Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A recombinant nonreplicating human adenovirus type 5, Ad5HCMVsp1lacZ, expressing the lacZ gene under control of the human cytomegalovirus immediate early promoter, was used to assess the effect of heat-shock (HS) on DNA repair of a UV-damaged reporter gene. Host cell reactivation (HCR) of beta-galactosidase (beta-gal) activity for UV-irradiated Ad5HCMVsp1lacZ was used as an indicator of DNA repair in the transcribed strand of an active gene. Repair was examined in heat-shock (HS) pretreated and mock-treated normal fibroblasts, normal lung epithelial cells, xeroderma pigmentosum group A, C, D and G fibroblasts (XP-A, XP-C, XP-D and XP-G), Cockayne's syndrome group A fibroblasts (CS-A), SV40-transformed normal fibroblasts (GM637f) and 5 tumour cell lines (SKOV-3, HeLa, HT29, SCC-25 and U20S). HS enhanced reactivation (HSER) of the reporter gene was detected in normal cells, HT29 tumour cells and XP-C fibroblasts. HSER was reduced or absent in all other XP, CS and tumour cell lines tested. HSER in normal and XP-C cell lines, but not CS-A, XP-A, XP-D or XP-G cells, suggests that HS treatment can enhance the repair of UV-damaged DNA through an enhancement of transcription coupled repair (TCR) or a mechanism which involves the TCR pathway. Since this response was absent in the SV40-transformed fibroblast cell line and 4 of 5 tumour cell lines examined, HSER of beta-gal activity for UV-irradiated Ad5HCMVsp1lacZ also requires some cellular function(s) affected by transformation.
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PMID:Heat-shock enhanced reactivation of a UV-damaged reporter gene in human cells involves the transcription coupled DNA repair pathway. 867 26

Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are human hereditary disorders characterized at the cellular level by an inability to repair certain types of DNA damage. Usually, XP and CS are clinically and genetically distinct. However, in rare cases, CS patients have been shown to have mutations in genes that were previously linked to the development of XP. The linkage between XP and CS has been difficult to study because few permanent cell lines have been established from XP/CS patients. To generate permanent cell lines, primary fibroblast cultures from two patients, displaying characteristics associated with CS and belonging to XP complementation group G, were transformed with anorigin-of-replication-deficient simian virus 40 (SV40). The new cell lines, summation operatorXPCS1LVo- and summation operatorXPCS1ROo-,were characterized phenotypically and genotypically to verify that properties of the primary cells are preserved after transformation. The cell lines exhibited rapid growth in culture and were shown, by immunostaining, to express the SV40 T antigen. The summation operatorXPCS1LVo- and summation operatorXPCS1ROo- cell lines were hypersensitive to UV light and had an impaired ability to reactivate a UV-irradiated reporter gene. Using polymerase chain reaction (PCR) amplification and restriction enzyme cleavage, the summation operatorXPCS1ROo- cells were shown to retain the homozygous T deletion at XPG position 2972. This mutation also characterizes the parental primary cells and was evident in the XPG RNA. Finally, to characterize the XPG DNA repair deficiency in these cell lines, an episomal expression vector containing wild-type XPG cDNA was used to correct UV-induced damage in a beta-galactosidase reporter gene.
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PMID:Complementation of transformed fibroblasts from patients with combined xeroderma pigmentosum-Cockayne syndrome. 971 45

The genetic disorders xeroderma pigmentosum (XP) and Cockayne syndrome (CS) exhibit deficiencies in the repair of UV-induced DNA damage. CS fibroblasts retain proficient nucleotide excision repair (NER) of inactive (or bulk) DNA, but are deficient in the transcription-coupled repair (TCR) of active genes. In contrast, XP complementation group C (XP-C) fibroblasts retain proficient TCR, but are deficient in bulk DNA repair. The remaining NER-deficient XP groups exhibit deficiencies in both repair pathways. Ad5HCMVsp1lacZ is a recombinant adenovirus vector that is unable to replicate in human fibroblasts, but can efficiently infect and express the beta-galactosidase reporter gene in these cells. We have examined the host cell reactivation (HCR) of beta-galactosidase activity for UV-irradiated Ad5HCMVsp1lacZ in non-irradiated and UV-irradiated normal, XP-B, XP-C, XP-D, XP-F, XP-G, CS-A and CS-B fibroblasts. HCR of beta-galactosidase activity for UV-irradiated Ad5HCMVsp1lacZ was reduced in non-irradiated cells from each of the repair-deficient groups examined (including XP-C) relative to that in non-irradiated normal cells. Prior irradiation of cells with low UV fluences resulted in an enhancement of HCR for normal and XP-C strains, but not for the remaining XP and CS strains. HCR of the UV-damaged reporter gene in UV-irradiated XP and CS strains was similar to measurements of TCR reported previously for these cells. These results suggest that UV treatment results in an induced repair of UV-damaged DNA in the transcribed strand of an active gene in XP-C and normal cells through an enhancement of TCR or a mechanism which involves the TCR pathway.
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PMID:UV-enhanced reactivation of a UV-damaged reporter gene suggests transcription-coupled repair is UV-inducible in human cells. 993 45

