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Xiao-Yong Man

Publications and source records attributed to Xiao-Yong Man.

4 recordsLinked to original sources
PubMed2006

Expression of VEGFR-2 on HaCaT cells is regulated by VEGF and plays an active role in mediating VEGF induced effects.

Vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 play important roles in mitogenesis and chemotaxis of endothelial cells. In normal human skin, VEGF is expressed and secreted by epidermal keratinocytes. Emerging data suggest that keratinocyte-derived VEGF targets other cell types besides the dermal endothelial cells. We have recently showed that keratinocytes from human normal skin expressed all five known VEGF receptors and co-receptors (neuropilin 1 and 2). To define the functional significance of VEGFR-2 in epidermis, we examined its role in a keratinocyte cell line, HaCaT cells, in response to VEGF treatment. Expression of VEGFR-2 on HaCaT cells was confirmed at both RNA and protein levels and was regulated by VEGF165 treatment. Treatment of HaCaT cells with VEGF165 induced tyrosine-autophosphorylation of VEGFR-2 and phosphorylation of PLC-gamma and p44/42 MAPK in a time-dependent manner. Preincubation with a neutralizing antibody for VEGFR-2 (MAB3571) completely abrogated these phosphorylation effects. Furthermore, VEGF165 stimulated proliferation and migration of HaCaT cells, and this effect was significantly blocked by a pretreatment with MAB3571. Neutralizing VEGFR-2 in HaCaT cells increased cell adhesion during culture. Our results suggest that VEGFR-2 expressed on HaCaT cells plays a crucial role in VEGF-mediated regulation of cell activity.

Cell Adhesion↗
PubMed2003

Reconstructing the evolutionary history of China: a caveat about inferences drawn from ancient DNA.

The decipherment of the meager information provided by short fragments of ancient mitochondrial DNA (mtDNA) is notoriously difficult but is regarded as a most promising way toward reconstructing the past from the genetic perspective. By haplogroup-specific hypervariable segment (HVS) motif search and matching or near-matching with available modern data sets, most of the ancient mtDNAs can be tentatively assigned to haplogroups, which are often subcontinent specific. Further typing for mtDNA haplogroup-diagnostic coding region polymorphisms, however, is indispensable for establishing the geographic/genetic affinities of ancient samples with less ambiguity. In the present study, we sequenced a fragment (approximately 982 bp) of the mtDNA control region in 76 Han individuals from Taian, Shandong, China, and we combined these data with previously reported samples from Zibo and Qingdao, Shandong. The reanalysis of two previously published ancient mtDNA population data sets from Linzi (same province) then indicates that the ancient populations had features in common with the modern populations from south China rather than any specific affinity to the European mtDNA pool. Our results highlight that ancient mtDNA data obtained under different sampling schemes and subject to potential contamination can easily create the impression of drastic spatiotemporal changes in the genetic structure of a regional population during the past few thousand years if inappropriate methods of data analysis are employed.

Asian People↗
PubMedDate not supplied

Immunolocalization and expression of vascular endothelial growth factor receptors (VEGFRs) and neuropilins (NRPs) on keratinocytes in human epidermis.

Vascular endothelial growth factor (VEGF) plays an important role in normal and pathological angiogenesis. VEGF receptors (VEGFRs, including VEGFR-1, VEGFR-2, and VEGFR-3) and neuropilins (NRPs, including NRP-1 and NRP-2) are high-affinity receptors for VEGF and are typically considered to be specific for endothelial cells. Here we showed expression of VEGFRs and NRPs on cultured epidermal keratinocytes at both mRNA and protein levels. We further localized these receptors by immunofluorescence (IF) staining in the epidermis of surgical skin specimens. We found positive staining for VEGFRs and NRPs in all layers of the epidermis except for the stratum corneum. VEGFR-1 and VEGFR-2 are primarily expressed on the cytoplasmic membrane of basal cells and the adjacent spinosum keratinocytes. All layers of the epidermis except for the horny cell layer demonstrated a uniform pattern of VEGFR-3, NRP-1, and NRP-2. Sections staining for NRP-1 and NRP-2 also showed diffuse intense fluorescence and were localized to the cell membrane and cytoplasm of keratinocytes. In another panel of experiments, keratinocytes were treated with different concentrations of VEGF, with or without VEGFR-2 neutralizing antibody in culture. VEGF enhanced the proliferation and migration of keratinocytes, and these effects were partially inhibited by pretreatment with VEGFR-2 neutralizing antibody. Adhesion of keratinocytes to type IV collagen-coated culture plates was decreased by VEGF treatment, but this reduction could be completely reversed by pretreatment with VEGFR-2 neutralizing antibody. Taken together, our results suggest that the expression of VEGFRs and NRPs on keratinocytes may constitute important regulators for its activity and may possibly be responsible for the autocrine signaling in the epidermis.

Adult↗