SummarySUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) is one of the flowering pathway integrators and regulates the expression of LEAFY (LFY), which links floral induction and floral development. However, the mechanism by which SOC1, a MADS box protein, regulates LFY has proved elusive. Here, we show that SOC1 directly binds to the distal and proximal region of the LFY promoter where critical cis-elements are located. Intragenic suppressor mutant analysis shows that a missense mutation in the MADS box of SOC1 causes loss of binding to the LFY promoter as well as suppression of the flowering promotion function. The full-length SOC1 protein locates in the cytoplasm if expressed alone in protoplast transient expression assay, but relocates to the nucleus if expressed with AGAMOUS-LIKE 24 (AGL24), another flowering pathway integrator and a MADS box protein. The domain analysis shows that co-localization of SOC1 and AGL24 is mediated by the MADS box and the intervening region of SOC1. Finally, we show that LFY is expressed only in those tissues where SOC1 and AGL24 expressions overlap. Thus, we propose that heterodimerization of SOC1 and AGL24 is a key mechanism in activating LFY expression.

The appropriate timing of flowering is pivotal for reproductive success in plants; thus, it is not surprising that flowering is regulated by complex genetic networks that are fine-tuned by endogenous signals and environmental cues. The Arabidopsis thaliana flowering-time gene SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) encodes a MADS box transcription factor and is one of the key floral activators integrating multiple floral inductive pathways, namely, long-day, vernalization, autonomous, and gibberellin-dependent pathways. To elucidate the downstream targets of SOC1, microarray analyses were performed. The analysis revealed that the soc1-2 knockout mutant has increased, and an SOC1 overexpression line has decreased, expression of cold response genes such as CBFs (for CRT/DRE binding factors) and COR (for cold regulated) genes, suggesting that SOC1 negatively regulates the expression of the cold response genes. By contrast, overexpression of cold-inducible CBFs caused late flowering through increased expression of FLOWERING LOCUS C (FLC), an upstream negative regulator of SOC1. Our results demonstrate the presence of a feedback loop between cold response and flowering-time regulation; this loop delays flowering through the increase of FLC when a cold spell is transient as in fall or early spring but suppresses the cold response when floral induction occurs through the repression of cold-inducible genes by SOC1.

Histone deacetylase 2 (HDAC2) is crucial for embryonic development, affects cytokine signaling relevant for immune responses, and is often significantly overexpressed in solid tumors, but little is known of its role in human lung cancer. In this study, we demonstrated the aberrant expression of HDAC2 in lung cancer tissues and investigated oncogenic properties of HDAC2 in human lung cancer cell lines. HDAC2 inactivation resulted in regression of tumor cell growth and activation of cellular apoptosis via p53 and Bax activation and Bcl2 suppression. In cell cycle regulation, HDAC2 inactivation caused induction of p21WAF1/CIP1 expression, and simultaneously suppressed the expressions of cyclin E2, cyclin D1, and CDK2, respectively. Consequently, this led to the hypophosphorylation of pRb protein in G1/S transition and thereby inactivated E2F/DP1 target gene transcriptions of A549 cells. In addition, we demonstrated that HDAC2 directly regulated p21WAF1/CIP1 expression in a p53-independent manner. However, HDAC1 was not related to p21WAF1/CIP1 expression and tumorigenesis of lung cancer. Lastly, we observed that sustained-suppression of HDAC2 in A549 lung cancer cells attenuated in vitro tumorigenic properties and in vivo tumor growth of the mouse xenograft model. Taken together, we suggest that the aberrant regulation of HDAC2 and its epigenetic regulation of gene transcription in apoptosis and cell cycle components play an important role in the development of lung cancer.

Histone deacetylases (HDACs) are known to play a central role in the regulation of several cellular properties interlinked with the development and progression of cancer. Recently, HDAC1 has been reported to be overexpressed in hepatocellular carcinoma (HCC), but its biological roles in hepatocarcinogenesis remain to be elucidated. In this study, we demonstrated overexpression of HDAC1 in a subset of human HCCs and liver cancer cell lines. HDAC1 inactivation resulted in regression of tumor cell growth and activation of caspase-independent autophagic cell death, via LC3B-II activation pathway in Hep3B cells. In cell cycle regulation, HDAC1 inactivation selectively induced both p21WAF1/Cip1 and p27Kip1 expressions, and simultaneously suppressed the expression of cyclin D1 and CDK2. Consequently, HDAC1 inactivation led to the hypophosphorylation of pRb in G1/S transition, and thereby inactivated E2F/DP1 transcription activity. In addition, we demonstrated that HDAC1 suppresses p21WAF1/Cip1 transcriptional activity through Sp1-binding sites in the p21WAF1/Cip1 promoter. Furthermore, sustained suppression of HDAC1 attenuated in vitro colony formation and in vivo tumor growth in a mouse xenograft model. Taken together, we suggest the aberrant regulation of HDAC1 in HCC and its epigenetic regulation of gene transcription of autophagy and cell cycle components. Overexpression of HDAC1 may play a pivotal role through the systemic regulation of mitotic effectors in the development of HCC, providing a particularly relevant potential target in cancer therapy.

