As Imortais Células HeLa

Em 1951, uma mulher americana, afro-descendente chamada Henrietta Lacks foi ao Hospital Johns Hopkins para ser tratada de um câncer de colo  úterino. Sem que soubesse suas células  foram disponibilizados para a pesquisa científica. Apesar da cirurgia em que foi submetida e do tratamento com radioterapia, Lacks morreu mais tarde naquele ano, mas sua linhagem de células – conhecidas como HeLa (sigla criada com as iniciais do seu nome ) ainda vivem e são utilizadas em diferentes áreas na pesquisa científica.

O fato de ter permanecido tanto tempo nas pesquisas é dado à enorme longevidade das células e na facilidade de cultivo e proliferação. São chamadas também de células imortais, por se dividirem um número ilimitado de vezes in vitro, uma característica compartilhada pela maioria das células malignas. Por  estes e outros motivos, que se tornaram células padrões para muitos estudos.Em comemoração à contribuição involuntária de Lacks para a ciência, 11 de outubro foi proclamado o seu dia oficial.

O site/blog WIRED Science publicou um infográfico com as descobertas realizadas com estas células. Realmente impressionante. O que pensaria se soubesse dos avanços que trouxe para ciência? fonte: Bio Interativa

wwp2 media Ubiquitinação da RNA polimerase em células embrionárias pluripotentes de ratos

Ubiquitination and the degradation of the large subunit of RNA polymerase II, Rpb1, is not only involved in DNA damage-induced arrest but also in other transcription-obstructing events. However, the ubiquitin ligases responsible for DNA damage-independent processes in mammalian cells remain to be identified. Here, we identified Wwp2, a mouse HECT domain ubiquitin E3 ligase, as a novel ubiquitin ligase of Rpb1. We found that Wwp2 specifically interacted with mouse Rpb1 and targeted it for ubiquitination both in vitro and in vivo. Interestingly, the interaction with and ubiquitination of Rpb1 was dependent neither on its phosphorylation state nor on DNA damage. However, the enzymatic activity of Wwp2 was absolutely required for its ubiquitin modification of Rpb1. Furthermore, our study indicates that the interactionbetween Wwp2 and Rpb1 was mediated through WW domain of Wwp2 and C-terminal domain of Rpb1, respectively. Strikingly, downregulation of Wwp2 expression compromised Rpb1 ubiquitination and elevated its intracellular steady-state protein level significantly. Importantly, we identified six lysine residues in the C-terminal domain of Rpb1 as ubiquitin acceptor sites mediated by Wwp2. These results indicate that Wwp2 plays an important role in regulating expression of Rpb1 in normal physiological conditions. Ver matéria (aqui)

efeito condrogênico da BMP-2 na diferenciação de células-tronco mesenquimais humanas adultas

Articular cartilage is essential for the motion of the skeleton. However, this tissue is unable to spontaneously repair once injured, since it is avascular and aneural. Numerous repair strategies are developed, but they do not lead to a functional tissue and research into cartilage repair focuses now on tissue engineering technics. Adultmesenchymal stemcells (MSC), present in various tissues, have the potential to differentiate into chondrocytes in vitro in response to specific growth factors. The members of the transforming growth factor b, among them the bone morphogenetic protein (BMP)-2, appear very promising inducers in this context. BMP-2 favours chondrogenic expression, in particular expression of type IIB collagen, the cartilage-specific isoform of this collagen. Therefore, collagen type IIB is a good indicator of the differentiation state of MSC. However, since BMP-2 has also osteogenic properties, it is critical to differentially control chondrogenic and osteogenic properties of BMP-2 when used withMSC. Strategies for this control are presented in this review.Most likely, this is the combination of growth factors such as BMP-2 with biomaterials that will lead to the successful use of MSC for cartilage repair. VER MATERIA

Efeitos de aerossol revestidos com hidroxiapatita em células-tronco mesenquimais

The bioactive properties of hydroxyapatite (HAP) are evaluated for applications involving the enhancement of biocompatible prostheses by seeding human pluripotent mesenchymal stem cells (MSCs). The in vitro response of humanMSCs seeded on aerosol–gel HAP coatings is addressed in this work. The processing of the HAP coatings has been carried out by the aerosol–gel technique using calcium nitrate and triethylphosphate as starting precursors. The characterization of the coatings was carried out by using transmission electron microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, energy disperse X-ray microanalysis, and surface force microscopy, which confirmed the high performance of the HAP coatings. In vitro tests show that humanMSCs adhere to aerosol–gel-derived HAP coatings and show proliferation signals on these surface. VER MATERIA