Ch 23 Connective Tissue

• adipocytes
• chondrocytes
• osteocytes
• myoblasts

cells secrete ECM to make themselves feel happy; information is passed to adjacent cells and knows it has friends around

chondrocytes secrete matrix that has a lot of collagen type II

ECM population and connections with adjacent cells= comfortable chondrocytes

• 1) not change media
• 2) not give nutrients
• 3) change pH
• 4) make them very scarce on the plate

they begin secreting collagen type I (an earlier cell type)

• giant droplet of fat surrounded by a thin membrane
• Prior to pre-adipocyte, they were mesenchymal cells

stem cell--> fibroblasts (which can become other things)--> pre-ad--> adipocytes

Begin with mesenchymal cell--proliferation and determination--> preadipocyte--prolif and differen--> immature multiocular adipocytes--hypertrophy--> adipocyte

Pref-1 (p21 is a factor as well)

belongs to the Notch/Delta/Serrate family of epidermal growth factor-like repeat-containing proteins

Delta is a transmembrane protein that contains internal and external domains with EGF-like repeats

it is the ligand that pairs with Notch; when in contact, they signal reactions in all

• cleavage events that turn Notch into a transcription factor protein
• Different inc ell that expresses Delta due to difference in expression

lead to different types; domain has a protease cleavage site

the first proteolytic processing step occurs within the trans Golgi network to generate the mature heterodimeric Notch receptor that is then displayed on the cell surface

The binding of Delta triggers the next two proteolytic steps: complex of Delta and the Notch subunit to which it is bound is endocytosed by the Delta-expressing cell, exposing the extracllular cleavage site in the transmembrane Notch subunit

Pref-1 highly expressed in preadipocytes--? proliferation

Differentiation leads to an inability to proliferate and no Pref-1 expression

False

not enough info or experiments to prove this

mutation in leptin causes obesity

Leptin tells you that you are full and to stop eating

Experiment: reincorporated leptin into an adenovirus and infected it with virus/ leptin circulates