Characterization of a novel murine Sost ERT2 Cre model targeting osteocytes.
Delphine B MaurelTsutomu MatsumotoJulian A VallejoMark L JohnsonSarah L DallasYukiko KitaseMarco BrottoMichael J WackerMarie A HarrisStephen E HarrisLynda F BonewaldPublished in: Bone research (2019)
Transgenic mice are widely used to delete or overexpress genes in a cell specific manner to advance knowledge of bone biology, function and disease. While numerous Cre models exist to target gene recombination in osteoblasts and osteoclasts, few target osteocytes specifically, particularly mature osteocytes. Our goal was to create a spatial and temporal conditional Cre model using tamoxifen to induce Cre activity in mature osteocytes using a Bac construct containing the 5' and 3' regions of the Sost gene (Sost ERT2 Cre). Four founder lines were crossed with the Ai9 Cre reporter mice. One founder line showed high and specific activity in mature osteocytes. Bones and organs were imaged and fluorescent signal quantitated. While no activity was observed in 2 day old pups, by 2 months of age some osteocytes were positive as osteocyte Cre activity became spontaneous or 'leaky' with age. The percentage of positive osteocytes increased following tamoxifen injection, especially in males, with 43% to 95% positive cells compared to 19% to 32% in females. No signal was observed in any bone surface cell, bone marrow, nor in muscle with or without tamoxifen injection. No spontaneous signal was observed in any other organ. However, with tamoxifen injection, a few positive cells were observed in kidney, eye, lung, heart and brain. All other organs, 28 in total, were negative with tamoxifen injection. However, with age, a muscle phenotype was apparent in the Sost-ERT2 Cre mice. Therefore, although this mouse model may be useful for targeting gene deletion or expression to mature osteocytes, the muscle phenotype may restrict the use of this model to specific applications and should be considered when interpreting data.
Keyphrases
- breast cancer cells
- estrogen receptor
- positive breast cancer
- genome wide
- bone marrow
- induced apoptosis
- mouse model
- skeletal muscle
- copy number
- ultrasound guided
- genome wide identification
- healthcare
- cell therapy
- single cell
- mesenchymal stem cells
- poor prognosis
- cell cycle arrest
- type diabetes
- bone mineral density
- cancer therapy
- gene expression
- machine learning
- magnetic resonance imaging
- artificial intelligence
- stem cells
- cell death
- magnetic resonance
- soft tissue
- computed tomography
- cell proliferation
- deep learning
- electronic health record
- endoplasmic reticulum stress
- multiple sclerosis
- blood brain barrier
- postmenopausal women
- brain injury
- atrial fibrillation
- high fat diet induced
- white matter
- binding protein
- fluorescent probe
- living cells
- wild type