TABLE 1:
Proposed functions of BMP components.
| Type | Component | Proposed Functions |
|---|---|---|
| BMPs | BMP2 | • Linked to WAT (27, 28) (h,m) • May have metabolic effects (28) (m) • Adipogenic effects vary in different progenitor cells (h,m) |
| BMP4 | • Essential for white adipogenesis (45, 46) (m), but is important UCP1 induction in BAT (57) (h) • Increases with cold exposure (58) (m) • Promotes adipocyte differentiation (51-55) (h, m) |
|
| BMP6 | • Increase in BAT with cold exposure (58) (m) • Induces brown-like characteristics in progenitor cells (63) (m,c) |
|
| BMP7 | • Essential for brown adipogenesis (63, 71) (m) • Stimulates adipose “browning” (72) (h) • Possible effect on food intake (66, 70) (m) |
|
| BMP8b | • Increases with cold exposure and high fat diet (58, 74) (m) | |
| BMP3 | • Stimulates proliferation of progenitor cells (75) (m) | |
| BMP14 | • Adipocyte-specific overexpression decreases body fat (80) (m) | |
| Inhibitors | Gremlin | • Silencing of Gremlin-1 promotes adipogenic differentiation and brown-like characteristics in progenitor cells (55, 86) (h,m) |
| Noggin | • Contradictory results | |
| MGP | • Strongly expressed in pre-adipocytes (94) (h) | |
| Follistatin | • Induced during brown differentiation and cold exposure (96, 97) (m) | |
| BAMBI | • Negative regulation of adipogenesis (107) (m) | |
| Chordin-like | • Overexpression protects against diet-induced obesity (109) (m) | |
| Follistatin-like | • Decreases during adipogenic induction (110) (m) • Increased in tissue of obese mice and serum of obese individuals (111) (h,m) • Gene deletion reduces body fat (112) (m) |
|
| Receptors | BMPR1A (ALK3) | • Higher adipose expression in obese individuals (113) (h) • Deletion in brown precursors led to less BAT (65) (m) • Overexpression, together with that of BMPR1B, promotes adipogenesis (114) (m) |
| BMPR2 | • Increased in adipose tissue of obese patients (115) (h) | |
| ActRIIB | • Blockade activates BAT function (117) (m) |
Abbreviations: h, human; m, mouse; WAT, white adipose tissue; BAT, brown adipose tissue; BMP, bone morphogenetic protein; MGP, matrix Gla protein; BAMBI; BMP and activin membrane bound inhibitor; BMPR, BMP receptor; ActR, activin receptor, UCP1, uncoupling protein 1.