Contribution of Distinct Homeodomain DNA Binding Specificities to Drosophila Embryonic Mesodermal Cell-Specific Gene Expression Programs

Homeodomain (HD) proteins are a large family of evolutionarily conserved transcription factors (TFs) having diverse developmental functions, often acting within the same cell types, yet many members of this family paradoxically recognize similar DNA sequences. Thus, with multiple family members having the potential to recognize the same DNA sequences in cis-regulatory elements, it is difficult to ascertain the role of an individual HD or a subclass of HDs in mediating a particular developmental function. To investigate this problem, we focused our studies on the Drosophila embryonic mesoderm where HD TFs are required to establish not only segmental identities (such as the Hox TFs), but also tissue and cell fate specification and differentiation (such as the NK-2 HDs, Six HDs and identity HDs (I-HDs)). Here we utilized the complete spectrum of DNA binding specificities determined by protein binding microarrays (PBMs) for a diverse collection of HDs to modify the nucleotide sequences of numerous mesodermal enhancers to be recognized by either no or a single subclass of HDs, and subsequently assayed the consequences of these changes on enhancer function in transgenic reporter assays. These studies show that individual mesodermal enhancers receive separate transcriptional input from both I–HD and Hox subclasses of HDs. In addition, we demonstrate that enhancers regulating upstream components of the mesodermal regulatory network are targeted by the Six class of HDs. Finally, we establish the necessity of NK-2 HD binding sequences to activate gene expression in multiple mesodermal tissues, supporting a potential role for the NK-2 HD TF Tinman (Tin) as a pioneer factor that cooperates with other factors to regulate cell-specific gene expression programs. Collectively, these results underscore the critical role played by HDs of multiple subclasses in inducing the unique genetic programs of individual mesodermal cells, and in coordinating the gene regulatory networks directing mesoderm development.National Institutes of Health (U.S.) (Grant R01 HG005287

Prothymosin alpha: a ubiquitous polypeptide with potential use in cancer diagnosis and therapy

The thymus is a central lymphoid organ with crucial role in generating T cells and maintaining homeostasis of the immune system. More than 30 peptides, initially referred to as “thymic hormones,” are produced by this gland. Although the majority of them have not been proven to be thymus-speciWc, thymic peptides comprise an eVective group of regulators, mediating important immune functions. Thymosin fraction Wve (TFV) was the Wrst thymic extract shown to stimulate lymphocyte proliferation and diVerentiation. Subsequent fractionation of TFV led to the isolation and characterization of a series of immunoactive peptides/polypeptides, members of the thymosin family. Extensive research on prothymosin (proT) and thymosin 1 (T1) showed that they are of clinical signiWcance and potential medical use. They may serve as molecular markers for cancer prognosis and/or as therapeutic agents for treating immunodeWciencies, autoimmune diseases and malignancies. Although the molecular mechanisms underlying their eVect are yet not fully elucidated proT and T1 could be considered as candidates for cancer immunotherapy. In this review, we will focus in principle on the eventual clinical utility of proT, both as a tumor biomarker and in triggering anticancer immune responses. Considering the experience acquired via the use of T1 to treat cancer patients, we will also discuss potential approaches for the future introduction of proT into the clinical setting

Activation of T lymphocytes for the adoptive immunotherapy of cancer

Background: Adoptive immunotherapy of malignancy involves the passive transfer of antitumor-reactive cells into a host in order to mediate tumor regression. Based on animal models, the transfer of immune lymphoid cells can eradicate widely disseminated tumors and establish long-term systemic immunity. Critical for successful adoptive immunotherapy is the ability to isolate large numbers of immune cells. For clinical therapy, it will require the development of in vitro methods to promote the sensitization and propagation of tumor-reactive cells. However, this is formidable task since human cancers are postulated to be poorly immunogenic because of their spontaneous origins.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41399/1/10434_2006_Article_BF02303568.pd

Role of glutamine transaminases in nitrogen, sulfur, selenium, and 1-carbon metabolism

Glutamine metabolism is largely controlled by two enzyme pathways: 1) Conversion of glutamine to glutamate catalyzed by glutaminases, followed by conversion of glutamate to α-ketoglutarate by a glutamate-linked aminotransferases (or by the action of glutamate dehydrogenase); and 2) conversion of glutamine to α-ketoglutaramate (KGM) catalyzed by glutamine-utilizing transaminases (aminotransferases), followed by conversion of KGM to α-ketoglutarate by the action of ω-amidase. The former pathway has been well documented and intensively studied for over 60 years, whereas only recently has research focused on the latter pathway, its importance in homeostasis and the control of anaplerotic metabolites. The glutamine transaminases are of fundamental importance 1) as repair enzymes (salvage of α-keto acids), 2) in nitrogen and sulfur homeostasis (closure of the methionine salvage pathway), 3) in 1-carbon metabolism, and 4) in metabolism of seleno amino acids. As a result of their broad substrate specificity the two principal mammalian glutamine transaminases (i.e. glutamine transaminases L and K) have also been characterized as kynurenine aminotransferases (KAT I and KAT III, respectively), responsible for the production of neuroactive kynurenate. The glutamine transaminases are also active with a variety of sulfur- and selenium-containing amino acids. Some of the products derived from the transamination of these amino acids may also be neuroactive (e.g. certain sulfur-containing cyclic ketimines) as well as chemopreventive (e.g. the α-keto acids derived from seleno amino acids). Of relevance to human health and disease, the glutamine transaminases may contribute to the bioactivation (toxification) of halogenated alkenes (and possibly other xenobiotic electrophiles), some of which are environmental contaminants. Finally, the role of the glutamine transaminases and ω-amidase in cancer biology has been little studied. However, the "glutamine addiction" of many tumors suggests that the glutamine transaminases together with ω-amidase may have a fundamental and influential role in regulating cancer progression.18 page(s