The Protein Composition of the Hepatocyte Nuclear Matrix Is Differentiation‐Stage Specific

Abstract

SummaryThe protein composition of hepatocyte nuclear matrices was examined in rats from the 16th day of gestation to 75 days after birth (adult). An overall increase in size of the nuclear matrix was accompanied by quantitative and qualitative changes in its protein content. Quantitative changes of the major proteins of the peripheral lamina surrounding the isolated nuclear matrix were detected. By Western analysis we established that in pre-and postnatal nuclear matrices the relative concentrations of lamin C were greater than lamin A. After birth, the relative concentrations of both lamins progressively increased. In the adult nuclear matrix, the concentration of lamin A was greater than lamin C. In contrast, the relative concentrations of lamin B remained unchanged throughout development and growth. The relative concentrations of two nuclear matrix -associated regulatory proteins studied changed with development and growth: transcription factor C/EBP® isoforms, which were detected during the gestation period, increased notably after the rst postnatal day, attaining a maximum at the adult stage; the high concentrations of the proliferating cell nuclear antigen (PCNA) perceptibly decreased after the 21st prenatal day. Changes in the composition of the nuclear matrix protein suggest that this structure coordinates nuclear functioning during cell differentiation.IUBMB Life, 49: 511 -517, 2000 Keywords C/EBPa ; hepatocyte development; lamins; nuclear matrix; PCNA.The nuclear matrix is a proteinaceous structural framework of the nucleus. The isolated matrix has a tripartite structure and

A structural basis for cellular senescence

“…However, the NM undergoes quantitative changes of the major constituent proteins such as lamins A, B and C, as well as changes in the ratios of such proteins [52,71], this is consistent with previous studies comparing the NM of young and aged human fibroblasts, using 2D electrophoresis [72]. The noticeable increase with age of the three nuclear lamins seems to be relevant to the obvious strengthening of the NM with age [52].…”

“…The mean compactness of the NM proteins decreases during development being in the adult rat one fourth of that in the 16-day foetus, suggesting that the NM protein network becomes more extended as development progresses [71]. Such a reduction of NM-protein compactness suggest the progressive shift from a nuclear substructure consisting of unconnected, merely clustered ribonucleoprotein (RNP) fibres and granules to a mature, continuous internal network consisting of interconnected and branched RNP filaments that connect to the nuclear lamina [39,74,75].…”