New molecular biologist perspective and insight: DNA topoisomerases production by recombinant DNA technology for medical laboratory application and pharmaceutical industry

DNA topoisomerases are essential enzymes that control the topological state of DNA replication during mitosis. These enzymes are classified based on their mechanisms and physical properties. During mitosis, superhelical DNA must be unwound or relaxed by DNA topoisomerases prior to a decoding step by DNA processing enzymes, such as DNA polymerase and RNA polymerase. By blocking the reaction of resealing the breaks in the DNA ultimately can result in cellular death. Compounds that inhibit the catalytic function of these enzymes can serve as potential anticancer agents. DNA topoisomerases are found in nature and used as high quality and well-validated targets for the screening of potential anticancer agents. Our current work focuses on determining potential anticancer agents from natural resources using DNA topoisomerases as the screening targets. Large scale production of these enzymes using recombinant DNA technology in our academic laboratory is utilised to avoid dependence on expensive commercially available enzymes. The in-house produced enzymes can also be used to enhance our research in the field of molecular medicine by providing an enzyme source that can be used to screen potential anticancer agents, and for other newly developed diagnostic and medical research projects in the near future as well as a step in moving our efforts into the industrial sector.

Biologia molecular dos defeitos genéticos de síntese, transporte e açäo periférica dos hormônios da glândula tireóide / Molecular biology of the genetic defects of synthesis, transport and peripheral action of the thyroid gland hormones

Os avanços da biologia molecular e o emprego de técnicas de identificaçäo de porçöes de DNA codificadoras para proteínas importantes na síntese, armazenamento, transporte e açäo periférica dos hormônios tireoideos, permitiram a elucidaçäo, a nivel molecular, da etiologia de várias condiçöes genéticas da tireóide. Em pacientes com defeito na peroxidase tireóidea (TPO) observou-se a presença de polimorfismo (RFLP) com a endonuclease Bgl-I que se segrega, em 2 alelos, com o fenótipo com bócio, hipotireoidismo e teste de perclorato positivo. Em defeitos da tireoglobulina (Tg), observou-se nível quantitativamente baixo de Tg, concomitante com a virtual ausência da RNA mensageiro para a Ig. Por outro lado, a ausência de incorporaçäo de ácido siálico na molécula de Tg, produz proteína com defeito estrutural que impede a síntese adequada de T3 e T4. Tais defeitos da Tg säo igualmente encontrados em animais com bócio congênito (gados bovino e caprino, e camundongos cog/cog). A presença de mutaçäo puntiforme no nucleotídeo 281 do exon 5 do RNA da globulina carreadora de T4 (TBG) leva a expressäo genética de proteína instável, com queda da TBG sérica. O efeito nos receptores nucleares de T3 estäo ligados ao gene codificador (c-erb-A-beta) localizado no cormossoma 3. A presença de polimorfismo EcorRV nos indivíduos, sugere gene mutante codificando proteína que poderia näo fixar T3 ou produzir proteína anômala com atividade bloqueadora da açäo de T3 impedindo a fixaçäo nuclear