PDZ domain-binding motif of human T-cell leukemia virus type 1 Tax oncoprotein is essential for the interleukin 2 independent growth induction of a T-cell line

BACKGROUND: Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia (ATL), whereas HTLV type 2 (HTLV-2), is not associated with ATL or any other leukemia. HTLV-1 encodes the transforming gene tax1, whose expression in an interleukin (IL)-2-dependent T-cell line (CTLL-2) induces IL-2-independent growth. RESULTS: In this study, we demonstrated that IL-2-independent growth induction by Tax1 was abrogated by mutations of the PDZ domain-binding motif (PBM) at the Tax1 C-terminus. HTLV-2 Tax2, which shares 75% amino acid identity with Tax1 but does not have a PBM, was not able to induce IL-2-independent growth of CTLL-2. CONCLUSION: Our results suggest that Tax1, through interaction with PDZ domain protein(s) induces IL-2-independent growth, which may be a factor in multi-step leukemogenesis caused by HTLV-1

Comprehensive survey of p94/calpain 3 substrates by comparative proteomics – Possible regulation of protein synthesis by p94

Calpain represents a family of Ca2+-dependent cytosolic cysteine proteases found in almost all eukaryotes and some bacteria, and is involved in a variety of biological phenomena, including brain function. Several substrates of calpain are aggressively proteolyzed under pathological conditions, e.g., in neurodegenerating processes, fodrin is proteolyzed by calpain. Because very small amounts of substrate are proteolyzed by calpain under normal biological conditions, the molecular identities of calpain substrates are largely unknown. In this study, an extensive survey of the substrates of p94/calpain 3 in COS7 cells was executed using iTRAQ™ labeling and 2-D LC-MALDI analysis. p94 was used because: (i) several p94 splicing variants are expressed in brain tissue even though p94 itself is a skeletal-muscle-specific calpain, and (ii) it exhibits Ca2+-independent activity in COS cells, which makes it useful for evaluating the effects of p94 protease activity on proteins without perturbing the cells. Our approach revealed several novel protein substrates for p94, including the substrates of conventional calpains, components of the protein synthesis system, and enzymes of the glycolytic pathway. The results demonstrate the usefulness and sensitivity of this approach for mining calpain substrates. A combination of this method with other analytical methods would contribute to elucidation of the biological relevance of the calpain family

Spontaneous resolution of thoracic radiation therapy-induced organizing pneumonia: A case series

We retrospectively analyzed the data of 9 patients with organizing pneumonia induced by radiation therapy. Radiation therapy had been administered for breast cancer in 8 patients and for lung cancer in 1 patient. Symptoms were detected in 8 patients; however, none of the patients developed hypoxemia or respiratory failure, and the clinical course was good. Steroid therapy was administered to 3 patients; however, all 3 patients developed recurrence. In contrast, none of the 6 patients who received symptomatic treatment developed recurrence. Steroid treatment is often provided for patients with organizing pneumonia; however, the effect of steroid administration on recurrence rate needs to be examined. In addition, none of the patients died and only 1 patient with lung cancer required mechanical ventilation. Therefore, considering the serious side effects of steroid use, initial symptomatic treatment, and not steroid administration, may be best for patients. One exception would be for patients with hypoxemia or those whose symptoms adversely affect the activities of daily living. The incidence of radiation therapy-induced organizing pneumonia in lung cancer patients is higher and its severity is greater than that in breast cancer patients; however, the time to onset may be longer in lung cancer patients. Therefore, more attention should be paid towards the diagnosis and treatment of radiation therapy-induced organizing pneumonia in patients with lung cancer as compared to that in patients with breast cancer