Abstract
Hutchinson–Gilford progeria syndrome (HGPS) is a rare, premature ageing syndrome in children. HGPS is normally caused by a mutation in the LMNA gene, encoding nuclear lamin A. The classical mutation in HGPS leads to the production of a toxic truncated version of lamin A, progerin, which retains a farnesyl group. Farnesyltransferase inhibitors (FTI), pravastatin and zoledronic acid have been used in clinical trials to target the mevalonate pathway in HGPS patients to inhibit farnesylation of progerin, in order to reduce its toxicity. Some other compounds that have been suggested as treatments include rapamycin, IGF1 and N-acetyl cysteine (NAC). We have analysed the distribution of prelamin A, lamin A, lamin A/C, progerin, lamin B1 and B2 in nuclei of HGPS cells before and after treatments with these drugs, an FTI and a geranylgeranyltransferase inhibitor (GGTI) and FTI with pravastatin and zoledronic acid in combination. Confirming other studies prelamin A, lamin A, progerin and lamin B2 staining was different between control and HGPS fibroblasts. The drugs that reduced progerin staining were FTI, pravastatin, zoledronic acid and rapamycin. However, drugs affecting the mevalonate pathway increased prelamin A, with only FTI reducing internal prelamin A foci. The distribution of lamin A in HGPS cells was improved with treatments of FTI, pravastatin and FTI + GGTI. All treatments reduced the number of cells displaying internal speckles of lamin A/C and lamin B2. Drugs targeting the mevalonate pathway worked best for progerin reduction, with zoledronic acid removing internal progerin speckles. Rapamycin and NAC, which impact on the MTOR pathway, both reduced both pools of progerin without increasing prelamin A in HGPS cell nuclei.
Highlights
The nuclear lamina underlying the inner nuclear membrane, consists of separate mesh-works of class V intermediate filament proteins known as nuclear lamins (Aebi et al 1986; de Leeuw et al 2018)
IGF1 and combination treatment of Farnesyltransferase inhibitors (FTI), pravastatin and zoledronic acid do not elicit any changes at all with respect to anti-progerin b Fig. 6 Scoring of lamin A/C stained AG01972 fibroblasts after drug treatment. 2DD and AG01972 nuclei fixed with methanol:acetone and stained using lamin A/C primary antibodies and FITC-conjugated secondary antibodies were scored by eye using an Olympus BX-41 fluorescence microscope with an UPlanFl 9100/1.30 objective lens (Olympus Corporation, Japan)
Scoring results for the treatments are shown as a FTI-277 (2.5 lM for 24 h), b pravastatin (1 lM for 24 h), c zoledronic acid (1 lM for 24 h), d rapamycin (10 nM for 24 h), e insulin-like growth factor 1 (50.0 ng ml-1 for 24 h), f) N-acetyl-L-cysteine (20 lM for 1 h), g FTI-277 and GGTI-2133, h pravastatin and zoledronic acid and i FTI-277 (2.5 lM for 24 h), pravastatin and zoledronic acid
Summary
The nuclear lamina underlying the inner nuclear membrane, consists of separate mesh-works of class V intermediate filament proteins known as nuclear lamins (Aebi et al 1986; de Leeuw et al 2018). The importance of a correctly structured lamina is borne out by the comprehensive range of cellular functions that it is involved with (Bridger et al 2014). Lamin B2 in particular is present in the vast majority of cell types, with the exception of hepatocytes, unlike lamin B1 which does not appear to be expressed in muscle or connective tissue in mammalian cells (Broers et al 1997)
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