This Article Abstract Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Tanaka, N. Articles by Tanne, K. Search for Related Content PubMed PubMed Citation Articles by Tanaka, N. Articles by Tanne, K. Social Bookmarking                         What's this?

Cyclic Mechanical Strain Regulates the PTHrP Expression in Cultured Chondrocytes via Activation of the Ca²⁺ Channel

N. Tanaka^1,, S. Ohno^1,*,, K. Honda¹, K. Tanimoto¹, T. Doi¹, M. Ohno-Nakahara¹, E. Tafolla², S. Kapila³ and K. Tanne¹

¹ Departments of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-Ku, Hiroshima 734-8553, Japan;
² Department of Stomatology, University of California-San Francisco, San Francisco, CA, USA; and
³ Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor, USA;

View larger version (50K): [in this window] [in a new window]   Figure 1. Effect of mechanical strain on chondrocyte metabolism. (A) The cell appearance in the cultures with (b,d) or without (a,c) 24-hour mechanical strain of 12% elongation at day 4 (a,b) and day 12 (c,d). Bar = 3 µm. The magnified appearance of a dividing cell is shown in the inset. The syntheses of DNA per well for proliferating chondrocytes (on day 4) (B), proteoglycan (C), and collagen (D) per well for matrix-forming chondrocytes (on day 12) were determined as described in MATERIALS & METHODS. = negative stress; = positive stress. Mean ± SD, n = 3, *p < 0.05.

View larger version (20K): [in this window] [in a new window]   Figure 2. Effect of mechanical strain on PTHrP expression in chondrocytes. (A) The expression of PTHrP mRNA varies during chondrocyte differentiation in cultured growth plate chondrocytes. The time-dependent expressions of PTHrP mRNA were determined at four-day intervals between days 4 and 24 of culture by real-time RT-PCR. Values were normalized with the expression level of GAPDH and denoted as the fold-increase of PTHrP mRNA expression relative to those of day 4 (proliferating) chondrocytes. (B) Cyclic mechanical strain induces PTHrP mRNA that is dependent upon the status of cellular differentiation. Proliferating, matrix-forming, and hypertrophic chondrocytes were subjected to cyclic mechanical strains of 7% or 12% elongation for 12 hrs, and the expression of PTHrP mRNA was examined by real-time RT-PCR. Values were normalized with the expression level of GAPDH and denoted as the fold-increase of PTHrP mRNA expression relative to control samples (0% elongation). Mean ± SD, n = 3, **p < 0.01, *p < 0.05.

View larger version (42K): [in this window] [in a new window]   Figure 3. Ca2+ channel blocker, but not the SA or Na+ or K+ channel blocker, inhibits the mechanical induction of PTHrP mRNA. Day 12 (matrix-forming) chondrocytes were subjected to a cyclic mechanical strain of 12% elongation in the presence of different channel blockers for 12 hrs, and the expression of PTHrP mRNA was examined by real-time RT-PCR. Values were normalized with the expression level of GAPDH and denoted as the fold-increase of PTHrP mRNA expression relative to control samples (0% elongation; without channel blockers). Mean ± SD, n = 3, **p < 0.01, *p < 0.05.

Journal of Dental Research, Vol. 84, No. 1, 64-68 (2005)
DOI: 10.1177/154405910508400111


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?