RESUMEN

The Chinese alligator (Alligator sinensis), a freshwater crocodilian endemic to China, is one of the most endangered crocodilian species; up to this date, very little is known about the endocrine regulation of its metabolic activities during different physiological states. In this study, we characterized the structure of the prepro-vasoactive intestinal peptide in Chinese alligator (prepro-caVIP) for the first time and examined its expression profiles in various tissues during the active and hibernating periods. The prepro-caVIP cDNA consists of a 221-bp 5'-untranslated region (UTR), a 606-bp complete coding region (CDS), and a 312-bp 3'-UTR, which encodes the 201-amino acid prepro-caVIP containing a 28-amino acid vasoactive intestinal peptide (VIP) and a 27-amino acid PHI (peptide histidine isoleucine). Multiple alignment analysis showed that VIP shares 100% identity with the given birds, reptiles, and African clawed frog, and 89% identity with mammals, 96% with fishes. Real-time quantitative PCR showed that the prepro-caVIP is widely expressed in all the examined tissues, and the expression level is significantly higher in small intestine, stomach, pancreas, lung, and skeletal muscle, whereas lower in heart, liver, spleen, kidney, ovary, and oviduct. During hibernation, the expression level of caVIP was significantly decreased in small intestine (P < 0.01), pancreas, and skeletal muscle (P < 0.05), whereas significantly increased in liver, spleen, and lung (P < 0.01). The wide distribution of caVIP and its differential expression changes in various tissues during hibernation implicated that it might play multiple effects in Chinese alligator and participate in the physiological adaptation of various organs in a paracrine and/or neurocrine manner.

Asunto(s)

RESUMEN

A new control approach for speed tracking and synchronization of multiple motors is developed, by incorporating an adaptive sliding mode control (ASMC) technique into a ring coupling synchronization control structure. This control approach can stabilize speed tracking of each motor and synchronize its motion with other motors' motion so that speed tracking errors and synchronization errors converge to zero. Moreover, an adaptive law is exploited to estimate the unknown bound of uncertainty, which is obtained in the sense of Lyapunov stability theorem to minimize the control effort and attenuate chattering. Performance comparisons with parallel control, relative coupling control and conventional PI control are investigated on a four-motor synchronization control system. Extensive simulation results show the effectiveness of the proposed control scheme.

RESUMEN

The skin and skin secretion of Chinese toad Bufo gargarizans have long been used in traditional Chinese medicine. However, the exact types and location of bioactive substances in Bufo gargarizans skin still have not been fully elucidated. The aim of the study was to investigate the distribution and density of six types of gastrointestinal (GI) hormone immunoreactive (IR) cells in the skin and parotoids of Bufo gargarizans. Immunohistochemistry was used for qualitative and semiquantitative analysis of GI hormone presence in the dorsal and ventral skin, and parotoids of eight adult Chinese toads. Six types of IR cells were found: serotonin (5-HT), glucagon (GLU), gastrin (GAS), somatostatin (SS), pancreatic polypeptide (PP) and neuropeptide Y(NPY) IR cells. They were mainly present in the epidermis and skin glands. 5-HT-IR cells were distributed in all layers of epidermis and glands, with higher density in the glands. Glucagon was prominently expressed in the epidermis and the bottle-shaped glands of parotoids; however, it was not present in the granular glands of skin and parotoids. The distributions of GAS and SS-IR cells were similar since they were present mainly in mucous, granular and bottle-shaped glands, while these cell types were absent in the differentiated glands of parotoids. PP-IR cells were predominant in the granular glands and the bottle-shaped glands. The expression of NPY was high in epidermal stratum granulosum and mucous glands of the dorsal skin, the bottle-shaped glands and differentiated glands of parotoids, while NPY-IR was rarely seen in the granular glands of ventral skin, and not present in the granular glands of dorsal skin and parotoids. The expression of several types of GI hormones in the skin and parotoids of Bufo gargarizans varies depending on tissue and type of glands.

Asunto(s)

RESUMEN

Polo-like kinase 1 (Plk1) is a conserved key regulator of the G2/M transition, but its upstream spatiotemporal regulators remain unknown. With the help of immunofluorescence, co-immunoprecipitation, and glutathione S-transferase (GST) pull-down assay, we found that calmodulin (CaM) is one such regulatory molecule that associates with Plk1 from G2 to metaphase. More importantly, this interaction results in considerable stimulation of Plk1 kinase activity leading to hyperphosphorylation of Cdc25C. Our results provide new insight into the role of CaM as an upstream regulator of Plk1 activation during mitotic entry.

Asunto(s)

RESUMEN

It is well accepted that cell scattering (dispersion of clustered cells into single cells) is the initial step of tumor metastasis, and the downregulation of E-cadherin is associated with metastatic potential of tumor cells; however, the molecular mechanisms underlying loss of E-cadherin during tumor development are still poorly understood. Here, we report that hepatocyte growth factor (HGF) induced E-cadherin downregulation and cell scattering are attributed to the activation of Wnt/beta-catenin signaling and transcriptional activation of matrix metalloproteinase MMP-7. Furthermore, the increased MMP-7 is secreted into the medium and cleaves the ectodomain of E-cadherin. Inhibition of HGF signal by siRNA of c-Met, blocking the beta-catenin transcriptional activity through a dominant negative form of TCF4, MMP-7 knockdown by siRNA or suppression of MMP-7 enzymatic activity with a neutralization antibody allowed inhibition of HGF-induced loss of E-cadherin and HepG2 scattering. Our data presented here revealed the intrinsic mechanism of HGF activated Wnt/beta-catenin signaling regulation of HepG2 cell scattering through MMP-7 transcription activation and E-cadherin degradation. The results suggest that the blocking of HGF/c-Met/beta-catenin/MMP-7/E-cadherin signaling pathway might present a practical therapeutic target for interference with hepatocellular carcinoma metastasis.

Asunto(s)

RESUMEN

c-Met is highly expressed and constitutively activated in various human tumors. We employed adenovirus-mediated RNA interference technique to knock down c-Met expression in hepatocellular carcinoma cells and observed its effects on hepatocellular carcinoma cell growth in vitro and in vivo. Among the five hepatocellular carcinoma and one normal human liver cell lines we analyzed, c-Met was highly expressed and constitutively tyrosine phosphorylated in only MHCC97-L and HCCLM3 hepatocellular carcinoma cells. Knockdown of c-Met could inhibit MHCC97-L cells proliferation by arresting cells at G0-G1 phase. Soft agar colony formation assay indicated that the colony forming ability of MHCC97-L cells decreased by approximately 70% after adenovirus AdH1-small interfering RNA (siRNA)/met infection. In vivo experiments showed that adenovirus AdH1-siRNA/met inhibited the tumorigenicity of MHCC97-L cells and significantly suppressed tumor growth when injected directly into tumors. These results suggest that knockdown of c-Met by adenovirus-delivered siRNA may be a potential therapeutic strategy for treatment of hepatocellular carcinoma in which c-Met is overexpressed.

Asunto(s)