A novel treatment approach based on zinc-finger DNA-binding proteins, designed to activate silenced progenitors UBE3A The gene successfully alleviated the signs and symptoms of Angelman syndrome in a mouse model.
The strategy has also shown efficacy in brain cells derived from Engelmann patients, it can be translated to human cells, and it may be safer than other approaches being tested, the researchers noted.
study,”Restoration of transcriptional reprogramming UBE3A Brain enlargement and rescues behavioral phenotypes in an Angelman syndrome mouse model‘ was published in the journal Nuclear therapy.
The treatment goal is the production of functional UBE3A enzyme
The UBE3A The gene carries instructions for the ubiquitin protein ligase E3A, an enzyme that targets other proteins for degradation and recycling, primarily in cells of the central nervous system (brain and spinal cord).
Usually, a copy of UBE3A A gene inherited from the mother is activated, while the other copy, inherited from the father, is selectively silenced by a molecule. UBE3A antisense transcript (UBE3A-ATS).
Deletion or corruption in the maternal copy UBE3A The gene causes Angelman syndrome.
A possible treatment approach is to activate the parent UBE3A By blocking the function of gene copy UBE3A-ATSallowing the production of functional UBE3A enzyme.
Antisense oligonucleotides (ASOs), designed to suppress short strands of genetic material (DNA or RNA) UBE3A-ATS The product, Angelman’s, is being tested in ongoing clinical trials as a treatment.
Zinc-finger protein therapeutics – called ZFPs – are another approach to blocking UBE3A-ATS. These proteins are involved in many biological processes, including the regulation of gene activity, and can be designed to target genes of choice. As such, they may be a safer approach, the researchers noted, adding that ZFPs have undergone clinical evaluation for other indications.
A team led by researchers at the University of California, Davis, designed ZFPs to suppress the prodn. UBE3A-ATSWith the goal of activating the parent UBE3A As a possible Angelman treatment.
First, the team tested their human ZFP candidate, called hATF-555, on patient-derived nerve cells. UBE3A Gene mutation. In these cells, which carried only one functional parental gene, there was an 11-fold increase. UBE3A-ATS with a 1.3-fold decrease in UBE3A enzyme activity.
hATF-555 was successfully degraded, delivered by a modified and harmless lentivirus UBE3A-ATS 1.25 times in nerve cells when the parent is partially activated UBE3A Activity 1.33 times.
No off-target treatment effects or inflammatory immune activity were observed in mice
To further evaluate this approach, the researchers treated an adult mouse model of Angelman syndrome with ZFP that blocked the mouse. Ube3a-ATSCalled ATF-S1K. Here, the treatment was injected into the tail vein with targeted delivery to the mouse brain using a modified and harmless AAV virus.
After five weeks of treatment, Ube3a-ATS Gene activity levels were 2.2-fold lower in brain tissue, and UBE3A enzyme levels increased in a dose-dependent manner to 26% of unaffected control animals. The average number of UBE3A-positive cells in the brains of treated Engelmann rats was similar to controls.
Notably, there was no further increase in UBE3A-positive cells when control mice were treated with ATF-S1K. The researchers also found no off-target effects on overall gene activity or inflammatory immune activation, “suggesting that ATF-S1K treatment is not only specific but also well tolerated.” Live [in living animals]” they wrote.
Mice were then subjected to the open field test to assess motor ability and willingness to explore. Without treatment, Angelman rats are less active than control rats. With ATF-S1K, Angelman rats showed motor improvements in horizontal orientation, vertical rearing, and exploration.
In the rotarod test for motor coordination and balance, Angelman mice performed significantly worse than controls. Treatment led to a slight improvement on average.
Angelman rats also had longer walking strides with lower stride frequency than controls in the hindlimb and forelimb, similar to the deficits seen in the patients, the researchers noted. AAV-S1K treatment improved motor abilities in the Angelman group, particularly for hindlimb function. No improvements were observed in other gait measures, including stride length or swing duration.
“We show that a single injection of AAV ATF-S1K (AAV-S1K) delivered into the tail vein rescues molecular and behavioral phenotypes in young adults. [Angelman syndrome] mice,” the team wrote. “The specificity and tolerability of a single AAV-S1K treatment in mice supports its use [ZFPs] For the treatment of [Angelman syndrome] and other genetic disorders.”