A research group led by Professor Ryo Iizuka of Tokyo University of Science has elucidated the cellular and molecular mechanisms involved in emergency hematopoiesis that occurs in tissues other than bone marrow during anemia and infectious diseases.
Hematopoietic stem / progenitor cells exist in the bone marrow and differentiate into various blood cells.However, it has been known that blood is produced in tissues other than bone marrow, especially the spleen, when leukocytes and red blood cells are urgently needed in large quantities such as infectious diseases and anemia. Was unknown.
Lipopolysaccharide (LPS) is a constituent of bacteria, and its administration causes extramedullary hematopoiesis as in the case of infection.As a result of analysis using such an extramedullary hematopoiesis model by LPS administration, an increase in the expression of Tlx1 (a transcription factor essential for splenic organ formation) and an increase in the production of hematopoietic regulators were observed in the mesenchymal cells of the spleen. , Hematopoietic stem / progenitor cells were found to be localized in close proximity to the main cells.
In addition, when Tlx1 was deleted from the spleen mesenchymal cells of mice, LPS did not increase the production of hematopoietic regulators and the number of hematopoietic stems and progenitor cells in the spleen.From this, it was found that increased Tlx1-expressing cells in the spleen and Tlx1 expression in the main cells are necessary for emergency hematopoiesis.Furthermore, it was found that high expression of Tlx1 can reproduce emergency hematopoiesis.
From the above results, it is necessary for emergency hematopoiesis to increase Tlx1 expression in splenic mesenchymal cells expressing Tlx1 and those cells, and hematopoiesis in bone marrow and other tissues is controlled by different cell groups and transcription factors. It became clear for the first time that it was.
This achievement will contribute to the elucidation of the common principles of environmental components related to the maintenance and function of hematopoietic stem / progenitor cells, and its application to the construction of hematopoietic stem cell culture systems using easily collectable splenic mesenchymal cells. Can also be expected.
Paper information:[Scientific Reports] Niche-induced extramedullary hematopoiesis in the spleen is regulated by the transcription factor Tlx1
