The RT6 system of the rat: developmental, molecular and functional aspects.
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.
Thiele
H G
HG
University Hospital, Hamburg, Germany.
Haag
F
F
D036002:ADP Ribose Transferases / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D058851:GPI-Linked Proteins; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D051381:Rats
D000945:Antigens, Differentiation, T-Lymphocyte; D058851:GPI-Linked Proteins; D008562:Membrane Glycoproteins; D036002:ADP Ribose Transferases; C449301:ART1 protein, human; C090163:Art2b protein, rat