LAPTM4A, also known as lysosomal-associated protein transmembrane 4 alpha, is a four-transmembrane-spanning protein encoded by the LAPTM4A gene, primarily residing in late endosomes and lysosomes [20]. Its structure includes four hydrophobic transmembrane domains, with the N-terminus and C-terminus exposed to the cytosol, facilitating interactions with cytoplasmic proteins [21]. The protein contains several putative lysosomal targeting signals, such as dileucine motifs and tyrosine-based sorting signals, which direct its trafficking from the Golgi apparatus to endolysosomal compartments. Additionally, LAPTM4A possesses proline-tyrosine (PY) motifs in its C-terminal region, enabling recruitment of ubiquitin ligases like neural precursor cell expressed developmentally downregulated 4-1 (NEDD4-1), which promotes ubiquitination and subsequent lysosomal degradation pathways [22]. This structural feature is conserved across species, underscoring its evolutionary importance in membrane dynamics.

In the context of the nervous system, LAPTM4A’s structural features are particularly relevant to neuronal homeostasis. Its four-transmembrane domain architecture enables stable integration into lysosomal and late endosomal membranes, which is essential for the high-turnover protein degradation demands of post-mitotic neurons. The cytosolic PY motifs facilitate recruitment of ubiquitin ligases such as NEDD4-1, promoting the ubiquitin-dependent degradation of misfolded proteins and damaged organelles that would otherwise accumulate in neurons. Furthermore, LAPTM4A’s interaction with human organic cation transporter 2 (hOCT2) has implications for neuronal detoxification, as this transporter mediates the clearance of cationic neurotoxins and metabolic byproducts from brain tissue. In glial cells, particularly microglia, LAPTM4A modulates polarization states, with its presence promoting macrophage 2 (M2) anti-inflammatory phenotypes that support neuronal survival and tissue repair.

Functionally, LAPTM4A acts as a regulator of endosomal sorting and lysosomal function. It interacts with various transporters and enzymes, modulating their activity and localization. For instance, LAPTM4A associates with hOCT2, influencing its endocytic recycling and thereby affecting cellular uptake of cationic compounds [23]. This interaction enhances hOCT2 trafficking between the plasma membrane and intracellular compartments, impacting drug transport and cellular detoxification. In lipid metabolism, LAPTM4A modulates globotriaosylceramide (Gb3) synthase activity post-transcriptionally, reducing Gb3 levels in lysosomes and preventing accumulation-related pathologies [24]. Loss of LAPTM4A leads to decreased Gb3 synthase function, highlighting its role in glycosphingolipid homeostasis. In immune and cancer contexts, LAPTM4A influences macrophage polarization. It promotes M2 polarization of tumor-associated macrophages (TAMs), enhancing tumor proliferation and invasion in gliomas by fostering an immunosuppressive microenvironment [25]. This is achieved through signaling pathways that support anti-inflammatory responses. Furthermore, LAPTM4A is involved in toxin resistance mechanisms; genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) screens have identified it as a factor in Shiga toxin and ricin susceptibility, where it facilitates toxin entry or processing in endosomes [26]. Structurally, its transmembrane domains enable ceramide interactions, potentially stabilizing lysosomal membranes and preventing leakage.

LAPTM4A’s expression correlates with prognosis in gliomas, including glioblastoma and low-grade glioma, where higher levels are associated with advanced grades, histological aggressiveness, and poorer outcomes [27]. Mechanistically, it interacts with microRNAs and circular RNAs, such as in the hsa_circ_0042260/miR-4782-3p/LAPTM4A axis, which promotes hepatocellular carcinoma progression by enhancing cell proliferation and invasion [28]. In ubiquitination pathways, LAPTM4A undergoes self-ubiquitination via ring finger protein 152 (RNF152), contributing to a conserved endosomal sorting complexes required for transport (ESCRT)-dependent internalization process that regulates membrane protein turnover [22]. Overall, LAPTM4A’s structure supports its multifaceted functions in trafficking, metabolism, and disease modulation, making it a key player in endolysosomal biology.

