Zhendong A Zhong1, Weihua Sun1, Haiyan Chen1, Hongliang Zhang2, Yu-An E Lay1, Nancy E Lane1, Wei Yao3. 1. Center for Musculoskeletal Health, Department of Internal Medicine, University of California Davis Medical Center, Sacramento, CA 95817, USA. 2. Center for Musculoskeletal Health, Department of Internal Medicine, University of California Davis Medical Center, Sacramento, CA 95817, USA; Department of Emergency Medicine The Second Xiangya Hospital of Central-South University, Changsha, Hunan, China. 3. Center for Musculoskeletal Health, Department of Internal Medicine, University of California Davis Medical Center, Sacramento, CA 95817, USA. Electronic address: yao@ucdavis.edu.
Abstract
UNLABELLED: For tamoxifen-dependent Cre recombinase, also known as CreER recombinase, tamoxifen (TAM) is used to activate the Cre to generate time- and tissue-specific mouse mutants. TAM is a potent CreER system inducer; however, TAM is also an active selective estrogen receptor modulator (SERM) that can influence bone homeostasis. The purpose of this study was to optimize the TAM dose for Cre recombinase activation while minimizing the effects of TAM on bone turnover in young growing mice. METHODS: To evaluate the effects of TAM on bone turnover and bone mass, 1-month-old wild-type male and female mice were intraperitoneally injected with TAM at 0, 1, 10 or 100mg/kg/day for four consecutive days, or 100, 300 mg/kg/day for one day. The distal femurs were analyzed one month after the last TAM injection by microCT, mechanical test, and surface-based bone histomorphometry. Similar doses of TAM were used in Col1 (2.3 kb)-CreERT2; mT/mG reporter male mice to evaluate the dose-dependent efficacy of Cre-ER activation in bone tissue. RESULTS: A TAM dose of 100 mg/kg × 4 days significantly increased trabecular bone volume/total volume (BV/TV) of the distal femur, femur length, bone strength, and serum bone turnover markers compared to the 0mg control group. In contrast, TAM doses ≤ 10 mg/kg did not significantly change any of these parameters compared to the 0mg group, although a higher bone strength was observed in the 10mg group. Surface-based histomorphometry revealed that the 100mg/kg dose of TAM dose significantly increased trabecular bone formation and decreased periosteal bone formation at 1-week post-TAM treatment. Using the reporter mouse model Col1-CreERT2; mT/mG, we found that 10mg/kg TAM induced Col1-CreERT2 activity in bone at a comparable level to the 100mg/kg dose. CONCLUSIONS: TAM treatment at 100mg/kg/day × 4 days significantly affects bone homeostasis, resulting in an anabolic bone effect on trabecular bone in 1-month-old male mice. However, a lower dose of TAM at 10 mg/kg/day × 4 days can yield similar Col1-CreERT2 induction efficacy with minimum effects on bone turnover in young male mice.
UNLABELLED: For tamoxifen-dependent Cre recombinase, also known as CreER recombinase, tamoxifen (TAM) is used to activate the Cre to generate time- and tissue-specific mouse mutants. TAM is a potent CreER system inducer; however, TAM is also an active selective estrogen receptor modulator (SERM) that can influence bone homeostasis. The purpose of this study was to optimize the TAM dose for Cre recombinase activation while minimizing the effects of TAM on bone turnover in young growing mice. METHODS: To evaluate the effects of TAM on bone turnover and bone mass, 1-month-old wild-type male and female mice were intraperitoneally injected with TAM at 0, 1, 10 or 100mg/kg/day for four consecutive days, or 100, 300 mg/kg/day for one day. The distal femurs were analyzed one month after the last TAM injection by microCT, mechanical test, and surface-based bone histomorphometry. Similar doses of TAM were used in Col1 (2.3 kb)-CreERT2; mT/mG reporter male mice to evaluate the dose-dependent efficacy of Cre-ER activation in bone tissue. RESULTS: A TAM dose of 100 mg/kg × 4 days significantly increased trabecular bone volume/total volume (BV/TV) of the distal femur, femur length, bone strength, and serum bone turnover markers compared to the 0mg control group. In contrast, TAM doses ≤ 10 mg/kg did not significantly change any of these parameters compared to the 0mg group, although a higher bone strength was observed in the 10mg group. Surface-based histomorphometry revealed that the 100mg/kg dose of TAM dose significantly increased trabecular bone formation and decreased periosteal bone formation at 1-week post-TAM treatment. Using the reporter mouse model Col1-CreERT2; mT/mG, we found that 10mg/kg TAM induced Col1-CreERT2 activity in bone at a comparable level to the 100mg/kg dose. CONCLUSIONS:TAM treatment at 100mg/kg/day × 4 days significantly affects bone homeostasis, resulting in an anabolic bone effect on trabecular bone in 1-month-old male mice. However, a lower dose of TAM at 10 mg/kg/day × 4 days can yield similar Col1-CreERT2 induction efficacy with minimum effects on bone turnover in young male mice.
