title: Human hair follicles are an extrarenal source and a nonhematopoietic target of erythropoietin.
abstract: Erythropoietin primarily serves as an essential growth factor for erythrocyte precursor cells. However, there is increasing evidence that erythropoietin (EPO)/EPO receptor (EPO-R) signaling operates as a potential tissue-protective system outside the bone marrow. Arguing that growing hair follicles (HF) are among the most rapidly proliferating tissues, we have here explored whether human HFs are sources of EPO and targets of EPO-R-mediated signaling. Human scalp skin and microdissected HFs were assessed for EPO and EPO-R expression, and the effects of EPO on organ-cultured HFs were assessed in the presence/absence of a classical apoptosis-inducing chemotherapeutic agent. Here, we show that human scalp HFs express EPO on the mRNA and protein level in situ, up-regulate EPO transcription under hypoxic conditions, and express transcripts for EPO-R and the EPO-stimulatory transcriptional cofactor hypoxia-inducible factor-1alpha. Although EPO does not significantly alter human hair growth in vitro, it significantly down-regulates chemotherapy-induced intrafollicular apoptosis and changes the gene expression program of the HFs. The current study points to intriguing targets of EPO beyond the erythropoietic system: human HFs are an extrarenal site of EPO production and an extrahematopoietic site of EPO-R expression. They may recruit EPO/EPO-R signaling e.g., for modulating HF apoptosis under conditions of hypoxia and chemotherapy-induced stress.
authors.affiliation: Department of Dermatology, University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany.
authors.forename: Eniko
authors.initials: E
authors.lastname: Bodó
authors.forename: Arno
authors.initials: A
authors.lastname: Kromminga
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Funk
authors.forename: Magdalena
authors.initials: M
authors.lastname: Laugsch
authors.forename: Ute
authors.initials: U
authors.lastname: Duske
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Jelkmann
authors.forename: Ralf
authors.initials: R
authors.lastname: Paus
mesh_terms: D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D017209:Apoptosis; D003520:Cyclophosphamide / Q000494:pharmacology; D004921:Erythropoietin / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018859:Hair Follicle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D009924:Organ Culture Techniques; D017467:Receptors, Erythropoietin / Q000235:genetics / Q000378:metabolism*; D012535:Scalp / Q000033:anatomy & histology; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D018906:Antineoplastic Agents, Alkylating; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D017467:Receptors, Erythropoietin; D004921:Erythropoietin; D003520:Cyclophosphamide