RESUMO
The Src-homology 2 (SH2) domain is a protein interaction domain that directs myriad phosphotyrosine (pY)-signaling pathways. Genome-wide screening of human SH2 domains reveals that â¼90% of SH2 domains bind plasma membrane lipids and many have high phosphoinositide specificity. They bind lipids using surface cationic patches separate from pY-binding pockets, thus binding lipids and the pY motif independently. The patches form grooves for specific lipid headgroup recognition or flat surfaces for non-specific membrane binding and both types of interaction are important for cellular function and regulation of SH2 domain-containing proteins. Cellular studies with ZAP70 showed that multiple lipids bind its C-terminal SH2 domain in a spatiotemporally specific manner and thereby exert exquisite spatiotemporal control over its protein binding and signaling activities in T cells. Collectively, this study reveals how lipids control SH2 domain-mediated cellular protein-protein interaction networks and suggest a new strategy for therapeutic modulation of pY-signaling pathways.
Assuntos
Metabolismo dos Lipídeos , Linfócitos T/metabolismo , Proteína-Tirosina Quinase ZAP-70/química , Proteína-Tirosina Quinase ZAP-70/metabolismo , Domínios de Homologia de src , Sítios de Ligação , Células Cultivadas , Humanos , Células Jurkat , Modelos Moleculares , Simulação de Acoplamento Molecular , Fosfotirosina/efeitos dos fármacos , Fosfotirosina/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Transdução de SinaisRESUMO
Although obesity is a risk factor for colorectal cancer, the underlying mechanism is not clear. Adiponectin is an adipokine that binds to 2 types of receptors, AdipoR1 and AdipoR2. The plasma concentrations of adiponectin are reduced in obese individuals and adiponectin has been reported to have anticarcinogenic properties. Furthermore, AdipoR1 and AdipoR2 have been reported to be expressed in several malignancies. However, little is known about the expression of AdipoR1 and AdipoR2 in colorectal cancer and its clinicopathological implications. In addition, the relationship between adiponectin and colorectal cancer has not yet been determined. Here, we sought to investigate adiponectin and adiponectin receptors in relation to colorectal cancer. AdipoR1 and AdipoR2 immunostaining was detected in 72 and 68% of human colorectal cancer tissue, respectively. AdipoR1 and AdipoR2 expression levels were inversely related to T stage. The lowest AdipoR1 and AdipoR2 expression were detected in poorly differentiated adenocarcinoma. RT-PCR also showed the expression of AdipoR1 and AdipoR2 in HCT116 and SW620. MTT assay and TUNEL assay demonstrated the tendency of growth inhibition and apoptosis induction in both cell lines after full-length adiponectin treatment although statistically insignificant. Microarray analysis revealed several gene responses to full-length adiponectin, including upregulation of ENDOGL1 and MT1G. In conclusion, AdipoR1 and AdipoR2 may be intimately related to the progression of colorectal cancer. Further studies may be warranted to assess adiponectin and its receptors as a novel target for inhibition of colorectal cancer growth.
Assuntos
Adenocarcinoma/metabolismo , Adiponectina/metabolismo , Biomarcadores Tumorais/metabolismo , Neoplasias Colorretais/metabolismo , Receptores de Adiponectina/metabolismo , Adenocarcinoma/genética , Adiponectina/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Apoptose , Biomarcadores Tumorais/genética , Western Blotting , Diferenciação Celular , Proliferação de Células , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Progressão da Doença , Feminino , Perfilação da Expressão Gênica , Humanos , Técnicas Imunoenzimáticas , Masculino , Pessoa de Meia-Idade , Análise de Sequência com Séries de Oligonucleotídeos , Prognóstico , RNA Mensageiro/genética , Receptores de Adiponectina/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de RiscoRESUMO
Normal monomeric tau can be converted into pathogenic aggregates and acquire protease resistance in a prion-like manner. This acquisition of partial protease-resistance in tau aggregates has to date only been partially investigated in various studies exploring the prion-like properties of tau. In this study, we induced the aggregation of tau repeat domain (RD) in cultured cells using detergent insoluble fractions of Alzheimer's brain tissue as seeds. The seeded aggregation of tau RD in cultured cells formed a ~7 kDa protease-resistant fragment in contrast to the ~12 kDa tau fragment characteristic of the AD seeds, suggesting that the in vitro generated tau aggregates were conformationally distinct from parent seeds.
Assuntos
Doença de Alzheimer/metabolismo , Encéfalo/patologia , Agregados Proteicos , Proteínas tau/química , Adulto , Idoso , Idoso de 80 Anos ou mais , Proteínas de Fluorescência Verde/metabolismo , Células HEK293 , Humanos , Pessoa de Meia-Idade , Peptídeo Hidrolases/metabolismo , Conformação Proteica , Proteínas Recombinantes/metabolismo , Sarcosina/análogos & derivados , Sarcosina/metabolismo , SolubilidadeRESUMO
A Helicobacter pylori mutant defective in a putative mfd gene was constructed and characterized. The mfd gene is required for DNA repair and is involved in DNA recombination processes. The mfd mutant strain displayed a greatly increased susceptibility to antibiotics, indicating that this gene plays a significant role in the antibiotic resistance of H. pylori strain J99.