LAPTM4B, or lysosomal-associated protein transmembrane 4 beta, is a tetratransmembrane protein overexpressed in various cancers, including hepatocellular carcinoma, where it serves as a prognostic marker [29]. Structurally, LAPTM4B comprises four transmembrane helices, with N- and C-terminal domains in the cytosol, and includes PY motifs that interact with ubiquitin ligases like NEDD4 [30]. It exists in two isoforms, LAPTM4B-35 and LAPTM4B-24, differing in their N-terminal regions, with LAPTM4B-35 being the predominant form in tumors [31]. The protein localizes to late endosomes and lysosomes, where its transmembrane domains facilitate lipid binding, particularly ceramides and phosphatidylinositol 4,5-bisphosphate [32].

Functionally, LAPTM4B regulates lysosomal ceramide export, preventing ceramide accumulation and promoting cell death resistance in tumors [33]. It interacts with ceramide to facilitate its removal from late endosomes, independently of sphingomyelin synthase activity, thus maintaining lysosomal integrity [33]. In autophagy, LAPTM4B promotes lysosomal acidification and maturation, essential for autophagosome-lysosome fusion, and its amplification enhances tumor growth by supporting autophagic flux [34]. LAPTM4B also recruits the leucine transporter L-type amino acid transporter 1 (LAT1)-4F2hc to lysosomes, enabling leucine uptake and mechanistic target of rapamycin complex 1 (mTORC1) activation, which drives cell proliferation under nutrient stress [35].

In cancer progression, LAPTM4B enhances multidrug resistance by promoting cell migration via integrin $\beta$1 activation and focal adhesion kinase (FAK)/AKT signaling [36]. It inhibits EGFR lysosomal degradation, prolonging signaling and contributing to oncogenesis [32]. In acute myeloid leukemia, LAPTM4B stabilizes ribosomal protein S9 (RPS9), activating signal transducer and activator of transcription 3 (STAT3) and promoting leukemogenesis [37]. Its polymorphism, particularly allele, is linked to increased susceptibility in gastric, colon, and ovarian cancers [38]. LAPTM4B controls sphingolipid and ether lipid profiles in extracellular vesicles, influencing tumor microenvironment communication [39].

In hepatocellular carcinoma, LAPTM4B is regulated by histone deacetylase 2 (HDAC2) and ETS translocation variant 1 (ETV1), enhancing autophagy and stemness [40]. It counteracts ferroptosis by stabilizing solute carrier family 7 member 11 (SLC7A11), reducing lipid peroxidation [41]. Serum LAPTM4B levels serve as diagnostic markers for breast cancer [42]. In glioblastoma, high LAPTM4B-35 expression correlates with poor prognosis and angiogenesis [14]. Amplification with tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ) contributes to chemotherapy resistance. In nasopharyngeal and bladder cancers, LAPTM4B drives migration and invasion [43].

Its role in lung adenocarcinoma prognosis underscores its oncogenic potential [44]. In B-cell acute lymphoblastic leukemia, LAPTM4B promotes progression and immune evasion. Polymorphisms associate with breast cancer risk, though not always significantly [45]. In colorectal cancer, overexpression predicts poor outcomes [46]. Noninvasive imaging targets LAPTM4B for hepatocellular carcinoma detection [47]. Overall, LAPTM4B’s structure enables its broad regulatory functions in lysosomal metabolism, signaling, and cancer biology.

LAPTM5, lysosomal-associated protein transmembrane 5, is a five-transmembrane-domain protein with three PY motifs and one ubiquitin-interacting motif (UIM), enabling interactions with substrates and ubiquitin ligases. Its structure includes cytosolic loops and termini, facilitating supramolecular assemblies and really interesting new gene (RING) domain interactions for cellular signaling [11]. The PY and UIM motifs are critical for recruiting enzyme 3 (E3) ligases like NEDD4, promoting protein degradation [48].

Functionally, LAPTM5 regulates lysosomal function by interacting with mucolipin-1 (MCOLN1), modulating ion channels and preventing mucolipidosis type IV-like phenotypes [49]. It promotes proinflammatory signaling in macrophages, enhancing cytokine secretion via NF-$\kappa$B and MAPK pathways [50]. In T-cell activation, LAPTM5 degrades cluster of differentiation 3 zeta (CD3$\zeta$) in lysosomes, negatively regulating T cell receptor (TCR) surface expression [51].

