High-mobility group box 1 (HMGB1) was recently shown to be an important extracellular mediator of systemic inflammation, and endothelial cell protein C receptor (EPCR) has been shown to be involved in vascular inflammation. Hyperoside is an active compound isolated from Rhododendron brachycarpum G. Don (Ericaceae) that was reported to have anti-oxidant, anti-hyperglycemic, anti-cancer, and anti-coagulant activities. Here, we show, for the first time, the anti-septic effects of hyperoside in HMGB1-mediated inflammatory responses and on the shedding of EPCR in vitro and in vivo. The data showed that hyperoside posttreatment suppressed lipopolysaccharide (LPS)-mediated release of HMGB1 and HMGB1-mediated cytoskeletal rearrangement. Hyperoside also inhibited HMGB1-mediated hyperpermeability and leukocyte migration in septic mice and phorbol-12-myristate 13-acetate (PMA) of cecal ligation and puncture (CLP)-induced EPCR shedding. In addition, hyperoside inhibited the production of tumor necrosis factor-α (TNF-α) and the HMGB1-mediated activation of Akt, nuclear factor-κB (NF-κB), and extracellular regulated kinase (ERK) 1/2 in HUVECs. Hyperoside also reduced the CLP-induced release of HMGB1, the production of interleukin (IL)-1β, and septic mortality. Collectively, these results suggest hyperoside as a candidate therapeutic agent for the treatment of vascular inflammatory diseases via inhibition of the HMGB1 signaling pathway.

Core binding factor β (Cbfβ) is a partner protein of Runx family transcription factors with minimally characterized function in cartilage. Here we address the role of Cbfβ in cartilage by generating chondrocyte-specific Cbfβ-deficient mice (Cbfb(Δch/Δch) ) from Cbfb-floxed mice crossed with mice expressing Cre from the Col2a1 promoter. Cbfb(Δch/Δch) mice died soon after birth and exhibited delayed endochondral bone formation, shorter appendicular skeleton length with increased proliferative chondrocytes, and nearly absent hypertrophic chondrocyte zones. Immunohistochemical and quantitative real-time PCR analyses showed that the number and size of proliferative chondrocytes increased and the expression of chondrocyte maturation markers at the growth plates, including Runx2, osterix, and osteopontin, significantly diminished in Cbfb(Δch/Δch) mice compared to wild type mice. With regard to signaling pathways, both PTHrP-Ihh and BMP signaling were compromised in Cbfb(Δch/Δch) mice. Mechanistically, Cbfβ deficiency in chondrocytes caused a decrease of protein levels of Runx transcription factors by accelerating polyubiquitination-mediated proteosomal degradation in vitro. Indeed, Runx2 and Runx3, but not Runx1, decreased in Cbfb(Δch/Δch) mice. Collectively, these findings indicate that Cbfβ plays a critical role for chondrocyte differentiation through stabilizing Runx2 and Runx3 proteins in cartilage.

A nucleosomal protein, high mobility group box 1 (HMGB1) is known to be a late mediator of sepsis. Dabrafenib is a B-Raf inhibitor and initially used for the treatment of metastatic melanoma therapy. Inhibition of HMGB1 and renewal of vascular integrity is appearing as an engaging therapeutic strategy in the administration of severe sepsis or septic shock. Here, we examined the effects of dabrafenib (DAB) on the modulation of HMGB1-mediated septic responses. DAB inhibited the release of HMGB1 and downregulated HMGB1-dependent inflammatory responses by enhancing the expressions of cell adhesion molecules (CAMs) in human endothelial cells. In addition, treatment with DAB inhibited the HMGB1 secretion by CLP and sepsis-related mortality and pulmonary injury. This study demonstrated that DAB could be alternative therapeutic options for sepsis or septic shock via the inhibition of the HMGB1 signaling pathway. [BMB Reports 2016; 49(4): 214-219]

