Temporal Analysis of Gene Expression by Microarray
Temporal Analysis of Gene Expression by Microarray
Wound healing is a complex biologic process that involves the action of hundreds of genes coordinated by growth factors and signaling molecules. However, little is known about the naturally occurring levels of growth factors/receptors expressed at the wound site. In this study, we used an in-house growth factor/receptor-enhanced microarray to determine the temporal gene expression profile of wound healing in the ear-punched tissue of MRL/MpJ-Fas1pr (MRL) mice. A hierarchical cluster analysis was performed to group genes on the basis of the temporal expression pattern. The altered gene expression profiles verified the involvement of many known growth factors/receptors and identified novel participants in wound healing. Two of the three most highly up-regulated genes that were identified at the inflammatory stage have no established roles in wound healing and merit further functional investigation. The dynamic change of expression over time and diverse patterns of expression support the concept that a complex local milieu, rather than a single growth factor, influences the rate of wound healing.
Fundamental to our understanding of wound-healing biology is a knowledge of the signals that trigger relatively sedentary cell lineages at the wound margin to proliferate, become invasive, and then synthesize new matrix in the wound gap. The growth factors are key players in providing the signals to initiate and coordinate this complex process. Topical applications of growth factors to different animal models have demonstrated their ability to accelerate wound healing, providing evidence to support their signaling roles in wound healing.
One of the major tasks ahead is to determine the temporal expression profiles and relative concentrations of growth factors and their isoforms at the wound site during healing. Several attempts have been made to detect and quantify growth factors in wound fluids during the healing process. Cromack, et al., demonstrated that TGFß levels in rat wound fluids increased initially after injury and then gradually declined with wound closure. Vogt, et al., determined the temporal secretion profiles of seven growth factors in human wound fluid and concluded that the different profiles could reflect their effects on the stimulation of epithelialization, matrix synthesis, and the inflammatory response. Other investigators localized growth factors in healing wounds using immunohistochemistry or in-situ hybridization and provided information on the potential functions of these growth factors. However, these methodologies were limited by the small number of growth factors that can be examined and thus cannot provide a comprehensive molecular description of the wound sites.
The high density cDNA microarray technology, with its capacity for two-color, simultaneous monitoring of thousands of genes, provides a unique opportunity for high-throughput analysis of gene expression in wound tissues. We used an in-house growth factors/receptors-enhanced microarray to analyze temporal gene expression profiles in the multicellular, ear-punched tissue of a fast healing/regeneration strain, MRL/MpJ-Faslpr (MRL) mouse during inflammatory, repair, and remodeling stages of wound healing. In this report, we will present data to show the dynamic change and diverse patterns of expression during the course of wound healing.
Wound healing is a complex biologic process that involves the action of hundreds of genes coordinated by growth factors and signaling molecules. However, little is known about the naturally occurring levels of growth factors/receptors expressed at the wound site. In this study, we used an in-house growth factor/receptor-enhanced microarray to determine the temporal gene expression profile of wound healing in the ear-punched tissue of MRL/MpJ-Fas1pr (MRL) mice. A hierarchical cluster analysis was performed to group genes on the basis of the temporal expression pattern. The altered gene expression profiles verified the involvement of many known growth factors/receptors and identified novel participants in wound healing. Two of the three most highly up-regulated genes that were identified at the inflammatory stage have no established roles in wound healing and merit further functional investigation. The dynamic change of expression over time and diverse patterns of expression support the concept that a complex local milieu, rather than a single growth factor, influences the rate of wound healing.
Fundamental to our understanding of wound-healing biology is a knowledge of the signals that trigger relatively sedentary cell lineages at the wound margin to proliferate, become invasive, and then synthesize new matrix in the wound gap. The growth factors are key players in providing the signals to initiate and coordinate this complex process. Topical applications of growth factors to different animal models have demonstrated their ability to accelerate wound healing, providing evidence to support their signaling roles in wound healing.
One of the major tasks ahead is to determine the temporal expression profiles and relative concentrations of growth factors and their isoforms at the wound site during healing. Several attempts have been made to detect and quantify growth factors in wound fluids during the healing process. Cromack, et al., demonstrated that TGFß levels in rat wound fluids increased initially after injury and then gradually declined with wound closure. Vogt, et al., determined the temporal secretion profiles of seven growth factors in human wound fluid and concluded that the different profiles could reflect their effects on the stimulation of epithelialization, matrix synthesis, and the inflammatory response. Other investigators localized growth factors in healing wounds using immunohistochemistry or in-situ hybridization and provided information on the potential functions of these growth factors. However, these methodologies were limited by the small number of growth factors that can be examined and thus cannot provide a comprehensive molecular description of the wound sites.
The high density cDNA microarray technology, with its capacity for two-color, simultaneous monitoring of thousands of genes, provides a unique opportunity for high-throughput analysis of gene expression in wound tissues. We used an in-house growth factors/receptors-enhanced microarray to analyze temporal gene expression profiles in the multicellular, ear-punched tissue of a fast healing/regeneration strain, MRL/MpJ-Faslpr (MRL) mouse during inflammatory, repair, and remodeling stages of wound healing. In this report, we will present data to show the dynamic change and diverse patterns of expression during the course of wound healing.
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