In cancers, LAPTM5 drives malignant phenotypes; in breast cancer, forkhead box protein 3 (FOXP3)-regulated LAPTM5 enhances proliferation, migration, and invasion [52]. In clear cell renal cell carcinoma, it promotes progression via elevated expression. LAPTM5 confers resistance to lenvatinib in hepatocellular carcinoma through CRISPR-identified mechanisms [53]. Zinc finger with KRAB and SCAN domains 5 (ZKSCAN5) activates LAPTM5 by recruiting SET domain-containing protein 7 (SETD7) for histone H3 lysine 4 trimethylation (H3K4me3) modification, supporting pancreatic ductal adenocarcinoma growth [54, 55]. In multiple myeloma, LAPTM5 promotes venetoclax resistance by enhancing myeloid cell leukemia 1 (MCL-1) stability [56]. It confers cisplatin resistance in non-small cell lung cancer by suppressing ferroptosis via cathepsin D release [57].

In kidney injury, LAPTM5 induces tubular senescence via WW domain-containing E3 ubiquitin protein ligase 2 (WWP2)/Notch receptor 1 (Notch1) signaling, exacerbating fibrosis [58]. Its role in autophagy activation links it to disease processes, including immunity and inflammation [11]. In chronic rhinosinusitis, LAPTM5 is part of M2 macrophage signatures [59]. Overall, LAPTM5’s unique structure underpins its functions in degradation, signaling, and pathology, with broad implications for therapeutic intervention. The structural features, expression patterns, and primary biological functions of the three LAPTM family members are comparatively summarized in Table 1.

Neurons, as highly specialized, post-mitotic cells, rely heavily on efficient lysosomal systems to maintain homeostasis by degrading damaged organelles and proteins through autophagy [62]. LAPTM proteins enhance this process by regulating lysosomal membrane stability and trafficking. For instance, LAPTM5 deficiency in mouse models exacerbates cerebral ischemia/reperfusion injury, leading to increased neuronal apoptosis and inflammation via heightened c-Jun N-terminal kinase (JNK)/p38 signaling and impaired lysosomal function [64]. Overexpression of LAPTM5 mitigates these effects, suggesting its protective role in neuronal stress responses [65]. In intracerebral hemorrhage models, LAPTM5 is upregulated in neurons surrounding hematomas, where it modulates lysosomal degradation to prevent secondary brain injury and support neuronal survival [66]. This protein interacts with apoptosis signal-regulating kinase 1 (ASK1) to suppress pro-apoptotic pathways, maintaining neuronal homeostasis under hemorrhagic stress.

LAPTM4A also contributes to neuronal homeostasis by interacting with transporters like hOCT2, which regulates cationic compound uptake in the brain, potentially aiding in detoxification and ion balance [23]. In Parkinson’s disease models, LAPTM4A is involved in mitochondrial-lysosomal crosstalk, where miR-5701 modulates its expression to regulate neuronal death by preventing excessive mitophagy and lysosomal overload [28]. Furthermore, LAPTM4A protects neurons from prion protein fragment-induced apoptosis, possibly through pathways mediated by imatinib (STI571) that stabilize lysosomal membranes and enhance autophagic clearance [67]. Its role in glycosphingolipid metabolism helps prevent lipid accumulation that could disrupt neuronal membrane integrity and signaling [24].

LAPTM4B supports neuronal homeostasis by facilitating ceramide export from lysosomes, preventing ceramide-induced apoptosis and maintaining autophagic flux [33]. In neuronal ceroid lipofuscinosis, LAPTM4B mutants contribute to abnormal triaging of misfolded proteins, leading to lipofuscin accumulation and disrupted proteostasis [68]. Copy number variations in LAPTM4B are associated with dementia with Lewy bodies, where they impair lysosomal degradation of alpha-synuclein, exacerbating neuronal toxicity [69]. In age-related hearing loss, LAPTM4B influences auditory neuron homeostasis by regulating gene expression profiles linked to lysosomal function [70].

