{"id":231747,"date":"2026-02-20T21:21:06","date_gmt":"2026-02-21T03:21:06","guid":{"rendered":"https:\/\/lifeboat.com\/blog\/2026\/02\/a-pi3k%ce%b4-foxo1-fasl-signaling-amplification-loop-rewires-cd4-t-cell-signaling-and-differentiation"},"modified":"2026-02-20T21:21:06","modified_gmt":"2026-02-21T03:21:06","slug":"a-pi3k%ce%b4-foxo1-fasl-signaling-amplification-loop-rewires-cd4-t-cell-signaling-and-differentiation","status":"publish","type":"post","link":"https:\/\/lifeboat.com\/blog\/2026\/02\/a-pi3k%ce%b4-foxo1-fasl-signaling-amplification-loop-rewires-cd4-t-cell-signaling-and-differentiation","title":{"rendered":"A PI3K\u03b4-Foxo1-FasL signaling amplification loop rewires CD4+ T cell signaling and differentiation"},"content":{"rendered":"<p style=\"padding-right: 20px\"><a class=\"aligncenter blog-photo\" href=\"https:\/\/lifeboat.com\/blog.images\/a-pi3kceb4-foxo1-fasl-signaling-amplification-loop-rewires-cd4-t-cell-signaling-and-differentiation.gif\"><\/a><\/p>\n<p>Dominic P. Golec, Pamela L. Schwartzberg and colleagues (National Institute of Allergy and Infectious Diseases (NIAID)) describe a PI3 Kinase-Foxo1-FasL signaling circuit that promotes amplified signaling and rewires transcriptional and epigenetic programs driving IFN-\u03b3 and altered T helper cell differentiation in CD4+ T cells from mice expressing an activating mutant of phosphoinositide 3-kinase delta.<\/p>\n<p>Immunodeficiency LymphocyteBiology<\/p>\n<hr>\n<p>While inputs regulating CD4<sup>+<\/sup> T helper (Th) cell differentiation are well defined, the integration of downstream signaling with transcriptional and epigenetic programs that define Th lineage identity remains incompletely resolved. PI3K signaling is a critical regulator of T cell function; activating mutations affecting PI3K\u03b4 result in an immunodeficiency with multiple T cell defects. Using mice expressing activated PI3K\u03b4, we found aberrant expression of proinflammatory Th1 signature genes under Th2-inducing conditions, both <em>in vivo<\/em> and <em>in vitro<\/em>. This dysregulation was driven by a PI3K\u03b4-IL-2-Foxo1 signaling amplification loop, fueling Foxo1 inactivation, loss of Th2 lineage restriction, and extensive epigenetic reprogramming. Surprisingly, ablation of <em>Fasl<\/em>, a Foxo1-repressed gene, normalized both Th2 differentiation and TCR signaling. BioID and imaging revealed Fas interactions with TCR signaling components, which were supported by Fas-mediated potentiation of TCR signaling that could occur in the absence of FADD. Our results highlight Fas-FasL signaling as a critical intermediate in phenotypes driven by activated PI3K\u03b4, thereby linking two key pathways of immune dysregulation.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Dominic P. Golec, Pamela L. Schwartzberg and colleagues (National Institute of Allergy and Infectious Diseases (NIAID)) describe a PI3 Kinase-Foxo1-FasL signaling circuit that promotes amplified signaling and rewires transcriptional and epigenetic programs driving IFN-\u03b3 and altered T helper cell differentiation in CD4+ T cells from mice expressing an activating mutant of phosphoinositide 3-kinase delta. Immunodeficiency [\u2026]<\/p>\n","protected":false},"author":662,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11,412],"tags":[],"class_list":["post-231747","post","type-post","status-publish","format-standard","hentry","category-biotech-medical","category-genetics"],"_links":{"self":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/231747","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/users\/662"}],"replies":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/comments?post=231747"}],"version-history":[{"count":0,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/231747\/revisions"}],"wp:attachment":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/media?parent=231747"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/categories?post=231747"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/tags?post=231747"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}