“Sonic hedgehog requires interactions with proteoglycans to achieve cell proliferation, but not tissue patterning”

What the heck does this mean?  It means an additional jigsaw-puzzle piece of knowledge relevant to the 14^th theory of aging in my Anti-Aging Firewalls treatise, which is Decline in Adult Stem Cell Differentiation.  In this instance Sonic hedgehog (Shh) is not a video game character but is a protein in the hedgehog family named after that videogame character. Shh plays an important role in the division of stem cells and in the formation of organs.  Cell proliferation during development and tissue patterning are in part controlled by the hedgehog pathway and Shh is implicated in the organization of human tissues including the brain.  Proteoglycans are heavily glycosylated glycopoteins which, roughly put, are a class of proteins that have a lot of sugar side chains.  Chondroitin sulphate is a proteoglycan which is an important structural component of cartilage and is also a dietary supplement commonly used to ward off osteoarthritis.  The quoted headline for this posting is from a recent report on research that indicates that Shh contains a proteoglycan-binding domain and that during neural development Shh-proteoglycan interactions regulate tissue growth. If Shh is to induce cell proliferation there apparently must be proteoglycan interactions involved.  However, without additional provisions for proper tissue patterning the proliferation may be without proper cell differentiation, a characteristic of oncogenesis.  What does this mean for longevity?  We don’t exactly know yet. That will depend on how this piece of the jigsaw puzzle fits in with a lot of other pieces to define a pattern that leads eventually to some kind of effective anti-aging intervention. 

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