Trends in Biochemical Sciences
ReviewmiRNAs, ‘stemness’ and skin
Section snippets
Are miRNAs expressed in skin?
MicroRNAs (miRNAs; see Glossary) are a class of non-coding RNA genes, the products of which are small single-stranded RNAs of 19–22 nucleotides (nts) that can suppress the expression of protein-coding genes by targeting the 3′UTR region of messenger RNAs (mRNAs) 1, 2, 3, 4 (Box 1). Studies in animal models have revealed essential functions for miRNAs in developmental control. Indeed, many miRNAs exhibit a temporal or tissue-specific expression pattern, indicating that they might have a crucial
miRNAs are important for skin development and homeostasis
To determine whether miRNAs are globally important for epidermal and hair follicle development, Dicer was specifically deleted in the epidermis 32, 33. Dicer is expressed in epidermis and in developing hair follicles both in mouse embryos (at the embryonic [E] 14.5 stage in which primary hair follicle development is initiated) and postnatally, as shown by in situ hybridization [33]. Conditional ablation in embryonic skin progenitors was achieved using Cre recombinase driven by the K14 promoter,
miRNA expression in the epidermis and hair follicle
Using two different microarray approaches, the Fuchs and Millar laboratories identified specific miRNAs expressed in developing mouse skin and hair follicles 32, 33. The Fuchs laboratory isolated and cloned small RNAs from E17.5 epidermis and hair follicles [32] (Table 1). By contrast, the Millar laboratory [33] identified miRNAs in full-thickness skin samples at postnatal day 1 and compared them with the miRNAs expressed in full-thickness skin of K14::DKK 1 (Dickkopf 1) transgenic mice (DKK1
miRNA-203 regulates the exit from ‘stemness’
miRNA-203 is abundantly expressed in the epidermis and in hair follicles between the E13.5 and E15.5 developmental stages. Its expression is absent in single-layered epidermal progenitors during early developmental stages but appears at E14.5 upon the induction of stratification [30]. In adult epidermis, miRNA-203 is not expressed in proliferating basal-layer keratinocytes but is detectable in the upper layers. Moreover, miRNA-203 is rapidly upregulated when primary keratinocytes isolated from
miRNAs are deregulated in epidermal diseases and tumours
miRNA expression profiles differ between healthy human skin and two chronic inflammatory diseases: psoriasis and atopic eczema [39] (Table 2). The differences include miRNA-21 upregulation in both diseases and specific miRNA-203 upregulation in psoriasis. miRNA-122 is downregulated in both psoriasis and atopic eczema, whereas miRNA-99b downregulation is observed specifically in psoriasis. The significant miRNA-203 upregulation in psoriatic plaques coincides with the downregulation of a
Concluding remarks and future perspectives
These new findings add epidermal development to the extensive role of miRNAs in overall animal development (as shown by the global Dicer disruption) and demonstrate that specific miRNAs participate in lineage differentiation in a wide variety of tissue types. The further investigation and elucidation of the molecular pathways that induce miRNA expression in skin will increase our understanding of the molecular mechanisms underlying skin diseases. Although studies of miRNAs in the epidermis
Acknowledgements
We thank Anna Maria Lena, Pia Rivetti di Val Cervo and Alessandro Terrinoni for scientific discussion. Work in our laboratory was supported by the Medical Research Council (to G.M.) and by grants from Telethon (GGP02251 to E.C.), AIRC (2743 to G.M.), EU (LSGBH-2005–019067-Epistem; LSHC-CT-2004–503576-Active p53) to G.M., MIUR to G.M., PRIN 06 to E.C., PRIN 06 to G.M., MinSan to G.M., ISS ‘Programma Italia–USA’ N526D5 to G.M., Philip Morris USA Inc. to G.M., ACC12 to G.M. and E.C. and by ANR
Glossary
- Adult (or somatic) stem cells
- undifferentiated cells found within a differentiated tissue that can renew themselves and differentiate (with certain limitations) to give rise to all the specialized cell types of the tissue from which it originated.
- Dicer
- a member of the RNase III family of nucleases that specifically cleaves double-stranded RNAs. Dicer processes long dsRNA into siRNAs of 21–23 nt.
- Differentiation
- the general process whereby an undifferentiated embryonic cell acquires the features of a
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Defining microRNA signatures of hair follicular stem and progenitor cells in healthy and androgenic alopecia patients
2021, Journal of Dermatological ScienceCitation Excerpt :Recently, Garza et al. reported that in AGA, the lack of an activator or existing inhibitor could lead to problems with follicular stem cell conversion into progenitor cells and result in decreased hair follicle size [3]. On the other hand, a role for miRNAs at the post-transcriptional level in regulating skin and hair stem cell proliferation and differentiation has been reported [4,8,24,25]. In this study, we characterized human hair cells in vivo by immunofluorescence and revealed that CD200+CD49f+CD34− cells were located in the bulge area of normal occipital hair.
High-throughput sequencing of hair follicle development-related micrornas in cashmere goat at various fetal periods
2018, Saudi Journal of Biological SciencesCitation Excerpt :The primary hair follicle cycle exists in each month, which can be classified into cell apoptosis and renewal. It displays little seasonal variation and shows obvious seasonal cycle compared with the secondary hair follicle (Song et al., 2013; Chandra et al., 2015; Aberdam and Candi, 2006). The production periodicity and complicated structure of secondary hair follicle in cashmere goat has controlled the growth and development of cashmere, which is also closely related to wool quality.
Kruppel-like factor 4 regulates keratinocyte senescence
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