Fibroblast proliferation and migration play important roles in wound healing. bFGF is known to promote both fibroblast proliferation and migration during the process of wound healing. However, the signal transduction of bFGF-induced fibroblast migration is still unclear, because bFGF can affect both proliferation and migration. Herein, we investigated the effect of bFGF on fibroblast migration regardless of its effect on fibroblast proliferation. We noticed involvement of the small GTPases of the Rho family, PI3-kinase, and JNK. bFGF activated RhoA, Rac1, PI3-kinase, and JNK in cultured fibroblasts. Inhibition of RhoA did not block bFGF-induced fibroblast migration, whereas inhibition of Rac1, PI3-kinase, or JNK blocked the fibroblast migration significantly. PI3-kinase-inhibited cells down-regulated the activities of Rac1 and JNK, and Rac1-inhibited cells down-regulated JNK activity, suggesting that PI3-kinase is upstream of Rac1 and that JNK is downstream of Rac1. Thus, we concluded that PI3-kinase, Rac1, and JNK were essential for bFGF-induced fibroblast migration, which is a novel pathway of bFGF-induced cell migration.

HuD is an RNA-binding protein that has been shown to induce neuronal differentiation by stabilizing labile mRNAs carrying AU-rich instability elements. Here, we show a novel mechanism of arginine methylation of HuD by coactivator-associated arginine methyltransferase 1 (CARM1) that affected mRNA turnover of p21 cip1/waf1 mRNA in PC12 cells. CARM1 specifically methylated HuD in vitro and in vivo and colocalized with HuD in the cytoplasm. Inhibition of HuD methylation by CARM1 knockdown elongated the p21 cip1/waf1 mRNA half-life and resulted in a slow growth rate and robust neuritogenesis in response to nerve growth factor (NGF). Methylation-resistant HuD bound more p21 cip1/waf1 mRNA than did the wild type, and its overexpression upregulated p21 cip1/waf1 protein expression. These results suggested that CARM1-methylated HuD maintains PC12 cells in the proliferative state by committing p21 cip1/waf1 mRNA to its decay system. Since the methylated population of HuD was reduced in NGF-treated PC12 cells, downregulation of HuD methylation is a possible pathway through which NGF induces differentiation of PC12 cells.

Microvascular tissue transfer has become an indispensable procedure for head and neck reconstruction. Although remarkable progress has been made technically, anastomosed vessel occlusion is still a serious complication. Even with technically skilled microsurgeons, anastomosed vessel occlusion occurs because the technique is not the sole prophylaxis against thrombosis in microsurgery. Therefore, to minimize the possibility of an unfavorable result in microsurgery, microsurgeons must be familiar with management options for a vascular compromised flap. Most investigators have agreed that venous obstruction occurs more often than arterial obstruction. Here, we reviewed the published literature on the salvage of venous compromised flaps from the viewpoints of surgical correction, including reanastomosis and catheter thrombectomy, and nonsurgical procedures, such as a medicinal leech, hyperbaric oxygen, and thrombolytic therapy.

Our study indicates that early aggressive debridement of diabetic foot ulcers with exposed bones down to a bleeding vascularized base and then grafting epidermal sheets significantly improves healing and reduces the rate of amputation.

The function of the p75(NTR) neurotrophin receptor (p75(NTR)) in nervous system regeneration is still controversial. Part of that controversy may be due to the fact that p75(NTR) is expressed by both neuronal and glial cell types and may have very distinct and even contradictory roles in each population. In this study, to elucidate the in vivo function of p75(NTR) in Schwann cells during remyelination after peripheral nerve injury, we established a new animal model for p75(NTR)-deficient Schwann cell transplantation in nude mice. We performed quantitative assessments of the functional, histological, and electrophysiological recovery after sciatic nerve injury, and compared them with those of the p75(NTR)(+/+) Schwann cell transplanted animals. At 7-10 weeks after injury, the motor recovery in the p75(NTR)(-/-) Schwann cell transplanted animals was significantly impaired compared with that in the p75(NTR)(+/+) Schwann cell transplanted animals. The lower number of the retrogradely labeled motoneurons and the hypomyelination in the p75(NTR)(-/-) Schwann cell transplanted animals were evident at 6 and 10 weeks after injury. At 10 weeks after injury, the radial growth in the axon caliber was also impaired in the p75(NTR)(-/-) Schwann cell transplanted animals. Measurement of the amount of myelin proteins and the nerve conduction velocity at 10 weeks after injury reflected these results. In summary, the p75(NTR) expression in Schwann cells is important for remyelination process, and the motor recovery after injury is impaired due to impaired axonal growth, remyelination, and radial growth in the axon calibers.

