Characterization of the collagens synthesized by Chinese hamster ovary cells: effect of colcemid and dibutyryl adenosine cyclic monophosphate

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Abstract
The collagens synthesized by Chinese hamster ovary cells were isolated and characterized. Although these cells produce very small amounts of collagen, at least 5 distinct collagenous chains could be identified from radiolabeled media and cell extracts after limited pepsin digestion. Two chains were characterized as .alpha.1(V) and .alpha.2(V), based on electrophoretic mobility, resistance to vertebrate collagenase, chromatographic properties on CM-cellulose, and cyanogen bromide patterns. Two smaller collagenous proteins (MW 34,000 and 37,000) were also isolated by CM cellulose chromatography and characterized by cyanogen bromide digestion patterns. These collagens showed similarities to type IV collagen fragments but may be unique to Chinese hamster ovary cells. A colcemid resistant mutant of Chinese hamster ovary cells designated CMR795 synthesized the same collagen chains but in different proportions. In the wild-type cells colcemid (0.05-0.1 .mu.g/ml) reduced the amount of type V collagen in the culture media but had little effect on the other collagen type, whereas the type V collagen reduction was less pronounced in the CMR795 cells treated with the same concentrations of colcemid. DibutyrylcAMP caused a fibroblast-like reverse transformation of the Chinese hamster ovary cells similar to that described previously. Collagen synthesis was increased only slightly. No apparent alteration in the types of collagens synthesized was detected.