Beyond individual members, the LAPTM family collectively ensures neuronal ion homeostasis by interacting with channels like mucolipin-1, preventing lysosomal storage disorders with neurological manifestations. In neuroblastomas, LAPTM5 promotes spontaneous regression through lysosomal destabilization and autophagic cell death, highlighting its role in neuronal progenitor homeostasis. LAPTM5 also regulates T-cell receptor degradation in neurons, indirectly supporting synaptic plasticity and homeostasis [71]. In spinocerebellar ataxia models, related transmembrane proteins underscore the importance of lysosomal integrity for Purkinje neuron survival [72]. Overall, LAPTM proteins safeguard neuronal homeostasis by optimizing lysosomal degradation, mitigating stress-induced apoptosis, and supporting metabolic balance, with deficiencies leading to vulnerability in ischemic, hemorrhagic, and degenerative states.

The intricate mechanisms involve LAPTM5’s PY motifs facilitating ubiquitin-dependent sorting, essential for neuronal protein turnover [12]. In low-grade gliomas, LAPTM expression correlates with prognosis, implying a role in neuronal-glial interactions during oncogenesis [8]. LAPTM4A’s upregulation in gliomas promotes tumor progression but may reflect compensatory mechanisms for neuronal homeostasis [25]. In chronic pain models, LAPTM5 in dorsal horn neurons modulates gene networks for inflammatory homeostasis. These findings emphasize LAPTM’s multifaceted contributions to neuronal stability.

Glial cells, including astrocytes, microglia, and oligodendrocytes, provide structural, metabolic, and immune support to neurons, with lysosomal functions critical for phagocytosis, cytokine regulation, and myelin maintenance. LAPTM proteins in glia regulate these processes to sustain nervous system homeostasis. LAPTM4A loss inhibits M2 polarization of tumor-associated macrophages in glioblastoma, promoting immune activation and enhancing anti-programmed cell death protein 1 (PD1) therapy [25]. This suggests LAPTM4A modulates microglial phenotypes, balancing pro- and anti-inflammatory states for glial homeostasis. Chemokine-like factor (CKLF) induces microglial activation via defective mitophagy, involving LAPTM4A in lysosomal dysfunction and neuroinflammation. In gliomas, high LAPTM4A expression correlates with poor prognosis, indicating disrupted glial homeostasis in malignancy [73].

LAPTM4B in glial cells regulates exosome release induced by ceramide, influencing intercellular communication and homeostasis in the tumor microenvironment [74]. In glioblastoma, LAPTM4B-35 overexpression is a prognostic factor, linked to glial proliferation and angiogenesis [14]. Its role in chemotherapy resistance in breast carcinomas extends to glial tumors, where copy number gains impair response to treatments. In hypomyelinating disorders, related transmembrane (TMEM) proteins like TMEM106B highlight LAPTM4B’s potential in oligodendrocyte myelin homeostasis [75].

LAPTM5 is prominently expressed in microglia, where it enhances proinflammatory signaling via NF-$\kappa$B and MAPK, crucial for glial immune homeostasis [76]. In cerebral ischemia, LAPTM5 deficiency aggravates glial inflammation, disrupting supportive functions [64]. LAPTM5-cluster of differentiation 40 (CD40) crosstalk in glioblastoma modulates glial invasion and temozolomide resistance, linking to tumor glial homeostasis [77]. Its impact on immune cell function extends to glial responses in neurological deficiencies. LAPTM5 interacts with CD1e in glial endosomes, potentially regulating antigen presentation and homeostasis [78]. In age-related hearing loss, LAPTM5 in glial networks supports cochlear homeostasis.