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Mobile DRAM is widely employed in portable electronic devices due to its feature of low power consumption. Recently, as the market trend renders integration of various features in one chip, mobile DRAM is required to have not only low power consumption but also high capacity and high speed. To attain these goals in mobile DRAM, we designed a 1Gb single data rate (SDR) Wide-I/O mobile SDRAM with 4 channels and 512 DQ pins, featuring 12.8GB/s data bandwidth. Figure 28.5.1 shows the chip architecture with 4-channels and 16 segmented 64Mb arrays. The whole chip is made up of 4 partitions which are symmetric with respect to the chip center, and each partition consists of 4×64Mb arrays, peripheral circuits and microbumps. Each channel has its own input pins while external power pins and internal voltage generators are shared with the other channels. In a single channel, 128 data lines are controlled to feed 128 DQs. Four 64Mb arrays in 1-channel can be configured in 4 banks with bank addresses BA [0:1] and row addresses RA [0:11], or in 2 banks with BA [0] and RA [0:12]. In a 4-bank structure, each bank has 4k row depth and 8k page depth.To reduce power consumption in 512b I/O operations and to support high data bandwidth, I/O driver loading is reduced by adoption of 44×6 microbump pads per channel, which are located in the middle of the chip. Figure 28.5.1 also shows a SEM image of the fabricated microbumps with 20×17μm 2 size and max 50μm pitch. To detect bump connection failure with other devices, a simple boundary scan test mode is implemented. It is a subset of IEEE Standard 1149.1 [1] in pin configurations and in operational modes to reduce chip size burden. Each channel has its own scan chain and scan clock input. To reduce the number of ballouts, this mode scans parallel data I/O and the scanned data propagates through the dedicated pins. Normal device operation is performed after the boundary scan test is finished. Figure 28.5.2 shows boundary scan block and AC timing diagram. This boundary scan chain is enabled when /SEN, scan enable pin, is low. The data input from the pad is captured when /SSH, scan shift pin, is low, and it is shifted along the chain when /SSH is high. SDI, SDO and SCK pins are for scan input, output and clock, respectively.We also adopt typical metal pads for test purposes since it is difficult to probe small microbumps directly. These pads are aligned in vertical direction at the chip center to allow precise correlation with microbumps and to reduce skews between channels. With test pads, this DRAM is handled as SDR×16, but internally as SDR×128 per channel. Selections of 16 out of 512 data can be done with column addresses, which are for the read-out of result data through test pads. Figure 28.5.3 shows correlation scheme between microbumps and test pads in data write/read operations. Through test pads, 9.3ns delayed outputs of microbumps, 2ns for clock propagation from pad and 7.3ns for data transfer from microbump to pad, are measured. Because we redirect outputs from microbumps and i...

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Contribution of autophagy and regulation of related proteins to the degeneration of retinal pigment epithelium (RPE) in age-related macular degeneration (AMD) remain unknown. We report that upregulation of KRT8 (keratin 8) as well as its phosphorylation are accompanied with autophagy and attenuated with the inhibition of autophagy in RPE cells under oxidative stress. KRT8 appears to have a dual role in RPE pathophysiology. While increased expression of KRT8 following autophagy provides a cytoprotective role in RPE, phosphorylation of KRT8 induces pathologic epithelial-mesenchymal transition (EMT) of RPE cells under oxidative stress, which is mediated by MAPK1/ERK2 (mitogen-activated protein kinase 1) and MAPK3/ERK1. Inhibition of autophagy further promotes EMT, which can be reversed by inhibition of MAPK. Thus, regulated enhancement of autophagy with concurrent increased expression of KRT8 and the inhibition of KRT8 phosphorylation serve to inhibit oxidative stress-induced EMT of RPE cells as well as to prevent cell death, suggesting that pharmacological manipulation of KRT8 upregulation through autophagy with combined inhibition of the MAPK1/3 pathway may be attractive therapeutic strategies for the treatment of AMD.