Overexpression of COMP-Angiopoietin-1 in K14-Expressing Cells Impairs Hematopoiesis and Disturbs Erythrocyte Maturation

Abstract

Numerous studies highlight the potential benefits potentials of supplemental cartilage oligomeric matrix proteinangiopoietin-1 (COMP-Ang1) through improved angiogenic effects. However, our recent findings show that excessive overexpression of COMP-Ang1 induces an impaired bone marrow (BM) microenvironment and senescence of hematopoietic stem cells (HSCs). Here, we investigated the underlying mechanisms of how excessive COMP-Ang1 affects the function of BM-conserved stem cells and hematopoiesis using K14-Cre;inducible-COMP-Ang1-transgenic mice. Excessive COMP-Ang1 induced peripheral egression and senescence of BM HSCs and mesenchymal stem cells (MSCs).Excessive COMP-Ang1 also caused abnormal hematopoiesis along with skewed differentiation of HSCs toward myeloid lineage rather than lymphoid lineage. Especially, excessive COMP-Ang1 disturbed late-stage erythroblast maturation, followed by decreased expression of stromal cell-derived factor 1 (SDF-1) and globin transcription factor 1 (GATA-1) and increased levels of superoxide anion and p-p38 kinase. However, transplantation with the mutant-derived BM cells or treatment with rhCOMP-Ang1 protein did not alter the frequency or GATA-1 expression of erythroblasts in recipient mice or in cultured BM cells. Together, our findings suggest that excessive COMP-Ang1 impairs the functions of BM HSCs and MSCs and hematopoietic processes, eventually leading to abnormal erythropoiesis via imbalanced SDF-1/CXCR4 axis and GATA-1 expression rather than Ang1/Tie2 signaling axis alterations.

Local and Systemic Overexpression of COMP-Ang1 Induces Ang1/Tie2-Related Thrombocytopenia and SDF-1/CXCR4-Dependent Anemia

“…1H ). These results together with our previous reports 19 , 20 indicate that transgenic overexpression of COMP-Ang1 increases angiogenesis-associated phenotypes regardless of its local and systemic expression, whereas BM retention and senescence of HSCs, hematopoietic development, BM levels of inflammatory cytokines and SDF-1, and survival rate were affected in relation to the amount of COMP-Ang1.…”

“…6H ). These results indicate that similar to the phenotypes shown in K14-Cre;c-Ang1 mice, 20 consecutive AMD3100 injection induces irrecoverable senescence of BM HSCs in mice, and this is coupled with impaired retention of the SDF-1/CXCR4 axis.…”

“…Similar to the K14-Cre;c-Ang1 mice, 19 , 20 the Col2.3-Cre;c-Ang1 mice exhibited more branched and enlarged vessels around the hind limbs ( Fig. 1A ) and a greater number of CD31-positive cells in the BM ( Fig.…”

“… 19 The mice also exhibited a defect in erythroblastic maturation, increased production of inflammatory cytokines, dysregulated expression of globin transcription factor 1 (GATA-1), and imbalanced retention of the stromal cell-derived factor-1 (SDF-1)/CXCR4 axis in the BM. 20 Our previous findings indicated that persistent and prolonged supplementation with Ang1 by transgenic overexpression did not induce a benefit on the BM microenvironment and hematopoiesis, rather than it dysregulates hematopoietic development via an imbalanced activation or disruption of the Ang1/Tie2 signaling axis, SDF-1/CXCR4 retention axis, GATA-1 expression, or all of these mechanisms.…”

“…Erythroblasts at four stages (ProE, proerythroblasts; BasoE, basophilic erythroblasts; PolyE, polychromatophilic; OrthE, orthochromatophilic erythroblasts) were discriminatively gated with PE- or FITC-conjugated anti-CD71 (BD Biosciences) and PE-Cy7-conjugated anti-TER-119 (BD Biosciences) as described previously. 20 MP cells were analyzed with PE-Cy7-conjugated anti-lineage markers (BD Biosciences), APC-Cy7-conjugated anti-Sca-1 (cat.#561681; BD Biosciences), Texas Red-conjugated anti-c-Kit (cat.#562417; BD Biosciences), PE-conjugated anti-FcR (cat.#553141; BD Biosciences), APC-conjugated anti-CD9 (cat.#17-0091-82; eBioscience), and PerCP-eFluor-conjugated anti-CD41 (cat.#46-0411-82; eBioscience). In this study, MP cells were defined as Lineage − , IL7Rα − , Sca-1 − , c-Kit + , CD9 + , FcR low , and CD41 + cells.…”