The Set of Structural DNA-Nuclear Matrix Interactions in Neurons Is Cell-Type Specific and Rather Independent of Functional Constraints.

In metazoans, nuclear DNA is organized during the interphase in negatively supercoiled loops anchored to a compartment or substructure known as the nuclear matrix. The interactions between DNA and the nuclear matrix (NM) are of higher affinity than those between DNA and chromatin proteins since the last ones do not resist the procedures for extracting the NM. The structural interactions DNA-NM constitute a set of topological relationships that define a nuclear higher order structure (NHOS) although there are further higher order levels of organization within the nucleus. So far, the evidence derived from studies with primary hepatocytes and naïve B lymphocytes indicates that the NHOS is cell-type specific at the local and at the large-scale level, and so it has been suggested that such NHOS is primary determined by structural and thermodynamic constraints. We carried out a comparative characterization of the NHOS of postmitotic cortical neurons with that of hepatocytes and naïve B lymphocytes. Our results indicate that the NHOS of neurons is completely different at the large scale and at the local level from that one observed in hepatocytes or in naïve B lymphocytes, confirming on the one hand that the set of structural DNA-NM interactions is cell-type specific and supporting, on the other hand the notion that structural constraints that impinge on chromosomal DNA and the NM are more important for determining this NHOS than functional constraints related to replication and/or transcription. J. Cell. Biochem. 118: 2151-2160, 2017. © 2016 Wiley Periodicals, Inc.