A critical unresolved question concerns the seemingly paradoxical dual roles of LAPTM5 in the nervous system. On one hand, LAPTM5 deficiency exacerbates cerebral ischemia-reperfusion injury and increases neuronal apoptosis, suggesting a neuroprotective function. On the other hand, LAPTM5 promotes proinflammatory signaling through NF-$\kappa$B and MAPK pathways in microglia, which could contribute to neurodegenerative pathology. This apparent contradiction may be reconciled by considering the temporal and contextual nature of LAPTM5 function. In acute injury settings, LAPTM5-mediated lysosomal activity may prioritize debris clearance and cellular repair, outweighing inflammatory effects. However, in chronic neurodegenerative conditions, sustained LAPTM5-driven inflammation may become detrimental. Additionally, the balance between LAPTM5’s pro-phagocytic function (beneficial for clearing pathological aggregates) and its pro-inflammatory signaling (potentially harmful when excessive) likely determines net outcomes. Future studies employing temporal and cell-type–specific genetic manipulations will be essential to dissect these context-dependent effects.

In astrocytes, LAPTM proteins facilitate lactate shuttling and cholesterol homeostasis, essential for neuronal support. Aquaporin-4 interactions in gliomas suggest LAPTM involvement in water-ion balance [79]. In neurodegenerative models, LAPTM5 promotes glial phagocytosis of neuronal debris, maintaining tissue integrity. Overall, LAPTM proteins in glial cells ensure lysosomal efficiency, inflammation control, and metabolic support, vital for nervous system homeostasis.

To elaborate further, in microglia, LAPTM5’s role in chronic rhinosinusitis parallels its function in brain inflammation, where it marks M2 signatures for resolution [11]. In renal cell carcinoma models, LAPTM5’s proliferative effects may be analogous to glial activation in brain tumors. LAPTM4B’s association with inositol status implies links to neural signaling homeostasis [53]. In frontotemporal lobar degeneration, TMEM-related proteins underscore lysosomal roles in glial pathology. Semaphorin family interactions with immune regulation highlight cross-talk between nervous and glial systems. Neurotrophins in energy homeostasis involve glial support, potentially modulated by LAPTM. Lysophospholipid receptors in glia regulate motility and differentiation. Innate lymphoid cells’ interaction with the nervous system implicates glial immune homeostasis. N-methyl-D-aspartate (NMDA)-independent long-term potentiation (LTP) in glial-neuronal circuits may involve lysosomal stability. Lysosome-associated membrane protein (LAMP) in neurite outgrowth suggests analogous roles for LAPTM in glial processes. In mucolipidosis type IV, LAPTM-mucolipin interactions affect glial ion channels. These diverse mechanisms illustrate LAPTM’s integral role in glial homeostasis [80]. These multifaceted molecular functions of the LAPTM protein family in neural cell homeostasis and their dysregulation in neurological disorders are illustrated in Fig. 1.

Fig. 1.

Molecular functions of the LAPTM protein family in neural cell homeostasis and neurological disorders. LAPTM family proteins are key regulators of lysosomal function that sustain neural health through multiple interconnected mechanisms. They maintain cellular homeostasis by facilitating the autophagic clearance of pathogenic protein aggregates (e.g., alpha-synuclein, A$\beta$). Specifically, LAPTM4B promotes cell growth and proliferation by activating mTORC1 via LAT1-mediated leucine transport, exporting ceramide to prevent lipotoxicity and apoptosis, and enhancing oncogenic EGFR/PI3K/Akt signaling. LAPTM4B also inhibits ferroptosis by stabilizing SLC7A11. In parallel, LAPTM5 drives neuroinflammation via NF-$\kappa$B/MAPK pathways and modulates cell death through interactions with ASK1 and MCOLN1. Red circles within the lysosome labeled with H⁺ represent hydrogen ions, maintaining the acidic luminal environment, while smaller unlabeled red dots symbolize lysosomal enzymes or protein substrates undergoing degradation. The dysregulation of these LAPTM-mediated pathways underpins their roles in neurodegenerative diseases, glioma progression, and ischemic injury. Note: H⁺, hydrogen ion; LAT1, L-type amino acid transporter 1; EGFR/PI3K/Akt, epidermal growth factor receptor/phosphatidylinositol 3-kinase/protein kinase B; SLC7A11, solute carrier family 7 member 11; NF-$\kappa$B/MAPK, nuclear factor $\kappa$B/mitogen-activated protein kinase; ASK1, apoptosis signal-regulating kinase 1; MCOLN1, mucolipin-1. Created with BioRender (https://www.biorender.com/).

