Mammal Digit Number

Protein sorting sets digit number

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Science  17 Oct 2014:
Vol. 346, Issue 6207, pp. 311-312
DOI: 10.1126/science.346.6207.311-b

Like human fingers and toes, mice have five digits on their front and back paws. To better understand the molecular mechanism behind this, Handschuh et al. studied mice with extra or fused digits caused by a mutation that leads to reduced expression of the protein Vps25. Vps25 helps to sort proteins at the cell surface in a process called endosomal protein trafficking. Such sorting ensures that cells express just the right amount of particular proteins, so things such as tissue development go off without a hitch. In Vps25 mutant mice, cells divided more in hindlimbs, and fewer cells in the spaces between digits died, which suggests that digit development requires that cells sort their proteins properly.

Cell Reports 10.1016/j.celrep.2014.09.019 (2014).

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