A Framework for Security-Enhanced Peer-to-Peer Applications in Mobile Cellular Networks

Due to the dual trends of increasing cellular network transmission capacity and coverage as well as improving computational capacity, storage and intelligence of mobile handsets, mobile peer-to-peer (MP2P) networking is emerging an attractive research field in recent years. However, these trends have not been clearly articulated in perspective of both technology and business. In this paper, we propose a novel MP2P framework that is based on existing cellular network architecture to provide secure and efficient P2P file sharing for 3G and future 4G systems. Our framework, which is built on P2P over Session Initiation Protocol (SIP) mechanism, provides to network operators and P2P service providers efficient data transmission in cellular networks. With a secure enhancement using identity-based cryptography, the framework also provides desirable support for security, group management, mobility, and chargeability to meet business requirements.

The deubiquitinase UCHLS/UCH37 positively regulates Hedgehog signaling by deubiquitinating Smoothened

The Hedgehog （Hh） signaling pathway plays important roles in developmental processes including pattern formation and tissue homeostasis. The seven-pass transmembrane receptor Smoothened （Smo） is the pivotal transducer in the pathway; it, and thus the pathway overall, is regulated by ubiquitin-mediated degradation, which occurs in the absence of Hh. In the presence of Hh, the ubiquitination levels of Smo are decreased, but the molecular basis for this outcome is not well understood. Here, we identify the deubiquitinase UCHL5 as a positive regulator of the Hh pathway. We provide both genetic and biochemical evidence that UCHL5 interacts with and deubiquitinates Smo, increasing stability and promoting accumulation at the cell membrane. Strikingly, we find that Hh enhances the interaction between UCHL5 and Smo, thereby stabilizing Smo. We also find that proteasome subunit RPN13, an activator of UCHL5, could enhance the effect of UCHL5 on Smo protein level. More importantly, we find that the mammalian counterpart of UCHL5, UCH37, plays the same role in the regulation of Hh signaling by modulating hSmo ubiquitination and stability. Our findings thus identify UCHL5/UCH37 as a critical regulator of Hh signaling and potential therapeutic target for cancers.

E3 ligase Herc4 regulates Hedgehog signalling through promoting Smoothened degradation

Hedgehog(Hh)signalling plays conserved roles in controlling embryonic development;its dysregulation causes many diseases including cancers.The G protein-coupled receptor Smoothened(Smo)is the key signal transducer of the Hh pathway,whose posttranslational regulation has been shown to be critical for its accumulation and activation.Ubiquitination has been reported an essential posttranslational regulation of Smo.Here,we identify a novel E3 ligase of Smo,Herc4,which binds to Smo,and regulates Hh signalling by controlling Smo ubiquitination and degradation.Interestingly,our data suggest that Herc4-mediated Smo degradation is regulated by Hh in PKA-primed phosphorylation-dependent and independent manners.