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The “occlusis” model of cell fate restriction
Author(s) -
Lahn Bruce T.
Publication year - 2011
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/bies.201000090
Subject(s) - biology , somatic cell , cell fate determination , germline , chromatin , gene , genetics , lineage (genetic) , genome , zygote , cellular differentiation , regulation of gene expression , microbiology and biotechnology , evolutionary biology , transcription factor , embryogenesis
A simple model, termed “occlusis”, is presented here to account for both cell fate restriction during somatic development and reestablishment of pluripotency during reproduction. The model makes three assertions: (1) A gene's transcriptional potential can assume one of two states: the “competent” state, wherein the gene is responsive to, and can be activated by, trans ‐acting factors in the cellular milieu, and the “occluded” state, wherein the gene is blocked by cis ‐acting, chromatin‐based mechanisms from responding to trans ‐acting factors such that it remains silent irrespective of whether transcriptional activators are present in the milieu. (2) As differentiation proceeds in somatic lineages, lineage‐inappropriate genes shift progressively and irreversibly from competent to occluded state, thereby leading to the restriction of cell fate. (3) During reproduction, global deocclusion takes place in the germline and/or early zygotic cells to reset the genome to the competent state in order to facilitate a new round of organismal development.