There is conflicting evidence for the role of the mismatch repair (MMR) genes hMLH1 and hMSH2 in the transcription-coupled repair (TCR) pathway of nucleotide excision repair. In the present work, we have examined the role of these MMR genes in nucleotide excision repair using two reporter gene assays. AdHCMVlacZ is a replication-deficient recombinant adenovirus that expresses the beta-galactosidase reporter gene under the control of the human cytomegalovirus immediate early promoter. We have reported previously a reduced host cell reactivation (HCR) for beta-galactosidase expression of UVC-irradiated AdHCMVlacZ in TCR-deficient Cockayne syndrome (CS) fibroblasts compared with normal fibroblasts, indicating that HCR depends, at least in part, on TCR. In addition, we have reported that UVC-enhanced expression of the undamaged reporter gene is induced at lower UVC fluences to cells and at higher levels after low UVC fluences in TCR-deficient compared with normal human fibroblasts, suggesting that persistent damage in active genes triggers increased activity from the human cytomegalovirus-driven reporter construct. We have examined HCR and UV-enhanced expression of the reporter gene in hMLH1-deficient HCT116 human colon adenocarcinoma cells and HCT116-chr3 cells (the MMR-proficient counterpart of HCT116) as well as hMSH2-deficient LoVo human colon adenocarcinoma cells and their hMSH2-proficient counterpart SW480 cells. We show a greater UV-enhanced expression of the undamaged reporter gene after low UVC exposure in HCT116 compared with HCT116-chr3 cells and in LoVo compared with SW480 cells. We show also a reduced HCR in HCT116 compared with HCT116-chr3 cells and in LoVo compared with SW480 cells. However, the reduction in HCR was less or absent when cells were pretreated with UVC. These results suggest that detection of an involvement of hMLH1 and hMSH2 in TCR is dependent on UVC (254 nm) fluence to cells.
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PMID:Detection of an involvement of the human mismatch repair genes hMLH1 and hMSH2 in nucleotide excision repair is dependent on UVC fluence to cells. 1517 95

We have used a non-replicating recombinant adenovirus, Ad5HCMVlacZ, which expresses the beta-galactosidase (beta-gal) reporter gene, to examine the time course of UV-inducible repair of UV-damaged DNA in human fibroblasts. Host cell reactivation (HCR) of beta-gal activity for UV-irradiated Ad5HCMVlacZ was examined in non-irradiated and UV-irradiated nucleotide excision repair (NER) proficient normal human fibroblasts, xeroderma pigmentosum (XP) group C fibroblasts which are defective in the global genomic repair (GGR) pathway of NER and Cockayne syndrome (CS) fibroblasts which are defective in the transcription coupled repair (TCR) pathway of NER. HCR was deficient in untreated XP-C and CS cells indicating that both TCR and GGR are involved in removal of photolesions from the transcribed strand of the reporter gene in unirradiated human cells as reported previously. Prior UV-irradiation of cells with low UV fluences resulted in a transient enhancement of HCR in normal and XP-C fibroblasts that reached a maximum when cells were infected at 25-35 h after UV. In contrast, UV-enhanced HCR was delayed in CS-B cells, reaching levels similar to that in normal cells only when cells were infected between 40 and 60 h after UV exposure. These results are consistent with a UV-induced up-regulation of GGR through a TCR dependent pathway in CS cells.
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PMID:Enhanced host cell reactivation of a UV-damaged reporter gene in pre-UV-treated cells is delayed in Cockayne syndrome cells. 1612 67

Ultraviolet (UV) light-induced DNA damage is repaired by nucleotide excision repair, which is divided into two sub-pathways: global genome repair (GGR) and transcription-coupled repair (TCR). While it is well established that the GGR pathway is dependent on the p53 tumour suppressor protein in human cells, both p53-dependent and p53-independent pathways have been reported for TCR. In the present work, we investigated the role of p53 in both GGR and TCR of a UVC-damaged reporter gene in human fibroblasts. We employed a non-replicating recombinant human adenovirus, AdCA17lacZ, that can efficiently infect human fibroblasts and express the beta-galactosidase (beta-gal) reporter gene under the control of the human cytomegalovirus promoter. We examined host cell reactivation (HCR) of beta-gal expression for the UVC-treated reporter construct in normal fibroblasts and in xeroderma pigmentosum (XP) and Cockayne syndrome (CS) fibroblasts deficient in GGR, TCR, or both. HCR was examined in fibroblasts that had been pre-infected with Ad5p53wt, which expresses wild-type p53, or a control adenovirus, AdCA18luc, which expresses the luciferase gene. We show that increased expression of p53 results in enhanced HCR of the UVC-damaged reporter gene in both untreated and UVC-treated cells for normal, CS-B (TCR-deficient), and XP-C (GGR-deficient), but not XP-A (TCR- and GGR-deficient) fibroblasts. These results indicate an involvement of p53 in both TCR and GGR of the UV-damaged reporter gene in human cells.
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PMID:Increased expression of p53 enhances transcription-coupled repair and global genomic repair of a UVC-damaged reporter gene in human cells. 1719 45