Autonomous informational stability in connective tissues.
No coherent theories currently explain connective tissue stability (i.e. 'memory') as well as spatial and temporal adaptability in the face of continual flux of its constituents. Furthermore, explanations of stability based exclusively upon DNA raise certain inherent problems, particularly with the spatial concordance of somatic tissues. As an alternative explanation, it is hypothesized that while connective tissue cells produce extracellular protein precursors through DNA-dependent processes, the assembly, location, orientation and configuration of the extracellular macromolecules as well as their degree of cell attachment depend primarily upon local micro-environmental conditions and/or self-organization rather than strictly cellular processes. The resulting extracellular matrix (ECM) serves as a time- and spatially-variable filter about each cell to afford a relatively consistent micro-environment for all similar cells, regardless of the more variable macro-environment. By insuring a consistent set of signals to the cell, the filter provides a non-genetic memory complementary to genetic memory. The half-lives of constituent molecules define the duration of the filter, allowing the filter to adapt to new environmental demands, yet to maintain a consistent milieu for the cell. The cell/matrix construct permits local, self-optimizing, non-deterministic tissue autonomy obviating the need to postulate certain intricate mechanisms coordinating spatial morphology and temporal behavior.
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Department of Orthopaedic Surgery, University of Iowa, Iowa City 52242.
D000818:Animals; D003238:Connective Tissue / Q000033:anatomy & histology / Q000502:physiology*; D004247:DNA / Q000235:genetics; D005109:Extracellular Matrix / Q000502:physiology; D006801:Humans; D008954:Models, Biological; D015398:Signal Transduction / Q000502:physiology
D004247:DNA