MSH regulation of tyrosinase in Cloudman S-91 mouse melanoma cell cultures

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5127159

Fuller, B B

Melanocyte Stimulating Hormone (MSH) causes an increase in tyrosinase activity (O-diphenol: O/sub 2/ oxidoreductase) in Cloudman S-91 mouse melanoma cell cultures following a lag period of approximately 9 hours. Treatment of cells with 2 x 10/sup -7/M ..cap alpha..- MSH for 6 days results in a 90 fold increase in the specific activity of the enzyme. The hormone mediated increase in tyrosinase activity is dependent upon continued transcription since the enzyme induction is suppressed by either cordycepin (1..mu..g/ml) or ..cap alpha..-amanitin (10..mu..g/ml). To determine if MSH is increasing the synthesis rate of tyrosinase, cell cultures, either exposed to MSH for various times or left untreated, were pulsed with (/sup 3/H)-leucine for 4 hours and tyrosinase immunoprecipitated with an anti-tyrosinase polyclonal antiserum raised in rabbits. The immunoprecipitates were solubilized and electrophoresed on SDS polyacrylamide gels. The proteins were electroblotted to nitrocellulose and the radioactivity in the tyrosinase bands determined. These studies have shown that while tyrosinase activity in hormone-treated cells may increase 90 fold, the rate of synthesis of the enzyme increases only 3 fold at most. Immunoprecipitation analysis of equivalence points of tyrosinase from control and MSH-treated cultures suggests the presence of inactive forms of the enzyme in melanoma cell cultures. These results suggest that, in addition to stimulating tyrosinase synthesis, MSH may also promote the activation of pre-existing enzyme molecules.

• Research Organization: Univ. of Oklahoma Health Sciences Center, Oklahoma City
• OSTI ID: 5127159
• Report Number(s): CONF-8606151-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
550901 -- Pathology-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMALS
BIOLOGICAL EFFECTS
CARBOXYLIC ACIDS
CELL CULTURES
DISEASES
ELECTROPHORESIS
ENZYME ACTIVITY
ENZYMES
HORMONES
HYDROXYLASES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEUCINE
MAMMALS
MELANOMAS
MICE
NEOPLASMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
RODENTS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
TYROSINASE
VERTEBRATES