Figure 9

Speculative models for CXCR7 signaling in prostate cancer cells. (A) CXCR7 and AR protein levels are modulated by AR and CXCR7 respectively, through post-transcriptional mechanisms (e.g., protein stability). (B) Reciprocal feedback loop regulating the expression of CXCR4 and CXCR7 in LNCaP prostate cancer cells, including protein trafficking pathways that could account for the transport of CXCR7 into the nuclear compartment. Question mark indicates that AR may directly or indirectly interact with CXCR7. (I) CXCR7 gains access to the nucleus through the nucleoplasmic reticulum (e.g. invaginations of the nuclear envelope) [73,77]. (II) CXCR7 gains access to the nucleus through the nuclear pore complex (e.g., transportin-dependent), as shown for other GPCRs and more recently for CXCR4 [69,70].