Transient introduction of human telomerase mRNA improves hallmarks of progeria cells

Abstract

Hutchinson–Gilford progeria syndrome (HGPS) is characterized by accelerated senescence due to a de novo mutation in the LMNA gene. The mutation produces an abnormal lamin A protein called progerin that lacks the splice site necessary to remove a farnesylated domain. Subsequently, progerin accumulates in the nuclear envelope, disrupting nuclear architecture, chromatin organization, and gene expression. These alterations are often associated with rapid telomere erosion and cellular aging. Here, we further characterize the cellular and molecular abnormalities in HGPS cells and report a significant reversal of some of these abnormalities by introduction of in vitro transcribed and purified human telomerase (hTERT) mRNA. There is intra‐individual heterogeneity of expression of telomere‐associated proteins DNA PKcs/Ku70/Ku80, with low‐expressing cells having shorter telomeres. In addition, the loss of the heterochromatin marker H3K9me3 in progeria is associated with accelerated telomere erosion. In HGPS cell lines characterized by short telomeres, transient transfections with hTERT mRNA increase telomere length, increase expression of telomere‐associated proteins, increase proliferative capacity and cellular lifespan, and reverse manifestations of cellular senescence as assessed by β‐galactosidase expression and secretion of inflammatory cytokines. Unexpectedly, mRNA hTERT also improves nuclear morphology. In combination with the farnesyltransferase inhibitor (FTI) lonafarnib, hTERT mRNA promotes HGPS cell proliferation. Our findings demonstrate transient expression of human telomerase in combination with FTIs could represent an improved therapeutic approach for HGPS.

Heterochromatin loss as a determinant of progerin‐induced DNA damage in Hutchinson–Gilford Progeria

“…Interestingly, this corresponds with the replication timing of heterochromatin and telomeres near the periphery, late in S-phase (Arnoult et al, 2010;Rhind & Gilbert, 2013). The timing of the progerin-induced DNA damage is also consistent with the fact that TERT's ability to rescue such DNA damage (Benson et al, 2010;Chojnowski et al, 2015;Kudlow et al, 2008;Li et al, 2019) is only apparent during DNA replication and leaves background DNA damage foci occurring at other stages entirely unaffected. However, the precise mechanisms how TERT, or hTERT mRNA prevent, or repair progerin-induced DNA damage, remains to be determined.…”

Interplay of the nuclear envelope with chromatin in physiology and pathology

“…In line with the interplay between the NE and chromatin organization and function, mutations of NE components or associated factors converge into common phenotypes linked with chromatin. Protein Class Compartment Mutation Organism NE defect Chromatin defect Telomere defect Mechanical defect REFs A-type lamins intermediate filament NE LMNA ko H. sapiens yes reorganization localization, length, aberrations reduced stiffness [ 94 , 95 , 151 ] LMNA ko M. musculus yes protrusions localization, length, aberrations increased deformability [ 94 , 96 ] LMNA kd H. sapiens no reorganization, positioning length high NE plasticity [ 97 – 99 ] HGPS H. sapiens yes reorganization, positioning aberrations, length increased stiffness [ 99 – 102 ] B-type amins intermediate filament NE LMNB1/2 ko M. musculus …”

Pharmacotherapy to gene editing: potential therapeutic approaches for Hutchinson–Gilford progeria syndrome

“…hTERT mRNA administration could also enhance the proliferative capacity, reduce the number of senescent cells, exacerbate senescenceassociated secretory phenotype (SASP), and rescue nuclear morphology. Combined treatment of FTI + hTERT mRNA had a synergistic effect on cell proliferation (Li et al 2019).…”

“…HGPS cells also exhibit increased shortening of telomeres and heterogeneity in their lengths (Decker et al 2009;Gonzalo and Kreienkamp 2015;Li et al 2019). The telomere attrition induces DDR that leads to proliferation arrest and senescence.…”