Cortactin (CTTN), N-WASP (WASL), and clathrin (CLTC) are present at podosome-like tubulobulbar complexes in the rat testis.
Tubulobulbar complexes are actin filament-rich plasma membrane protrusions that form at intercellular junctions in the seminiferous epithelium of the mammalian testis. They are proposed to internalize intact junctions during sperm release and during the translocation of spermatocytes through basal junction complexes between neighboring Sertoli cells. Tubulobulbar complexes morphologically resemble podosomes found at cell/substrate attachments in other systems. In this study we probe apical tubulobulbar complexes in fixed epithelial fragments and fixed frozen sections of rat testis for two key actin-related components found at podosomes, and for the endocytosis-related protein clathrin. N-WASP and cortactin, two regulators of actin network assembly known to be components of podosomes, are concentrated at tubulobulbar complexes. Clathrin-positive structures occur in Sertoli cell regions containing tubulobulbar complexes when analyzed by immunofluorescence microscopy and occur at the ends of the complexes when evaluated by immunoelectron microscopy. Our results are consistent with the conclusion that tubulobulbar complexes are podosome-like structures. We propose that the formation of tubulobulbar complexes may be clathrin initiated and that their growth is due to the dendritic assembly of a membrane-related actin network.
Young
J'Nelle S
JS
Department of Cellular and Physiological Sciences, Faculty of Medicine, Life Sciences Centre, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.
Guttman
Julian A
JA
Vaid
Kuljeet S
KS
Shahinian
Hasmik
H
Vogl
A Wayne
AW
D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism*; D002966:Clathrin / Q000378:metabolism*; D058966:Contactins; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D008858:Microscopy, Phase-Contrast; D051381:Rats; D017207:Rats, Sprague-Dawley; D012670:Seminiferous Epithelium / Q000378:metabolism* / Q000648:ultrastructure; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal / Q000378:metabolism*
D015816:Cell Adhesion Molecules, Neuronal; D002966:Clathrin; D058966:Contactins; C495770:Wasl protein, rat; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal