Remodeling the nucleus

杨柳

Garc赤a-Blanco/Elsevier# T: t3 R5 n* ?- \9 T; f

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1 ]# z3 E+ F% d+ m, o7 `; n4 mDaniel Col車n-Ramos, Mariano A. Garc赤a-Blanco (Duke University, Durham, NC), and colleagues demonstrate in a recent article that Chlamydomonas nuclear architecture changes to accommodate cytoplasmic needs.
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7 l' c, G  p  f6 `4 V, \Chlamydomonas is a highly polarized cell that offers a unique system to study changes in nuclear shape. Loss of this algae's flagella (after certain chemical or mechanical stresses) causes the nucleus to adopt a pear-like shape and take an anterior position in the cell, nearer where the flagella once sat.
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! D: Y, w* j: IGarc赤a-Blanco wondered whether sites of transcription of the ? tubulin gene, which is strongly up-regulated upon deflagellation, move closer to the flagella to expedite their rebuilding. Immunocytochemistry and electron microscopy revealed that the ? tubulin gene did not move from its posterior nuclear position. But the experiments did uncover an unexpected asymmetry of nuclear pore complex distribution.7 f2 l+ Y: N) L0 k; Y7 ?

* x- i( ~# l5 {/ `. c: ]" YEven in flagellated cells, the complexes were preferentially located at the posterior side of the nucleus, near a polysome-rich portion of the cytoplasm. Deflagellation further exaggerated the asymmetry. The changes correlated with accumulation of ? tubulin transcripts near the concentrated translation machinery. Says Garc赤a-Blanco, "what we don't know yet is what causes what." He hopes to find mutants that uncouple events following deflagellation to determine whether nuclear architecture directly targets mRNA cytoplasmic localization.; h; C8 x- ]3 t% _) Z
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Reference:
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Col車n-Ramos, D., et al. 2003. Dev. Cell. 4:941–952.(NPCs (white) move to the posterior side )