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September 29, 2015

CiRA Seminar: Dr. Momoko Yoshimoto September 16 (Wed)

CiRA will invite Dr. Momoko Yoshimoto from Indiana University as a speaker and hold a seminar targeted to researchers on September 16th.

CiRA holds a series of seminars at random times, inviting speakers inviting speakers from Japan and abroad. Admission is free and pre-registration is not required.

CiRA Seminar
Speaker Momoko Yoshimoto, MD., PhD
Indiana University School of Medicine
Lecture title HSC-independent B lymphocytes persist into the postnatal life
Date / Time September 16 (Wed), 13:30 - 15:00
Venue Auditorium at the Center for iPS Cell Research and Application, Kyoto University (Language: English)
Host Center for iPS Cell Research and Application, Kyoto University
Contact Center for iPS Cell Research and Application
Assistant to Dr Tatsutoshi Nakahata
Ms. Harumi Watanabe
Tel: 075-366-7033
E-mail: nakahata-g[at]cira.kyoto-u.ac.jp
(Please change [at] to @)
Abstruct In developing mouse embryos, several waves of hematopoiesis occur sequentially, overlapping each other. The primitive erythropoiesis and definitive erythro-myeloid progenitors (EMPs) appear mainly in extra-embryonic yolk sac (YS), followed by the emergence of hematopoietic stem cells (HSCs) in the aorta-gonado-mesonephros (AGM) region at embryonic day (E) 11. The primitive erythropoiesis and YS EMP-derived hematopoiesis have been considered to be transient to sustain embryonic homeostasis until HSC-derived hematopoiesis is established; however, recent evidence indicates that YS EMP-derived macrophages persist as tissue macrophages in adult life. In addition, accumulated evidence indicates the presence of lymphoid cell development prior to HSC emergence, challenging the stem cell theory that all lymphoid cells are derived from HSCs. We have demonstrated that the first wave of B lymphoid cells are derived from hemogenic endothelial cells (HECs) in both YS and para-aortic spranchnopleura (P-Sp) and belong to innate type B-1 cell lineage. These HEC-derived B-1 cells secrete natural antibodies and are transplantable when injected into the irradiated recipient peritoneal cavity: important characteristics of B-1 cells. Furthermore, in order to prove that the first wave of B cells are not HSC derived, we utilized an unique transgenic mouse model where HSC are absent in the fetal liver but EMP and few lymphoid cells exist. We have demonstrated the presence of functional transplantable B-1 progenitor cells in the HSC-deficient embryo. This proves the presence of HSC-independent lymphopoiesis and layered immune theory that was proposed by Dr. Herzenberg in1989. Our recent studies on the lineage-tracing mouse model showing HSC-independent B-1 cell contribution into post-natal life, B-1 cell self-renewal mechanisms, and application for mouse ES cell system will be described.
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