Axons of the adult central nervous system have very limited ability to regenerate after injury. This inability may be, at least partly, attributable to myelin-derived proteins, such as myelinassociated glycoprotein, Nogo and oligodendrocyte myelin glycoprotein. Recent evidence suggests that these proteins inhibit neurite outgrowth by activation of Rho through the neurotrophin receptor p75 NTR /Nogo receptor complex. Despite rapidly growing knowledge on these signals at the molecular level, it remained to be determined whether Rho is activated after injury to the central nervous system. To assess this question, we establish a new method to visualize endogenous Rho activity in situ. After treatment of cerebellar granular neurons with the Nogo peptide in vitro, Rho is spatially activated and colocalizes with p75 NTR . Following spinal cord injury in vivo, massive activation of Rho is observed in the injured neurites. Spatial regulation of Rho activity may be necessary for axonal regulation by the inhibitory cues.

We investigated whether or not the topographic regulation of melanocyte differentiation is determined by mesenchymal–epithelial interactions via fibroblast-derived factors. The melanocyte density in palmoplantar human skin (i.e., skin on the palms and the soles) is five times lower than that found in nonpalmoplantar sites. Palmoplantar fibroblasts significantly suppressed the growth and pigmentation of melanocytes compared with nonpalmoplantar fibroblasts. Using cDNA microarray analysis, fibroblasts derived from palmoplantar skin expressed high levels of dickkopf 1 (DKK1; an inhibitor of the canonical Wnt signaling pathway), whereas nonpalmoplantar fibroblasts expressed higher levels of DKK3. Transfection studies revealed that DKK1 decreased melanocyte function, probably through β-catenin–mediated regulation of microphthalmia-associated transcription factor activity, which in turn modulates the growth and differentiation of melanocytes. Thus, our results provide a basis to explain why skin on the palms and the soles is generally hypopigmented compared with other areas of the body, and might explain why melanocytes stop migrating in the palmoplantar area during human embryogenesis.

One of the most striking features of neurons in the mature peripheral nervous system is their ability to survive and to regenerate their axons following axonal injury. To perform a comprehensive survey of the molecular mechanisms that underlie peripheral nerve regeneration, we analyzed a cDNA library derived from the distal stumps of post-injured sciatic nerve which was enriched in non-myelinating Schwann cells using cDNA microarrays. The number of up-and down-regulated genes in the transected sciatic nerve was 370 and 157, respectively, of the 9596 spotted genes. In the up-regulated group, the number of known genes was 216 and the number of expressed sequence tag (EST) sequences was 154. In the down-regulated group, the number of known genes was 103 and that of EST sequences was 54. We obtained several genes that were previously reported to be involved in regeneration of the injured neurons, such as cathepsin D, ninjurin 1, tenascin C, and co-receptor for glial cell line-derived neurotrophic factor family of trophic factors. In addition to unknown genes, there seemed to be a lot of annotated genes whose role in nerve regeneration remains unknown. Keywords: cDNA microarrays, injury-induced molecules, nerve regeneration, Schwann cell, sciatic nerve. One of the most striking features of neurons in the mature PNS is their ability to survive and to regenerate their axons following axonal injury. It has been increasingly evident that the success of axonal regeneration is dependent on the intrinsic as well as extrinsic growth properties of the axotomized neuron. The environment in which PNS axons regenerate consists of Schwann cells and their basal laminae, fibroblasts, collagen, degenerating myelin and phagocytic cells (Fawcett and Keynes 1990;Bunge and Griffin 1992;Araki and Milbrandt 1996). After nerve injury, the distal axonal and myelin segment undergoes dissolution and absorption by the surrounding cellular environment, a process called Wallerian degeneration. Then, the remaining Schwann cells divide and align longitudinally within basal lamina tubes. Growth cones from regenerating axons extend along the Schwann cell bands (the band of Bü ngner), growing along the Schwann cell membranes and basal laminae (Keynes 1987;Reichert et al. 1994;Grill and Tuszynske 1999). Such biological and morphological changes of Schwann cells are thought to be controlled by injury-induced molecules that are expressed by neurons and Schwann cells themselves. Especially, at around 7 days after nerve injury, many nerve regeneration-related factors, such as p75 NTR , co-receptor for glial cell line-derived neurotrophic factor family of trophic factors (GFRa1) and ninjurin 1 and 2, reach peak levels (Taniuchi et al. 1988;Araki and Milbrandt 1996;Baloh et al. 1997;Araki and Milbrandt 2000), and the growth cones of regenerating axons begin to move over the Schwann cell surface (Taniuchi et al. 1988;Goodrum et al. 1994). Successive large-scale screening, however, is required to reveal the spectrum of genes involved in this regenerat...