Is there a correlation between biophotonical, biochemical, histological, and visual changes in the cartilage of osteoarthritic knee-joints?

The aim of this study was to detect characteristic structural changes in the cartilage composition of osteoarthritis (OA), hereby improving the arthroscopic identification of cartilage pathology by the use of a non-destructive technique - NIRS (Near-Infrared Spectroscopy). 682 cartilage samples out of 25 knees with OA were classified visually, using the ICRS system, biophotonically, histologically (n = 66), using the Score of Mankin and the Score of Otte, and biochemically (n = 616), determining the content of glycosaminoglycan (GAG) and hydroxyproline (HP). Significant correlations were found between biophotonical, histological, biochemical and visual characteristics of cartilage lesions. NIRS values corresponded to the content of GAG, HP and to the Score of Mankin and Otte. The data show that changes in the composition and structure of articular cartilage influence the optical properties and can be measured objectively by NIRS. The ease of use during arthroscopy, the quick response and the non-destructive nature of NIRS make it a promising addition to the assessment of disease intervention in OA.

BMP-2 shows characteristic extracellular patterns in osteoarthritic cartilage: a preliminary report.

To determine bone morphogenetic protein (BMP)-2 protein and Aggrecan in osteoarthritic and healthy cartilage with special regard to localization and degree of cartilage damage 95 samples representing osteoarthritic cartilage and 17 samples out of normal cartilage were graded histological by Mankin Score and were studied by immunohistochemistry for the expression of BMP-2 and Aggrecan. BMP-2 protein was detected intracellular in normal and in osteoarthritic cartilage. Extracellular BMP-2 was detected exclusively in osteoarthritic cartilage and exhibits characteristic extracellular patterns: samples with BMP-2 in the extracellular matrix show BMP-2 negative coronae around BMP-2 positive cells. There is a statistically significant increase in the prevalence of extracellular BMP-2 with increasing ICRS grade/Mankin grade. Aggrecan was detected in the extracellular matrix und exhibited coronas throughout all layers. A decline of extracellular Aggrecan with increasing ICRS grade could be observed. Normal cartilage shows no intracellular Aggrecan whereas an increase in the prevalence of intracellular Aggrecan could be detected in osteoarthritic cartilage. The appearance of intracellular Aggrecan is often associated with extracellular BMP-2. The detection of BMP-2 protein in normal as well as in osteoarthritic cartilage highlights the importance of BMP-2 in tissue homeostasis and point to a putative role for maintaining tissue integrity during the development of osteoarthritis. The co-appearance of extracellular BMP-2 and intracellular Aggrecan indicates a functional relationship. The most interesting result is the characteristic distribution of extracellular BMP-2. These coronas seem to have an impact during progression of osteoarthritis and need to be further investigated.

SMC5 and MMS21 are required for chromosome cohesion and mitotic progression.

Members of the structural maintenance of chromosome (SMC) protein family have essential functions during mitosis, ensuring chromosome condensation (SMC2/4) and cohesion (SMC1/3). The SMC5/6 complex has been implicated in a variety of DNA maintenance processes but unlike the other SMC proteins, SMC5/6 have not been attributed any role in mitosis. Here, we find that ablation of either SMC5 or the SUMO-ligase MMS21 leads to premature sister chromatid separation prior to anaphase. The failure of normal chromosome alignment activates the spindle assembly checkpoint and blocks mitotic progression. Interestingly, there is no similar mitotic response to ablation of SMC6. Further, we show that mitotic SMC5 co-elutes from column fractions that contain MMS21 but lack SMC6. Our results thus establish that SMC5 is crucial for mitotic progression and maintenance of sister chromatid cohesion during mitosis, and that this role of SMC5 seems to be independent of the SMC5/6 complex.

Differential expression of cancer-related genes by single and permanent exposure to bone morphogenetic protein 2.

PURPOSE: Bone morphogenetic proteins (BMPs) are multifunctional regulators of various cell functions. The BMP-signalling network plays a pivotal role during embryogenesis and tumorigenesis. BMPs, e.g. BMP-2 exert their biological function in a time and concentration-dependent manner but also modulated by the context of the cellular microenvironment. In this study, we investigated the effect of a steady high level of BMP-2 versus a single application of BMP-2 on the breast cancer cell line MCF-7. METHODS: The effect of the incubation regimes was analysed by DNA microarray expression profiling. Data were verified by real-time PCR. The protein expression of apoptosis-related genes was studied by western blot analysis. RESULTS: We found a clear difference in the altered gene expression between the constant high level and the single application of BMP-2. After grouping the genes of interest into the biological processes of Gene Ontology, the group of apoptosis-related genes like BAX, BAG5 or PKR, was predominantly affected under the single-application regime of BMP-2. Among these protein kinase R was the most prominently regulated. Further studies on the protein level showed activation of PKR after 4 h with a subsequent enhanced phosphorylation of the PKR substrate eIF2alpha for several hours. CONCLUSIONS: The duration of treatment and the concentration of BMP-2 affect the global expression pattern of MCF-7 cells. Among the regulated cancer-related genes, the cohort of the apoptosis-related genes showed the pronounced alterations. Our data point to a novel role of BMP-2 in the regulation of the PKR pathway in tumorigenesis.

Modification of subtelomeric DNA.

There is a discrepancy in telomere length as measured by signal intensity of telomere restriction fragments on gels and fluorescence in situ hybridization analysis. This difference has been ascribed to the X-region, a segment of subtelomeric DNA that is resistant to being cut by restriction enzymes. To explore the nature of this region, we analyzed the digestibility of an artificial seeded telomere in HeLa cells as well as the Xp/Yp autosomal telomere in human BJ fibroblasts. We found that there is a substantial fraction of subtelomeric DNA containing restriction sites that is not digested with enzymes such as EcoRI, NlaIII, and SphI. Comparison of methylation-sensitive and -resistant enzymes excluded the possibility of the X-region being maintained by DNA methylation. We show that the X-region represents a variable domain whose size changes with telomere length, and neither non-TTAGGG sequences nor cytidine methylation can adequately explain the size of the X-region.

Telomere biology and cellular aging in nonhuman primate cells.

To determine how cellular aging is conserved among primates, we analyzed the replicative potential and telomere shortening in skin fibroblasts of anthropoids and prosimians. The average telomere length of the New World primates Ateles geoffroyi (spider monkey) and Saimiri sciureus (squirrel monkey) and the Old World primates Macaca mulatta (rhesus monkey), Pongo pygmaeus (orangutan), and Pan paniscus (pigmy chimpanzee) ranged from 4 to 16 kb. We found that telomere shortening limits the replicative capacity of anthropoid fibroblasts and that the expression of human telomerase produced telomere elongation and the extension of their in vitro life span. In contrast the prosimian Lemur catta (ring-tailed lemur) had both long and short telomeres and telomere shortening did not provide an absolute barrier to immortalization. Following a transient growth arrest a subset of cells showing a reduced number of chromosomes overgrew the cultures without activation of telomerase. Here we show that the presence of continuous TTAGGG repeats at telomeres and rigorous control of replicative aging by telomere shortening appear to be conserved among anthropoid primates but is less effective in prosimian lemurs.