What are Growth Factors and How Do They Work?

First discovered by Rita Levi-Montalcini, growth factors are compact polypeptides, that bind to transmembrane receptors harboring kinase activity, to stimulate specific combinations of intracellular signaling pathways. The intracellular signaling pathways that are activated by growth factors are mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K), phospholipase C-γ, and transcription factors like the signal transducers and activators of transcription (STATs) or SMAD proteins. This activation of growth factor receptors creates a short, time-limited signal, which causes different parts of cellular proliferation and differentiation such as mitosis, clonal expansion, gene regulation, and cell apoptosis. Unlike hormones which have a wider systemic influence, growth factors usually transmit signals between cells to modulate their activity. They act as chemical messengers, communicating with different cells to stimulate growth. Depending on their function, growth factors can produce endocrine, paracrine, autocrine, or juxtracrine responses in cells.

The assessment of a drug candidate’s cross-activity with human xenobiotic-sensing receptors provides important early indications of that drug’s potential for downstream drug-drug interactions or other toxicology concerns. Prior to moving into human trials, preclinical studies utilize animals as human surrogates to assess a drug’s pharmacokinetic and toxicologic profiles. A wide range of animal models are used in preclinical studies for drug discovery including mice, rats, dogs, zebrafish, rabbits, and non-human primates. In research, these animals are used because they are orthologs. Orthologs are animals of different species that share genes that evolved from a common ancestor and have retained a similar function to those genes in humans.

The zebrafish (Danio rerio) is a small fish that has been making big waves as a popular vertebrate model for research. Zebrafish are a species of tropical fresh-water fish, that are native to southeast Asia specifically India, Nepal, Bhutan, Pakistan, Bangladesh, and Myanmar. Zebrafish live in schools and range from about 1 inch to 1.5 inches long. The name “zebrafish” comes from the blue stripes on both sides of their bodies and because of this, zebrafish were found in pet stores around the U.S long before they were used for research.

The discovery process is time consuming and expensive, and it is becoming increasingly more important that if you do fail that you fail fast before moving onto clinical trials. When planning your research, there are different options to test compounds for nuclear receptor activation or hepatotoxicity. The project might include performing cell-based reporter assays and if it does, you may consider designing your own assay rather than working with a company who specializes in this work. Before adding the process of designing an assay to a new project, consider these three important questions.

Modern drug discovery involves the identification of screening hits, medicinal chemistry, and optimization of those hits to increase the affinity, selectivity, efficacy/potency, metabolic stability, and bioavailability. This process is time-consuming, costly, and risky. Nuclear receptors are ideal targets for drug discovery. They control a variety of biological and disease processes through the expression of specific genes. Nuclear receptors do this by binding to lipophilic substances known as ligands.

Pharmacotherapy is based on the interplay of pharmacokinetics and pharmacodynamics, which allows scientists to understand the effect drugs have on the human body and helps researchers develop drugs that are safe and effective. These two concepts explain how the body impacts drugs (pharmacokinetics) and how those drugs can then impact the body (pharmacodynamics).

Biliary excretion is the crucial process of removing drugs from the human body and it plays an important role in drug processing. Researchers and drug development teams frequently examine this active process relative to differences in drug responses and challenges with drug toxicity.

Utilizing the human multidrug resistance protein 1 is a core component of modern drug development as it aids the assessment of drug-drug interaction. Learn more about MDR1 through a brief overview of its function in the human body and its role in public health and safety.

Through further examination of enzyme induction and its relationship to drug-drug interaction, we can better understand the effects of certain drugs and develop safer solutions for diseases and conditions.

From research available to us today, we know that there are many environmental chemicals that carry the potential to greatly impact the endocrine system. These are known as endocrine disrupting chemicals (EDCs), which are compounds that can alter drug and xenobiotic metabolic processes and interfere with the production, release, metabolism, and elimination of naturally occurring hormones.