ISSN:
0886-1544
Keywords:
chondrocytes
;
matrix vesicle formation
;
actin
;
tubulin
;
myosin
;
vinculin
;
alkaline phosphatase
;
immunofluorescence
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Matrix vesicles, extracellular microstructures known to eb involved in endochondral calcification, are rich in alkaline phosphatase and have been shown to contain actin. The mechanism of matrix vesicle formation in chondrocytes in not well understood. Chondrocytes from the epiphyseal growth plate, when grown in primary culture, elaborate alkaline phosphatase-rich vesciles. We examined the distribution of the cytoskeletal proteins actin, myosin, tubulin, and vinculin at various time-points during culture using indirect immunofluorescent labeling. Concomitantly, the production of alkaline phosphatase-containing matrix vesicles was also followed. Cell morphology changed noticeably at two distinct stages during the 22-day culture period: Immediately after release from the growth plate the cells were founded, but after 4 days of cultre they began to spread out and acquire irregular shapes with distinct filopodia. By 13 datsm as tge cekks attaubed confluency, they reacquired a rounded, polygonal appearance. At all time-point, tubulin was seen as a dense network of microtubules radiating from the perinuclear region throughout the cytoplasm toward the cell periphery. Initially actin was seen in filamentous from, but displayed a punctate distribution focused at contact points during the cell-spreading stage of culture. After confluency, actin was concentrated at cell-cell junctions. Initially, vinculin was diffusely distributed, but became focused in multiple adhesion plaques and at the termini of filpodia during the cell-spreading stage of culture. Following confluency vinculin became concentrated at cell-cell junctions. Myosin was observed at all time-points in small, intensely localized focal points in the cytoplasmic region of the cells and was consistently absent from the nuclear and peripheral regions. The amount of myosin in the cells increased steadily with time in culture. Elaboration of alkaline phosphatase-rich vesicles, which corresponded closely with the rounded morphology of early and late stages of culture, may be correlated with contact inhibition.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cm.970030517
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