Ccpg1, or cell cycle progression 1, is a key protein involved in non-canonical autophagy pathways, especially in reticulophagy, which is the selective autophagic degradation of the endoplasmic reticulum (ER) [2,3,5,6]. As an ER-phagy receptor, Ccpg1 binds to Atg8-family proteins and RB1CC1/FIP200, facilitating the removal of abnormal proteins from the ER lumen, thus maintaining ER proteostasis and cellular homeostasis [3,6].

In corneal Aspergillus fumigatus infection, the expression of Ccpg1 in human corneal epithelial cells and human myeloid leukemia mononuclear cells macrophages increases in a time-dependent manner after infection, suggesting its involvement in the corneal antifungal immune response [1]. In hepatocellular carcinoma, lower expression of Ccpg1 is significantly correlated with tumor number and differentiation, and is associated with poor overall survival and disease-free survival, indicating its potential as a prognostic marker [4].

In conclusion, Ccpg1 is essential for maintaining ER proteostasis through its role in reticulophagy. Its involvement in corneal antifungal immune response and its association with hepatocellular carcinoma prognosis highlight its significance in understanding fungal infections and liver cancer. Research on Ccpg1, especially through in vivo studies like those in relevant disease models, helps in uncovering the underlying mechanisms of these biological processes and diseases.

References:

1. Wang, Li-Mei, Chen, Xiao-Meng, Yan, Hai-Jing, Lu, Dan-Li, Che, Cheng-Ye. 2022. CCPG1 involved in corneal Aspergillus fumigatus infection. In International journal of ophthalmology, 15, 541-546. doi:10.18240/ijo.2022.04.03. https://pubmed.ncbi.nlm.nih.gov/35450172/

2. Chino, Haruka, Hatta, Tomohisa, Natsume, Tohru, Mizushima, Noboru. 2019. Intrinsically Disordered Protein TEX264 Mediates ER-phagy. In Molecular cell, 74, 909-921.e6. doi:10.1016/j.molcel.2019.03.033. https://pubmed.ncbi.nlm.nih.gov/31006538/

3. Ishii, Shunsuke, Chino, Haruka, Ode, Koji L, Mizushima, Noboru, Itakura, Eisuke. 2023. CCPG1 recognizes endoplasmic reticulum luminal proteins for selective ER-phagy. In Molecular biology of the cell, 34, ar29. doi:10.1091/mbc.E22-09-0432. https://pubmed.ncbi.nlm.nih.gov/36735498/

4. Wang, Gangpu, Liu, Zhiqian, Wang, Qi, Liu, Bingqi, Li, Jie. . Clinical and prognostic significance of CCPG1 in hepatocellular carcinoma. In General physiology and biophysics, 42, 431-442. doi:10.4149/gpb_2023017. https://pubmed.ncbi.nlm.nih.gov/37702448/

5. Lahiri, Vikramjit, Klionsky, Daniel J. . CCPG1 is a noncanonical autophagy cargo receptor essential for reticulophagy and pancreatic ER proteostasis. In Autophagy, 14, 1107-1109. doi:10.1080/15548627.2018.1467199. https://pubmed.ncbi.nlm.nih.gov/29911925/

6. Smith, Matthew D, Wilkinson, Simon. 2018. CCPG1, a cargo receptor required for reticulophagy and endoplasmic reticulum proteostasis. In Autophagy, 14, 1090-1091. doi:10.1080/15548627.2018.1441473. https://pubmed.ncbi.nlm.nih.gov/29916296/