Mitogener

Mitogener (English: mitogen) is a substance that stimulates cell division, promoting proliferation and progression of cells through the cell cycle. In many contexts, mitogener agents activate cells that are resting or quiescent, driving entry into the S phase and subsequent mitosis. The term encompasses a range of molecules, from proteins and carbohydrates to microbial components and small molecules, whose effect is to increase DNA synthesis and cell numbers.

Mechanisms of action vary by agent and cell type but commonly involve activation of intracellular signaling pathways such as MAPK/ERK and PI3K/Akt, upregulation of cyclins and cyclin-dependent kinases, and inactivation of cell-cycle inhibitors like the retinoblastoma protein. Some mitogener effects arise from receptor-mediated signaling at the cell surface, while others result from more complex interactions with immune or germline cells. In immune cells, mitogenic stimulation often requires co-stimulatory signals that shape the magnitude and nature of the proliferative response.

Classic examples include plant lectins such as phytohemagglutinin (PHA) and concanavalin A (ConA), which stimulate T-cell proliferation; pokeweed mitogen (PWM), which can activate B cells; and bacterial components like lipopolysaccharide (LPS), also used to induce B-cell proliferation. Growth factors such as epidermal growth factor (EGF) and other mitogenic cytokines can act as mitogens in susceptible cell types, though their effects depend on the cellular context.

Applications of mitogens are common in laboratory research and clinical settings. They are used to study the cell cycle, to probe signaling pathways, and to expand lymphocytes in vitro for research or therapeutic purposes. Mitogenic responses can also serve as indicators of immune competence or cellular activation.