October 20th, 2009

homuncul

Про стволовые клетки: непорядок

Journal of Biology опубликовал заметку Arthur D. Lander, уважаемого специалиста по клеточной биологии из Калифорнийского университета. Автор утверждает, что стволовую клетку следует рассматривать не как тип, а как состояние. Будет ли клетка иметь «стволовые» свойства, определяется не ее молекулярным содержанием, а ее положением в ткани и обратной связью с окружением (через транскрипционные регуляторы). Фактически, стволовая клетка - это не сущность, а свойство ниши, возникающей в популяции клеток.

The 'stem cell' concept: is it holding us back? (2009):

…it suggests that stemness is a property of systems, rather than cells, with the relevant system being, at minimum, a cell lineage, and more likely a lineage plus an environment. A system with stemness is typically one that can achieve a controlled size, maintain itself homeostatically, and regenerate when necessary. Moreover, it most probably does so by exploiting basic principles of feedback control. If stemness is a system-level property, then the concept of stem cell is really fundamentally different from that of, say, gene. A more similar concept might be something like 'rate-limiting enzyme', which also defines a class of tangible, physical objects, but only does so in terms of their functional roles within a system, not their intrinsic biochemical properties.

Аргументацию понял не до конца. Однако в другой статье не менее уважаемый специалист по стволовым клеткам утверждает то же самое:

I therefore propose that small, quantitative differences in gene expression account for the establishment of a stem-cell state, using molecular machineries that are also found in the differentiated state and are ubiquitous to all cells, such as the cell-cycle control proteins and signalling cascades. Stemness might be a transient and reversible trait that almost any cell can assume given the correct trigger (niche) and that is characterized by having many potential outcomes but no specialization.

Nature Reviews Genetics The nature of stem cells: state rather than entity

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