Extracellular matrix protein expression during mouse detrusor development.
OBJECTIVE
Extracellular matrix proteins are implicated in regulating cell proliferation and differentiation. The authors systematically analysed the expression of elastin; collagen types I, III, IV; laminin; and fibronectin during mouse detrusor muscle development, a period during which downregulation of detrusor proliferation and increasing smooth muscle differentiation is known to occur.


METHODS
Embryonic days 14 (E14) and 18 (E18), and postnatal day 1 (D1) and week 6 (6wk) were examined, a period spanning the inception of the bladder to postnatal maturity. Immunohistochemistry of whole bladders was used to immunolocalise protein expression, and Western blot of dissected detrusor layers was used to semiquantify soluble protein expression.


RESULTS
All proteins were detected at all 4 stages. Statistically significant increases were documented for elastin (E14 to 6wk), collagen type I (E18 to 6wk), collagen type III (D1 to 6wk) and laminin (E14 to 6wk). Fibronectin levels were relatively high up to D1, after which levels declined significantly. Collagen type IV levels decreased significantly (E18 to 6wk).


CONCLUSIONS
The authors postulate that changing levels of laminin and fibronectin have opposing effects on the transition from proliferating primitive mesenchymal cells to differentiated detrusor muscle. Furthermore, changes in collagen type III and elastin may be important for bladder compliance.
Smeulders
N
N
Nephro-Urology Unit, Institute of Child Health, University College London, London, England.
Woolf
A S
AS
Wilcox
D T
DT
D000818:Animals; D000831:Animals, Newborn; D001391:Azo Compounds / Q000378:metabolism; D015153:Blotting, Western; D004801:Eosine Yellowish-(YS) / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis*; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D008739:Methyl Green / Q000378:metabolism; D051379:Mice; D009092:Mucous Membrane / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D024510:Muscle Development / Q000502:physiology*; D009130:Muscle, Smooth / Q000098:blood supply / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism*; D012727:Sex Characteristics; D001743:Urinary Bladder / Q000098:blood supply / Q000196:embryology / Q000254:growth & development / Q000502:physiology; D019459:Urothelium / Q000196:embryology / Q000254:growth & development / Q000378:metabolism
D001391:Azo Compounds; D016326:Extracellular Matrix Proteins; C017768:trichrome stain; D008739:Methyl Green; D004801:Eosine Yellowish-(YS)