Insulin receptors mediate growth effects in cultured fetal neurons. I. Rapid stimulation of protein synthesis
- Univ. of California-San Diego, La Jolla (USA)
In this study we have examined the effects of insulin on protein synthesis in cultured fetal chick neurons. Protein synthesis was monitored by measuring the incorporation of (3H)leucine (3H-leu) into trichloroacetic acid (TCA)-precipitable protein. Upon addition of 3H-leu, there was a 5-min lag before radioactivity occurred in protein. During this period cell-associated radioactivity reached equilibrium and was totally recovered in the TCA-soluble fraction. After 5 min, the incorporation of 3H-leu into protein was linear for 2 h and was inhibited (98%) by the inclusion of 10 micrograms/ml cycloheximide. After 24 h of serum deprivation, insulin increased 3H-leu incorporation into protein by approximately 2-fold. The stimulation of protein synthesis by insulin was dose dependent (ED50 = 70 pM) and seen within 30 min. Proinsulin was approximately 10-fold less potent than insulin on a molar basis in stimulating neuronal protein synthesis. Insulin had no effect on the TCA-soluble fraction of 3H-leu at any time and did not influence the uptake of (3H)aminoisobutyric acid into neurons. The isotope ratio of 3H-leu/14C-leu in the leucyl tRNA pool was the same in control and insulin-treated neurons. Analysis of newly synthesized proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that insulin uniformly increased the incorporation of 14C-leu into all of the resolved neuronal proteins. We conclude from these data that (1) insulin rapidly stimulates overall protein synthesis in fetal neurons independent of amino acid uptake and aminoacyl tRNA precursor pools; (2) stimulation of protein synthesis is mediated by the brain subtype of insulin receptor; and (3) insulin is potentially an important in vivo growth factor for fetal central nervous system neurons.
- OSTI ID:
- 5478776
- Journal Information:
- Endocrinology; (USA), Vol. 125:3; ISSN 0013-7227
- Country of Publication:
- United States
- Language:
- English
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INSULIN
RECEPTORS
NERVE CELLS
CELL DIVISION
PROTEINS
BIOSYNTHESIS
AMINO ACIDS
BRAIN
CARBON 14 COMPOUNDS
CELL CULTURES
CHICKENS
CYCLOHEXIMIDE
DOSE-RESPONSE RELATIONSHIPS
EMBRYOS
LEUCINE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMAL CELLS
ANIMALS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
BIRDS
BODY
CARBOXYLIC ACIDS
CENTRAL NERVOUS SYSTEM
DRUGS
FOWL
FUNGICIDES
HORMONES
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MEMBRANE PROTEINS
NERVOUS SYSTEM
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PESTICIDES
SOMATIC CELLS
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques