Aß biology and its contribution to Alzheimer's disease

A doença de Alzheimer (DA) é uma desordem neurodegenerativa progressiva patologicamente caracterizada pela presença de placas de amilóide (placas senis) insolúveis e também pela presença de tranças neurofibrilhares,formadas pela proteína Tau hiperfosforiladada. O principal constituinte das placas senis é o peptídeo beta-amilóide (Ab), que deriva do processamento proteolítico da proteína precursora de amilóide de Alzheimer (APP). Embora Ab exista como um agregado pouco solúvel nas placas senis, ele é secretado pelas células como uma molécula solúvel. O Ab “per se” pode afectar o metabolismo da APP. Alguns autores sugerem que o Ab exerce o seu efeito alterando o processamento ou catabolismo da APP, outros sugerem que ele também induz a transcrição da APP, onde aumentando os níveis da APP pode estar a contribuir para a sua própria produção (mecanismo de “feedback” positivo). Assim sendo, torna-se difícil consolidar todas estas observações e identificar as potenciais funções fisiológicas do Ab “in vivo”, ou as consequências da sua produção. Neste trabalho caracterizaram-se os efeitos do Ab no metabolismo da APP. Os nossos estudos revelaram que um dos mecanismos induzidos pelo Ab é a acumulação intracelular do fragmento neuroprotector sAPP (isAPPa) em estruturas com características vesiculares associadas ao citosqueleto. Estudos adicionais em culturas primárias revelaram que o Ab estava a exercer o seu efeito ao nível da secreção vesicular, provavelmente interferindo com o transporte de APP/sAPP ao longo da rede do citosqueleto. Esta hipótese é sustentada pelo facto do Ab estar a afectar a estabilidade e a polimerização de proteínas envolvidas na dinâmica do citosqueleto. Contrariamente a publicações anteriores o Ab não induziu a transcrição da APP, na verdade em culturas primárias neuronais foi observado uma diminuição nos níveis de expressão da APP. Isto foi acompanhado por um aumento nos fragmentos C-terminais da APP (CTFs) e uma diminuição na localização nuclear do seu domínio intracelular (AICD), sugerindo alterações na sinalização nuclear da APP. O Ab pode afectar outras vias de sinalização, particularmente alterando o balanço entre as actividades das proteínas cinases e fosfatases, o que pode ter consequências para o desenvolvimento da doença. Os dados obtidos indicam que o Ab é capaz de inibir a actividade da proteína fosfatase1, a sua importância numa perspectiva de futuras terapias é discutida. Devido à relevância da agregação do Ab para a sua toxicidade, a formação de complexos com proteínas que promovem a sua desagregação/degradação e o seu efeito no processamento da APP foi avaliado. Na presença destes complexos observou-se uma reversão da acumulação isAPP, demonstrando o potencial terapêutico destas proteínas como moduladores do metabolismo da APP. Este trabalho permitiu compreender melhor os mecanismos envolvidos nos efeitos do Ab no processamento da APP e descobrir algumas moléculas que podem ser relevantes numa perspectiva de diagnóstico e terapia na DA.

Suppressors of cytokine signaling : functions in normal biology and roles in disease

Suppressor of cytokine signaling (SaCS) proteins have been identified as key negative regulators of cytokine and growth factor signaling. Therefore, given the diverse roles played by cytokines and growth factors in development and disease, it is not surprising that the sacs proteins themselves possess equally diverse and important functions, such as the control of hematopoiesis, immune function, growth and placental development. Significantly, more recent studies are increaSingly highlighting the crucial roles played by SOCS proteins in disease, particularly their tumor suppressor and anti-infammatory functions. Collectively, this research has served to confirm the importance of this class of proteins and suggests that therapeutic strategies for modulating SOCS proteins might be relevant for a range of diseases.

Dissecting ADAMTS proteoglycanase biology in development and disease

 This research was focused upon members of the ADAMTS family of 'proteinases', proteins that have enzymatic activity. Their dysregulation can cause developmental defects and disease. This thesis describes the expression and regulation of ADAMTS15, as well as new developmental functions and inhibition of ADAMTS5 in arthritis.

Transcriptomics and systems biology analysis in identification of specific pathways involved in cacao resistance and susceptibility to witches' broom disease

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Chagas disease and triatomine biology (Heteroptera, Triatominae), with emphasis on aspects of spermatogenesis

A century after the discovery of Chagas disease, it is still one of the most important parasitic diseases affecting humans. The subfamily Triatominae is important in medical health, because these insects are vectors of Trypanosoma cruzi, the etiologic agent of Chagas disease. These insects are also of important cytological relevance because they have particular cell characteristics, such as persistence of nucleolar material in spermatogenesis. The germ cells of the animal kingdom have chromatoid bodies (CBs) in their cytoplasm that can originate from nucleolar material that is fragmented in the early stages of spermatogenesis and plays an important role in cellular communication between the spermatids during spermiogenesis. Currently, there are few studies on the function and formation of the CB in nucleologenesis, especially with emphasis on the ultrastructure of the cells involved in spermatogenesis of insects. Considering the importance of knowledge about the triatomine fauna, we conducted a study of the biogeography and reports of these insects and a survey of patients with Chagas disease in the northwestern region of São Paulo State. Data collected from 1995 to 2009 indicated 700 individuals with Chagas disease, demonstrating a range of 0 to 40 years, which shows that the disease may be active in this region. Moreover, of the 1150 patients treated for cardiomyopathy, 44% were chagasic. Regarding the triatomines noted and captured in the period from 2004 to 2009, the species were Triatoma sordida and Rhodnius neglectus, with T. sordida being the most abundant. In addition, some triatomines were infected by T. cruzi in various developmental stages. We also analyzed the nucleolar cycle and fibrillarin nucleolar protein expression in CB of spermatogenic cells of T. infestans and T. sordida, using histological, ultrastructural and immunocytochemical techniques. The results revealed fibrillarin nucleolar protein expression in the nucleus and in some cytoplasmic spots of germ cells during spermatogenesis in triatomines. These data suggest that fibrillarin could be a constituent of CB, which was most likely derived from nucleolar fragmentation. This is the first time that fibrillarin protein expression has been shown in CB during spermatogenesis progression in triatomines. Knowledge about the biology of triatomines was deepened in this study and, in particular, the structural and ultrastructural aspects of spermatogenesis in triatomines. This study showed that the disease may be active in the northwestern region of São Paulo and expanded our knowledge of the biology of triatomines, the main vectors of Chagas disease. © FUNPEC-RP.

Toward cell therapy using placenta-derived cells: disease mechanisms, cell biology, preclinical studies, and regulatory aspects at the round table

Among the many cell types that may prove useful to regenerative medicine, mounting evidence suggests that human term placenta-derived cells will join the list of significant contributors. In making new cell therapy-based strategies a clinical reality, it is fundamental that no a priori claims are made regarding which cell source is preferable for a particular therapeutic application. Rather, ongoing comparisons of the potentiality and characteristics of cells from different sources should be made to promote constant improvement in cell therapies, and such comparisons will likely show that individually tailored cells can address disease-specific clinical needs. The principle underlying such an approach is resistance to the notion that comprehensive characterization of any cell type has been achieved, neither in terms of phenotype nor risks-to-benefits ratio. Tailoring cell therapy approaches to specific conditions also requires an understanding of basic disease mechanisms and close collaboration between translational researchers and clinicians, to identify current needs and shortcomings in existing treatments. To this end, the international workshop entitled "Placenta-derived stem cells for treatment of inflammatory diseases: moving toward clinical application" was held in Brescia, Italy, in March 2009, and aimed to harness an understanding of basic inflammatory mechanisms inherent in human diseases with updated findings regarding biological and therapeutic properties of human placenta-derived cells, with particular emphasis on their potential for treating inflammatory diseases. Finally, steps required to allow their future clinical application according to regulatory aspects including good manufacturing practice (GMP) were also considered. In September 2009, the International Placenta Stem Cell Society (IPLASS) was founded to help strengthen the research network in this field.

Special cytology; the form and function of the cell in health and disease; a textbook for students of biology and medicine,

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Recent advances in the molecular biology of Leifsonia xyli subsp xyli, causal organism of ratoon stunting disease

Twelve years ago our understanding of ratoon stunting disease (RSD) was confined almost exclusively to diagnosis of the disease and control via farm hygiene, with little understanding of the biology of the interaction between the causal agent (Leifsonia xyli subsp. xyli) and the host plant sugarcane (Saccharum spp. hybrids). Since then, research has focused on developing the molecular tools to dissect L. xyli subsp. xyli, so that better control strategies can be developed to prevent losses from RSD. Within this review, we give a brief overview of the progression in research on L. xyli subsp. xyli and highlight future challenges. After a brief historical background on RSD, we discuss the development of molecular tools such as transformation and transposon mutagenesis and discuss the apparent lack of genetic diversity within the L. xyli subsp. xyli world population. We go on to discuss the sequencing of the genome of L. xyli subsp. xyli, describe the key findings and suggest some future research based on known deficiencies that will capitalise on this tremendous knowledge base to which we now have access.

