Smooth muscle cell-specific housekeeping genes?

Sheryl White slw at med.uvm.edu
Mon Jan 23 14:56:09 EST 1995


Kevin Pumiglia (pumiglk at aa.wl.com) wrote:
: In article <Hsieh.1140924755A at oitnews.harvard.edu>, Hsieh at cvlab.harvard.edu
: (Chung-Ming Hsieh) wrote:

: > Hi!
: > 
: > I am doing some RNA analyses to study several possible smooth muscle
: > cell-specific gene expression among different tissues, such as in various
: > portions of the digestive system and in the cardiovascular system.  
    Despite
: > I loaded the same amount of total RNA in Northern analysis, it is hard to
: > determine how much of the RNA really came out from the smooth muscle cells
: > in each particular tissue/organ since most tissues are comprised of many
: > different cell types.
: > 
: > I am wondering if one can find a smooth muscle cell-specific housekeeping
: > gene and use it as a probe to control the smooth muscle cell RNA 
    proportion
: > in various tissues.  I have looked into alpha-smooth muscle actin and 
    it is
: > not expressed at the same level in the digestive system and the vascular 
    system.
: > 
: > The other solution to this is to do in situ hybridization, but that's
: > another story...
: > 
: > Thanks in advance for your input!
: > 
: > Chung-Ming Hsieh
: > Hsieh at cvlab.harvard.edu
: > Cardiovascular Biology Laboratory
: > Harvard School of Public Health

: Its been a while since I thought about smooth muscle, but isn't there a
: myosin subtype (smooth muscle myosin) that is expressed in a restricted
: fashion?

  You are quite right, smooth muscle myosin is highly specific for smooth 
muscle cells and is a really excellent marker for differentiated smooth 
muscle cells (unlike smooth muscle actin).  The one major problem with 
using smooth muscle myosin as a probe for Northerns and other such 
hybridization based applications is that is will cross-hybridize to the 
non-muscle (cellular) myosin which can be found in all cells.  One can 
either run the Northern for a longer period in the hope of separating the 
two myosin types (non-muscle myosin mRNA is a bit longer than the smooth 
muscle myosin mRNA) or analyze the RNA by RNase-protection using a smooth 
muscle myosin specific probe.  I would recommend analyzing the RNA by 
RNase protection, if you have a workable probe for the other smooth 
muscle messages you are trying to examine.  (By the way, smooth muscle 
myosins are expressed at somewhat lower levels in vascular tissue versus 
G.I. system).  Good luck,
 Sheryl



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