Cerebrovascular phenotype analysis in Gucy1a3 loss-of-function mice: insights into moyamoya disease susceptibility
Pingkai Wang1, Tian Wang2, Jipeng Yu2
1Department of Neurology, Western Theater General Hospital of the Chinese People's Liberation Army, Chengdu, China.
Background:
Moyamoya disease (MMD) is characterized by progressive stenosis of the internal carotid artery and compensatory moyamoya angiogenesis. Although multiple studies have identified GUCY1A3 (encoding the α1 subunit of soluble guanylate cyclase) as a susceptibility gene for MMD, genome‑wide association studies (GWAS) have not yet established it as a significant locus. To address this discrepancy, this study used Gucy1a3 loss‑of‑function mice (Gucy1a3 -/-) to investigate the potential causal relationship between GUCY1A3 loss‑of‑function and the cerebrovascular phenotype in MMD.
Methods:
Intracranial arterial anatomy was assessed using 7.0T high‑resolution magnetic resonance angiography (MRA) and cerebral vascular casting. Vasoconstrictive remodeling was evaluated by calculating diameter ratios - specifically, internal carotid artery (ICA)/basilar artery (BA) and middle cerebral artery (MCA)/BA ratios. Histopathological evaluation was performed using hematoxylin and eosin (H&E) staining, elastic van Gieson (EVG) staining, and α‑smooth muscle actin (α‑SMA) immunohistochemistry to assess intracerebral macrovascular pathology. Cortical microvascular density and caliber were quantified using CD31 immunohistochemistry, while leptomeningeal vascular architecture was systematically analyzed using vascular casting, followed by skeletonization and topological analysis.
Results:
Gucy1a3 -/- developed normally, with no significant differences in intracranial vascular anatomy, diameter ratios, or large‑vessel histopathology compared to wild‑type mice (Wt). However, the leptomeningeal vascular network in Gucy1a3 -/- exhibited significant simplification, characterized by reduced vascular branching (365.90 ± 14.92 versus 330.00 ± 9.72, p = 0.0003) and density (total junctions, 174.10 ± 10.43 versus 155.80 ± 11.39, p = 0.0101; Vascular area%, 29.57 ± 4.40 versus 20.75 ± 2.01, p = 0.0021). In addition, cortical microvessel density (vascular density/ mm2, 515.70 ± 15.53 versus 351.20 ± 80.69, p = 0.0022; area%, 0.83 ± 0.20 versus 0.44 ± 0.18, p = 0.0152) and average diameter (3.5mm versus 2.5mm) were significantly reduced in Gucy1a3 -/-.
Conclusion:
Under early adult (8-12 weeks) conditions, GUCY1A3 deficiency did not produce detectable large‑artery stenosis typical of MMD. Instead, it induced a unique cerebrovascular phenotype marked by "rarefaction" of both cortical microvessels and leptomeningeal networks. Whether large‑vessel pathology develops in aged mice remains to be determined. These findings suggest that GUCY1A3 loss‑of‑function may contribute to MMD susceptibility primarily by compromising small‑vessel integrity, necessitating additional triggers for full disease manifestation.
Insights
Loss of GUCY1A3 function in mice impairs small blood vessel development, suggesting a role in Moyamoya disease susceptibility. This study reveals a unique cerebrovascular phenotype, distinct from typical Moyamoya disease, highlighting the importance of GUCY1A3 in maintaining small vessel integrity.
Area of Science:
- Neuroscience
- Genetics
- Vascular Biology
Background:
- Moyamoya disease (MMD) involves internal carotid artery stenosis and compensatory angiogenesis.
- GUCY1A3 is a known susceptibility gene for MMD, but its role is not fully established by GWAS.
- This study investigates the causal link between GUCY1A3 loss-of-function and MMD's cerebrovascular phenotype using mouse models.
Purpose of the Study:
- To investigate the cerebrovascular phenotype associated with GUCY1A3 loss-of-function.
- To determine if GUCY1A3 deficiency causes MMD-like large-artery stenosis.
- To explore the role of GUCY1A3 in small vessel integrity within the brain.
Main Methods:
- Utilized Gucy1a3 loss-of-function mice (Gucy1a3-/-) and wild-type (Wt) littermates.
- Assessed intracranial arterial anatomy via high-resolution MRI and vascular casting.
- Performed histopathological analysis (H&E, EVG, α-SMA) and quantified microvascular density (CD31).
Main Results:
- Gucy1a3-/- mice showed normal large-vessel anatomy and histopathology.
- Significant simplification of the leptomeningeal vascular network was observed in Gucy1a3-/- mice, with reduced branching and density.
- Cortical microvessel density and caliber were significantly reduced in Gucy1a3-/- mice compared to Wt.
Conclusions:
- GUCY1A3 deficiency induces a cerebrovascular phenotype characterized by microvessel and leptomeningeal network rarefaction, not large-artery stenosis.
- This suggests GUCY1A3 loss-of-function contributes to MMD susceptibility by compromising small-vessel integrity.
- Additional triggers may be necessary for the full manifestation of MMD in the context of GUCY1A3 deficiency.
