The RT6 system of the rat: developmental, molecular and functional aspects

• Published in: Immunological reviews 2001-12, Vol.184 (1), p.96-108
• Main Authors: Thiele, Heinz-Günter, Haag, Friedrich
• Format: Article
• Language: English
• Subjects: ADP Ribose Transferases - chemistry; ADP Ribose Transferases - genetics; ADP Ribose Transferases - immunology; Animals; Antigens, Differentiation, T-Lymphocyte; GPI-Linked Proteins; Humans; Membrane Glycoproteins - chemistry; Membrane Glycoproteins - genetics; Membrane Glycoproteins - immunology; Rats
• ISSN: 0105-2896; 1600-065X
• DOI: 10.1034/j.1600-065x.2001.1840109.x

RT6 is a developmentally regulated cell‐surface membrane adenosine 5′‐diphosphate‐ribosyltransferase/nicotinamide adenine dinucleotide‐glycohydrolase inserted within the membrane by a glycophosphatidylinositol anchor. In the rat it is restricted to mature T lymphocytes and a subpopulation of natural killer cells. With respect to the data now available, three aspects concerning the function of RT6 are discussed: first, the meaning of the marked polymorphisms; second, its enzymatic activity; third, its possible role concerning T‐cell survival. The observation that the rat RT6 gene contains two transcription start sites suggests their different use by distinct subpopulations of T cells. The fact that the expression of RT6 is defective in lymphopenic diabetes prone (DP‐BB) rats, although the RT6 gene is structurally not grossly altered in these animals, makes this rat strain a promising model to study the biological meaning of RT6. While it mostly is believed that the RT6 expression defect of the DP‐BB rat is a consequence of the lymphopenia, the present paper discusses the possibility that the RT6 expression defect is causally involved in the lymphopenia, and that a normal expression of RT6 may protect the recent thymic emigrants from apoptosis.