Involvement of NFκB signaling in mediating the effects of GRK5 on neural stem cells.

Nuclear factor κB (NFκB) signaling plays ubiquitous roles in inflammation, immune response and neurogenesis. G protein-coupled receptor kinase 5 (GRK5) can protect neurons from degeneration. GRK5 also mediates tumor necrosis factor-α (TNFα)-induced NFκB signaling through the phosphorylation of IκBα. Here, we show that NFκB signaling is involved in neural stem cell (NSC) differentiation. The IκBα/p65 pathway was activated by phorbol myristate acetate (PMA), a stimulator of protein kinase C (PKC). Once the NFκB was activated, the initial stage of neural differentiation was induced, with an increased level of GRK5 in NSCs. This finding was reversed in response to the NFκB inhibitor N-acetyl cysteine (NAC). To evaluate the effect of GRK5-NFκB signaling crosstalk on NSC neurogenesis and apoptosis, GRK5 was knocked down by siRNAs in cell culture. SiRNAs against GRK5 not only impaired neural differentiation and axogenesis, but also induced apoptosis of NSC. GRK5 knockdown affected the transcription of NFκB, phosphorylation of the liver kinase B1 (LKB1) and the activity of caspase 3, thereby modulated neurogenesis and apoptosis. Taken together, our findings reveal a novel function of GRK5 in neurogenesis and provide insight into the molecular mechanisms underlying neurodevelopmental disorders and neurodegenerative diseases.

Reduction expression of thrombomodulin and endothelial cell nitric oxide synthase in dermatomyositis.

Dermatomyositis (DM) is a systemic microvasculitis predominantly involving the capillaries. We investigated the expression of thrombomodulin (TM) and endothelial cell nitric oxide synthase (eNOS) in microvessels of DM patients. Twelve patients with acute or subacute onset of proximal muscle weakness and erythematous rash over their faces and shoulders were included in this study. Serum creatine phosphokinase was elevated in almost all patients. Electromyograph showed a myopathic pattern in all patients. Muscle biopsies were performed in all patients and 10 non-DM controls and studied with histological, enzyme histochemical and immunohistochemical staining. von Willebrand factor, TM and eNOS antibodies were used as the primary antibodies. Perifascicular degeneration and inflammatory cell infiltration in the perimysium were noted in almost all patients. Non-special esterase staining was markedly positive in capillary and microvascular endothelium. Marked reduction in TM and eNOS staining was noted in DM patients in perimysium microvessels and perifascicular area capillaries. Vascular lesions in DM were not only limited to capillaries. The low expression of TM and eNOS in microvessels suggests the anticoagulation and vasodilation functions of vascular endothelium is reduced. DM is an inflammatory vascular endothelial disease.

[Immunopathological changes of micro-vessels in dermatomyositis].

OBJECTIVE: To investigate the immunopathological changes of micro-vessels in dermatomyositis. METHODS: Twelve patients with dermatomyositis, 5 males and 7 females, aged 40.8 (6 - 72), underwent muscle biopsy of biceps muscle of arm (n = 11) or deltoid muscle (n = 1). The specimens underwent routine histological, enzyme histochemical, and immunohistochemical staining and microscopy. Ten biopsy specimens from patients with other diseases were used as controls. RESULTS: Perifascicular atrophy of muscular fibers and inflammatory infiltration in perimysium were seen in all patients with dermatomyositis. Non-specific esterase staining showed deep staining of capillaries and micro vascular endothelium among the muscular fibers. Immunohistochemistry showed remarkable reduction of capillaries positive in von Willebrand factor (vWF), thrombomodulin (TM), and endothelial cell nitric oxide synthase (eNOS) in the perifascicular region, and low expression of .eNOS and TM in the microvascular endothelium in the perimysium. CONCLUSION: The vascular lesions of dermatomyositis are located not only in capillaries, but also in other microvessels. Lower expression of TM and eNOS in vascular endothelium suggests the reduction of anticoagulation and vasodilation functions of vascular endothelium. Dermatomyositis is an inflammatory vascular endothelial disease.

[Diffuse muscular calcification with subcutaneous cysts].

OBJECTIVE: Diffuse muscular calcification was rare myopathological change due to abnormal metabolism of calcium, which was mainly found in dermatomyositis and myositis ossificans progressiva. Here we reported a case of diffuse muscular calcification that clinically mimicked myositis ossificans progressiva. The disease might be a new type of congenital calcium metabolic disease. METHODS: A 15-year-old girl developed subcutaneous cysts in the wrist and ankle when she was 1 year old. At the age of 9, she developed recurrent fever with myalgia, fatigue and diffuse muscular calcification. It was difficult for her to squat, run or walk. Protuberance presented in the subcutaneous tissue of her trunk. Some nodules ruptured with outflow of chalky material. ESR, ENA, RF, CRP, PTH, CK were in normal limits. EMG was unremarkable. X-ray confirmed diffuse calcification in the muscle and subcutaneous tissues. Biceps muscle biopsy was performed. RESULTS: Numerous inflammatory cells infiltrated around vessels in the perimyosium with perifascicular muscle fiber atrophy and degeneration. Many RRF and SDH positive fibers were also observed. EM showed tubular reticular inclusions in vascular endothelium. CONCLUSION: Diffuse muscular calcification indicated existence of systemic calcium metabolic abnormality. As the clinical symptoms and distribution pattern of calcification were different from dermatomyositis with subcutaneous calcification and myositis ossificans progressiva, our case might be a new type of disease. The microvascular changes might result in the lesion of muscle fibers.