The expression of shelterin genes and telomere repeat analysis and their effect on Alzheimer's disease

Alzheimer's disease (AD) is an age-related dementia disorder characterized by memory loss and behavioral changes. Maintaining the integrity of telomere shortening in AD is important for cellular survival and homeostasis in all cells, especially glial cells. The shelterin protein complex provides telomere integrity. Measuring the expression levels of shelterin genes and determining the telomere lengths regulated by this complex will reveal their effects on AD progression and adult neurogenesis and will allow the detection of the disease or the determination of the progression process from an accessible tissue.

The study population included 111 patients and 91 healthy controls (male and female, < 50 age). The clinical histories (age, gender, hypertension, diabetes mellitus, obesity, cardiovascular disease, MMSE, medication use, family history, sleep disorders, seizure), covariates (HGB, ESR, Na, P, Cl, BUN, CRP, B12, TSH, Glucose, and MRI findings) and the expressional changes of shelterin genes (TERF1, TERF2, TINF2, POT1, TPP1, and RAP1) between the patient and control groups were evaluated relatively. ROC analyses determined the diagnostic power of telomere repeats and gene expressions.

In conclusion, upregulation of expression of shleterin complex genes was detected in AD, where telomeres are significantly shorter than in controls (P < 0.05). However, only TERF2 and RAP1 were significant (P < 0.05). A positive relationship was detected between telomere repeats and these genes (P < 0.05). Telomere repeats may be a strong diagnostic criterion to distinguish AD individuals from healthy individuals (AUC = 1.000). The upregulation of TERF2 and RAP1 core genes required for telomere integrity results in the instability of excessively shortened telomeres. Expression silencing of these genes may increase telomerase activity and maintain cellular survival. Also, the detection of telomere repeats has potential in the early diagnosis of AD patients.