Dysregulated RNA splicing is a well-recognized characteristic of colorectal cancer (CRC); however, its intricacies remain obscure, partly due to challenges in profiling full-length transcript variants at the single-cell level. Here, we employ high-depth long-read scRNA-seq to define the full-length transcriptome of colorectal epithelial cells in 12 CRC patients, revealing extensive isoform diversities and splicing alterations. Cancer cells exhibited increased transcript complexity, with widespread 3'-UTR shortening and reduced intron retention. Distinct splicing regulation patterns were observed between intrinsic-consensus molecular subtypes (iCMS), with iCMS3 displaying even higher splicing factor activities and more pronounced 3'-UTR shortening. Furthermore, we revealed substantial shifts in isoform usage that result in alterations of protein sequences from the same gene with distinct carcinogenic effects during tumorigenesis of CRC. Allele-specific expression analysis revealed dominant mutant allele expression in key oncogenes and tumor suppressors. Moreover, mutated PPIG was linked to widespread splicing dysregulation, and functional validation experiments confirmed its critical role in modulating RNA splicing and tumor-associated processes. Our findings highlight the transcriptomic plasticity in CRC and suggest novel candidate targets for splicing-based therapeutic strategies.
Humans ; Colorectal Neoplasms/metabolism* ; RNA Isoforms/metabolism* ; Single-Cell Analysis ; RNA Splicing ; Gene Expression Regulation, Neoplastic ; RNA, Neoplasm/metabolism* ; Transcriptome

Mammals exhibit limited heart regeneration ability, which can lead to heart failure after myocardial infarction. In contrast, zebrafish exhibit remarkable cardiac regeneration capacity. Several cell types and signaling pathways have been reported to participate in this process. However, a comprehensive analysis of how different cells and signals interact and coordinate to regulate cardiac regeneration is unavailable. We collected major cardiac cell types from zebrafish and performed high-precision single-cell transcriptome analyses during both development and post-injury regeneration. We revealed the cellular heterogeneity as well as the molecular progress of cardiomyocytes during these processes, and identified a subtype of atrial cardiomyocyte exhibiting a stem-like state which may transdifferentiate into ventricular cardiomyocytes during regeneration. Furthermore, we identified a regeneration-induced cell (RIC) population in the epicardium-derived cells (EPDC), and demonstrated Angiopoietin 4 (Angpt4) as a specific regulator of heart regeneration. angpt4 expression is specifically and transiently activated in RIC, which initiates a signaling cascade from EPDC to endocardium through the Tie2-MAPK pathway, and further induces activation of cathepsin K in cardiomyocytes through RA signaling. Loss of angpt4 leads to defects in scar tissue resolution and cardiomyocyte proliferation, while overexpression of angpt4 accelerates regeneration. Furthermore, we found that ANGPT4 could enhance proliferation of neonatal rat cardiomyocytes, and promote cardiac repair in mice after myocardial infarction, indicating that the function of Angpt4 is conserved in mammals. Our study provides a mechanistic understanding of heart regeneration at single-cell precision, identifies Angpt4 as a key regulator of cardiomyocyte proliferation and regeneration, and offers a novel therapeutic target for improved recovery after human heart injuries.
Humans ; Mice ; Rats ; Cell Proliferation ; Heart/physiology* ; Mammals ; Myocardial Infarction/metabolism* ; Myocytes, Cardiac/metabolism* ; Pericardium/metabolism* ; Single-Cell Analysis ; Zebrafish/metabolism*

Objective To study the clinical value of cerebrospinal fluid cytology(csfc)and specific stain in tuberculous meningitis(TBM)-purulent meningitis(PM)and cryptococcal meningitis(CM).Methods The csfc data of 179 patients with TBM,PM and CM were retrospectively analyzed.The samples collected from all of these patients were analyzed by csfc May-Grunwald-Giemsa(MGG)staining,aricine blue staining and Indian ink staining. And the cytospin smears from 70 TBM were simultaneously stained by the immunofluorescence(IF)and immunocytological method to demonstrate the presence of mycobacterial antigen.Results ①TBM group showed a mixed-cell response.At the early stage of disease,the proportion of neutrophilic granulocyte reached 80%,and then reduced gradually.Lyumphoidocyte reaction was the most obvious in 1～2 months.The immunofluorescence(IF)and immunocytological method present a sensitivity of 82.9%and 85.7%,respectively.②Neutrophilic granulocyte was the most cell at acute stage of PM,and it descended quickly once treated with effective antibiotics.③The positive rates to detect CM with csfc MGG,aricine and Indian ink staining were 83.3%,81.8%,and 76.5%,respectively.Conclusion Dynamic observation on cerebrospinal fluid cytology is helpful to boost the differential diagnosis of intracranial infection.