Rekayasa Bakteri Untuk Ternak Dan Manusia: Pembuatan Mutan Escherichia Coli Penghasil Protein Rekombinan

Protein rekombinan seperti vaksin, antibodi, hormon, dan obat-obatan, semakin dibutuhkan oleh ternak dan manusia. Hambatan utama untuk menghasilkan protein rekombinan pada Escherichia coli sebagai inang yang digunakan paling luas adalah degradasi oleh enzim proteolitik. Hal ini disebabkan karena E. coli memiliki sejumlah enzim proteolitik yang tersebar di dalam sitoplasmanya. Untuk itu, lebih dari 90% degradasi protein terjadi di dalam sitoplasmanya. Pada penelitian ini, peneliti telah menghasilkan mutant E. coli BW25113 yang tidak memiliki gen penyandi enzim protease dengan menggunakan kombinasi metode pengerusakan kromosom dan metode transduksi phage P1. Pembuatan mutan tersebut dimulai dengan pengerusakan gen penyandi enzim protease pada kromosom bakteri dengan produk PCR yang memiliki bagian yang homolog dengan gen target. Mutan-mutan yang dihasilkan kemudian digunakan untuk menghasilkan mutan ganda dengan metode Transduksi phage P1. Analisis fenotif dan genotif menunjukkan bahwa kombinasi kedua metode tersebut sangat efektif untuk membuat lebih dari satu mutasi pada E. coli. Untuk itu, mutan E. coli yang telah diperoleh akan sangat bermanfaat untuk menghasilkan aneka protein rekombinan untuk ternak dan manusia

The expression of the ubiquitin ligase SIAH2 (seven in absentia homolog 2) is mediated through gene copy number in breast cancer and is associated with a basal-like phenotype and p53 expression

Introduction: The seven in absentia homolog 2 (SIAH2) protein plays a significant role in the hypoxic response by regulating the abundance of hypoxia-inducible factor-α; however, its role in breast carcinoma is unclear. We investigated the frequency and expression pattern of SIAH2 in two independent cohorts of sporadic breast cancers.Methods: Immunohistochemical evaluation of SIAH2protein expression was conducted in normal breast tissues and in tissue microarrays comprising ductal carcinoma in situ (DCIS) and a cohort of invasive breast carcinomas. Correlation analysis was performed between SIAH2 and clinicopathological variables and intrinsic breast cancer subgroups and validated in a cohort of 293 invasive ductal carcinomas. Promoter methylation, gene copy number and mRNA expression of SIAH2 were determined in a panel of basal-like tumors and cell lines.Results: There was a significant increase in nuclear SIAH2 expression from normal breast tissues through to DCIS and progression to invasive cancers. A significant inverse correlation was apparent between SIAH2 and estrogen receptor and progesterone receptor and a positive association with tumor grade, HER2, p53 and an intrinsic basal-like subtype. Logistic regression analysis confirmed the significant positive association between SIAH2 expression and the basal-like phenotype. No SIAH2 promoter methylation was identified, yet there was a significant correlation between SIAH2 mRNA and gene copy number. SIAH2-positive tumors were associated with a shorter relapse-free survival in univariate but not multivariate analysis.Conclusions: SIAH2 expression is upregulated in basal-like breast cancers via copy number changes and/or transcriptional activation by p53 and is likely to be partly responsible for the enhanced hypoxic drive through abrogation of the prolyl hydroxylases