"Expression of an olfactomedin-related gene in rat hair follicular papilla cells"Cao, Qiong; Yu, Dawen; Lee, Andy; Kasai, Yuko; Tychsen, Birte; Paus, Ralf; FREEDBERG, IRWIN M; Sun, Tung-Tien
Follicular papilla (FP) cells, but not their closely related dermal fibroblasts, can maintain hair growth suggesting cell type-specific molecular signals. To define the molecular differences between these two cell types, we generated a subtraction complementary DNA (cDNA) library highly enriched in FP-specific cDNA. Differential screening identified FP-1 as the most abundant cDNA sequence in this subtraction library. FP-1 message RNA is highly abundant in cultured rat vibrissa FP cells, can be detected at very low levels in the stomach and the ovary, and is undetectable in cultured dermal fibroblasts and in 16 rat non-follicular tissues. The full-length, 2.3 kb FP-1 cDNA encodes a protein of 549 amino acids harboring a signal peptide, collagen triple helix repeats, and an olfactomedin-like domain. Monospecific rabbit antibodies to FP-1 recognize in cultured FP cells a single approximately 72 kDa glycoprotein with a approximately 60 kDa protein core. FP-1 protein is expressed in vivo in a hair cycle-dependent manner, as it can be detected in FP during anagen, but not in catagen and telogen phases of the hair cycle. FP-1 is presumably a highly specific extracellular matrix protein synthesized by FP cells and may be involved in the organization of FP during certain phases of normal or pathological hair growth.
"TBF and DIGM" [Meeting Abstract]FREEDBERG, IM
"Report on "Burden of Skin Disease" Workshop. NIAMS, September 2002"Qureshi, Abrar A; FREEDBERG, IRWIN; Goldsmith, Lowell; Moshell, Alan
"Specificity in Stress Response: Epidermal Keratinocytes Exhibit Specialized UV-Responsive Signal Transduction Pathways"Adachi, Makoto; Gazel, Alix; Pintucci, Giuseppe; Shuck, Alyssa; Shifteh, Shiva; Ginsburg, Dov; Rao, Laxmi S; Kaneko, Takehiko; FREEDBERG, IRWIN M; Tamaki, Kunihiko; Blumenberg, Miroslav
GRANTS:AR30682/AR/NIAMS NIH HHS/United States;AR39176/AR/NIAMS NIH HHS/United States;AR40522/AR/NIAMS NIH HHS/United States;AR41850/AR/NIAMS NIH HHS/United States
UV light, a paradigmatic initiator of cell stress, invokes responses that include signal transduction, activation of transcription factors, and changes in gene expression. Consequently, in epidermal keratinocytes, its principal and frequent natural target, UV regulates transcription of a distinctive set of genes. Hypothesizing that UV activates distinctive epidermal signal transduction pathways, we compared the UV-responsive activation of the JNK and NFkappaB pathways in keratinocytes, with the activation of the same pathways by other agents and in other cell types. Using of inhibitors and antisense oligonucleotides, we found that in keratinocytes only UVB/UVC activate JNK, while in other cell types UVA, heat shock, and oxidative stress do as well. Keratinocytes express JNK-1 and JNK-3, which is unexpected because JNK-3 expression is considered brain-specific. In keratinocytes, ERK1, ERK2, and p38 are activated by growth factors, but not by UV. UVB/UVC in keratinocytes activates Elk1 and AP1 exclusively through the JNK pathway. JNKK1 is essential for UVB/UVC activation of JNK in keratinocytes in vitro and in human skin in vivo. In contrast, in HeLa cells, used as a control, crosstalk among signal transduction pathways allows considerable laxity. In parallel, UVB/UVC and TNFalpha activate the NFkappaB pathway via distinct mechanisms, as shown using antisense oligonucleotides targeted against IKKbeta, the active subunit of IKK. This implies a specific UVB/UVC responsive signal transduction pathway independent from other pathways. Our results suggest that in epidermal keratinocytes specific signal transduction pathways respond to UV light. Based on these findings, we propose that the UV light is not a genetic stress response inducer in these cells, but a specific agent to which epidermis developed highly specialized responses.
"Palmoplantar keratoderma of Sybert"Leonard, Aimee L; FREEDBERG, IRWIN M
A 13-year-old boy and a 7-year-old boy, who are brothers, presented with a life-long history of erythema, hyperkeratosis, and desquamation of the hands and feet. Symptoms improved with the use of topical glucocorticoids and keratolytics. PPK of Sybert is characterized by palmoplantar hyperkeratosis with transgrediens, autosomal dominant inheritance, and the absence of associated systemic features.
"Keratins and the keratinocyte activation cycle"FREEDBERG IM; Tomic-Canic M; Komine M; Blumenberg M
GRANTS:AR30682/AR/NIAMS NIH HHS/United States;AR40522/AR/NIAMS NIH HHS/United States;AR41850/AR/NIAMS NIH HHS/United States;AR45974/AR/NIAMS NIH HHS/United States
In wound healing and many pathologic conditions, keratinocytes become activated: they turn into migratory, hyperproliferative cells that produce and secrete extracellular matrix components and signaling polypeptides. At the same time, their cytoskeleton is also altered by the production of specific keratin proteins. These changes are orchestrated by growth factors, chemokines, and cytokines produced by keratinocytes and other cutaneous cell types. The responding intracellular signaling pathways activate transcription factors that regulate expression of keratin genes. Analysis of these processes led us to propose the existence of a keratinocyte activation cycle, in which the cells first become activated by the release of IL-1. Subsequently, they maintain the activated state by autocrine production of proinflammatory and proliferative signals. Keratins K6 and K16 are markers of the active state. Signals from the lymphocytes, in the form of Interferon-gamma, induce the expression of K17 and make keratinocytes contractile. This enables the keratinocytes to shrink the provisional fibronectin-rich basement membrane. Signals from the fibroblasts, in the form of TGF-beta, induce the expression of K5 and K14, revert the keratinocytes to the healthy basal phenotype, and thus complete the activation cycle.
