Biology subjects

Setiawan, N. J.

Publications and source records attributed to Setiawan, N. J..

2 recordsLinked to original sources

bioRxiv2025

Depletion of microenvironmental syndecan-2 impairs hematopoietic stem cell self-renewal and cytokine responses

Syndecan-2 is a heparan sulfate proteoglycan highly enriched on murine bone marrow hematopoietic stem cells (HSCs) compared to terminally differentiated hematopoietic cells. Syndecan-2 binds growth factors via its heparan sulfate glycosaminoglycan chains to coordinate cell signaling. Knockdown of syndecan-2 reduces HSC self-renewal ability and promotes cell cycling via Cdkn1c. In this study, we analyzed the function of syndecan-2 expressed by bone marrow niche cells in hematopoiesis and HSC self-renewal. We determined that syndecan-2 is highly expressed by bone marrow mesenchymal stromal cells and moderately expressed by endothelial cells. To test the function of niche-expressed syndecan-2 in hematopoiesis, we generated transgenic mice depleted of Sdc2 in Lepr-targeted mesenchymal stromal cells (Sdc2{Delta}MSC mice) or Cdh5-targeted endothelial cells (Sdc2{Delta}EC mice). Loss of syndecan-2 from endothelial or mesenchymal stromal cells did not change bone marrow HSC frequencies or numbers. However, depletion of syndecan-2 from Lepr-targeted mesenchymal stromal cells, but not Cdh5-targeted endothelial cells, diminishes HSC self-renewal ability analyzed by competitive transplants into lethally irradiated mice. Ex vivo studies further show that HSCs co-cultured with HS-5 stromal cells depleted of SDC2 exhaust more rapidly than HSCs cultured with control HS-5 cells. Single-cell RNA sequencing analyses reveal that the depletion of Sdc2 from mesenchymal stromal cells significantly remodels the HSC transcriptome by enriching for pathways associated with excessive growth factor signaling. Together, our findings suggest that HSC self-renewal is supported by cell-extrinsic mechanisms enacted by syndecan-2 from the MSC niche, highlighting the importance of the niche proteoglycome in HSC functions. KEY POINTSO_LIThe heparan sulfate proteoglycan syndecan-2 expressed by mesenchymal stromal cells but not endothelial cells regulates HSC self-renewal C_LIO_LIDepletion of syndecan-2 from Lepr-targeted mesenchymal stromal cells remodels the hematopoietic stem cell transcriptional landscape C_LI

cell biology↗

bioRxiv2025

The bone marrow niche and hematopoietic system are distinctly remodeled by CD45-targeted astatine-211 radioimmunotherapy

Radioimmunotherapy (RIT) is used to treat patients with hematological malignancies known to infiltrate the bone marrow (BM) microenvironment. RIT uses target-specific monoclonal antibodies stably conjugated to radionuclides to deliver cytotoxic radiation to cells of interest. While RIT is effective at delivering radiation to cancer cells, normal tissue is also exposed to radiation upon RIT, the consequences of which are largely unknown. Here, we studied the cellular and molecular effects of CD45-targeted astatine-211 (211At) RIT, IgG non-targeted 211At RIT, and Cesium-137 total-body irradiation (TBI) on hematopoietic cells and their BM niche in wild-type immunocompetent mice. Relative to non-targeted RIT or TBI, CD45-targeted RIT significantly delayed hematopoietic regeneration overall in the peripheral blood and BM and reduced hematopoietic stem/progenitor cell recovery and colony-forming ability. While BM endothelial cells (ECs) do not express the CD45 antigen, CD45-targeted RIT significantly depleted BM ECs compared to non-targeted RIT or TBI. RNA sequence analysis revealed significantly different transcriptomic profiles of BM ECs from CD45-RIT-treated mice compared to non- targeted RIT or TBI. ECs from CD45-RIT-treated mice, but not TBI or IgG-RIT-treated mice, were transcriptionally enriched for TGF{beta}, NOTCH, and IFN signaling pathways compared to untreated mice. Collectively, our study indicates that CD45-targeted RIT severely impacts hematopoietic and EC niche recovery compared to non- targeted approaches. Future studies are required to determine the long-term consequences of such RIT-driven effects on BM niche physiology and how BM niche reprogramming by RIT affects cancer cells. KEY POINTSO_LICD45-targeted radioimmunotherapy more effectively suppresses the hematopoietic system than non- targeted radiation delivery. C_LIO_LIThe bone marrow vascular niche is differentially reprogrammed by CD45-targeted radioimmunotherapy compared to non-targeted radiation delivery. C_LI

cell biology↗