During development, chemical signals such as hepatocyte growth factor (HGF) cause individual cells to migrate to different locations, increase in number and differentiate into mature cells during tubule formation in the kidney, liver and breast. All of these cellular changes must be carefully coordinated over space and time. Dr. Keith E. Mostov from the Department of Anatomy at the University of California, San Francisco, and colleagues investigated the HGF-stimulated molecular mechanisms that are required for coordination of these cellular behaviors. The researchers used Madin-Darby canine kidney (MDCK) cells grown in collagen gels and stimulated with HGF. This experimental protocol results in the formation of branching tubules that resemble the development of tubules in many organs in vivo and allows for examination of molecular events that occur during tubulogenesis. "We found that downstream targets of HGF coordinately regulate successive stages of tubule development," says Dr. Mostov. "Activation of extracellular-regulated kinase (ERK) is necessary and sufficient for the initial stage when the cells migrate but ERK is not required later on when the cells differentiate. Conversely, matrix metalloproteases (MMPs) are required for the differentiation stage but not the initial migration phase."
The researchers conclude that HGF directs the complex process of tubule development by dividing it into two distinct phases that are controlled by different molecular signals provided by ERK and MMPs. According to Dr. Mostov, "Proper timing and sequence of cellular events is crucial for successful morphoge
Contact: Heidi Hardman