Involvement of multiple CCN family members in platelets that support regeneration of joint tissues

The Evaluation of Meniscus Regenerative Effects of LIPUS-Induced CCN Proteins: Induction by LIPUS of CCN2 and Meniscus-Related Genes in Cultured Meniscus Cells and Meniscus Tissues

Menisci are a pair of crescent-shaped fibrocartilages and composed primarily of type I collagen. Inner region of the meniscus has similar characteristics to articular cartilage. Low-intensity pulsed ultrasound (LIPUS) has been reported to have chondroprotective effects on chondrocytes by inducing the expression of chondrocyte differentiation markers and CCN2/CTGF production. Here, we describe an experimental approach that investigates the distinct cellular behavior of human inner and outer meniscus cells in response to LIPUS stimulation. Our experimental model can analyze the relationships between LIPUS-induced CCN2 and its repairing role in the meniscus.

The thrombospondin module 1 domain of the matricellular protein CCN3 shows an atypical disulfide pattern and incomplete CWR layers

The members of the CCN (Cyr61/CTGF/Nov) family are a group of matricellular regulatory proteins that are essential to a wide range of functional pathways in cell signalling. Through interacting with extracellular matrix components and growth factors via one of their four domains, the CCN proteins are involved in critical biological processes such as angiogenesis, cell proliferation, bone development, fibrogenesis and tumorigenesis. Here, the crystal structure of the thrombospondin module 1 (TSP1) domain of CCN3 (previously known as Nov) is presented, which shares a similar three-stranded fold with the thrombospondin type 1 repeats of thrombospondin-1 and spondin-1, but with variations in the disulfide connectivity. Moreover, the CCN3 TSP1 domain lacks the typical π-stacked ladder of charged and aromatic residues on one side of the domain that is seen in other TSP1 domains. Using conservation analysis among orthologous domains, it is shown that a charged cluster in the centre of the domain is the most conserved site and this cluster is predicted to be a potential functional epitope for heparan sulfate binding. This variant TSP1 domain has also been used to revise the sequence determinants of TSP1 domains and to derive improved Pfam sequence profiles for the identification of novel TSP1 domains in more than 10 000 proteins across diverse phyla.

Recent strategies in cartilage repair: A systemic review of the scaffold development and tissue engineering

Osteoarthritis results in irreparable loss of articular cartilage. Due to its avascular nature and low mitotic activity, cartilage has little intrinsic capacity for repair. Cartilage loss leads to pain, physical disability, movement restriction, and morbidity. Various treatment strategies have been proposed for cartilage regeneration, but the optimum treatment is yet to be defined. Tissue engineering with engineered constructs aimed towards developing a suitable substrate may help in cartilage regeneration by providing the mechanical, biological and chemical support to the cells. The use of scaffold as a substrate to support the progenitor cells or autologous chondrocytes has given promising results. Leakage of cells, poor cell survival, poor cell differentiation, inadequate integration into the host tissue, incorrect distribution of cells, and dedifferentiation of the normal cartilage are the common problems in tissue engineering. Current research is focused on improving mechanical and biochemical properties of scaffold to make it more efficient. The aim of this review is to provide a critical discussion on existing challenges, scaffold type and properties, and an update on ongoing recent developments in the architecture and composition of scaffold to enhance the proliferation and viability of mesenchymal stem cells. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2343-2354, 2017.

CCN family of proteins: critical modulators of the tumor cell microenvironment

The CCN family of proteins consisting of CCN1 (Cyr61), CCN2 (CTGF), CCN3 (NOV), CCN4 (WISP-1), CCN5 (WISP-2) and CCN6 (WISP-3) are considered matricellular proteins operating essentially in the extracellular microenvironment between cells. Evidence has also been gradually building since their first discovery of additional intracellular roles although the major activity is triggered at the cell membrane. The proteins consist of 4 motifs, a signal peptide (for secretion} followed consecutively by the IGFBP, VWC, TSP1 and CT (C-terminal cysteine knot domain) motifs, which signify their potential binding partners and functional connections to a variety of key regulators of physiological processes. With respect to cancer it is now clear that, whereas certain members can facilitate tumor behavior and progression, others can competitively counter the process. It is therefore clear that the net outcome of biological interactions in the matrix and what gets signaled or inhibited can be a function of the interplay of these CCN 1-6 proteins. Because the CCN proteins further interact with other key proteins, like growth factors in the matrix, the balance is not only important but can vary dynamically with the physiological states of tumor cells and the surrounding normal cells. The tumor niche with its many cell players has surfaced as a critical determinant of tumor behavior, invasiveness, and metastasis. It is in this context that CCN proteins should be investigated with the potential of being recognized and validated for future therapeutic approaches.