Lysosome-associated membrane proteins 1 and 2 (LAMP1 and LAMP2) are the most abundant lysosomal membrane proteins, constituting approximately 50% of all lysosomal membrane proteins [81]. While both LAMP and LAPTM families localize to lysosomal membranes, their functions are distinct yet complementary. LAMP proteins primarily serve structural roles, protecting the lysosomal membrane from degradation by luminal hydrolases through their heavily glycosylated luminal domains. In contrast, LAPTM proteins function predominantly as regulators of membrane trafficking, substrate transport, and signaling pathway modulation. For instance, whereas LAMP2A serves as the receptor for chaperone-mediated autophagy (CMA), LAPTM4B facilitates ceramide export and mTORC1 activation [33, 35]. In the context of neurological diseases, LAMP2 deficiency causes Danon disease with prominent neurological manifestations, while LAPTM dysregulation contributes to more diverse pathologies, including gliomas and ischemic injury. Importantly, LAPTM5 interacts functionally with LAMP1 to stabilize lysosomal membranes and sustain autophagic flux, as demonstrated in cisplatin resistance models [57]. This functional interplay suggests that LAPTM and LAMP proteins may represent complementary therapeutic targets for lysosomal modulation in neurological disorders.

TFEB is the master regulator of lysosomal biogenesis and autophagy gene expression, coordinating the transcription of over 500 genes in the CLEAR (Coordinated Lysosomal Expression and Regulation) network [13]. While TFEB operates at the transcriptional level to increase lysosomal capacity, LAPTM proteins function post-translationally to modulate lysosomal membrane dynamics and cargo processing. These two regulatory layers are interconnected: LAPTM4B-mediated mTORC1 activation influences TFEB phosphorylation and nuclear translocation, thereby affecting lysosomal gene expression [35]. Conversely, TFEB activation may upregulate LAPTM expression as part of the coordinated lysosomal response. In neurodegenerative diseases, TFEB activation has shown therapeutic promise for enhancing aggregate clearance [13]. Combining TFEB activators with LAPTM modulators could potentially produce synergistic effects by simultaneously increasing lysosomal capacity (via TFEB) and optimizing lysosomal function (via LAPTM). Furthermore, as discussed in Section 4.1.1, Sirtuin 1 (SIRT1) deacetylates TFEB to promote its nuclear translocation, suggesting a SIRT1-TFEB-LAPTM regulatory axis that warrants therapeutic exploration [82, 83].

Mucolipin-1, encoded by the MCOLN1 gene, is a lysosomal cation channel essential for calcium signaling, membrane fusion, and lysosomal trafficking [49]. Mutations in MCOLN1 cause mucolipidosis type IV, a lysosomal storage disorder with severe neurological manifestations. Critically, LAPTM family members physically interact with mucolipin-1 to regulate lysosomal ion homeostasis [49]. This interaction is particularly relevant for neural cells, where precise calcium signaling is essential for synaptic function and neuronal survival. LAPTM5’s interaction with MCOLN1 modulates lysosomal calcium release, affecting downstream processes including autophagosome-lysosome fusion and TFEB activation. Disruption of LAPTM-MCOLN1 interactions may contribute to the lysosomal dysfunction observed in neurodegenerative diseases. Therefore, therapeutic strategies targeting LAPTM proteins must consider their effects on MCOLN1-dependent ion homeostasis to avoid unintended consequences on neuronal calcium signaling.

The positioning of LAPTM proteins within the lysosomal regulatory network has important implications for therapeutic development. Unlike TFEB, which broadly upregulates lysosomal function, or LAMP proteins, which primarily serve structural roles, LAPTM family members offer opportunities for more selective modulation of specific lysosomal processes—such as ceramide metabolism (LAPTM4B), inflammatory signaling (LAPTM5), or immune cell polarization (LAPTM4A). This functional specificity may enable more precise therapeutic interventions with fewer off-target effects compared to broader lysosomal modulators. However, the interconnected nature of lysosomal regulation also means that LAPTM-targeted therapies may produce cascading effects on TFEB activity, MCOLN1 function, and overall lysosomal homeostasis, necessitating careful evaluation in preclinical models.

