Members of the AP-1 family of transcription factors participate in the regulation of bone cell proliferation and differentiation. We report here a potent AP-1-related regulator of osteoblast function: DeltaFosB, a naturally occurring truncated form of FosB that arises from alternative splicing of the fosB transcript and is expressed in osteoblasts. Overexpression of DeltaFosB in transgenic mice leads to increased bone formation throughout the skeleton and a continuous post-developmental increase in bone mass, leading to osteosclerosis. In contrast, DeltaFosB inhibits adipogenesis both in vivo and in vitro, and downregulates the expression of early markers of adipocyte differentiation. Because osteoblasts and adipocytes are thought to share a common precursor, it is concluded that DeltaFosB transcriptionally regulates osteoblastogenesis, possibly at the expense of adipogenesis.

We report stable and reproducible switching and memory effects in self-assembled monolayers (SAMs). We demonstrate realization of negative differential resistance (NDR) and charge storage in electronic devices that utilize single redox-center-contained SAM as the active component; and compare the effects of various redox centers to switching and storage behavior. The devices exhibit electronically programmable and erasable memory bits with bit retention times greater than 15 min at room temperature. Ó

Inactivation of the neurofibromatosis type 2 (NF2) tumor suppressor gene function has been observed not only in familial schwannomas and other central nervous system tumors, but also in malignant tumors unrelated to the NF2 syndrome, indicating a broader role of NF2 in human tumorigenesis. The NF2-encoded protein Merlin is closely related to the Ezrin-Radixin-Moesin family of membrane/ cytoskeleton linker proteins, and has been demonstrated to suppress tumor growth by inhibiting extracellular signal-regulated kinase (ERK) and Rac1 activation. Interestingly, serum deprivation has been shown to regulate Merlin at the protein level, however, exactly how such condition affects Merlin remains elusive. In this study, we provide evidence to show that Merlin is regulated in a Roc1-Cullin4A-DDB1-dependent manner. Following serum stimulation, Merlin is recruited to the E3 ligase complex through a direct interaction with the WD40-containing adaptor protein VprBP. Loading of Merlin to the E3 ubiquitin ligase complex resulted in its polyubiquitination, and consequently its proteasomemediated degradation. Consistently, VprBP depletion abolished the in vivo interaction of Merlin and Roc1-Cullin4A-DDB1, which resulted in Merlin stabilization and inhibited ERK and Rac activation. Together, our data revealed a novel regulatory mechanism for the tumor suppressor function of Merlin.

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