned comment added by 158.227.41.93 (talk) 09:45, 19 April 2013 (UTC)

Substances known to induce ceramide generation - No references or citations

Many people may be drawn to this wiki as Ceramide is quoted often on the Web to have a possible involvement in the search for a cure for cancer. In this respect "Substances known to induce ceramide generation" is an important section and has no citations at all which makes one wonder where this information came from and whether it is valid. As huge numbers of people are searching for cancer cures it is important that information such as this is verified or at least cited. Andrew ranfurly (talk) 19:38, 12 November 2016 (UTC)

No explanation or discussion of the different ceramides

Sounds like the fatty acid residue part of the molecule can vary, but no discussion on what variations are found (eg in human skin or any natural sources) or how they affect any properties ? - Rod57 (talk) 13:36, 5 October 2017 (UTC)