{"id":229649,"date":"2026-01-23T01:32:33","date_gmt":"2026-01-23T07:32:33","guid":{"rendered":"https:\/\/lifeboat.com\/blog\/2026\/01\/afg3l2-couples-mitochondrial-vitamin-b12-trafficking-to-amino-acid-metabolism-to-safeguard-hematopoietic-stem-cell-homeostasis"},"modified":"2026-01-23T01:32:33","modified_gmt":"2026-01-23T07:32:33","slug":"afg3l2-couples-mitochondrial-vitamin-b12-trafficking-to-amino-acid-metabolism-to-safeguard-hematopoietic-stem-cell-homeostasis","status":"publish","type":"post","link":"https:\/\/lifeboat.com\/blog\/2026\/01\/afg3l2-couples-mitochondrial-vitamin-b12-trafficking-to-amino-acid-metabolism-to-safeguard-hematopoietic-stem-cell-homeostasis","title":{"rendered":"Afg3l2 couples mitochondrial vitamin B12 trafficking to amino acid metabolism to safeguard hematopoietic stem cell homeostasis"},"content":{"rendered":"

<\/a><\/p>\n

To identify the critical mitochondrial protease regulating HSPC homeostasis, we performed real-time PCR to examine the expression levels of various mitochondrial proteases in EPCR+<\/sup>SLAM-HSCs from mouse bone marrow (BM). Among them, the m<\/i>-AAA protease Afg3l2<\/i> was the most highly expressed (Figure S1 <\/a>A),18<\/sup><\/a> suggesting its potential significance in HSC regulation. Furthermore, we conducted a comprehensive analysis of Afg3l2<\/i> expression across the hematopoietic hierarchy by examining EPCR+<\/sup> SLAM-HSCs, SLAM-LT-HSCs, SLAM-ST-HSCs, SLAM-MPPs (multipotent progenitors), LSK (Lin-<\/sup>Sca-1+<\/sup>c-Kit+<\/sup>) cells, Lin\u2212<\/sup> cells, and mature blood cells (B cells, T cells, and myeloid cells). Our results demonstrate that Afg3l2<\/i> expression is highest in the most primitive EPCR+<\/sup>SLAM-HSC population and gradually decreases with differentiation, supporting its crucial role in hematopoietic stem cells (HSCs) (Figure S1 <\/a>B). Afg3l2<\/i> dysfunction has been linked to neurodegenerative disorders such as spinocerebellar ataxia19<\/sup><\/a>,<\/sup>20<\/sup><\/a>,<\/sup>21<\/sup><\/a>; however, its role in hematopoietic cells and its broader metabolic implications remain unexplored. To systemically investigate the function of Afg3l2<\/i> in HSPCs, we generated a conditional knockout (KO) allele of the Afg3l2<\/i> gene (Afg3l2<\/i>f\/+<\/i><\/sup>), in which exons 4 and 5 were flanked by loxP<\/i> sites (Figure S1 <\/a>C). Afg3l2<\/i>f\/+<\/i><\/sup> mice were then crossed with Mx1-Cre<\/i> transgenic mice to obtain Afg3l2<\/i>f\/f<\/i><\/sup>;Mx1-Cre<\/i><\/i>+<\/sup> animals. Deletion of Afg3l2<\/i> in hematopoietic cells was induced by administering polyinosinic-polycytidylic acid (pIpC) to 6-to 8-week-old mice, and KO efficiency was confirmed by real-time PCR and western blot analysis (Figures S1 <\/a>D\u2013S1G). On day 14 after the final pIpC administration, complete blood count analysis revealed a significant reduction in white blood cell, lymphoid cell, and platelet counts in Afg3l2<\/i>f\/f<\/i><\/sup> mice (wild-type [WT]) compared to Afg3l2<\/i>f\/f<\/i><\/sup>;Mx1-Cre<\/i><\/i>+<\/sup> mice (KO) (Figures S1 <\/a>H\u2013S1J). Interestingly, red blood cell counts and hemoglobin levels remained comparable between WT and KO groups (Figures S1 <\/a>K and S1L). Flow cytometry analysis of BM revealed a significant reduction in multiple hematopoietic populations in Afg3l2<\/i>-<\/i>KO mice, including LT-HSCs, ST-HSCs, MPPs, common myeloid progenitors, granulocytic\/monocytic progenitors, and megakaryocyte\/erythroid progenitors (Figures S1 <\/a>M\u2013S1P). Notably, the EPCR+<\/sup>SLAM-HSC population, a highly purified HSC subset, was also remarkably diminished (Figure S1 <\/a>Q).<\/p>\n

Consistently, functional colony-forming unit (CFU) assays showed that CFU-granulocyte, erythrocyte, macrophage, megakaryocyte (CFU-GEMM); CFU-granulocyte and macrophage (CFU-GM); and burst-forming unit-erythroid (BFU-E) were markedly decreased in Afg3l2<\/i>-<\/i>KO BM cells (Figures S1 <\/a>R and S1S). These findings indicate that Afg3l2<\/i> deficiency causes leukopenia and impairs steady-state hematopoiesis.<\/p>\n

To assess the in vivo<\/i> function of Afg3l2<\/i> in HSPCs, we performed competitive BM transplantation. Lethally irradiated recipient mice (CD45.1) were transplanted with a 1:1 mixture of total BM cells from WT or Afg3l2<\/i>-<\/i>KO donor mice (CD45.2) and competitor BM cells (CD45.1\/CD45.2) (Figure 1A). CD45 chimerism in peripheral blood (PB) was monitored every four weeks, and BM composition was analyzed 16 weeks post-transplantation. The percentage of donor-derived CD45.2+<\/sup> cells in PB was significantly lower in recipients receiving Afg3l2<\/i>-<\/i>KO BM compared to those transplanted with WT BM (Figures 1B and 1C). The percentage of donor BM cells-derived CD45.2+<\/sup> cells, HPCs, Lin\u2212<\/sup>Sca-1+<\/sup>c-Kit+<\/sup> (LSK) cells, HSCs, myeloid cells, B cells, and T cells was dramatically decreased in the BM of the Afg3l2<\/i>-<\/i>KO cell transplanted group 16 weeks after transplantation (Figures 1D and 1E).<\/p>\n","protected":false},"excerpt":{"rendered":"

To identify the critical mitochondrial protease regulating HSPC homeostasis, we performed real-time PCR to examine the expression levels of various mitochondrial proteases in EPCR+SLAM-HSCs from mouse bone marrow (BM). Among them, the m-AAA protease Afg3l2 was the most highly expressed (Figure S1 A),18 suggesting its potential significance in HSC regulation. Furthermore, we conducted a comprehensive [\u2026]<\/p>\n","protected":false},"author":662,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11,47],"tags":[],"class_list":["post-229649","post","type-post","status-publish","format-standard","hentry","category-biotech-medical","category-neuroscience"],"_links":{"self":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/229649","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=229649"}],"version-history":[{"count":0,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/229649\/revisions"}],"wp:attachment":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/media?parent=229649"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/categories?post=229649"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/tags?post=229649"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}