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Human keratinocytes that have not terminally differentiated synthesize laminin and fibronectin but deposit only fibronectin in the pericellular matrix
Author(s) -
Clark Richard A. F.,
Nielsen Larry D.,
Howell Samuel E.,
Folkvord Joy M.
Publication year - 1985
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240280206
Subject(s) - fibronectin , laminin , extracellular matrix , microbiology and biotechnology , secretion , matrix (chemical analysis) , chemistry , biology , biochemistry , chromatography
Abstract Fibronectin and laminin production by human keratinocytes cultured in serum‐free, low‐calcium medium without a fibroblast feeder layer were examined by several techniques. By indirect immunofluorescence, fibronectin but not laminin appeared as short radial fibrils between the cells and the substratum, and in the pericellular matrix. Synthesis of fibronectin and laminin by 7‐day keratinocyte cultures was determined by 18 hr 35 S‐methionine metabolic labeling followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography. Fibronectin accounted for 2.9% of total synthesized protein, 26.5% of fluid phase protein secretion, and 4.3% of deposited ECM protein. In contrast, only 0.1% of the total synthesized protein was laminin, little (6.3%) of this product was secreted, and none of this product was deposited in the ECM. Our results indicate that human keratinocytes under culture conditions that prevent terminal differentiation in vitro can synthesize, secrete, and deposit fibronectin in the extracellular matrix. Although these cells synthesize laminin, they secrete very little and deposit no detectable laminin in the matrix under these culture conditions. From these data we believe that fibronectin may play an important role in the interaction of epidermal cells with connective tissue matrix during wound healing or morphogenesis in in vivo situations in which the epidermis is not terminally differentiated.