PMID- 3768460
OWN - NLM
STAT- MEDLINE
DCOM- 19861202
LR  - 20190511
IS  - 0006-3363 (Print)
IS  - 0006-3363 (Linking)
VI  - 35
IP  - 2
DP  - 1986 Sep
TI  - Receptor-mediated endocytosis of transferrin by Sertoli cells of the rat.
PG  - 393-405
AB  - Binding of 125I-transferrin (125I-Tf) to the plasma membrane of Sertoli cells and 
      its endocytosis were analyzed by means of light- and electron-microscope 
      quantitative radioautography. Five minutes after 125I-Tf was injected into the 
      interstitial space of the testis, a strong labeling of the basal aspect of the 
      seminiferous epithelium was observed in light-microscope radioautographs. 
      Injection of the same dose of 125I-Tf plus a 200-fold excess of cold transferrin 
      resulted in a marked diminution of the radioautographic reaction, indicating that 
      the initial strong labeling with radiolabeled transferrin was specific. These 
      results were consistent with the localization of immunoreactive fluorescence of 
      transferrin receptor at the base of the seminiferous epithelium. In 
      electron-microscope radioautographs of tubules collected at 5 min after 
      injection, the membrane of Sertoli cells facing the basement membrane was well 
      labeled with 125I-Tf. At 15 and 30 min, the plasma membrane was less intensely 
      labeled, but the silver grains were then seen overlying multivesicular bodies 
      with an electron-lucent matrix, identified as endosomes. This population of 
      endosomes was always seen at a short distance from the basal membrane of Sertoli 
      cells. At 90 min, no more labeling of the plasma membrane, endosomes, or any 
      other cytoplasmic component was observed. Isolated seminiferous tubules and 
      Sertoli cells labeled with 125I-Tf at 4 degrees C were rinsed and reincubated in 
      a label-free medium at 37 degrees C for various periods of time from 5 to 90 min. 
      A radioactive protein precipitated by trichloroacetic acid, presumably intact 
      transferrin, was released from the tubules into the incubating medium; when 
      measured, it was found to increase rapidly from 5 to 45 min and stabilize 
      thereafter. These results suggest that transferrin was internalized by 
      receptor-mediated endocytosis, reached endosomes, and then was released to the 
      extratubular space. When native ferritin (NF), a tracer for fluid-phase 
      endocytosis, was infused within the lumen of seminiferous tubules and 125I-Tf was 
      simultaneously injected into the interstitial space, both markers rapidly reached 
      different populations of endosomes. Endosomes labeled with NF, scattered 
      throughout the cytoplasm, evolved with time into dense multivesicular bodies and 
      secondary lysosomes, whereas radiolabeled transferrin reached only the endosomes 
      located in the basal cytoplasm of Sertoli cells. The latter thus appeared to be 
      principally involved in the uptake and recycling of transferrin.
FAU - Morales, C
AU  - Morales C
FAU - Clermont, Y
AU  - Clermont Y
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Biol Reprod
JT  - Biology of reproduction
JID - 0207224
RN  - 0 (Receptors, Transferrin)
RN  - 0 (Transferrin)
SB  - IM
MH  - Animals
MH  - Autoradiography
MH  - Cell Membrane/metabolism
MH  - *Endocytosis
MH  - In Vitro Techniques
MH  - Male
MH  - Microscopy, Electron
MH  - Rats
MH  - Receptors, Transferrin/*physiology
MH  - Sertoli Cells/*physiology/ultrastructure
MH  - Transferrin/*metabolism
EDAT- 1986/09/01 00:00
MHDA- 1986/09/01 00:01
CRDT- 1986/09/01 00:00
PHST- 1986/09/01 00:00 [pubmed]
PHST- 1986/09/01 00:01 [medline]
PHST- 1986/09/01 00:00 [entrez]
AID - 10.1095/biolreprod35.2.393 [doi]
PST - ppublish
SO  - Biol Reprod. 1986 Sep;35(2):393-405. doi: 10.1095/biolreprod35.2.393.