Function of the amino-terminal region of human MCM4 in helicase activity

MCM complex members MCM3 and MCM7 are associated with a phenotypic spectrum from Meier-Gorlin syndrome to lipodystrophy and adrenal insufficiency

The MCM2-7 helicase is a heterohexameric complex with essential roles as part of both the pre-replication and pre-initiation complexes in the early stages of DNA replication. Meier-Gorlin syndrome, a rare primordial dwarfism, is strongly associated with disruption to the pre-replication complex, including a single case described with variants in MCM5. Conversely, a biallelic pathogenic variant in MCM4 underlies immune deficiency with growth retardation, features also seen in individuals with pathogenic variants in other pre-initiation complex encoding genes such as GINS1, MCM10, and POLE. Through exome and chromium genome sequencing, supported by functional studies, we identify biallelic pathogenic variants in MCM7 and a strong candidate biallelic pathogenic variant in MCM3. We confirm variants in MCM7 are deleterious and through interfering with MCM complex formation, impact efficiency of S phase progression. The associated phenotypes are striking; one patient has typical Meier-Gorlin syndrome, whereas the second case has a multi-system disorder with neonatal progeroid appearance, lipodystrophy and adrenal insufficiency. We provide further insight into the developmental complexity of disrupted MCM function, highlighted by two patients with a similar variant profile in MCM7 but disparate clinical features. Our results build on other genetic findings linked to disruption of the pre-replication and pre-initiation complexes, and the replisome, and expand the complex clinical genetics landscape emerging due to disruption of DNA replication.

Coexpression Analysis of the EZH2 Gene Using The Cancer Genome Atlas and Oncomine Databases Identifies Coexpressed Genes Involved in Biological Networks in Breast Cancer, Glioblastoma, and Prostate Cancer

BACKGROUND This study aimed to perform coexpression analysis of the EZH2 gene using The Cancer Genome Atlas (TCGA) and the Oncomine databases to identify coexpressed genes involved in biological networks in breast cancer, glioblastoma, and prostate cancer, with functional analysis of the EZH2 gene in the C4-2 human prostate cancer cell line in vitro. MATERIAL AND METHODS Data from TCGA and Oncomine databases were analyzed to determine the expression of EZH2 and the top five coexpressed genes in breast cancer, glioblastoma, and prostate cancer and the clinical significance the coexpressed genes. Gene Ontology (GO) analysis was performed to predict the functions and pathways of EZH2 using pathway annotation. The role of EZH2 in the C4-2 human prostate cancer cell line was studied in vitro. RESULTS Analysis of 16 micro-arrays identified 185 genes that were coexpressed with EZH2. The top five coexpressed genes were MCM4, KIAA0101, MKI67, RRM2, and CDC25a. Increased expression of these genes and EZH2 were associated with reduced survival. Coexpressed genes were involved in biological networks associated with the cell cycle, mitosis, and DNA damage. The effects of EZH2 on prostate cancer cell was validated in vitro as knockdown of EZH2 resulted in a G2/M cell cycle arrest, increased DNA damage, and reduced colony number. CONCLUSIONS Coexpression analysis of EZH2 identified its role in the cell cycle, mitosis, and DNA repair. The molecular mechanisms involved in EZH2 gene expression in the cell response to DNA damage requires further study to determine whether EZH2 is a potential human cancer biomarker.