Proenzyme from of cathepsin L produced by thymic epithelial cells promotes proliferation of immature thymocytes in the presence of IL-1, IL-7, and anti-CD3 antibody.
A thymic epithelial cell line (TEC1-4) established from newborn mouse thymus produced a cofactor to promote proliferation of double-negative (CD4-8-) thymocytes in the presence of IL-1, IL-7, and anti-CD3 antibody. Based upon the sequence of 8 amino acid residues near the N terminal portion, the factor was identified as the mouse proenzyme form of cathepsin L which is almost identical to the rat proenzyme form of cathepsin L (95% in homology). Production of the proenzyme form of cathepsin L was confirmed in the TEC1-4 and mouse embryonic thymus by Western blotting analysis and Northern blotting analysis. Furthermore, immunohistologically, the presence of cathepsin L was observed in the epithelial cells of the subcapsular layer and around the small vessels in the thymic cortex. It has been concluded that a subpopulation of thymic cortical epithelial cells produces the proenzyme form of cathepsin L which can act as a cofactor to promote proliferation of DN immature thymocytes.
Kasai
M
M
Department of Pathology, Tokyo Metropolitan Institute of Gerontology, Japan.
Shirasawa
T
T
Kitamura
M
M
Ishido
K
K
Kominami
E
E
Hirokawa
K
K
D000595:Amino Acid Sequence; D000818:Animals; D017252:CD3 Complex / Q000502:physiology*; D056668:Cathepsin L; D002403:Cathepsins / Q000494:pharmacology*; D003546:Cysteine Endopeptidases; D010450:Endopeptidases; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000494:pharmacology; D004847:Epithelial Cells; D004848:Epithelium / Q000201:enzymology; D005260:Female; D015870:Gene Expression; D007375:Interleukin-1 / Q000494:pharmacology*; D015851:Interleukin-7 / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D016176:T-Lymphocyte Subsets / Q000166:cytology*; D013950:Thymus Gland / Q000166:cytology* / Q000201:enzymology
D017252:CD3 Complex; D004792:Enzyme Precursors; D007375:Interleukin-1; D015851:Interleukin-7; D012333:RNA, Messenger; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D056668:Cathepsin L; C534278:Ctsl protein, mouse; C534280:Ctsl protein, rat