Modulation of secreted proteins of mouse mammary epithelial cells by the collagenous substrata
It has been shown previously that cultures of mouse mammary epithelial cells retain their characteristic morphology and their ability to produce ..gamma..-casein, a member of the casein gene family, only if they are maintained on floating collagen gels. In this paper we show: (a) Cells on floating collagen gels secrete not only ..gamma..-casein but also ..cap alpha../sub 1/-, ..cap alpha../sub 2/-, and ..beta..-caseins. These are not secreted by cells on plastic and are secreted to only a very limited extent by cells on attached collagen gels. (b) The floating collagen gel regulates at the level of synthesis and/or stabilization of the caseins rather than at the level of secretion alone. Contraction of the floating gel is important in that cells cultured on floating glutaraldehyde cross-linked gels do not secrete any of the caseins. (c) The secretion of an 80,000-mol-wt protein, most probably transferrin, and a 67,000-mol-wt protein, probably butyrophilin, a major protein of the milk fat globule membrane, are partially modulated by substrata. However, in contrast to the caseins, these are always detectable in media from cells cultured on plastic and attached gels. (d) Whey acidic protein, a major whey protein, is actively secreted by freshly isolated cells but is secreted in extremely limited quantities in cultured cells regardless of the nature of the substratum used. Lactalbumin secretion is also decreased significantly in cultured cells. (e) A previously unreported set of proteins, which may be minor milk proteins, are prominently secreted by the mammary cells on all substrata tested. We conclude that while the substratum profoundly influences the secretion of the caseins, it does not regulate the expression of every milk-specific protein in the same way. The mechanistic implications of these findings are discussed.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5906222
- Journal Information:
- J. Cell Biol.; (United States), Vol. 98:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PROTEINS
BIOSYNTHESIS
ALBUMINS
BIOCHEMISTRY
CELL CULTURES
COLLAGEN
CULTURE MEDIA
CYTOLOGICAL TECHNIQUES
EPITHELIUM
MAMMARY GLANDS
MICE
MILK
SUBSTRATES
TRANSFERRIN
WHEY
ANIMAL TISSUES
ANIMALS
BIOLOGICAL MATERIALS
BODY
BODY FLUIDS
CHEMISTRY
FOOD
GLANDS
GLOBULINS
GLOBULINS-BETA
INDUSTRIAL WASTES
MAMMALS
MATERIALS
METALLOPROTEINS
ORGANIC COMPOUNDS
ORGANS
RODENTS
SCLEROPROTEINS
SYNTHESIS
TISSUES
VERTEBRATES
WASTES
550300* - Cytology
550200 - Biochemistry