BSP & osteoponton Flashcards
What are two types of bones?
Hard cortical bone
spongy cancellous bone
Cancellous bone composition
25% organic
- 90% collagen I and V
- 10% other stuff
70% hydroxyapatite
5% water
what is ceramic?
an inorganic compound that is heated and cooled quickly
what is bioceramic? example?
a biocompatible ceramic
calcium hydroxyapatite
Do osteoblasts and osteoclasts come from the same progenitor stem cells?
no.
osteoblasts < mesenchymal SC
osteoclasts < hematopoietic SC
What do Osteoblasts become after mineralization?
osteocytes
(commitment) Mesenchymal progenitor > osteo-progenitor. Which signals?
BMP, runx, wnt
(proliferation) Osteo-progenitor > Immature osteoblast. Which signals?
runx, osterix
(mature matrix) immature osteoblats > osteoblats. Which signals?
BSP, alkaline phosphatase, collagen I
What is the matrix produced around osteoblasts called and what happens to it
osteoid and it gets mineralized
What fits in the gaps of the spongy bones?
bone marrow
What is the formula for hydroxyapatite
Ca10 (PO4)6 (OH)2
What are two of the important non-collagenous proteins that bind to hydroxyapatite?
BSP (bone sialoprotein)
OPN (Osteopontin)
What are some characterists similar and different between BSP and OPN?
similarities
- binds to hydroxyapatite
- binds to RGD integrins
- highly phosphorylated
Differences
- BSP: 2-3 glutamic motif
- BSP is more tissue specific
- BSP is highly sulfated too
- BSP has high sialic acid content
- OPN: polyaspartic motif
- OPN is broad tissue specific
What are some characterists similar and different between BSP and OPN?
similarities
- binds to hydroxyapatite
- binds to RGD integrins
- highly phosphorylated
Differences
- BSP: 2-3 glutamic motif
- BSP is more tissue specific
- BSP is highly sulfated too
- BSP has high sialic acid content
- OPN: polyaspartic motif
- OPN is broad tissue specific
What are some characterists similar and different between BSP and OPN?
similarities
- binds to hydroxyapatite
- binds to RGD integrins
- highly phosphorylated
Differences
- BSP: 2-3 glutamic motif
- BSP is more tissue specific
- BSP is highly sulfated too
- BSP has high sialic acid content
- OPN: polyaspartic motif
- OPN is broad tissue specific
Which proteins are expressed during the differentiation phase?
Alkaline Phosphatase
BSP (also early mineralization)
Which proteins are expressed during the Mineralization phase?
OPN
SPARC (always)
Draw a western blot for termporal expression of all protein
haha
Where are early crystals formed?
What are these crystals made of?
What promotes this growth?
in the collagen hole zones
hydroxyapatite crystals
BSP
vesicles (w/ alkaline phosphatase and nucleotide
pyrophosphatase/phosphodiesterase, Annexin)
What are the main places the vesicles start minerlizing?
osteoid
cartiliage
dentin
What brings in calcium in the vesicles?
annexin
What brings in phosphate in the vesicles?
Type III Na dependent transporters
What do MMPs do inside vesicles?
growth factor activation
Which molecule facilitates the transport of crystals to the collagen?
annexin transporters bind Ca2+ and collagen and does this
KO of which gene would cause no osteoblast differntiation in the endochondral and intramembranous skeleton?
Runx
In Runx/Cbfa-1 null mice, osteoblast differentiation
Is arrested in?
endochondral and intramembranous skeleton
osterix contains which motif?
zinc finger
without which transcription factor, no mineralization is shown?
osterix
What reabsorbs bone? What is its precursor?
osteoclasts.
myeloid progenitor
What is needed for osteoclasts to form instead of macrophages?
RANKL on osteoblasts
What happens to osteoclasts after their work?
apoptosis
How do osteoclasts bind to bone?
OPN and integrin avb3
How is the mineral dissolved?
By forming a ruffled ring with actin where proton is pimped lower ph. dissolving the mineral in lacuna.
Matrix-GLA-protein (MGP) KO characteristic?
What else shows this result?
How to know if the effects are actually from MGP
mineralization of the arteries
OPN -/-
bring back KO gene
How to stain for phosphate?
Van Kossa stain
photochemical reaction in which silver ions react with phosphate (not calcium)
in the Presence of acidic materials.
How to stain for calcium?
alizarin red