Trappc8, as a subunit of the transport protein particle (TRAPP) complex, is involved in multiple cellular processes. The TRAPP complex has different forms (TRAPPI, II, and III), and Trappc8 is specific to TRAPPIII. It functions in membrane traffic, autophagy, and ciliogenesis. In membrane traffic, TRAPPIII, with Trappc8 as a key subunit, acts as a guanine nucleotide exchange factor (GEF) for Rab GTPases, regulating vesicle transport. In autophagy, it is part of a complex required for proper autophagosome formation and the trafficking of Atg9A through recycling endosomes [3,4,5].

In ciliogenesis, Trappc8 has a distinct role. It interacts with the ciliopathy protein oral-facial-digital syndrome 1 (OFD1). Trappc8 is necessary for the association of OFD1 with pericentriolar material 1 (PCM1). Depletion of Trappc8 reduces the colocalized signals between OFD1 and PCM1, affecting ciliogenesis [1]. Also, Trappc8 has been identified as a host factor required for human papillomavirus (HPV) cell entry. Knockdown of Trappc8 in HeLa and HaCaT cells leads to reduced susceptibility to HPV infection, indicating its crucial role in the native HPV infection process [2].

In conclusion, Trappc8 is essential for various biological functions including membrane traffic, autophagy, and ciliogenesis. Its role in HPV cell entry also shows its significance in viral infection-related diseases. Studies on Trappc8, especially through loss-of-function experiments, help us understand its functions in these complex biological processes and disease-related mechanisms.