BackgroundPreviously published reports indicated that some enzymes of the central carbon metabolism (CCM), particularly those involved in glycolysis and the tricarboxylic acid cycle, may contribute to regulation of DNA replication. However, vast majority of such works was performed with the use of cancer cells, in the light of carcinogenesis. On the other hand, recent experiments conducted on bacterial models provided evidence for the direct genetic link between CCM and DNA replication. Therefore, we asked if silencing of genes coding for glycolytic and/or Krebs cycle enzymes may affect the control of DNA replication in normal human fibroblasts.ResultsParticular genes coding for these enzymes were partially silenced with specific siRNAs. Such cells remained viable. We found that silencing of certain genes resulted in either less efficient or delayed enterance to the S phase. This concerned following genes: HK2, PFKM, TPI, GAPDH, ENO1, LDHA, CS1, ACO2, SUCLG2, SDHA, FH and MDH2. Decreased levels of expression of HK2, GADPH, CS1, ACO2, FH and MDH2 caused also a substantial impairment in DNA synthesis efficiency.ConclusionsThe presented results illustrate the complexity of the influence of genes coding for enzymes of glycolysis and the tricarboxylic acid cycle on the control of DNA replication in human fibroblasts, and indicate which of them are especially important in this process.Electronic supplementary materialThe online version of this article (doi:10.1186/s12860-015-0062-8) contains supplementary material, which is available to authorized users.

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Mucopolysaccharidoses (MPS) are severe inherited metabolic disorders caused by storage of glycosaminoglycans (GAGs). The level of accumulated GAGs is an important parameter in assessment of the severity of the disease and the efficacy of treatment; unfortunately, biochemical methods are often unreliable and only semi-quantitative. Therefore, finding other methods for estimation of GAG levels and/or assessment of the efficacy of applied therapy is very important. Although monitoring of GAG levels during therapy is crucial, in this work it is proposed that analysis of the ultrastructure of MPS cells by electron microscopic techniques can be considered as an alternative and reliable method for assessment of lysosomal storage. The number of complex lysosomal structures was found to be significantly higher in MPS cells relative to controls, while it decreased significantly in response to either enzyme replacement therapy or substrate reduction therapy. Thus, this parameter, easily assessed by electron microscopy, appears to correspond to the physiological state of MPS cells.