Novel RNA Target Improves Outcomes in Chronic Limb Ischemia
- Research from Mass General Brigham identifies a key regulator of angiogenesis in severe peripheral artery disease, offering a potential new therapeutic avenue.
- Chronic Limb-Threatening Ischemia (CLTI) is a severe form of peripheral artery disease (PAD) characterized by chronic, severe blockage of arteries in the legs and feet.
- For decades, research into CLTI has primarily focused on endothelial-derived factors - substances released by the cells lining blood vessels - and their role in angiogenesis (the formation...
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CARMN lncRNA: A Novel target for Chronic Limb-Threatening Ischemia
Table of Contents
Research from Mass General Brigham identifies a key regulator of angiogenesis in severe peripheral artery disease, offering a potential new therapeutic avenue.
understanding Chronic Limb-Threatening Ischemia (CLTI)
Chronic Limb-Threatening Ischemia (CLTI) is a severe form of peripheral artery disease (PAD) characterized by chronic, severe blockage of arteries in the legs and feet. This restriction of blood flow leads to non-healing wounds,pain,and a high risk of limb amputation. approximately 20% of individuals with PAD progress to CLTI, and the condition affects an estimated 1-2% of the population over 75 years old.
The Limitations of Current Approaches
For decades, research into CLTI has primarily focused on endothelial-derived factors – substances released by the cells lining blood vessels – and their role in angiogenesis (the formation of new blood vessels). The rationale was that stimulating angiogenesis would improve blood flow to the affected limbs and reduce amputation risk. However, clinical trials testing growth factors identified in these studies have consistently failed to demonstrate meaningful improvements in patient outcomes.
This lack of success prompted researchers to explore alternative mechanisms driving impaired angiogenesis in CLTI. The study led by Dr. Mark Feinberg shifted the focus from endothelial cells to vascular smooth muscle cells, a previously underappreciated component of the angiogenic process.
Identifying CARMN: A smooth Muscle Cell lncRNA
Dr. Feinberg and his team screened skeletal muscle samples from patients with CLTI, comparing them to control samples. Surprisingly, they found that differences weren’t in growth factors, but in a long non-coding RNA (lncRNA) called CARMN. Crucially, CARMN was expressed *only* in vascular smooth muscle cells, not in endothelial cells.
LncRNAs are RNA molecules longer than 200 nucleotides that do not code for proteins but play crucial regulatory roles in gene expression. CARMN’s specific location and function suggested it might very well be a key regulator of angiogenesis within the smooth muscle cells surrounding blood vessels.
How CARMN Regulates Angiogenesis
The research revealed that CARMN regulates angiogenesis through a specific signaling pathway involving miR-143-3p and Hedgehog Interacting Protein (HHIP). CARMN acts as a “sponge” for miR-143-3p, preventing it from suppressing HHIP expression. HHIP, in turn, promotes angiogenesis.
In CLTI patients, CARMN expression is reduced, leading to increased miR-143-3p levels, decreased HHIP expression, and ultimately, impaired angiogenesis. This creates a vicious cycle of reduced blood flow and tissue damage.
| Component | Role in Angiogenesis (CLTI) |
|---|---|
| CARMN | lncRNA; reduced expression in CLTI, promotes angiogenesis by sequestering miR-143-3p. |
| miR-143-3p | MicroRNA; increased levels in CLTI due to reduced CARMN,suppresses HHIP expression. |
| HHIP | Hedgehog Interacting Protein; decreased expression in CLTI, promotes angiogenesis. |