Table 2.

Summary of other sensing proteins.

Molecules	Reference(s)	Findings
Purinergic type 2 (P2X) receptors and Pannexin1 (Panx1)	[26,42]	•P2X7 receptor highly expressed in osteocyte processes •Form complex with stretch activated channel protein Panx1 •Loading activated Panx1, leading to ATP release and P2X7 receptor activation which resulted in Ca2+ influx to osteocytes
Calcium channel CaV3	[42]	•Co-localized with integrin complex at focal adhesion site •Integrin-CaV3 cluster created stress concentration •Loading induced Ca2+ mobilization, release of ATP and PGE2
Adenylyl cyclase 6 (AC6)	[27,31,39]	•Highly expressed in osteocyte primary cilium •Catalyze conversion of ATP to cyclic adenosine monophosphate (cAMP) •Mediate fluid flow induced decrease in cAMP •Mediate fluid flow induced increase in cyclooxygenase-2 (COX-2) •Inhibition of AC6 impaired bone formation
Zinc finger protein	[45,49]	•Zinc finger protein of cerebellum transcription factor (Zic1) •Interact with Gli1 and Gli3 at osteocyte cilium to regulate bone development via hedgehog pathway •Inhibition of Zic1 abolished the load-induced increase in T cell factor/lymphoid enhanced factor (TCF/LEF) transcription factor of Wnt pathway •Osteocyte cilia movement activated Wnt/TCF1 pathway