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Li-Ling Tang

Publications and source records attributed to Li-Ling Tang.

4 recordsLinked to original sources
PubMed2006

The MGF expression of osteoblasts in response to mechanical overload.

Cell proliferation and mRNA expression of insulin-like growth factor (IGF-I) and "mechanogrowth factor" (MGF) were studied in osteoblasts in response to overload. Static and cyclic-stretching were used to apply superphysiological strains to cells. Overload was found to increase cell growth. IGF-I and its splicing variant, MGF, were measured using reverse transcriptase-polymerase chain reaction method and were found to be regulated differentially by mechanical signals at the mRNA level. Cyclic-stretching had a more significant effect on cell proliferation and mRNA expression levels of IGF-I and MGF, while unstrained cells did not express MGF at the mRNA level. These results demonstrated that gene expression is regulated by mechanical stimulation. MGF expression in osteoblasts in response to strain may be related to an autocrine mechanism.

Animals↗
PubMed2004

The stress reaction and its molecular events: splicing variants.

The growth of cells and tissues is regulated by stress. When body is injured, it manifests a large spectrum of metabolic, endocrine, and immune alterations, which is named stress reaction. Among them, the production of growth factors may play a critical role. For osteoblasts and myoblasts, IGF-I has been shown to be involved in the process of cells in response to overloads. There are two splicing forms, one is IGF-Ea, the other is the IGF-IEb in the rodents and corresponds to IGF-IEc in humans. The latter is markedly up-regulated in response to overloads. Therefore, it has been named mechanogrowth factor. The link between the mechanical stimulus and the gene expression represents a new and important area in cell science. Understanding the process of splicing in IGF-I helps one to investigate the mechanotransduction of cells in response to mechanical stimulation at molecular level.

Animals↗
PubMed2004

The effect of step-wise increased stretching on rat calvarial osteoblast collagen production.

Mechanical forces regulate the function of bone cells. In this paper, the effects of cyclic stretching on osteoblasts derived from rat calvaria were studied at a magnitude occurring in physiological loaded bone tissue. A four-point bending apparatus was used to apply cyclic stretching on osteoblasts. Stretching at 500 microepsilon for 2-24 h resulted in an increase in matrix synthesis(P<0.01). In contrast, the cyclic stretching at 1000 and 1500 microepsilon for 2-24 h inhibited osteoblast collagen production (P<0.01). We also described our new loading method to increase strain magnitude step-by-step. The strain magnitude increased by 500 microepsilon increments from 500 to 1500 microepsilon every 2 or 12 h, respectively. Results showed that osteoblasts could absorb large amount of proline for collagen synthesis when stretched at 500 microepsilon. However, not all the absorbed proline was used to synthesize collagen. Some of it was stored in cells. When the suitable signal (500 microepsilon) was changed to an inhibiting signal (1000 microepsilon), cells responded to it accordingly and released proline to medium. These results demonstrate that the response of osteoblasts is dependent on the magnitude of the strain applied and cells can adjust their bio-chemical response to adapt to the changing environmental stimulation.

Animals↗