Re: Is there a connection between the nuclear lamina and signal transduction?

	The nuclear lamina is a meshwork of intermediate fillament proteins 
(called nuclear lamins) that adhere to the inner surface of the double-
layered nuclear membrane. This "meshwork" gives structural support to the 
nucleus and acts as a structural bridge between the chromatin and the the 
nuclear envelope.  The DNA (chromatin) binds to the nuclear lamina and, in 
turn, the lamina is bound to the envelope.  
	Signal trasduction is the process by which an extracellular signal is 
transmitted from the outside to a specific response by the cells.  A cell 
will usually "respond" to particular signal by inducing or altering the 
expression of various genes (to produce specific proteins).  Gene 
expression is activated/inhibited by specific transcription factors which 
bind to the DNA and stimulate/inhibit transcription.  In order for genes to 
be activated, therefore, a signal must lead from the plasma membrane to the 
cytosol and finally the nucleus where the DNA is located. The traffic of 
molecules into and out of the nucleus in strictly monitered by the nuclear 
pore complex.  Molecules (such as transcription factors) carrying a 
specific code (called a Nuclear localization signal) are allowed to pass 
through the Nuclear Pore Complex.  This complex is composed of many 
proteins which create a pore or gate-like structure which regulates nuclear 
molecular traffic. 
	The nuclear lamina meshwork is organized on the inner side of the 
nuclear envelope so that molecules can enter the nucleaus.  There must be 
spaces, therefore, to allow signaling molecules to reach the DNA and 
produce a response.  I could not find any evidence of the nuclear lamina 
providing any "active" role in signal transduction, however, the structural 
role of the lamina provides a close spatial connection between a signal 
"gate" (the nuclear pore complex) and the genes which are modified (the 
DNA).

Admin note: there's a picture of a nuclear pore complex at
http://www.madsci.org/posts/archives/oct98/908808710.Cb.r.html