"Interleukin-1 Induces Transcription of Keratin K6 in Human Epidermal Keratinocytes"Komine M; Rao LS; FREEDBERG IM; Simon M; Milisavljevic V; Blumenberg M
GRANTS:AR30682/AR/NIAMS NIH HHS/United States;AR39176/AR/NIAMS NIH HHS/United States;AR41850/AR/NIAMS NIH HHS/United States;DK16636/DK/NIDDK NIH HHS/United States
Keratinocytes respond to injury by releasing the proinflammatory cytokine interleukin-1, which serves as the initial 'alarm signal' to surrounding cells. Among the consequences of interleukin-1 release is the production of additional cytokines and their receptors by keratinocytes and other cells in the skin. Here we describe an additional effect of interleukin-1 on keratinocytes, namely the alteration in the keratinocyte cytoskeleton in the form of the induction of keratin 6 expression. Keratin 6 is a marker of hyperproliferative, activated keratinocytes, found in wound healing, psoriasis, and other inflammatory disorders. Skin biopsies in organ culture treated with interleukin-1 express keratin 6 in all suprabasal layers of the epidermis, throughout the tissue. In cultured epidermal keratinocytes, the induction of keratin 6 is time and concentration dependent. Importantly, only confluent keratinocytes respond to interleukin-1, subconfluent cultures do not. In the cells starved of growth factors, epidermal growth factor or tumor necrosis factor-alpha, if added simultaneously with interleukin-1, they synergistically augment the effects of interleukin-1. Using DNA-mediated cell transfection, we analyzed the molecular mechanisms regulating the keratin 6 induction by interleukin-1, and found that the induction occurs at the transcriptional level. We used a series of deletions and point mutations to identify the interleukin-1 responsive DNA element in the keratin 6 promoter, and determined that it contains a complex of C/EBP binding sites. The transcription factor C/EBPbeta binds this element in vitro, and the binding is augmented by pretreatment of the cells with interleukin-1. The interleukin-1 responsive element is clearly distinct from the epidermal growth factor responsive one, which means that the proinflammatory and proliferative signals independently regulate the expression of keratin 6. Thus, interleukin-1 initiates keratinocyte activation not only by triggering additional signaling events, but also by inducing directly the synthesis of keratin 6 in epidermal keratinocytes, and thus changing the composition of their cytoskeleton.
"Rays and arrays: the transcriptional program in the response of human epidermal keratinocytes to UVB illumination"Li D; Turi TG; Schuck A; FREEDBERG IM; Khitrov G; Blumenberg M
The epidermis, our first line of defense from ultraviolet (UV) light, bears the majority of photodamage, which results in skin thinning, wrinkling, keratosis, and malignancy. Hypothesizing that skin has specific mechanisms to protect itself and the organism from UV damage, we used DNA arrays to follow UV-caused gene expression changes in epidermal keratinocytes. Of the 6,800 genes examined, UV regulates the expression of at least 198. Three waves of changes in gene expression can be distinguished, 0.5-2, 4-8, and 16-24 h after illumination. The first contains transcription factors, signal transducing, and cytoskeletal proteins that change cell phenotype from a normal, fast-growing cell to an activated, paused cell. The second contains secreted growth factors, cytokines, and chemokines; keratinocytes, having changed their own physiology, alert the surrounding tissues to the UV damage. The third wave contains components of the cornified envelope, as keratinocytes enhance the epidermal protective covering and, simultaneously, terminally differentiate and die, removing a carcinogenic threat. UV also induces the expression of mitochondrial proteins that provide additional energy, and the enzymes that synthesize raw materials for DNA repair. Using a novel skin organ culture model, we demonstrated that the UV-induced changes detected in keratinocyte cultures also occur in human epidermis in vivo.
"Preserving medical dermatology. A colleague lost, a call to arms, and a plan for battle"Werth VP; Voorhees J; FREEDBERG IM; Sontheimer RD
Change within dermatology as a clinical discipline is expected and inevitable. However dermatology may change as a medical specialty in the new millennium, there will still be patients with medical dermatologic disease whose optimal care will depend on skin disease specialists' having the highest level of training and experience in medical dermatology. Dermatologists who have subspecialized in medical dermatology will provide the role models for new generations of dermatologists, perform the patient-oriented research, and care for the more complicated patients. Thus, if during its evolution, dermatology loses the ability to train and support medical dermatologists, it will be weakened as the discipline that can best care for skin disease. Clearly, the loss of talented academicians such as the person whose career was outlined in the case report presented at the beginning of this article should be a huge warning sign that the future of medical dermatology as a specialty is uncertain. The Medical Dermatology Society hopes to develop a coalition with all other leadership organizations within dermatology to deal with this problem effectively. There is a need for a broader discussion within organized dermatology of the growing crisis in this area and how all dermatology leadership organizations working together can develop an action plan for effectively dealing with this important but challenging problem. Dermatology must ask itself what it wants to look like as a medical specialty in the future. Without an steady stream of young clinician-investigators focused on the many challenging problems in medical dermatology, dermatology will not exist as the specialty it is today.