The molecular biology of senile plaques and neurofibrillary tangles in Alzheimer’s disease

Since the earliest descriptions of the disease, senile plaques (SP) and neurofibrillary tangles (NFT) have been regarded as the pathological 'hallmarks' of Alzheimer's disease (AD). Whether or not SP and NFT are sufficient cause to explain the neurodegeneration of AD is controversial. The major molecular constituents of these lesions, viz., beta-amyloid (Ass) and tau, have played a defining role both in the diagnosis of the disease and in studies of pathogenesis. The molecular biology of SP and NFT, however, is complex with many chemical constituents. An individual constituent could be the residue of a pathogenic gene mutation, result from cellular degeneration, or reflect the acquisition of new proteins by diffusion and molecular binding. This review proposes that the molecular composition of SP and NFT is largely a consequence of cell degeneration and the later acquisition of proteins. Such a conclusion has implications both for the diagnosis of AD and in studies of disease pathogenesis.

Ghrelin gene-related peptides : multifunctional endocrine/autocrine modulators in health and disease

Ghrelin is a multi-functional peptide hormone which affects various processes including growth hormone and insulin release, appetite regulation, gut motility, metabolism and cancer cell proliferation. Ghrelin is produced in the stomach and in other normal and pathological cell types. It may act as an endocrine or autocrine/paracrine factor. The ghrelin gene encodes a precursor protein, preproghrelin, from which ghrelin and other potentially active peptides are derived by alternative mRNA splicing and/or proteolytic processing. The metabolic role of the peptide obestatin, derived from the preproghrelin C-terminal region, is controversial. However, it has direct effects on cancer cell proliferation. The regulation of ghrelin expression and the mechanisms through which the peptide products arise are unclear. We have recently re-examined the organisation of the ghrelin gene and identified several novel exons and transcripts. One transcript, which lacks the ghrelin-coding region of preproghrelin, contains the coding sequence of obestatin. Furthermore, we have identified an overlapping gene on the antisense strand of ghrelin, GHRLOS, which generates transcripts that may function as non-coding regulatory RNAs or code for novel, short bioactive peptides. The identification of these novel ghrelin-gene related transcripts and peptides raises critical questions regarding their physiological function and their role in obesity, diabetes and cancer.

Molecular characterisation of six badnavirus species associated with leaf streak disease of banana in East Africa

Banana leaf streak disease, caused by several species of Banana streak virus (BSV), is widespread in East Africa. We surveyed for this disease in Uganda and Kenya, and used rolling-circle amplification (RCA) to detect the presence of BSV in banana. Six distinct badnavirus sequences, three from Uganda and three from Kenya, were amplified for which only partial sequences were previously available. The complete genomes were sequenced and characterised. The size and organisation of all six sequences was characteristic of other badnaviruses, including conserved functional domains present in the putative polyprotein encoded by open reading frame (ORF) 3. Based on nucleotide sequence analysis within the reverse transcriptase/ribonuclease H-coding region of open reading frame 3, we propose that these sequences be recognised as six new species and be designated as Banana streak UA virus, Banana streak UI virus, Banana streak UL virus, Banana streak UM virus, Banana streak CA virus and Banana streak IM virus. Using PCR and species-specific primers to test for the presence of integrated sequences, we demonstrated that sequences with high similarity to BSIMV only were present in several banana cultivars which had tested negative for episomal BSV sequences.

The expanding roles of the ghrelin-gene derived peptide obestatin in health and disease

Obestatin is a 23 amino acid, ghrelin gene-derived peptide hormone produced in the stomach and a range of other tissues throughout the body. While it was initially reported that obestatin opposed the actions of ghrelin with regards to appetite and food intake, it is now clear that obestatin is not an endogenous ghrelin antagonist of ghrelin, but it is a multi-functional peptide hormone in its own right. In this review we will discuss the controversies associated with the discovery of obestatin and explore emerging central and peripheral roles of obestatin, roles in adipogenesis, pancreatic homeostasis and cancer.