PKCε is a regulator of hypertrophic differentiation of chondrocytes in osteoarthritis.

OBJECTIVE: Osteoarthritis (OA) is a common and highly debilitating degenerative disease whose complex pathogenesis and the multiplicity of the molecular processes involved, hinder its complete understanding. Protein Kinase C (PKC) novel isozyme PKCε recently proved to be an interesting molecule for further investigations as it can represent an intriguing, new actor in the acquisition of a OA phenotype by the chondrocyte. DESIGN: PKCε was modulated in primary chondrocytes from human OA patient knee cartilage samples by means of short hairpin RNA (ShRNA) and the expression of cartilage specific markers observed at mRNA and protein level. The involvement of Histone deacetylases (HDACs) signaling pathway was also investigated through the use of specific inhibitors MS-275 and Inhibitor VIII. RESULTS: PKCε loss induces up-regulation of Runt-domain transcription factor (RUNX2), Metalloproteinase 13 (MMP13) and Collagen X (COL10) as well as an enhanced calcium deposition in OA chondrocyte cultures. In parallel, PKCε knock-down also leads to SOX9 and Collagen II (COL2) down-modulation and to a lower deposition of glycosaminoglycans (GAGs) in the extracellular matrix (ECM). This novel regulatory role of PKCε over cartilage hypertrophic phenotype is exerted via an HDAC-mediated pathway, as HDAC2 and HDAC4 expression is modulated by PKCε. HDAC2 and HDAC4, in turn, are at least in part responsible for the modulation of the master transcription factors RUNX2 and SOX9, key regulators of chondrocyte phenotype. CONCLUSIONS: PKCε prevents the phenotypic progression of the OA chondrocyte, acting on cartilage specific markers through the modulation of the transcription factors SOX9 and RUNX2. The loss of PKCε enhances, in fact, the OA hypertrophic phenotype, with clear implications in the pathophysiology of the disease.

PKCε as a novel promoter of skeletal muscle differentiation and regeneration.

INTRODUCTION: Satellite cells are muscle resident stem cells and are responsible for muscle regeneration. In this study we investigate the involvement of PKCε during muscle stem cell differentiation in vitro and in vivo. Here, we describe the identification of a previously unrecognized role for the PKCε-HMGA1 signaling axis in myoblast differentiation and regeneration processes. METHODS: PKCε expression was modulated in the C2C12 cell line and primary murine satellite cells in vitro, as well as in an in vivo model of muscle regeneration. Immunohistochemistry and immunofluorescence, RT-PCR and shRNA silencing techniques were used to determine the role of PKCε and HMGA1 in myogenic differentiation. RESULTS: PKCε expression increases and subsequently re-localizes to the nucleus during skeletal muscle cell differentiation. In the nucleus, PKCε blocks Hmga1 expression to promote Myogenin and Mrf4 accumulation and myoblast formation. Following in vivo muscle injury, PKCε accumulates in regenerating, centrally-nucleated myofibers. Pharmacological inhibition of PKCε impairs the expression of two crucial markers of muscle differentiation, namely MyoD and Myogenin, during injury induced muscle regeneration. CONCLUSION: This work identifies the PKCε-HMGA1 signaling axis as a positive regulator of skeletal muscle differentiation.

The "at-home LLLT" in temporo-mandibular disorders pain control: a pilot study.

OBJECTIVES: The Temporo-Mandibular Disorders (TMD) are a set of dysfunctional patterns concerning the temporo-mandibular joints (TMJ) and the masticatory muscles; its main symptom is pain, probably caused by inflammatory changes in the synovial membrane, alterations in the bone marrow of the mandibular condyle and impingement and compression. The aim of this preliminary study was to investigate the effectiveness in the TMD pain reduction of a new laser device recently proposed by the commerce that, due to its reduced dimensions and to be a class I laser according the ANSI classification, may be used at home by the patient himself. MATERIAL AND METHODS: Twenty-four patients with TMD were randomly selected: the inclusion criteria for the sample was the diagnosis of mono- or bi-lateral TMD, with acute pain restricted to the joint area, associated with the absence of any muscle tenderness during palpation. The patients were randomly assigned to two groups: Group 1 (12 patients): patients receiving real LLLT (experimental group). Group 2 (12 patients): patients receiving inactive laser (placebo group). The treatment was performed once a day for two weeks with an 808 nm diode laser by the patient himself with irradiation of the cutaneous zone corresponding to the TMJ for 15 minutes each side. Each patient was instructed to express its pain in a visual analogue scale (VAS) making a perpendicular line between the two extremes representing the felt pain level. Statistical analysis was realized with GraphPad Instat Software, where P<0.05 was considered significant and P<0.01 very significant. RESULTS: The patient's pain evaluation was expressed in the two study groups before the treatment, 1 week and two weeks after the treatment. The differences between the two groups result extremely significant with p<0.0001 for the comparison of VAS value after 1 and 2 weeks. CONCLUSION: This study, even if it may be considered such a pilot study, investigated a new way to control the pain in the temporo-mandibular diseases by an at home self administered laser device. RESULTS are encouraging but they will have to be confirmed by greater studies.