Proceedings of the National Academy of Sciences

Texto completo: acesso restrito. p. 5750-5755 Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-09-04T12:49:04Z No. of bitstreams: 1 PNAS-2010-Galvão-5750-5.pdf: 1691733 bytes, checksum: 7c44e87f181c5d7302d142ee4539ef03 (MD5) Approved for entry into archive by Rodrigo Meirelles (rodrigomei@ufba.br) on 2013-11-26T13:13:55Z (GMT) No. of bitstreams: 1 PNAS-2010-Galvão-5750-5.pdf: 1691733 bytes, checksum: 7c44e87f181c5d7302d142ee4539ef03 (MD5) Made available in DSpace on 2013-11-26T13:13:55Z (GMT). No. of bitstreams: 1 PNAS-2010-Galvão-5750-5.pdf: 1691733 bytes, checksum: 7c44e87f181c5d7302d142ee4539ef03 (MD5) Previous issue date: 2010 Cell differentiation in multicellular organisms is a complex process whose mechanism can be understood by a reductionist approach, in which the individual processes that control the generation of different cell types are identified. Alternatively, a large-scale approach in search of different organizational features of the growth stages promises to reveal its modular global structure with the goal of discovering previously unknown relations between cell types. Here, we sort and analyze a large set of scattered data to construct the network of human cell differentiation (NHCD) based on cell types (nodes) and differentiation steps (links) from the fertilized egg to a developed human. We discover a dynamical law of critical branching that reveals a self-similar regularity in the modular organization of the network, and allows us to observe the network at different scales. The emerging picture clearly identifies clusters of cell types following a hierarchical organization, ranging from sub-modules to super-modules of specialized tissues and organs on varying scales. This discovery will allow one to treat the development of a particular cell function in the context of the complex network of human development as a whole. Our results point to an integrated large-scale view of the network of cell types systematically revealing ties between previously unrelated domains in organ functions.