Ultrastructural evidence for the accumulation of insulin in nuclei of intact 3T3-L1 adipocytes by an insulin-receptor mediated process

Journal Article · Thu Jan 01 04:00:00 EST 1987 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.84.2.459· OSTI ID:6216138

Smith, R M; Jarett, L

Monomeric ferritin-labeled insulin (F/sub m/-Ins), a biologically active, electron-dense marker of occupied insulin receptors, was used to characterize the internalization of insulin in 3T3-L1 adipocytes. F/sub m/-Ins bound specifically to insulin receptors and was internalized in a time- and temperature-dependent manner. In the nucleus, several F/sub m/-Ins particles usually were found in the same general location-near nuclear pores, associated with the periphery of the condensed chromatin. Addition of a 250-fold excess of unlabeled insulin or incubation at 15/sup 0/C reduced the number of F/sub m/-Ins particles found in nuclei after 90 min by 99% or 92%, respectively. Nuclear accumulation of unlabeled ferritin was only 2% of that found with F/sub m/-Ins after 90 min at 37/sup 0/C. Biochemical experiments utilizing /sup 125/I-labeled insulin and subcellular fractionation indicated that intact 3T3-L1 adipocytes internalized insulin rapidly and that approx. = 3% of the internalized ligand accumulated in nuclei after 1 hr. These data provide biochemical and high-resolution ultrastructural evidence that 3T3-L1 adipocytes accumulate potentially significant amounts of insulin in nuclei by an insulin receptor-mediated process. The transport of insulin or the insulin-receptor complex to nuclei in this cell or in others may be directly involved in the long-term biological effects of insulin - in particular, in the control of DNA and RNA synthesis.

• Research Organization: Univ. of Pennsylvania, Philadelphia
• OSTI ID: 6216138
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 84:2; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550301* -- Cytology-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADIPOSE TISSUE
ANIMAL CELLS
ANIMAL TISSUES
BETA DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
CELL NUCLEI
CONNECTIVE TISSUE
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELECTRON MICROSCOPY
FAT CELLS
HORMONES
INSULIN
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
LABELLED COMPOUNDS
MEMBRANE PROTEINS
MICROSCOPY
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PROTEINS
RADIOISOTOPES
RECEPTORS
SOMATIC CELLS
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
TISSUES
TRANSMISSION ELECTRON MICROSCOPY
UPTAKE