Runx1 overexpression triggers early intervertebral disc degeneration

A new research paper was published in Volume 17, Issue 9 of Aging-US on September 8, 2025, titled, “Runx1 overexpression induces early onset of intervertebral disc degeneration.”

In this study, led by first author Takanori Fukunaga from Emory University School of Medicine and corresponding author Hicham Drissi from Emory and the Atlanta VA Medical Center, researchers found that the Runx1 gene, when overactive in spinal disc cells, can accelerate age-related degeneration of the intervertebral discs. The findings offer new insight into the genetic factors that drive disc aging and suggest possible directions for treating chronic back pain.

Intervertebral discs cushion the spine and support movement. Their deterioration is a major cause of lower back pain, especially with aging. At the center of each disc is the nucleus pulposus (NP), a gel-like core that contains proteins such as collagen and aggrecan, which help retain water and maintain structure. As people age, NP cells often lose their function, contributing to disc breakdown.

Using a genetically modified mouse model, the researchers activated Runx1 specifically in NP cells. These mice developed signs of disc degeneration by five months of age, which is much earlier than normal. The overexpression of Runx1 led to the loss of healthy NP cells, an increase in abnormal cell types, and damage to disc structure. Levels of essential proteins like aggrecan and type II collagen decreased, while type X collagen increased, signaling unhealthy tissue changes.

“To achieve NP-specific postnatal overexpression of Runx1, we crossed Krt19CreERT mice with Rosa26-Runx1 transgenic mice previously generated in our laboratory.”

A key finding was that Runx1 overactivity did not kill cells directly. Instead, it caused premature cellular aging, known as senescence. Senescent cells lose the ability to repair tissue, creating an environment that accelerates degeneration. Markers of senescence were significantly elevated in the affected discs.

The researchers also observed a dose-dependent response. The more Runx1 was activated, the more severe the degeneration was. This suggests that targeting Runx1 may be a promising strategy to prevent or slow disc aging.

Overall, this study highlights the genetic and cellular processes that contribute to intervertebral disc degeneration, a leading cause of disability. By identifying Runx1 as a potential driver of early disc aging, the research opens new opportunities for intervention and treatment of degenerative spine conditions.