biostudies-literatureHoelbl AAustrian Science Fund FWF4898-906https://www.ebi.ac.uk/biostudies/studies/S-EPMC2875852biostudies-literatureUnknown107(12)The Stat5 transcription factors Stat5a and Stat5b have been implicated in lymphoid development and transformation. Most studies have employed Stat5a/b-deficient mice where gene targeting disrupted the first protein-coding exon, resulting in the expression of N-terminally truncated forms of Stat5a/b (Stat5a/b(DeltaN/DeltaN) mice). We have now reanalyzed lymphoid development in Stat5a/b(null/null) mice having a complete deletion of the Stat5a/b gene locus. The few surviving Stat5a/b(null/null) mice lacked CD8(+) T lymphocytes. A massive reduction of CD8(+) T cells was also found in Stat5a/b(fl/fl) lck-cre transgenic animals. While gammadelta T-cell receptor-positive (gammadeltaTCR(+)) cells were expressed at normal levels in Stat5a/b(DeltaN/DeltaN) mice, they were completely absent in Stat5aBloodClarifying the role of Stat5 in lymphoid development and Abelson-induced transformation.PMC2875852F 2810F 2810-B20F 2807-B20F 2807F 2802-B20F 2801F 2802F 2801-B20Hennighausen LMoriggl RSexl VCui YHoelbl AKovacic BBeug HWarsch WKerenyi MASimma OfalseClarifying the role of Stat5 in lymphoid development and Abelson-induced transformation.The Stat5 transcription factors Stat5a and Stat5b have been implicated in lymphoid development and transformation. Most studies have employed Stat5a/b-deficient mice where gene targeting disrupted the first protein-coding exon, resulting in the expression of N-terminally truncated forms of Stat5a/b (Stat5a/b(DeltaN/DeltaN) mice). We have now reanalyzed lymphoid development in Stat5a/b(null/null) mice having a complete deletion of the Stat5a/b gene locus. The few surviving Stat5a/b(null/null) mice lacked CD8(+) T lymphocytes. A massive reduction of CD8(+) T cells was also found in Stat5a/b(fl/fl) lck-cre transgenic animals. While gammadelta T-cell receptor-positive (gammadeltaTCR(+)) cells were expressed at normal levels in Stat5a/b(DeltaN/DeltaN) mice, they were completely absent in Stat5a2006-01-01T00:00:00Z2006 Jun2025-06-01T12:33:21.332Z2025-06-01T12:33:21.332ZS-EPMC28758521649300810.1182/blood-2005-09-3596