Authors: I Kalajzic; Z Kalajzic; M Kaliterna; G Gronowicz; S H Clark; A C Lichtler; D Rowe Journal: J Bone Miner Res Date: 2002-01 Impact factor: 6.741
Authors: B Ettinger; D M Black; B H Mitlak; R K Knickerbocker; T Nickelsen; H K Genant; C Christiansen; P D Delmas; J R Zanchetta; J Stakkestad; C C Glüer; K Krueger; F J Cohen; S Eckert; K E Ensrud; L V Avioli; P Lips; S R Cummings Journal: JAMA Date: 1999-08-18 Impact factor: 56.272
Authors: Sarah K Amugongo; Wei Yao; Junjing Jia; Weiwei Dai; Yu-An E Lay; Li Jiang; Danielle Harvey; Elizabeth A Zimmermann; Eric Schaible; Neil Dave; Robert O Ritchie; Donald B Kimmel; Nancy E Lane Journal: Bone Date: 2014-07-10 Impact factor: 4.398
Authors: Gabriel L Galea; Lee B Meakin; Toshihiro Sugiyama; Noureddine Zebda; Andrew Sunters; Hanna Taipaleenmaki; Gary S Stein; Andre J van Wijnen; Lance E Lanyon; Joanna S Price Journal: J Biol Chem Date: 2013-01-29 Impact factor: 5.157
Authors: Whitney A Bullock; April M Hoggatt; Daniel J Horan; Karl J Lewis; Hiroki Yokota; Steven Hann; Matthew L Warman; Aimy Sebastian; Gabriela G Loots; Fredrick M Pavalko; Alexander G Robling Journal: J Bone Miner Res Date: 2019-08-05 Impact factor: 6.741
Authors: Jessica Garbern; Amy C Kristl; Vinicius Bassaneze; Ana Vujic; Henk Schoemaker; Rebecca Sereda; Liming Peng; Elisabeth M Ricci-Blair; Jill M Goldstein; Ryan G Walker; Shalender Bhasin; Amy J Wagers; Richard T Lee Journal: Am J Physiol Heart Circ Physiol Date: 2019-05-24 Impact factor: 4.733
Authors: Lisa Y Lawson; Nicole Migotsky; Christopher J Chermside-Scabbo; John T Shuster; Kyu Sang Joeng; Roberto Civitelli; Brendan Lee; Matthew J Silva Journal: FASEB J Date: 2022-09 Impact factor: 5.834
Authors: Claes Ohlsson; Petra Henning; Karin H Nilsson; Jianyao Wu; Karin L Gustafsson; Klara Sjögren; Anna Törnqvist; Antti Koskela; Fu-Ping Zhang; Marie K Lagerquist; Matti Poutanen; Juha Tuukkanen; Ulf H Lerner; Sofia Movérare-Skrtic Journal: J Endocrinol Date: 2018-03-12 Impact factor: 4.286
Authors: Chenlin Dai; Junjing Jia; Alexander Kot; Xueping Liu; Lixian Liu; Min Jiang; Nancy E Lane; Barton L Wise; Wei Yao Journal: Bone Date: 2019-12-19 Impact factor: 4.398