Temporal lobe epilepsy (TLE) is associated with pathological changes in signaling pathways that contribute to epileptogenesis. Among these, TGFβ signaling has been identified as a key contributor. SARA (Smad Anchor for Receptor Activation) is an intracellular regulator that facilitates Smad-dependent TGFβ signaling, and its steady-state level is controlled by ubiquitination mediated by the E3 ubiquitin ligase Smurf2. Prior to this study, the role of the SARA–Smurf2 regulatory axis in TLE and its potential as a therapeutic target had not been described.
This work aimed to determine whether dysregulation of the SARA–Smurf2 axis characterizes TLE and whether pharmacologic modulation can restore molecular patterns and affect seizure outcomes.
The investigators used two complementary systems: an in vivo pilocarpine-induced status epilepticus (SE) rat model to model TLE-related pathophysiology, and primary astrocytes derived from patients with refractory TLE to evaluate disease-relevant changes in human cells. The combination of an established experimental SE model and patient-derived astrocytes provided parallel lines of evidence for molecular alterations in astrocytic regulation of TGFβ signaling. Specific experimental parameters, sample sizes, and numerical results were not provided in the source summary.
In the pilocarpine SE rats, investigators observed a significant increase in SARA protein levels alongside increased immunoreactivity for Glial Fibrillary Acidic Protein (GFAP), a marker of astrocyte reactivity. Although Smurf2 was induced in the SE animals, the induction was described as insufficient to prevent accumulation of SARA. These findings indicate an imbalance in the regulatory axis that controls SARA turnover, concomitant with astrocytic activation in the epileptic hippocampal or temporal regions modeled by the SE paradigm.
The source does not include numerical measures, p values, or time-course details in the summary; those specifics must be consulted in the full manuscript for quantitative interpretation.
Astrocytes obtained from patients with refractory TLE showed a pattern consistent with the animal model: elevated SARA and GFAP immunoreactivity, indicating both accumulation of the SARA regulator and astrocyte reactivity. In contrast to the SE animals, patient-derived astrocytes demonstrated reduced Smurf2 immunoreactivity and an altered subcellular distribution of Smurf2. Together, these observations suggest impaired Smurf2-mediated ubiquitination and clearance of SARA in human TLE astrocytes, potentially sustaining dysregulated TGFβ signaling in the disease state.
Treatment with Losartan, an angiotensin receptor blocker with previously reported effects on TGFβ signaling in other contexts, was tested in both experimental systems. Losartan administration restored SARA and Smurf2 immunoreactivity toward a control-like pattern in the SE rat model and in TLE-derived astrocytes. In the SE animals, Losartan also reduced seizure frequency and seizure duration.
The summary reports these outcome directions but does not include dosing regimens, timing relative to SE induction, statistical details, or exact magnitudes of seizure reduction. Those methodological and quantitative details are not reported in the provided source summary.
The concordant findings in an animal SE model and in patient-derived astrocytes support the interpretation that dysregulation of the SARA–Smurf2 regulatory axis is a molecular signature of TLE. The data nominate SARA as a potential therapeutic target because its accumulation co-occurs with astrocyte reactivity and altered Smurf2 regulation.
The observed restoration of axis markers and the reduction in seizure burden after Losartan treatment provide preclinical evidence that pharmacologic modulation of this pathway may have therapeutic benefit for drug-resistant epilepsy. The authors propose Losartan as a candidate for repositioning in this context and call for further translational and clinical investigation.
The source text is a research preprint summary and does not report detailed quantitative results, experimental timelines, dosing, or statistical analyses. It also does not provide mechanistic dissection linking SARA accumulation directly to seizure generation, nor does it report long-term outcome data or safety/tolerability details of Losartan in the epilepsy models.
Further work needed includes: replication with full methodological transparency, dose–response and timing studies for Losartan, mechanistic experiments to define how SARA accumulation alters astrocyte function and neuronal excitability, and ultimately formal translational and clinical trials to test efficacy and safety in people with drug-resistant TLE.
The preprint reports funding from national and international research agencies and declares no competing interests. This work is available as a bioRxiv preprint with DOI 10.64898/2026.08.10.743913. The summary does not include peer-review status or further publication details.