ADAM10 Overexpression Shifts Lympho- and Myelopoiesis by Dysregulating Site 2/Site 3 Cleavage Products of Notch

Abstract

Although the physiological consequences of Notch signaling in hematopoiesis have been extensively studied, the differential effects of individual notch cleavage products remain to be elucidated. Given that ADAM10 is a critical regulator of Notch and that its deletion is embryonically lethal, we generated mice that overexpress ADAM10 (ADAM10 transgenic [A10Tg]) at early stages of lympho- and myeloid development. Transgene expression resulted in abrogated B cell development, delayed T cell development in the thymus, and unexpected systemic expansion of CD11b+Gr-1+ cells, also known as myeloid-derived suppressor cells. Mixed bone marrow reconstitution assays demonstrated that transgene expression altered hematopoiesis via a cell-intrinsic mechanism. Consistent with previously reported observations, we hypothesized that ADAM10 overexpression dysregulated Notch by uncoupling the highly regulated proteolysis of Notch receptors. This was confirmed using an in vitro model of hematopoiesis via culturing A10Tg hematopoietic Lineage−Sca-1+c-Kit+ cells with OP-9 stromal cells in the presence or absence of Delta-like 1, a primary ligand for Notch. Blockade of the site 2 (S2) and site 3 (S3) cleavage of the Notch receptor demonstrated differential effects on hematopoiesis. OP9-DL1 cultures containing the ADAM10 inhibitor (S2 cleavage site) enhanced and rescued B cell development from wild-type and A10Tg Lineage−Sca-1+c-Kit+ cells, respectively. In contrast, blockade of γ-secretase at the S3 cleavage site induced accumulation of the S2 product and consequently prevented B cell development and resulted in myeloid cell accumulation. Collectively, these findings indicate that the differential cleavage of Notch into S2 and S3 products regulated by ADAM10 is critical to hematopoietic cell-fate determination.

Physiological functions of the amyloid precursor protein secretases ADAM10, BACE1, and Presenilin

“…During lymphoid-and myeloid-development, the Notch-signaling pathway needs to be tightly regulated to control cell-fate-and lineage-decision events. Increasing the expression of ADAM10 during early stages of hematopoiesis abrogated B-cell development, delayed T-cell development and led to a systemic expansion of myeloidderived suppressor cells (Gibb et al 2011). Conversely, the usage of a specific ADAM10 inhibitor in a coculture model of hematopoietic stem cells (HSCs) and bone marrow stromal cells (BMSCs) showed the expansion of B-lymphocytes.…”

“…Conversely, the usage of a specific ADAM10 inhibitor in a coculture model of hematopoietic stem cells (HSCs) and bone marrow stromal cells (BMSCs) showed the expansion of B-lymphocytes. These observations suggest that ADAM10 plays an essential role for Notch-mediated cell-fate decisions during hematopoiesis and could therefore serve as a potential target for hematological disorders (Gibb et al 2011).…”

Myeloproliferation and hematopoietic stem cell dysfunction due to defective Notch receptor modification by O-fucose glycans

“…The cell-intrinsic expansion of Gr-1 + CD11b + cells in the ADAM10 over-expression transgenic mice was related to the accumulation of the S2 product and was also accompanied by mild defective T cell development and abrogated B cell development [98]. In comparison, both cell-autonomous and non-hematopoietic components were identified to contribute to the aberrant expansion of myeloid compartment in ADAM10-deficient mice [99].…”

“…Not surprisingly, not only does the loss of function of S3 cleavage enzyme complex cause myeloproliferation, but also number of defective Notch S2 cleavage, either through over-expression [98] or conditional inactivation of AD-AM10 [99], leading to a myeloid hyperplasia phenotype. The cell-intrinsic expansion of Gr-1 + CD11b + cells in the ADAM10 over-expression transgenic mice was related to the accumulation of the S2 product and was also accompanied by mild defective T cell development and abrogated B cell development [98].…”

ADAM-family metalloproteinases in lung inflammation: potential therapeutic targets

“…Overexpression of ADAM10 in early lymphoid and myeloid development resulted in abrogated B cell development and dysregulated myelopoiesis. In vitro experiments with hematopoietic cells revealed that overexpression of ADAM10 increases the proteolysis of Notch receptors and thereby shifts lympho-and myelopoiesis (51). B cell-specific ADAM10 deficiency in mice (driven by CD19-Cre) prevented marginal zone B cell development, which is dependent on Notch2 signaling (50).…”