LAPTM4B and LAPTM5 play crucial roles in regulating lysosomal acidification, membrane stability, and autophagosome-lysosome fusion [13]. In neurodegenerative diseases, pathological protein aggregation and mitochondrial damage are common. Targeting and enhancing the function of LAPTM can promote the clearance of abnormal proteins and damaged organelles, thereby delaying the progression of the disease. Studies have shown that knocking down LAPTM5 exacerbates cerebral ischemia-reperfusion injury [64], while its overexpression can significantly improve neuronal survival rate and inhibit inflammation [65]. This finding suggests that enhancing LAPTM activity through gene delivery or small molecule agonists may become a novel intervention strategy for stroke and ischemic brain injury.

LAPTM4B promotes the transport of ceramides within nerve cells and maintains lipid homeostasis, preventing apoptosis caused by lipid overload [74]. Additionally, the latest research suggests that LAPTM4B can inhibit ferroptosis by stabilizing SLC7A11 [41]. This mechanism may have potential protective effects in the context of ischemia-reperfusion and neurodegenerative diseases, where oxidative stress is prevalent. Targeted regulation of the LAPTM4B-SLC7A11 axis is expected to become a new approach for future therapies against oxidative stress and ferroptosis.

Notably, the anti-aging gene SIRT1 represents a promising upstream regulator that may modulate LAPTM-mediated pathways. SIRT1 has been extensively documented to regulate autophagy, lysosome function, and exosome secretion through its deacetylase activity on transcription factors and autophagy-related proteins [96, 97]. In the context of neurological diseases, SIRT1 activation prevents amyloid beta aggregation, reduces oxidative stress, inhibits neuronal apoptosis, and suppresses glioma progression [82, 98]. Furthermore, SIRT1 plays a pivotal role in immune regulation and autoimmunity, which may intersect with LAPTM5-mediated inflammatory responses [83, 99]. Given the shared functional targets of SIRT1 and LAPTM proteins in lysosomal integrity and autophagy flux, future therapeutic strategies may benefit from combinatorial approaches that target both pathways. SIRT1 activators, such as resveratrol and its derivatives, could potentially enhance LAPTM-mediated neuroprotection by reinforcing the autophagy-lysosome axis and mitigating oxidative damage [100]. The interplay between SIRT1 and LAPTM warrants further investigation to establish optimal therapeutic regimens.

The success of LAPTM-targeted therapies may critically depend on the coordinated modulation of SIRT1 activity. SIRT1 serves as a primary control point for lysosomal integrity through its deacetylation of TFEB and other transcription factors that govern lysosomal biogenesis and autophagy gene expression. In neurodegenerative diseases where enhanced autophagy flux is desired, combining LAPTM-enhancing strategies with SIRT1 activators (such as resveratrol or synthetic activators like SRT1720) may produce synergistic neuroprotective effects. These combinations could simultaneously enhance LAPTM4B-mediated lysosomal stability, promote autophagosome-lysosome fusion, and reduce oxidative stress through SIRT1’s antioxidant signaling [83]. However, in glioma and other CNS tumors where LAPTM4B overexpression promotes tumor survival, SIRT1 inhibition may be a more appropriate strategy. A study has shown that SIRT1 knockdown inhibits glioma cell proliferation and potentiates temozolomide toxicity through facilitation of reactive oxygen species generation [82]. Therefore, the therapeutic context—neuroprotection versus tumor suppression—must guide the decision between SIRT1 activation and inhibition in LAPTM-targeted treatment regimens.

LAPTM5 can activate NF-$\kappa$B and MAPK signaling in macrophages and microglia to enhance the secretion of inflammatory factors [12]. In the central nervous system, appropriately regulating the polarization state of microglia is crucial for inhibiting chronic neuroinflammation and promoting tissue repair. A recent study has shown that the deletion of LAPTM4A can inhibit the M2 polarization of tumor-associated microglia in glioblastoma and enhance the immune treatment response [25]. Therefore, by using small molecule inhibitors or RNA interference to reduce the expression of LAPTM in the tumor immunosuppressive environment, it may improve the efficacy of immune checkpoint inhibitors.

