Expression pattern, subcellular localization and structure--function relationship of rat Tpx-1, a spermatogenic cell adhesion molecule responsible for association with Sertoli cells.
The gene for a testicular cell adhesion protein called Tpx-1, which mediates the binding of spermatogenic cells to Sertoli cells of the rat in primary culture, was previously cloned. Here the characterization of Tpx-1 is reported. Tpx-1 messenger ribonucleic acid (mRNA) became detectable in pachytene spermatocytes and continued to be present throughout development into elongated spermatids, while the amount of Tpx-1 protein seemed to increase some time after the increment of mRNA. Tpx-1 protein was also present, although less abundantly, in spermatozoa prepared from the epididymis. Tpx-1 contains a cluster of hydrophobic amino acid residues near the amino terminus and a cysteine-rich region in the carboxyl-terminal half. Tpx-1 fused with green fluorescence protein was secreted into the medium when expressed in a cultured cell line, depending on the presence of the amino-terminal hydrophobic region. Moreover, Tpx-1 was present in the medium of testicular cell primary culture. Structure-function analysis revealed that the amino-terminal 101 amino acid residues were sufficient for cell adhesion activity, whereas the carboxyl-terminal cysteine-rich region was dispensable. In conclusion, Tpx-1 is produced and secreted from spermatogenic cells at various differentiation stages, and mediates the interaction of those cells with Sertoli cells.
Maeda
T
T
Faculty of Pharmaceutical Sciences, Kanazawa University, Takara-machi, Ishikawa, Japan.
Nishida
J
J
Nakanishi
Y
Y
D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics*; D002454:Cell Differentiation; D002478:Cells, Cultured; D018507:Gene Expression Regulation, Developmental; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D049452:Green Fluorescent Proteins; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008164:Luminescent Proteins; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D012708:Sertoli Cells / Q000378:metabolism*; D013087:Spermatids / Q000378:metabolism; D013090:Spermatocytes / Q000378:metabolism; D013091:Spermatogenesis / Q000235:genetics; D013329:Structure-Activity Relationship
C062790:CRISP2 protein, rat; D015815:Cell Adhesion Molecules; D006023:Glycoproteins; D008164:Luminescent Proteins; D012333:RNA, Messenger; D049452:Green Fluorescent Proteins