Insulin retroendocytosis can occur in human monocytes without activation of receptor kinase activity

V. Trischitta, R. Scalisi, L. Benzi, M. K. Treutelar, I. D. Goldfine, M. L. Arpi, R. Vigneri

Research output: Contribution to journalArticlepeer-review


We studied, in human monocytes the fate of internalized insulin and correlated it to insulin receptor kinase activity. After 125I-insulin binding and internalization approximately 40% of the intracellular radioactivity was released by human monocytes over the following 30 min. As indicated by both 10% TCA precipitability and RP-HPLC analysis, also intact insulin, together with degradative products, was released by human monocytes indicating that insulin retroendocytosis is present in these cells. Insulin retroendocytosis was increased by the addition of 10-7 M insulin or antibody MA-10, a monoclonal antibody against the human insulin receptor. Since both insulin and MA-10 induce receptor internalization while only insulin, but not MA-10, stimulates receptor kinase activity in purified insulin receptor preparations, our findings suggest that insulin retroendocytosis may be regulated through mechanisms that are independent of receptor kinase activity. Insulin receptor internalization, instead, may play a role in the regulation of insulin retroendocytosis.

Original languageEnglish
Pages (from-to)253-258
Number of pages6
JournalDiabetes, Nutrition and Metabolism - Clinical and Experimental
Issue number4
Publication statusPublished - 1991

ASJC Scopus subject areas

  • Food Science
  • Endocrinology
  • Medicine (miscellaneous)
  • Endocrinology, Diabetes and Metabolism
  • Internal Medicine

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