Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
BRCF Microscopy Core, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
Nat Commun. 2022 Sep 12;13(1):5351. doi: 10.1038/s41467-022-33025-1.
The mannose-6-phosphate (M6P) biosynthetic pathway for lysosome biogenesis has been studied for decades and is considered a well-understood topic. However, whether this pathway is regulated remains an open question. In a genome-wide CRISPR/Cas9 knockout screen, we discover TMEM251 as the first regulator of the M6P modification. Deleting TMEM251 causes mistargeting of most lysosomal enzymes due to their loss of M6P modification and accumulation of numerous undigested materials. We further demonstrate that TMEM251 localizes to the Golgi and is required for the cleavage and activity of GNPT, the enzyme that catalyzes M6P modification. In zebrafish, TMEM251 deletion leads to severe developmental defects including heart edema and skeletal dysplasia, which phenocopies Mucolipidosis Type II. Our discovery provides a mechanism for the newly discovered human disease caused by TMEM251 mutations. We name TMEM251 as GNPTAB cleavage and activity factor (GCAF) and its related disease as Mucolipidosis Type V.
甘露糖-6-磷酸（M6P）生物合成途径在溶酶体发生中的作用已被研究了数十年，被认为是一个被充分理解的课题。然而，该途径是否受到调控仍然是一个悬而未决的问题。在全基因组 CRISPR/Cas9 敲除筛选中，我们发现 TMEM251 是 M6P 修饰的第一个调节剂。由于 TMEM251 的缺失导致大多数溶酶体酶失去 M6P 修饰并积累大量未消化的物质，从而导致它们的靶向错误。我们进一步证明，TMEM251 定位于高尔基体，并且是催化 M6P 修饰的酶 GNPT 的切割和活性所必需的。在斑马鱼中，TMEM251 的缺失导致严重的发育缺陷，包括心脏水肿和骨骼发育不良，这与粘脂贮积症 II 型表型相同。我们的发现为 TMEM251 突变引起的新发现的人类疾病提供了一种机制。我们将 TMEM251 命名为 GNPTAB 切割和活性因子（GCAF），并将其相关疾病命名为粘脂贮积症 V 型。
