References: Hair growth and hair loss
Planta. 1997;201(2):209-18.
Growth and ultrastructure of Arabidopsis root hairs: the rhd3 mutation alters vacuole enlargement and tip growth.
Galway ME, Heckman JW Jr, Schiefelbein JW.
Department of Biology, University of Michigan, Ann Arbor 48109-1048, USA.
The root hairs of plants are tubular projections of root epidermal cells and are suitable for investigating the control of cellular morphogenesis. In wild-type Arabidopsis thaliana (L.) Heynh, growing root hairs were found to exhibit cellular expansion limited to the apical end of the cell, a polarized distribution of organelles in the cytoplasm, and vesicles of several types located near the growing tip. The rhd3 mutant produces short and wavy root hairs with an average volume less than one-third of the wild-type hairs, indicating abnormal cell expansion. The mutant hairs display a striking reduction in vacuole size and a corresponding increase in the relative proportion of cytoplasm throughout hair development. Beadlabeling experiments and ultrastructural analyses indicate that the wavy-hair phenotype of the mutant is caused by asymmetric tip growth, possibly due to abnormally distributed vesicles in cortical areas flanking the hair tips. It is suggested that a major effect of the rhd3 mutation is to inhibit vacuole enlargement which normally accompanies root hair cell expansion.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9084218&dopt=Abstract
J Cutan Pathol. 1997 Mar;24(3):137-44.
Immunohistochemical localization of muscarinic acetylcholine receptors in primary and metastatic malignant melanomas.
Lammerding-Koppel M, Noda S, Blum A, Schaumburg-Lever G, Rassner G, Drews U.
Institute of Anatomy, University of Tuebingen, Germany.
In embryos morphogenetically active cells transiently express the cholinergic system comprising cholinesterase activity and muscarinic acetylcholine receptors. Malignant melanomas develop from melanocytes, which are derived from the neural crest. Neural crest cells express the embryonic muscarinic system during migration. Using the monoclonal antibody M35, we now show that normal melanocytes carry no muscarinic receptors, whereas malignant melanoma cells express them again. In primary melanomas and metastatic melanomas, we identified muscarinic receptors in solid strands or groups of atypical cells. In all primary malignant melanomas studied we found inhomogeneous distributions of M35-immunoreactivity subdividing the tumors into three different zones. In the tumor center, groups or single cells often showed only little or even no immunofluorescence. In contrast, pericentrally we detected strong immunostaining in the conglomerations of atypical melanocytes. In the peripheral infiltration zone, intensely fluorescent cells in clusters or single, were spreading into the normal tissue, leading to a more patchy staining pattern. Melanocytes of nevi also possess muscarinic receptors, showing similar distribution patterns as in the melanoma. We suggest that in malignant melanomas muscarinic receptors might play a regulative role in infiltrative growth and metastasis.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9085148&dopt=Abstract
J Interferon Cytokine Res. 1997 Mar;17(3):151-7.
Interleukin-1beta is differentially expressed by human dermal papilla cells in response to PKC activation and is a potent inhibitor of human hair follicle growth in organ culture.
Xiong Y, Harmon CS.
Preclinical Dermatology Research, Hoffmann-La Roche, Nutley, NJ 07110, USA.
The dermal papilla plays an important role in the regulation of hair follicle matrix cell proliferation and hair fiber production, at least in part through mesenchymal-epithelial interactions. In the present study, we have investigated the regulation of interleukin-1 (IL-1) production by protein kinase C in cultured human dermal papilla cells. Treatment of dermal papilla cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) elicited the rapid and transient production of mature (17 kDa) cytosolic IL-1beta protein, but not IL-1alpha, with maximal levels achieved after 12 h. Rapid secretion of IL-1beta into the medium occurred subsequent to increased intracellular cytokine levels, after which medium IL-1beta protein levels were stable for 4 days. Northern blot analysis showed that TPA treatment elicited a transient induction of IL-1beta mRNA expression, maximal after 12 h, indicating that TPA regulates dermal papilla cell IL-1beta production at the transcriptional level. Pretreatment of dermal papilla cells with Ro 31-7549, a selective protein kinase C inhibitor, dose dependently and completely reversed phorbol-induced IL-1beta protein production. In addition, we demonstrated that IL-1beta is a highly potent inhibitor of the growth of human hair follicles in whole-organ culture, with an IC50 value of approximately 5 pg/ml. These findings, taken together with a previous report that follicular matrix cells express type I IL-1 receptors but dermal papilla cells do not, raise the possibility that dermal papilla cell-derived IL-1beta may act as a negative paracrine factor in the regulation of matrix cell proliferation.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9085940&dopt=Abstract
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