Researchers mixed two plates of cells, one being ovarian follicle granulosa cell

Question

Researchers mixed two plates of cells, one being ovarian follicle granulosa cells and the second cardiac muscle cells (which contract in response to norepinephrine). They noticed that the cardiac cells responded to follicle stimulating hormone (FSH) by contracting, even though in unmixed plates of cardiac muscle cells, there was no response. Answer the following 3 questions.

a) What does FSH signaling produce to which cardiac cells may react?

b) How would this compound be transferred to the cardiac cells?

Explanation / Answer

a) Cardiac myocytes have high affinity receptors for norepinephrine, which granulose cells lack. However, granulose cells have receptors for follicle stimulating hormone (FSH), which is absent in cardiac myocytes. FSH binds to FSHR in granulose cells and the downstream signaling leads to production of plasminogen activator via secondary messenger cAMP. Plasminogen activator (PA) is a serine protease involved in tissue remodeling during follicular development and ovulation. cAMP produced by the granulosa cells will pass into the cardiac cells and cause them to contract.

b) The cAMP from granulose cells is transferred to cardiac cells through gap junctions that are formed between the two cell types. Gap junction creates a contact between the two cells. There is no direct or indirect fusion. Small molecules such as cAMP can easily pass through the gap junctions.

c) Co-culture cardiomyocytes with granulose cells, treat with FSH, perform time-lapse experiment for development of intracellular connection (cells come closer), and confirm with western blot for increased gap junction proteins (connexins) and transmission electron microscopy.

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