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Figure 3 | Stem Cell Research & Therapy

Figure 3

From: The less-often-traveled surface of stem cells: caveolin-1 and caveolae in stem cells, tissue repair and regeneration

Figure 3

Caveolin-1 stabilization of cell phenotype. (A) Hypothesized role for caveolin-1 and caveolae in contributing to the control of cell growth and differentiation. In undifferentiated quiescent stem cells, low levels of caveolin-1 are expressed. Caveolin-1 binding to growth and differentiation receptors and their secondary messengers within caveolae may suppress signaling. A decrease in caveolin-1 expression at the cell surface (perhaps triggered by chemical signals and/or nonmuscle myosin II activity) leads to receptor and signaling protein redistribution. Consequently, stem cells enter a pre-differentiation state more able to respond to growth and differentiation cues. Upon cell differentiation, caveolin-1 expression increases dramatically. Receptors and their secondary messengers are re-captured by caveolae to confine or internalize them and prevent continued growth. MSC, mesenchymal stem cell. (B) Proposed role for caveolin-1 in the control of mammary gland development based on in vitro and in vivo observations [88, 89]. Prolactin, estrogen and progesterone compete to control caveolin-1 expression. Caveolin-1 inhibits prolactin signaling by binding to the prolactin receptor-associated kinase Jak2. At birth, levels of prolactin are high and levels of estrogen and progesterone drop. Prolactin is thus able to suppress caveolin-1 expression, positively feeding back on its own signaling pathway by releasing Jak2 from caveolin-1 inhibition. The elevation in prolactin signaling triggers mammary gland development.

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