LAPTM5, short for Lysosomal Protein Transmembrane 5, is a lysosomal transmembrane protein preferentially expressed in hematopoietic cells. Its protein contains five transmembrane domains, three PY motifs, and one UIM, which can interact with various substrates, mediating protein sorting from Golgi to lysosome and participating in intracellular substrate transport and lysosomal stability regulation. LAPTM5 is involved in multiple biological processes, such as autophagy activation, immunity, and inflammation regulation [2].

In various disease-related functional studies, LAPTM5 shows diverse roles. In hepatocellular carcinoma, a genome-scale CRISPR screen identified LAPTM5 as driving lenvatinib resistance [1]. In B-cell related research, LAPTM5 mediates immature B cell apoptosis and B cell tolerance by regulating the WWP2-PTEN-AKT pathway [3]. In HIV-1 infection, Vpr counteracts LAPTM5, a potent inhibitor of HIV-1 particle infectivity, to enhance HIV-1 infection in macrophages [4]. In glioblastoma, knockdown of LAPTM5 unleashes CD40-mediated NFκB activation, leading to enhanced invasiveness and temozolomide resistance [5]. In B-cell lymphomas, c-Myc inhibits LAPTM5 expression through transcriptional and post-transcriptional modifications [6]. In non-alcoholic steatohepatitis, hepatocyte-specific depletion of Laptm5 in male mice exacerbates NASH symptoms, while overexpression alleviates them by promoting the degradation of CDC42 [7]. In CKD, tubule-specific deletion of Laptm5 in mice inhibits tubular epithelial cell senescence and alleviates tubulointerstitial fibrosis [8]. In breast cancer, LAPTM5, negatively regulated by FOXP3, promotes malignant phenotypes through activating the Wnt/β-catenin pathway [9].

In conclusion, LAPTM5 plays essential roles in multiple biological processes and is closely associated with various diseases. Studies using gene knockout (KO) or conditional knockout (CKO) mouse models, as well as in vivo studies, have revealed its functions in diseases such as cancer, viral infections, and non-alcoholic steatohepatitis, providing insights into potential therapeutic targets for these diseases.

References:

1. Pan, Jiaomeng, Zhang, Mao, Dong, Liangqing, Fan, Jia, Gao, Qiang. 2022. Genome-Scale CRISPR screen identifies LAPTM5 driving lenvatinib resistance in hepatocellular carcinoma. In Autophagy, 19, 1184-1198. doi:10.1080/15548627.2022.2117893. https://pubmed.ncbi.nlm.nih.gov/36037300/

2. Zhang, Man-Man, Liang, Ming-Jun, Zhang, Dong-Mei, Zhang, Jian-Ping, Li, Yang-Ling. 2024. The function and mechanism of LAPTM5 in diseases. In Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 178, 117237. doi:10.1016/j.biopha.2024.117237. https://pubmed.ncbi.nlm.nih.gov/39096616/

3. Wang, Ying, Liu, Jun, Akatsu, Chizuru, Tsubata, Takeshi, Wang, Ji-Yang. 2022. LAPTM5 mediates immature B cell apoptosis and B cell tolerance by regulating the WWP2-PTEN-AKT pathway. In Proceedings of the National Academy of Sciences of the United States of America, 119, e2205629119. doi:10.1073/pnas.2205629119. https://pubmed.ncbi.nlm.nih.gov/36037365/

4. Zhao, Li, Wang, Shumei, Xu, Meng, Shang, Hong, Liang, Guoxin. 2021. Vpr counteracts the restriction of LAPTM5 to promote HIV-1 infection in macrophages. In Nature communications, 12, 3691. doi:10.1038/s41467-021-24087-8. https://pubmed.ncbi.nlm.nih.gov/34140527/

5. Berberich, Anne, Bartels, Frederik, Tang, Zili, Abdollahi, Amir, Lemke, Dieter. 2020. LAPTM5-CD40 Crosstalk in Glioblastoma Invasion and Temozolomide Resistance. In Frontiers in oncology, 10, 747. doi:10.3389/fonc.2020.00747. https://pubmed.ncbi.nlm.nih.gov/32582531/

6. Zhang, Yanqing, Zhang, Xin, Zhang, Yi, Deng, Bin, Yu, Duonan. 2023. c-Myc inhibits LAPTM5 expression in B-cell lymphomas. In Annals of hematology, 102, 3499-3513. doi:10.1007/s00277-023-05434-9. https://pubmed.ncbi.nlm.nih.gov/37713124/

7. Jiang, Lang, Zhao, Jing, Yang, Qin, Ye, Ping, Xia, Jiahong. 2023. Lysosomal-associated protein transmembrane 5 ameliorates non-alcoholic steatohepatitis by promoting the degradation of CDC42 in mice. In Nature communications, 14, 2654. doi:10.1038/s41467-023-37908-9. https://pubmed.ncbi.nlm.nih.gov/37156795/

8. Liu, Xiaohan, Zhan, Ping, Zhang, Yang, Liu, Min, Yi, Fan. 2024. Lysosomal-Associated Protein Transmembrane 5, Tubular Senescence, and Progression of CKD. In Journal of the American Society of Nephrology : JASN, 35, 1655-1670. doi:10.1681/ASN.0000000000000446. https://pubmed.ncbi.nlm.nih.gov/39078711/

9. Han, Sijia, Jin, Xueying, Hu, Tianyu, Chi, Feng. 2023. LAPTM5 regulated by FOXP3 promotes the malignant phenotypes of breast cancer through activating the Wnt/β‑catenin pathway. In Oncology reports, 49, . doi:10.3892/or.2023.8497. https://pubmed.ncbi.nlm.nih.gov/36799186/