Understanding the Function and Mechanism of Zebrafish Tmem39b in Regulating Cold Resistance

Abstract

Autophagy and endoplasmic reticulum (ER) stress response are among the key pathways regulating cold resistance of fish through eliminating damaged cellular components and facilitating the restoration of cell homeostasis upon exposure to acute cold stress. The transmembrane protein 39A (TMEM39A) was reported to regulate both autophagy and ER stress response, but its vertebrate-specific paralog, the transmembrane protein 39B (TMEM39B), has not been characterized. In the current study, we generate tmem39b-knockout zebrafish lines and characterize their survival ability under acute cold stress. We observed that the dysfunction of Tmem39b remarkably decreased the cold resilience of both the larval and adult zebrafish. Gene transcription in the larvae exposed to cold stress and rewarming were characterized by RNA sequencing (RNA-seq) to explore the mechanisms underlying functions of Tmem39b in regulating cold resistance. The results indicate that the deficiency of Tmem39b attenuates the up-regulation of both cold- and rewarming-induced genes. The cold-induced transcription factor genes bif1.2, fosab, and egr1, and the rewarming-activated immune genes c3a.3, il11a, and sting1 are the representatives influenced by Tmem39b dysfunction. However, the loss of tmem39b has little effect on the transcription of the ER stress response- and autophagy-related genes. The measurements of the phosphorylated H2A histone family member X (at Ser 139, abbreviated as γH2AX) demonstrate that zebrafish Tmem39b protects the cells against DNA damage caused by exposure to the cold-warming stress and facilitates tissue damage repair during the recovery phase. The gene modules underlying the functions of Tmem39b in zebrafish are highly enriched in biological processes associated with immune response. The dysfunction of Tmem39b also attenuates the up-regulation of tissue C-reactive protein (CRP) content upon rewarming. Together, our data shed new light on the function and mechanism of Tmem39b in regulating the cold resistance of fish.

Comparative Transcriptome Analyses Provide New Insights into the Evolution of Divergent Thermal Resistance in Two Eel Gobies

“…Some DEGS include those genes (e.g., chaperones such as HSP90, HSP10) that are typically involved in cold stress response in a variety of animals [52,53]. These correspond well with previous studies, which demonstrate that all these biological processes are closely involved in cold tolerance when exposed to chilled waters in teleosts [54][55][56][57][58][59][60]. However, such transcriptomic response to cold stress was basically tissue specific both at the transcriptome or specific-gene expression level [61], as was also evident in other teleost fish when exposed to thermal stress [36,62].…”

Human spermatogonial stem cells retain states with a foetal-like signature

“…A tantalising explanation for why proliferation would be 'paused' is to facilitate DNA damage repair prior to differentiation. Consistent with this, GO terms enriched among the set of genes differentially upregulated only in state 0Bwhich include ERCC3, a nucleotide excision repair gene 78 , TMEM39B, which in zebrafish protects against oxidative DNA damage induced by cold stress 79 , PSTK, a phosphorylase kinase with a protective role against oxidative stress 80 , RPL3, involved in multiple DNA repair pathways in response to chemotherapy 81 , and WWOX, which modulates the double-strand break response 82,83 -include 'positive regulation of response to DNA damage stimulus' and 'positive regulation of apoptotic signalling pathway' (Supplementary Table 10). Moreover, a pairwise 'state 0B relative to state 0' comparison shows enrichment for the GO term 'positive regulation of DNA repair' (Supplementary Table 11).…”

Dysfunction of Prkcaa Links Social Behavior Defects with Disturbed Circadian Rhythm in Zebrafish

“…Cell culture, transfection and microphotography were performed as previously described [ 50 ]. Briefly, the 293T cells (ATCC number CRL-3216) were cultured in DMEM/High glucose (Hyclone, Logan, UT, USA), supplemented with 10% fetal bovine serum (PAN-Biotech, Aidenbach, Germany).…”

“…Gene-knockout zebrafish lines were generated using the CRISPR/Cas9 system according to our previous protocols [ 50 ]. The target sequence for the prkcaa gene was 5′-GGACCGCCGACTGGCTGTGG-3′, located in the 7th exon of the gene.…”

“…The workflow of RNA-seq data analysis was slightly modified from a previous study [ 50 ]. Briefly, the raw sequencing reads were preprocessed by fastp (v0.23.2) [ 55 ] with default settings to trim low-quality bases and filter low-quality reads.…”