The high expression of LAPTM4A/4B is closely related to the grading, prognosis and chemotherapy resistance of glioma [14]. The detection of its mRNA or protein levels can serve as a new biomarker for early diagnosis and efficacy assessment. Non-invasive imaging techniques have enabled the visualization of LAPTM4B expression in liver cancer. This approach, using tools such as radiolabeled peptide positron emission tomography (PET) probes, is expected to be extended to central nervous system tumors in the future. Meanwhile, LAPTM5 is highly co-expressed with the risk genes of microglial cell networks in AD [47], suggesting its value in the early diagnosis of neurodegenerative diseases.

Based on the transmembrane structure and ligand-binding characteristics of LAPTM, developing small molecules or monoclonal antibodies to regulate its activity is a feasible strategy. For instance, targeting LAPTM4B can inhibit its promotion of prolonged EGFR signaling and enhanced autophagy, thereby reducing tumor resistance [32]. In the future, through high-throughput screening to find LAPTM agonists or inhibitors, or using PROteolysis targeting chimera (PROTAC) technology for specific degradation, all have potential application value.

CRISPR/Cas9 has been used to screen the function of LAPTM and reveal its role in drug resistance [54]. Gene editing is expected to achieve precise regulation of LAPTM in animal models to verify its role in neuroprotection or tumor suppression. In addition, vectors targeting the nervous system, such as adeno-associated virus, can be used to deliver the LAPTM gene or regulatory elements to specific nerve cells, providing new ideas for the treatment of ischemic or neurodegenerative diseases [71].

LAPTM regulates the tumor microenvironment and the polarization of immune cells, suggesting its potential value in combined immunotherapy with immune checkpoint inhibitors or chimeric antigen receptor T-cell (CAR-T) therapy [88]. In a glioblastoma mouse model, interfering with LAPTM expression significantly increased the response rate to anti-PD1 treatment. In the future, it can be explored to combine LAPTM inhibitors with oncolytic viruses, immune adjuvants, etc., to improve the immune tolerance of refractory CNS tumors.

Despite the promising therapeutic potential of LAPTM-targeted interventions, several significant challenges must be addressed for successful clinical translation. First, blood-brain barrier (BBB) penetration remains a fundamental obstacle for most neurological therapeutics. Small-molecule LAPTM modulators must be designed with appropriate lipophilicity and molecular weight to cross the BBB, or alternative delivery strategies such as nanoparticle encapsulation, focused ultrasound-mediated BBB opening, or intranasal administration must be employed.

Second, achieving lysosomal targeting presents unique pharmacological challenges. Therapeutic agents must traverse the plasma membrane and endosomal compartments to reach their intracellular targets without premature degradation. Lysosomotropic agents that accumulate in acidic compartments may provide one solution, but their non-specific accumulation in all lysosomes raises concerns about off-target effects on healthy cells.

Third, the ubiquitous expression of LAPTM proteins across multiple cell types raises concerns about systemic toxicity. Cell-type–specific delivery systems or prodrug approaches that are activated only in target cells may be necessary to achieve therapeutic selectivity. Additionally, the distinct and sometimes opposing functions of LAPTM family members (e.g., LAPTM4A promoting tumor immunity while LAPTM4B promotes tumor survival) necessitate isoform-specific modulators that can selectively target individual family members without affecting others.

Fourth, biomarker validation for LAPTM-targeted therapies requires substantial additional work. While preclinical studies suggest that LAPTM expression levels correlate with disease severity and treatment response, prospective clinical validation studies with standardized assays are needed to establish their utility in patient stratification and treatment monitoring.

Finally, current preclinical models have limitations in recapitulating human LAPTM biology. Species differences in expression patterns and functional consequences may limit translational applicability. The development of humanized mouse models and patient-derived organoid systems will be essential for more accurate preclinical evaluation of LAPTM-targeted interventions.