Table 1

Functions of Jun and Fos proteins

Activator protein 1 protein
Phenotype
Affected organs/cells

Transgenic


     H2Kb-Jun
None
None
     Ubiquitin C-JunBa
Increased bone mass
Not defined
     CD4-JunB
Enhanced T helper cell 2 maturation
Thymus, CD4 thymocytes
     Ubiquitin C-JunD
Peripheral T cells and B cells reduced
Lymphocytes
     H2Kb-Fos
Osteosarcoma
Bone, osteoblasts
     H2Kb-Fos/Rsk-2-/y
Reduced osteosarcoma
Bone, osteoblasts
     H2Kb-FosB
None
Bone
     TCRβ-ΔFosB
Impaired T cell differentiation
Thymus, immature thymocytes
     NSE-ΔFosB
Osteosclerosis
Bone, osteoblasts
     H2Kb-Fra-1
Osteosclerosis
Bone, osteoblasts
     CMV-Fra-2
Occular malformations
Anterior eye structure
     H2Kb-Fra-2a
Increased bone mass, fibrosis
Bone, internal organs, skin
Knockout


     Jun
Embryonic lethal on embryonic day 12.5
Liver, heart, neural crest
     JunB
Embryonic lethal on embryonic day 10
Extraembryonic tissues
     JunD
Male sterility
Testis, spermatides
     c-Fos
Osteopetrosis
Bone, osteoclasts
     FosB
Nurturing defect
Brain, hypothalamus
     Fra-1
Embryonic lethal on embryonic day 9.5
Extraembyonic tissue
     Fra-2
Lethal at birth
Bone, osteoclasts
Conditional


     Alfp-cre Jun
Liver regeneration defect
Liver, hepatocytes
     Col2a1-cre Jun
Scoliosis
Bone, notochordal cells
     Nestin-cre Jun
Axonal regeneration defect
Central nervous system, motoneurons
     MORE-cre JunB
Osteopenia
Bone, osteoclasts, osteoblasts
     K5-cre Jun
Eyes open at birth, reduced skin tumors
Keratinocytes
     Nestin-cre Fos
Learning defects
Brain, hippocampal neurons
     MORE-cre Fra-1
Osteopenia
Bone, osteoblasts
Inducible


     K5-creERTJunB + Jun
Psoriasis-like disease
Skin, joints, keratinocytes

Knockout, conditional knockout and gain of function (transgenic) approaches applied to study the role of Jun and Fos proteins during development and in diseases. The gain-of-function approaches were performed with different promoters, either leading to ubiquitous expression (for example, H2Kb, ubiquitin C, or cytomegalovirus (CMV)) or to tissue-specific expression (for example, CD4, TCRβ, or neuron-specific enolase (NSE)) of the transgenes. aUnpublished data from the Wagner Laboratory.

Zenz et al. Arthritis Research & Therapy 2008 10:201   doi:10.1186/ar2338