Systemic sclerosis (SSc) is a complex autoimmune inflammatory disorder with multiple organ involvement. Skin changes present the hallmark of SSc and coincide with poor prognosis. Interstitial lung diseases (ILD) are the most widely reported complications in SSc patients and the primary cause of death. It has been proposed that the processes of autophagy and apoptosis could play a significant role in the pathogenesis and clinical course of different autoimmune diseases, and accordingly in SSc. In this manuscript, we review the current knowledge of autophagy and apoptosis processes in the skin and lungs of patients with SSc. Profiling of markers involved in these processes in skin cells can be useful to recognize the stage of fibrosis and can be used in the clinical stratification of patients. Furthermore, the knowledge of the molecular mechanisms underlying these processes enables the repurposing of already known drugs and the development of new biological therapeutics that aim to reverse fibrosis by promoting apoptosis and regulate autophagy in personalized treatment approach. In SSc-ILD patients, the molecular signature of the lung tissues of each patient could be a distinctive criterion in order to establish the correct lung pattern, which directly impacts the course and prognosis of the disease. In this case, resolving the role of tissue-specific markers, which could be detected in the circulation using sensitive molecular methods, would be an important step toward development of non-invasive diagnostic procedures that enable early and precise diagnosis and preventing the high mortality of this rare disease.

Phenylketonuria (PKU) is the most common inherited disorder of amino acid metabolism, characterized by high levels of phenylalanine (Phe) in the blood and brain, leading to cognitive impairment without treatment. Nevertheless, Phe-mediated brain dysfunction is not fully understood. The objective of this study was to address gene expression alterations due to excessive Phe exposure in the human neuronal model and provide molecular advances in PKU pathophysiology. Hence, we performed NT2/D1 differentiation in culture, and, for the first time, we used Phe-treated NT2-derived neurons (NT2/N) as a novel model for Phe-mediated neuronal impairment. NT2/N were treated with 1.25 mM, 2.5 mM, 5 mM, 10 mM, and 30 mM Phe and subjected to whole-mRNA short-read sequencing. Differentially expressed genes (DEGs) were analyzed and enrichment analysis was performed. Under three different Phe concentrations (2.5 mM, 5 mM, and 10 mM), DEGs pointed to the PREX1, LRP4, CDC42BPG, GPR50, PRMT8, RASGRF2, and CDH6 genes, placing them in the context of PKU for the first time. Enriched processes included dendrite and axon impairment, synaptic transmission, and membrane assembly. In contrast to these groups, the 30 mM Phe treatment group clearly represented the neurotoxicity of Phe, exhibiting enrichment in apoptotic pathways. In conclusion, we established NT2/N as a novel model for Phe-mediated neuronal dysfunction and outlined the Phe-induced gene expression changes resulting in neurite impairment and altered synaptic connectivity.

Introduction: Chronic endoplasmic reticulum (ER) stress and increased apoptosis are involved in the pathogenesis of glycogen storage disease Ib (GSD Ib), whereas small molecule phenylbutyrate (4‐PBA) showed the capability of reducing ER stress‐induced apoptosis. The objective was to generate an in vitro system in which capability of small molecules (SMs) to influence ER stress and apoptosis could be screened at the expression level.Methods: G6PT‐deficient FlpInHEK293 cell line was created and validated using the CRISPR/Cas9 knockout method. Molecular markers of unfolded protein response (ATF4, DDIT3, HSPA5, XBP1s), and apoptosis (BCL2/BAX, CASP3, CASP7) in G6PT‐deficient cells were analyzed using RT‐qPCR method before and upon the treatment with 4‐PBA.Results: Treatment with the most effective dose of 1 mM 4‐PBA reduced the expression of UPR markers and executioner caspases, while increased BCL2/BAX ratio in G6PT‐deficient cells. Our results proved the concept that 4‐PBA could alleviate markers of ER stress detected in the GSD Ib in vitro model system and prevent cell death.Conclusion: This cost‐effective in vitro model screens the therapeutic potential of SMs affecting ER stress and apoptosis in G6PT‐deficient kidney cells, offering a first‐line screening assay for promising compounds. 4‐PBA's potential repurposing for GSD Ib patients opens new research directions.

Glycogen storage disease Ib (GSD Ib) is an ultra-rare metabolic disease caused by variants in the SLC37A4 gene affecting activity of the glucose-6-phosphate transporter (G6PT). G6PT mediates transport of glucose-6 phosphate from the cytoplasm into the lumen of the endoplasmic reticulum, thereby playing a key role in glucose homeostasis. To date, no approved therapies directly restore G6PT function, highlighting a major unmet need. Pharmacological chaperone (PC) therapies, including those targeting membrane transporters, are a known and clinically employed therapeutic strategy. The efficacy of PC therapy is highly dependent on the underlying pathogenic variant. While certain missense variants may respond favorably, particularly those associated with protein misfolding and residual function, null variants are generally considered unsuitable targets due to the absence of a protein that could be rescued. To the best of our knowledge, no previous review has systematically examined the global landscape of SLC37A4 variants. The aim of this review was to collect the spectrum and frequency of SLC37A4 variants reported worldwide and connect them with all available structural and functional data. In 425 GSD Ib patients, we found that approximately 10% of all variants are strong PC candidates and 14–30% are reasonable but lower-confidence candidates (other missense non-deactivating variants), while the rest are poor PC candidates (substrate-pocket variants) and null variants (nonsense, frameshift and splicing). Although functional studies are required to definitely validate PC-responsive missense variants in the SLC37A4 gene, our review suggests, for the first time, the existence of a minimal threshold at which a PC approach may become clinically relevant for GSD Ib patients.