Hypoxic pulmonary hypertension develops when the lungs are deprived of adequate oxygen over long periods, as occurs at high altitude or in chronic lung disease. The low-oxygen environment provokes an aggressive remodeling of the small pulmonary arteries: the muscular walls thicken, cells proliferate excessively, and the vessel lumens narrow, driving up resistance to blood flow. The right side of the heart, forced to pump against this rising resistance, experiences elevated pressure and eventually fails. Current treatments dilate vessels or target a handful of known signaling pathways, but they do not reverse the structural remodeling itself, which is why investigators continue to search for the molecular switches that govern it.

SCAMP3 belongs to a family of proteins embedded in the membranes of secretory carriers, the intracellular vesicles that shuttle material between cellular compartments. Although its day job involves membrane trafficking, SCAMP3 has recently attracted attention in cancer biology, where studies have linked it to the proliferation and migration of triple-negative breast cancer cells through modulation of AKT, ERK, and STAT3 signaling, and to tumor progression via a c-MYC–β-catenin–SQSTM1 axis. Elevated SCAMP3 expression has also been documented in pancreatic adenocarcinoma. What remained unknown was whether this trafficking protein plays any role in the vascular smooth muscle cells whose runaway growth defines pulmonary hypertension.

To find out, the team led by Peng Ye, Le Zhu, and corresponding authors Juan Zhang and Xiaomin Jiang turned to a well-established mouse model. Fifty mice were randomly divided into five groups of ten: a blank control group, a group exposed to hypoxia to induce pulmonary hypertension, a group receiving a non-targeting small interfering RNA as a negative control, a group treated with siRNA against SCAMP3, and a combined group receiving siRNA against both SCAMP3 and WWP1. The researchers then measured right ventricular systolic pressure, the Fulton index—the ratio of right ventricle weight to left ventricle plus septum weight, a standard gauge of right heart hypertrophy—and pulmonary function, while hematoxylin-eosin staining revealed the architecture of the pulmonary vessels.

The results were striking. Compared with normoxic animals, mice in the hypoxia group showed significantly increased SCAMP3 expression, both at the message and protein levels, alongside the expected rises in right ventricular systolic pressure and Fulton index and clear signs of vascular remodeling. In parallel experiments on human pulmonary artery smooth muscle cells grown under low-oxygen conditions, hypoxia again raised SCAMP3 protein and increased cell proliferation as measured by OD450 values in proliferation assays, while apoptosis rates fell and WWP1 protein levels dropped. In other words, the hypoxic environment simultaneously boosted the pro-growth trafficking protein and suppressed the ubiquitin ligase that would normally restrain growth.

Silencing SCAMP3 reversed this picture. In the hypoxia plus si-SCAMP3 group, SCAMP3 expression fell, proliferation of the pulmonary artery smooth muscle cells declined, and apoptosis rose significantly, with WWP1 protein expression climbing in step. In the living animals, knocking down SCAMP3 eased the hemodynamic and structural consequences of hypoxia: right ventricular systolic pressure and the Fulton index dropped, and the remodeling indexes calculated from stained vessel sections improved. The findings suggest that SCAMP3 acts as a brake release on the abnormal growth of vascular smooth muscle cells, and that removing it restores a healthier balance between cell division and cell death in the remodeled pulmonary arteries.

The mechanistic twist came from the double-knockdown group. When the researchers silenced WWP1 alongside SCAMP3, the benefits of SCAMP3 knockdown were partially undone: SCAMP3 expression crept back up, proliferation resumed, apoptosis declined, and WWP1 protein fell. This partial rescue implies that WWP1 sits downstream of SCAMP3 in the pathway, and that the protective effect of removing SCAMP3 depends at least in part on allowing WWP1 to accumulate. WWP1, a WW domain-containing E3 ubiquitin ligase, is known to tag other proteins for degradation and to regulate signaling cascades such as transforming growth factor-beta, and it has previously been implicated in cardiac hypertrophy, where targeting WWP1 prevented pathological heart muscle growth by destabilizing DVL2 through inhibition of K27-linked ubiquitination.

The statistical rigor of the study lends weight to its conclusions. All comparisons between the hypoxia group and the normoxia group, between the hypoxia plus si-SCAMP3 group and the hypoxia group, and between the double-knockdown group and the single SCAMP3 knockdown group reached significance at P less than 0.05. The animal work was approved by the Institutional Animal Care and Use Committee of Nanjing First Hospital and conducted in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals, with efforts made to minimize animal suffering. The study was funded by the National Natural Science Foundation of China and the Nanjing Health Science and Technology Development Special Fund Project, and the authors declared no conflicts of interest.

For the field, the study adds SCAMP3 to a growing roster of trafficking and ubiquitination proteins implicated in pulmonary vascular disease, a list that includes recent work on ErbB3 in endothelial dysfunction, BRCC3 regulation of ALK2 in vascular smooth muscle, and endothelial fIS1 deSUMOylation. What distinguishes the new findings is the proposed SCAMP3–WWP1 axis, which links membrane trafficking to the ubiquitin-proteasome machinery that decides the fate of growth-regulating proteins. If future work confirms the interaction at the molecular level—for example by identifying which substrates WWP1 tags when SCAMP3 is depleted—the pathway could yield drug targets capable of not just dilating vessels but reversing the wall thickening that makes pulmonary hypertension so lethal.

The caveats are real. The double knockdown only partially restored the disease phenotype, suggesting that other pathways downstream of SCAMP3 remain to be discovered, and the experiments were confined to mice and cultured cells rather than human tissue. The authors note that all original data are available upon reasonable request, which should help other laboratories test the mechanism independently. Still, the core message is clear and potentially consequential: a protein once regarded as a mundane component of the cellular shipping system appears to help orchestrate the vascular remodeling that underlies hypoxic pulmonary hypertension, and dialing it down—perhaps through RNA-based therapeutics or small molecules that stabilize WWP1—may one day offer patients a way to halt, or even reverse, the structural damage that current drugs cannot touch.

Subject of Research: The role of SCAMP3 knockdown and the E3 ubiquitin ligase WWP1 in attenuating hypoxic pulmonary hypertension and pulmonary vascular remodeling.

Article Title: Secretory Carrier Membrane Protein 3 Knockdown Attenuates Hypoxic Pulmonary Hypertension Potentially Involving WW Domain-Containing E3 Ubiquitin Protein Ligase 1

Article References: Secretory Carrier Membrane Protein 3 Knockdown Attenuates Hypoxic Pulmonary Hypertension Potentially Involving WW Domain-Containing E3 Ubiquitin Protein Ligase 1. (n.d.). https://doi.org/10.1007/s10528-026-11446-7

Image Credits: AI Generated

DOI: 10.1007/s10528-026-11446-7

Keywords: SCAMP3, WWP1, hypoxic pulmonary hypertension, pulmonary vascular remodeling, pulmonary artery smooth muscle cells, E3 ubiquitin ligase, apoptosis, cell proliferation, right ventricular systolic pressure, Fulton index, hypoxia, Biochemical Genetics