RESUMO
BACKGROUND: SnoN and Ski proteins function as Smad transcriptional corepressors and are implicated in the regulation of diverse cellular processes such as proliferation, differentiation and transformation. Transforming growth factor-ß (TGF-ß) signaling causes SnoN and Ski protein degradation via proteasome with the participation of phosphorylated R-Smad proteins. Intriguingly, the antibiotics anisomycin (ANS) and puromycin (PURO) are also able to downregulate Ski and SnoN proteins via proteasome. METHODS: We explored the effects of ANS and PURO on SnoN protein downregulation when the activity of TGF-ß signaling was inhibited by using different pharmacological and non-pharmacological approaches, either by using specific TßRI inhibitors, overexpressing the inhibitory Smad7 protein, or knocking-down TßRI receptor or Smad2 by specific shRNAs. The outcome of SnoN and Ski downregulation induced by ANS or PURO on TGF-ß signaling was also studied. RESULTS: SnoN protein downregulation induced by ANS and PURO did not involve the induction of R-Smad phosphorylation but it was abrogated after TGF-ß signaling inhibition; this effect occurred in a cell type-specific manner and independently of protein synthesis inhibition or any other ribotoxic effect. Intriguingly, antibiotics seem to require components of the TGF-ß/Smad pathway to downregulate SnoN. In addition, SnoN protein downregulation induced by antibiotics favored gene transcription induced by TGF-ß signaling. CONCLUSIONS: ANS and PURO require TGF-ß/Smad pathway to induce SnoN and Ski protein downregulation independently of inducing R-Smad2 phosphorylation, which facilitates TGF-ß signaling. GENERAL SIGNIFICANCE: Antibiotic analogs lacking ribotoxic effects are useful as pharmacological tools to study TGF-ß signaling by controlling Ski and SnoN protein levels.
Assuntos
Anisomicina/farmacologia , Proteínas Oncogênicas/metabolismo , Puromicina/farmacologia , Fator de Crescimento Transformador beta1/metabolismo , Animais , Linhagem Celular , Linhagem Celular Tumoral , Regulação para Baixo/efeitos dos fármacos , Células HeLa , Células Hep G2 , Humanos , Vison/genética , Proteínas Oncogênicas/genética , Fosforilação/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Proteína Smad2/genética , Proteína Smad2/metabolismo , Proteína Smad7/genética , Proteína Smad7/metabolismo , Transcrição Gênica/efeitos dos fármacos , Fator de Crescimento Transformador beta1/genéticaRESUMO
A family of 15 N-substituted phenothiazines was designed, synthesized and their acaricidal activity against Rhipicephalus microplus was determined in vitro. The synthetic methodology is simple and can be employed in multigram scale. The rationale for the structure-based design of these compounds is the potential for azines and phenothiazine to engage in π-π interactions; these fragments, joined together by a short, flexible alkoxide linker, structurally resemble phenothiazine-based cholinesterase inhibitors, while their weak basicity implies a neutral active form, rather than a cationic one, thus facilitating penetration of the cuticle of ticks. One compound displayed excellent acaricidal activity (LD50=0.58 µg/mL). Preliminary SAR analysis suggests that the activity is influenced by the presence of a weakly basic nitrogen atom, as well as the substitution pattern within the heterocycles.
Assuntos
Desenho de Fármacos , Fenotiazinas/farmacologia , Rhipicephalus/efeitos dos fármacos , Controle de Ácaros e Carrapatos , Animais , Relação Dose-Resposta a Droga , Estrutura Molecular , Fenotiazinas/síntese química , Fenotiazinas/química , Relação Estrutura-AtividadeRESUMO
A phenylene-bridged steroidal dimer derived from 17α-ethynyl-5α,10α-estran-17ß-ol with molecular rotor-like architecture was synthesized to investigate the supramolecular interactions directing the crystallization of these systems. Structures with varying importance in complementarity between H-bonding and hydrophobic interactions can be observed directing the packing of the obtained crystals, depending on the synthetic stage, though conserving the same space group for both systems. Such behavior clearly shows the versatility achievable using steroids as crystal packing directors. Alongside this structural study, the complete NMR assignment is presented for the dimer, and precursors, in which the steroids present an unconventional and noteworthy A-B ring fusion.
Assuntos
Acetileno/química , Esteroides/síntese química , Acetileno/análogos & derivados , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Conformação Molecular , Esteroides/químicaRESUMO
Treatment of 12-oxosteroids with PhI(OAc)(2) and KOH in refluxing methanol triggers a quasi-Favorskii C-ring contraction leading to the corresponding 11α-alcoxycarbonyl-C-norsteroids in moderate yields. This constitutes the first one-step synthetic alternative to C-norsteroids starting from 12-oxosteroids.
Assuntos
Iodo/química , Cetosteroides/química , Noresteroides/química , Cristalografia por Raios X , Hidrólise , Cetosteroides/síntese química , Conformação Molecular , Noresteroides/síntese químicaRESUMO
In addition to a previous report, the reaction of tigogenin acetate with ICl in refluxing CHCl(3) produced the hitherto unknown 23R-iodotigogenin acetate, bearing an axial iodine atom at C-23 and its already reported 23S-epimer. The same treatment of sarsasapogenin acetate led to a single diasteromer characterized as 23S-iodosarsasapogenin acetate. A full characterization of the obtained compound including (1)H, (13)C NMR, MS and X-ray diffraction is provided.