Sulforaphane enhances progerin clearance in Hutchinson-Gilford progeria fibroblasts.

Hutchinson-Gilford progeria syndrome (HGPS, OMIM 176670) is a rare multisystem childhood premature aging disorder linked to mutations in the LMNA gene. The most common HGPS mutation is found at position G608G within exon 11 of the LMNA gene. This mutation results in the deletion of 50 amino acids at the carboxyl-terminal tail of prelamin A, and the truncated protein is called progerin. Progerin only undergoes a subset of the normal post-translational modifications and remains permanently farnesylated. Several attempts to rescue the normal cellular phenotype with farnesyltransferase inhibitors (FTIs) and other compounds have resulted in partial cellular recovery. Using proteomics, we report here that progerin induces changes in the composition of the HGPS nuclear proteome, including alterations to several components of the protein degradation pathways. Consequently, proteasome activity and autophagy are impaired in HGPS cells. To restore protein clearance in HGPS cells, we treated HGPS cultures with sulforaphane (SFN), an antioxidant derived from cruciferous vegetables. We determined that SFN stimulates proteasome activity and autophagy in normal and HGPS fibroblast cultures. Specifically, SFN enhances progerin clearance by autophagy and reverses the phenotypic changes that are the hallmarks of HGPS. Therefore, SFN is a promising therapeutic avenue for children with HGPS.

Naïve adult stem cells isolation from primary human fibroblast cultures.

Over the last decade, several adult stem cell populations have been identified in human skin (1-4). The isolation of multipotent adult dermal precursors was first reported by Miller F. D laboratory (5, 6). These early studies described a multipotent precursor cell population from adult mammalian dermis (5). These cells--termed SKPs, for skin-derived precursors-- were isolated and expanded from rodent and human skin and differentiated into both neural and mesodermal progeny, including cell types never found in skin, such as neurons (5). Immunocytochemical studies on cultured SKPs revealed that cells expressed vimentin and nestin, an intermediate filament protein expressed in neural and skeletal muscle precursors, in addition to fibronectin and multipotent stem cell markers (6). Until now, the adult stem cells population SKPs have been isolated from freshly collected mammalian skin biopsies. Recently, we have established and reported that a population of skin derived precursor cells could remain present in primary fibroblast cultures established from skin biopsies (7). The assumption that a few somatic stem cells might reside in primary fibroblast cultures at early population doublings was based upon the following observations: (1) SKPs and primary fibroblast cultures are derived from the dermis, and therefore a small number of SKP cells could remain present in primary dermal fibroblast cultures and (2) primary fibroblast cultures grown from frozen aliquots that have been subjected to unfavorable temperature during storage or transfer contained a small number of cells that remained viable (7). These rare cells were able to expand and could be passaged several times. This observation suggested that a small number of cells with high proliferation potency and resistance to stress were present in human fibroblast cultures (7). We took advantage of these findings to establish a protocol for rapid isolation of adult stem cells from primary fibroblast cultures that are readily available from tissue banks around the world (Figure 1). This method has important significance as it allows the isolation of precursor cells when skin samples are not accessible while fibroblast cultures may be available from tissue banks, thus, opening new opportunities to dissect the molecular mechanisms underlying rare genetic diseases as well as modeling diseases in a dish.

Naïve adult stem cells from patients with Hutchinson-Gilford progeria syndrome express low levels of progerin in vivo.

Hutchinson-Gilford progeria syndrome (HGPS, OMIM 176670) is a rare disorder characterized by segmental accelerated aging and early death from coronary artery disease or stroke. Nearly 90% of HGPS sufferers carry a G608G mutation within exon 11 of LMNA, producing a truncated form of prelamin A, referred to as "progerin". Here, we report the isolation of naïve multipotent skin-derived precursor (SKP) cells from dermal fibroblast cultures from HGPS donors. These cells form spheres and express the neural crest marker, nestin, in addition to the multipotent markers, OCT4, Sox2, Nanog and TG30; these cells can self-renew and differentiate into smooth muscle cells (SMCs) and fibroblasts. The SMCs derived from the HGPS-SKPs accumulate nuclear progerin with increasing passages. A subset of the HGPS-naïve SKPs express progerin in vitro and in situ in HGPS skin sections. This is the first in vivo evidence that progerin is produced in adult stem cells, and implies that this protein could induce stem cells exhaustion as a mechanism contributing to aging. Our study provides a basis on which to explore therapeutic applications for HGPS stem cells and opens avenues for investigating the pathogenesis of other genetic diseases.

rAAV2-mediated restoration of LEKTI in LEKTI-deficient cells from Netherton patients.

BACKGROUND: Netherton syndrome (NS, MIM 256500) is a potential live threatening autosomal-recessive skin disorder clinically characterized by the trias of congenital erythroderma, hair shaft anomalies and atopic diathesis. It is caused by mutations in the gene SPINK5 resulting in a deficiency of its processed protein named lympho-epithelial Kazal-type related inhibitor (LEKTI). LEKTI controls the activity of several serine proteases in the skin that are involved in terminal differentiation. Loss of LEKTI results in protease hyperactivity, increased degradation of intercellular junctions, reduced stratum corneum adhesion and impaired skin barrier function. Today NS can only be treated symptomatically. OBJECTIVE: Does gene transfer offer a therapeutic option for NS in the future? METHODS: A recombinant adeno-associated virus type 2 vector was constructed containing the full length cDNA (rAAV2/C-SPINK5) of functional human LEKTI. Infectious virus particles were used for transfection of LEKTI-deficient-keratinocytes of NS patients in vitro. RESULTS: Gene transfer of SPINK5 in NS-keratinocytes led to a five-fold increase in mRNA expression of SPINK5 reaching almost 75% of normal value. The functionality of the expressed LEKTI was proven in a hydrolytic activity assay demonstrating that the activity of LEKTI after gene transfer increased closely to the level seen in keratinocytes of healthy individuals. CONCLUSION: The results provide first evidence that gene transfer of SPINK5 results in increased LEKTI activity in NS-keratinocytes, thus offering a rational to further pursue such a gene therapy approach for NS.