Tumors need less regulation

نویسنده

  • William A. Wells
چکیده

Structure with a light touch ike a blind man tapping around a neighborhood, colleagues have used atomic force microscopy (AFM) to picture the organization of a photosynthetic membrane. The arrangement explains how light energy is channeled from antenna-like collectors to an energy-transforming reaction center (RC) complex. When the structure of the RC was solved in 1985 it was the first X-ray structure of a membrane protein. X-ray structures of the other photosynthetic complexes—the light harvesting LH1 and LH2 complexes—followed. But, says Hunter, " it was a bit like a jigsaw—nobody had seen how the pieces were put together. " Light energy is initially absorbed by LH2 complexes, each of which is a ring of ‫ف‬ 27 chlorophylls and associated proteins. The energy whizzes around the LH2 ring, hops to neighboring LH2 rings, and transfers to the lower energy states available in any nearby LH1 ring. The energy then circulates around the LH1 complex until the RC, which plugs the donut hole of the LH1 complex, is free to accept it. The Dutch and English groups used tapping mode AFM to detect the protrusions of membrane proteins and thus map the arrangement of the complexes. (Similar results have also been reported by Scheuring et al. [2004].) Large patches of the smaller LH2 complexes " funnel down to form these narrow channels separating linear arrays of RC-LH1 complexes, " says Hunter. The RC-LH1 complexes are mostly present as linear arrangements of dimers surrounded by the more randomly L Tumors need less regulation fforts to induce anti-tumor immunity have so far proven disappointing. Now, suggest that greater success may come if clinicians first disable regulatory T (T reg) cells. These cells, say the group, are recruited by human tumors to damp down any immune response against tumor cells. T reg cells have been studied primarily for their ability to turn off immune responses during organ transplantation or autoimmune disease. Preliminary results in mice suggested that depletion of T reg cells might improve tumor prognosis, although these experiments may have depleted other cell types. Now, Zou's team finds that human malignant ovarian cancers contain substantial numbers of T reg cells, with more T reg cells present at later tumor stages. The patients also have fewer than normal T reg cells in their lymph nodes—the normal home of the cells. In mice containing human tumor cells the T reg accumulation in tumors is dependent on …

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عنوان ژورنال:
  • The Journal of Cell Biology

دوره 166  شماره 

صفحات  -

تاریخ انتشار 2004