ascorbic acid and fibroblasts

Bryan L. Ford fordb at bcc.orst.edu
Mon Mar 3 01:34:06 EST 1997


Leonid A. Sadofiev wrote:
> 
> In his letter Dr. Bijur wrote:

> >Is there anybody out there who knows if ascorbic acid (vitamin C) causes
> >differentiation of fibroblasts. It has been established that ascobate does
> >induce the synthesis of collagen.  
 
> >Gautam Bijur

> Dear Gautam,
> 
>   Sorry, but something is wrong. Ascorbic acid does't induce the collagen synthesis.
>   During collagen formation there are some posttranslational
> modification occures. One of them is hydroxylation of some proline
> residies in the chain giving 4- or 3-hydroxyproline.
> Such a process is absolutely neccessary for collagen formation.
> This hydroxylation is an enzymatic process and requers the presence
> of ascorbic acid. Without vitamin C this reaction does't occur.
> So, ascorbic acid does't affect collagen genes transcription, but
> only give the ability to build normal, mature collagen.
> 
 Leonid A. Sadofiev
> 
Dear Sirs:

Something may be wrong, but it appears not to be the assertion (and
question) of Gautam Bijur. Please see: S. Kurata, H. Senoo and R. Hata
in Exp. Cell Res. 206, 63-71 (1993) "Transcriptional activation of type
I collagen genes by ascorbic acid-2-phosphate in human skin fibroblasts
and its failure in cells from a patient with alpha 2(I)-chain-defective
Ehlers-Danlos Syndrome". The article also ascribes similar activity to
sodium ascorbate.

Such a relationship should not be too surprising considering the
necessities of integrating complex biochemical and cellular events. One
frequently finds that a rate-limiting cofactor, metablic intermediate or
substrate in a biosynthetic pathway will itself strongly regulate one or
more of the critical genes of that same biosynthetic pathway. Very
"handy" from teleological standpoint, I would think. Since ascorbate is
also involved in type II collagen maturation one should not be surprised
to see that it also regulated transcription of these genes as well.

I regret that I can't shed much if any light on the original issue of
fibroblast differentiation, but I would say the question is still at
least open. 

Yours sincerely,

Bryan



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