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- Curtis, Bruce A., et al.
(författare)
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Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 492:7427, s. 59-65
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Tidskriftsartikel (refereegranskat)abstract
- Cryptophyte and chlorarachniophyte algae are transitional forms in the widespread secondary endosymbiotic acquisition of photosynthesis by engulfment of eukaryotic algae. Unlike most secondary plastid-bearing algae, miniaturized versions of the endosymbiont nuclei (nucleomorphs) persist in cryptophytes and chlorarachniophytes. To determine why, and to address other fundamental questions about eukaryote-eukaryote endosymbiosis, we sequenced the nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. Both genomes have >21,000 protein genes and are intron rich, and B. natans exhibits unprecedented alternative splicing for a single-celled organism. Phylogenomic analyses and subcellular targeting predictions reveal extensive genetic and biochemical mosaicism, with both host-and endosymbiont-derived genes servicing the mitochondrion, the host cell cytosol, the plastid and the remnant endosymbiont cytosol of both algae. Mitochondrion-to-nucleus gene transfer still occurs in both organisms but plastid-to-nucleus and nucleomorph-to-nucleus transfers do not, which explains why a small residue of essential genes remains locked in each nucleomorph.
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| 4. |
- Sobti, R. C., et al.
(författare)
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Aberrant promoter methylation and loss of suppressor of cytokine signalling-1 gene expression in the development of uterine cervical carcinogenesis
- 2011
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Ingår i: Cellular Oncology. - : Springer Science and Business Media LLC. - 2211-3428 .- 2211-3436. ; 34:6, s. 533-43
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cervical cancer is a leading cause of cancer related deaths in women worldwide caused due to infection of high-risk human papillomaviruses. As JAK/STAT signalling pathway has been shown to play an important role during carcinogenesis, we studied the role of silencing of Suppressor of Cytokine Signalling-1 (SOCS-1) gene, a negative regulator of JAK/STAT pathway in cervical cancer.METHODS: The expression pattern of SOCS-1 mRNA and protein was analyzed in different stages of cervical tumor biopsies while normal cervical tissues served as controls. RT-PCR, immunohistochemistry and methylation-specific PCR (MSP) were performed to assess the expression pattern and promoter methylation of SOCS-1 gene in a total of 120 fresh surgically resected cervical tissue specimens comprising precancer (n = 12), cancer (n = 78) and normal controls (n = 30).RESULTS: Compared with expression of SOCS-1 in normal tissues, 64% of the tumor tissues expressed either undetectable or reduced expression. Aberrant promoter methylation of SOCS-1 was found in 61% of the cervical tumor tissues. SOCS-1 expression and methylation were significantly associated with severity of the disease (p < 0.01).CONCLUSION: We demonstrate for the first time the transcriptional inactivation of SOCS-1 gene due to hypermethylation and synergism with HPV infection which may play an important role in cervical carcinoma.
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| 5. |
- Sobti, R. C., et al.
(författare)
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Overexpression of STAT3 in HPV-mediated cervical cancer in a north Indian population
- 2009
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Ingår i: Molecular and Cellular Biochemistry. - : Springer Science+Business Media B.V.. - 0300-8177 .- 1573-4919. ; 330:1-2, s. 193-9
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Tidskriftsartikel (refereegranskat)abstract
- The constitutively activated STAT family members, particularly STAT3, have been shown to possess transforming properties, and are strongly correlated with tumor development and progression. STAT3 transmits signals from many cytokines and growth factors to target genes in the nucleus through the Jak/Stat signaling pathway. HPV is the main etiological factor in the development of cervical cancer. In the current study, the expression of STAT3 was analyzed in various stages of HPV-mediated cervical carcinogenesis. Tissue biopsies from 100 patients with cervical cancer of different stages and normal tissues from patients undergoing hysterectomy were selected for studying the HPV status and STAT3 expression. HPV status of each corresponding biopsy was analyzed by PCR and typing. The mRNA expression was analyzed by reverse-transcriptase polymerase chain reaction (RT-PCR). HPV infection was detected in majority of cases: 75% (9/12) in precancer, 85% (34/40) stage I & II, and 95% (36/38) in stage III & IV of cervical cancer cases by L1 PCR. Further sub typing revealed HPV16 in 100% (9/9) of L1 positives in precancerous & 90% (63/70) in different stages of cancer. Significant level of STAT3 mRNA expression was predominantly found in cervical cancer cases as compared to normal controls (P = 0.001). We also found a significant correlation of STAT3 expression in cases infected with HPV (P = 0.001). Our results indicate a potentially interactive effect between HPV 16/18 and transcriptional activation of STAT3 gene in cervical carcinogenesis. To our knowledge, this is the first such study to be reported from India. Further investigations are needed to determine the influence of STAT3 expression on cervical carcinogenesis and its possible interaction with HPV infection status.
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