Question

what is the function of HSPGs in the stem cell niche in your own words

Answer 1

HSPG full form is Heparan Sulphate ProteoGlycans are the transmembrane proteins which help in tissue development and repair . They occur as cell surface components, in extracellular Matrix and as basement membrane.They have a aminoacid composition of serine, glycine, aspartic acid and glutamic acid.

Stem cell Niche:

Cell niche is defined as the local physiological microenvironment helping the cell and driving externally from outside the cell which is composed of extracellular matrix (ECM) components for attachment, diffusible biomolecules for cell signalling, cell surface ligands for signal transduction and for cell cell interactions. Stem cells are undifferentiated embryonic or adult cells which can self renew and possess the capacity to produce a full organism from a fertilized egg. The components of stem cell niche are extracellular matrix, neighbouring cells, cell signalling factors such as growth factors and cytokines, physical parameters, environmental signals of metabolites, etc.,

HSPG in stem cells niche:

• Proteoglycan such as Heparan Sulfate Proteo Glycan along with others such as Chondroitin sulfate proteoglycans, Derman sulfate proteoglycans help in signal transduction in brain.
• They facilitate the binding of FGF -2 (Fibroblast Growth Factor) to cognate receptors and help in promoting precursor cell proliferation in neurogenic niche.
• The growth factors such as BMPs (Bone Morphogenetic Proteins), PDGF (Platelet Derived Growth Factor), VEGF (Vascular Endothelial Growth Factor) function through HSPG.
• HSPG along with fractones helps in Neurogenesis.
• Fractones with HSPG helps in binding and subsequent signalling of the growth factor HGF -2 (Hepatocyte Growth Factor)
• In Hematopoeitic stem cells the Proteoglycan help in cell signalling