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なぜかこのところ立て続けにpolyploidyに関するレビューがpublishされた。しかもどれもflyguy達によるものばかり。

Polyploidy.  Current Biology 25: R353–R358.

When bigger is better: the role of polyploidy in organogenesis.  Trends in Genetics 31: 307–315.

The expanding implications of polyploidy.  JCB 209: 485–491.

個人的に一番面白かったのは、Dr. TOWの「When bigger is better」かな。例えば、polyploidyのadvantageとdisadvantageについての以下の記述。

At the cellular level, several advantages have been proposed for large polyploid cells over a comparable mass of diploid cells: (i) large cells can act as a tissue envelope; (ii) the absence of mitosis and cell division has been argued to permit polyploid cells to be more metabolically active; (iii) in contrast to the many diploid cells filling a comparable area through proliferation, each polyploid cell is essentially a homogenous clone.  Thus, diploid cells can be plastic, because they can acquire different characteristics as they divide, whereas the polyploid cell can have a more stable, differentiated state; (iv) multiple genome copies within a cell provide protection against mutations and thus confer damage resistance; and (v) apoptosis is inactivated in at least some polyploid cells, possibly lengthening lifespan.

There are potential disadvantages to implementing polyploidy as a growth strategy.  The clearest one is that, as the volume of a spherical nucleus increases, the surface area does not keep up.  Thus processes such as nuclear export likely to depend on surface area of the nuclear envelope may become compromised.  This may account for why many polyploid nuclei are flat or contain indentations throughout the nuclear envelope that increase surface area.  An additional disadvantage appears in polyploid cells capable of resuming cell proliferation, such as mammalian hepatocytes and Drosophila rectal papillar cells.  In these cases the presence of multiple chromosome copies, multiple centrosomes, and the absence of apoptosis cause frequent aneuploidy if polyploidization is followed by mitotic divisions.  It has been hypothesized that in these cells polyploidy preceding mitosis may provide a mechanism for genetic variation in the final daughter cells.

そういやバルセロナで、EGFR+microRNA のoverexpression cloneがendocycleに入って巨大化して周りの細胞を食べ始めるとかいう恐ろしい話をしてた人がいたな。あれはなんなんやろうか。。。