Mitochondrion harbors its own DNA (mtDNA), which encodes many critical proteins for the assembly and activity of mitochondrial respiratory complexes. mtDNA is packed by many proteins to form a nucleoid that uniformly distributes within the mitochondrial matrix, which is essential for mitochondrial functions. Defects or mutations of mtDNA result in a range of diseases. Damaged mtDNA could be eliminated by mitophagy, and all paternal mtDNA are degraded by endonuclease G or mitophagy during fertilization. In this review, we describe the role and mechanism of mtDNA distribution and elimination. In particular, we focus on the regulation of paternal mtDNA elimination in the process of fertilization.

Mitochondrial cristae are the principal sites of oxidative phosphorylation and are central to mitochondria-dependent energy metabolism. Rather than static folds, cristae are dynamic bioenergetic compartments that remodel in response to physiological and stress cues. During remodeling, their number, length, width, lateral alignment, curvature/stiffness, and the geometry of crista junctions (CJs) can change. Depending on cellular context, cristae may increase in abundance, tighten or widen, and exhibit opening or closure of CJs, with corresponding effects on respiratory-chain organization and supercomplex assembly. Key regulators include OPA1 (and its proteolytic processing), the MICOS complex that scaffolds CJs, F₁Fo-ATP synthase dimerization/oligomerization that shapes high-curvature ridges, and cardiolipin, which stabilizes inner-membrane architecture. Abnormal cristae compromise electron transport, ATP production, and mitochondrial metabolism, contributing to neurodegeneration and metabolic disease etc. In this review, we synthesize current insights into the molecular control of cristae ultrastructure and its impact on mitochondrial metabolism, delineate structural features and quantitative readouts, and highlight mechanisms that govern cristae remodeling under physiological and stress conditions, with an emphasis on diseases arising from aberrant crista architecture.

Mitochondria play essential roles in cancer cell adaptation to hypoxia, but the underlying mechanisms remain elusive. Through mitochondrial proteomic profiling, we here find that the prolyl hydroxylase EglN1 (PHD2) accumulates on mitochondria under hypoxia. EglN1 substrate-binding region in the β2β3 loop is responsible for its mitochondrial translocation and contributes to breast tumor growth. Furthermore, we identify AMP-activated protein kinase alpha (AMPKα) as an EglN1 substrate on mitochondria. The EglN1-AMPKα interaction is essential for their mutual mitochondrial translocation. After EglN1 prolyl-hydroxylates AMPKα under normoxia, they rapidly dissociate following prolyl-hydroxylation, leading to their immediate release from mitochondria. In contrast, hypoxia results in constant EglN1-AMPKα interaction and their accumulation on mitochondria, leading to the formation of a Ca²⁺ /calmodulin-dependent protein kinase 2 (CaMKK2)-EglN1-AMPKα complex to activate AMPKα phosphorylation, ensuring metabolic homeostasis and breast tumor growth. Our findings identify EglN1 as an oxygen-sensitive metabolic checkpoint signaling hypoxic stress to mitochondria through its β2β3 loop region, suggesting a potential therapeutic target for breast cancer.

Mitochondria are crucial for a wide range of cellular processes. One of the most important is innate immunity regulation. Apart from functioning as a signaling hub in immune reactions, mitochondrial nucleic acids can themselves act as damage-associated molecular patterns (DAMPs) to participate in immune processes directly. This review synthesizes the current understanding of mitochondrial RNA (mtRNA) biology and its link to immune activation through aberrant accumulation. We focus on its origin through bidirectional mitochondrial transcription and metabolism, encompassing maturation (cleavage, polyadenylation, modification) and degradation. Dysregulation of mtRNA metabolism leads to mt-dsRNA (mitochondrial double-stranded RNA) accumulation, which escapes mitochondria via specific channels into the cytosol and serves as DAMPs to trigger an immune response. We discuss the critical roles of key regulatory factors, including PNPT1 (PNPase, Polyribonucleotide Nucleotidyltrans ferase 1), in controlling mt-dsRNA levels and preventing inappropriate immune activation. Finally, we review the implications of mt-dsRNA-driven inflammation in human diseases, including autoimmune disorders, cellular senescence, and viral infection pathologies, highlighting unresolved questions regarding mt-dsRNA release mechanisms.

Gastrointestinal malignant tumors account for approximately one-third of global cancer-related deaths, primarily including colorectal, gastric, pancreatic ductal adenocarcinoma, and hepatocellular carcinomas. These tumors have a high incidence, are often asymptomatic, and are prone to metastasis and recurrence, posing a significant public health burden. Although traditional methods such as radiotherapy and chemotherapy can delay disease progression, their nonspecific effects often lead to severe side effects and drug resistance, resulting in limited efficacy. Therefore, developing novel treatment strategies with high target specificity and favorable biological safety is a critical scientific issue in this field. Peptide drugs offer advantages such as good biocompatibility, low immunogenicity, diverse structures, and ease of modification, collectively demonstrating unique potential for tumor treatment. They can not only achieve precise delivery by specifically recognizing tumor receptors but can also directly interfere with signal transduction, metabolism, and immune regulation, producing multi-target antitumor effects. This article systematically reviews the research progress of peptide drugs in gastrointestinal tumors, focusing on their molecular mechanisms, delivery modification strategies, and the latest applications. It also summarizes the challenges and future directions for clinical translation, providing a theoretical foundation and future perspectives for the precise treatment of gastrointestinal tumors and the design of new drugs.