The transdifferentiation of vascular smooth muscle cells (VSMCs) into osteoblast-like cells has been implicated in the context of vascular calcification. We investigated the roles of vitamin D receptor (Vdr) and runt-related transcription factor 2 (Runx2) in the osteoblastic differentiation of VSMCs in response to vitamin D3 using in vitro VSMCs cultures and in vivo in Vdr knockout (Vdr -/-) and Runx2 carboxy-terminus truncated heterozygous (Runx2 +/ΔC) mice. Treatment of VSMCs with active vitamin D3 promoted matrix mineral deposition, and increased the expressions of Vdr, Runx2, and of osteoblastic genes but decreased the expression of smooth muscle myosin heavy chain in primary VSMCs cultures. Immunoprecipitation experiments suggested an interaction between Vdr and Runx2. Furthermore, silencing Vdr or Runx2 attenuated the procalcific effects of vitamin D3. Functional cooperation between Vdr and Runx2 in vascular calcification was also confirmed in in vivo mouse models. Vascular calcification induced by high-dose vitamin D3 was completely inhibited in Vdr -/- or Runx2 +/ΔC mice, despite elevated levels of serum calcium or alkaline phosphatase. Collectively, these findings suggest that functional cooperation between Vdr and Runx2 is necessary for vascular calcification in response to vitamin D3.

Collectively, DICAM suppressed angiogenesis by attenuating AKT and p38 MAP kinase signalling, which suggests that DICAM may be a novel negative regulator of angiogenesis.

Core binding factor beta (Cbfb), the partner protein of Runx family transcription factors, enhances Runx function by increasing the binding of Runx to DNA. Null mutations of Cbfb result in embryonic death, which can be rescued by restoring fetal hematopoiesis but only until birth, where bone formation is still nearly absent. Here, we address a direct role of Cbfb in skeletal homeostasis by generating osteoblast-specific Cbfb-deficient mice (Cbfb Dob/Dob ) from Cbfb-floxed mice crossed with mice expressing Cre from the Col1a1 promoter. Cbfb Dob/Dob mice showed normal growth and development but exhibited reduced bone mass, particularly of cortical bone. The reduction of bone mass in Cbfb Dob/Dob mice is similar to the phenotype of mice with haploinsufficiency of Runx2. Although the number of osteoblasts remained unchanged, the number of active osteoblasts decreased in Cbfb Dob/Dob mice and resulted in lower mineral apposition rate. Immunohistochemical and quantitative real-time PCR analyses showed that the expression of osteogenic markers, including Runx2, osterix, osteocalcin, and osteopontin, was significantly repressed in Cbfb Dob/Dob mice compared with wild-type mice. Cbfb deficiency also reduced Runx2 protein levels in osteoblasts. The mechanism was revealed by forced expression of Cbfb, which increased Runx2 protein levels in vitro by inhibiting polyubiquitination-mediated proteosomal degradation. Collectively, these findings indicate that Cbfb stabilizes Runx2 in osteoblasts by forming a complex and thus facilitates the proper maintenance of bone mass, particularly cortical bone.

CXCL12a promoted the proliferation and maturation of chondrocytes, which strongly suggest that CXCL12a may have a negative effect on articular cartilage and contribute to OA progression.

Chondroitin sulfate (CS) is the most abundant glycosaminoglycan (GAG) in articular cartilage and the loss of CS-GAG occurs early in OA. As a major component of perichondral matrix interacting directly with chondrocytes, the active turnover of CS can affect to break the homeostasis of chondrocytes. Here we employ CS-based 3-dimensional (3D) hydrogel scaffold system to investigate how the degradation products of CS affect the catabolic phenotype of chondrocytes. The breakdown of CS-based ECM by the chondroitinase ABC (ChABC) resulted in a hypertrophy-like morphologic change in chondrocytes, which was accompanied by catabolic phenotypes, including increased MMP-13 and ADAMTS5 expression, nitric oxide (NO) production and oxidative stress. The inhibition of Toll-like receptor 2 (TLR2) or TLR4 with OxPAPC (TLR2 and TLR4 dual inhibitor) and LPS-RS (TLR4-MD2 inhibitor) ameliorated these catabolic phenotypes of chondrocytes by CS-ECM degradation, suggesting a role of CS breakdown products as damage-associated molecular patterns (DAMPs). As downstream signals of TLRs, MAP kinases, NF-kB, NO and STAT3-related signals were responsible for the catabolic phenotypes of chondrocytes associated with ECM degradation. NO in turn reinforced the activation of MAP kinases as well as NFkB signaling pathway. Thus, these results propose that the breakdown product of CS-GAG can recapitulate the catabolic phenotypes of OA.