Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0265264 (HOS)
 1,119 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hydroxyapatite (HA) is a bioactive dental implant material which accelerates bone formation on its surface. The mechanism of this acceleration is not clear. The elucidation of the cell adhesion might be the key to the understanding of the bioactive mechanism of HA. In this study, we analyzed the adhesion of HOS human osteoblasts onto HA and titanium to find the particular adhesion to HA. In short-term cultures in fetal bovine serum-pre-coated materials, a significantly higher number of cells adhered to HA than to titanium. In addition, serum-free conditions with phosphate-buffered saline pre-coating or bovine serum albumin pre-coating materials were tested. The results were nearly the same among all pre-coating conditions, suggesting that the quantity of cell adhesion was not affected by serum components. However, in the morphological observations by SEM, the form of adhesion was found to differ among pre-coating conditions. The osteoblasts tightly adhered and spread onto both HA and titanium with serum pre-coating, whereas the cells loosely adhered and did not spread without serum. To evaluate the Arg-Gly-Asp (RGD) sequence-specific adhesion, we used synthetic RGD peptides for a competitive inhibition test. The results showed that RGD peptides remarkably inhibited the tight adhesion and spreading of osteoblasts onto HA, whereas they did not strongly inhibit adhesion and spreading onto titanium. These results demonstrate that the regulation of cell adhesion to HA is different from that to titanium. Our study suggests that the RGD-containing serum proteins might have a major role in regulating the specific adhesion of osteoblasts to HA, and in inducing enhanced cell growth and differentiation.
 ...
PMID:RGD peptides regulate the specific adhesion scheme of osteoblasts to hydroxyapatite but not to titanium. 949 21

ROC1 is a common component of a large family of ubiquitin E3 ligases that regulate cell cycle progression and signal transduction pathways. Here we present evidence suggesting that a conserved RING-H2 structure within ROC1 is critical for its ubiquitin ligation function. Mercury-containing sulfhydryl modification agents (rho-hydroxymercuribenzoate and mercuric chloride) irreversibly inhibit the ROC1-CUL1 ubiquitin ligase activity without disrupting the complex. Consistent with this, these reagents also eliminate the ability of the Skp1-CUL1-HOS-ROC1 E3 ligase complex to support the ubiquitination of IkappaBalpha. Site-directed mutagenesis analysis identifies RING-H2 finger residues Cys(42), Cys(45), Cys(75), His(77), His(80), Cys(83), Cys(94), and Asp(97) as being essential for the ROC1-dependent ubiquitin ligase activity. Furthermore, C42S/C45S and H80A mutations reduce the ability of ROC1 to interact with CUL1 in transfected cells and diminish the capacity of ROC1-CUL1 to form a stable complex with Cdc34 in vitro. However, C75S, H77A, C94S, and D97A substitutions have no detectable effect on ROC1 binding activities. Thus, the ROC1 RING-H2 finger may possess multiple biochemical properties that include stabilizing an interaction with CUL1 and recruiting Cdc34. A possible role of the RING finger in facilitating the Ub transfer reaction is discussed.
 ...
PMID:The conserved RING-H2 finger of ROC1 is required for ubiquitin ligation. 1074 83