Deficiency of LARP1 Impairs Spermatogenesis and Leads to Male Subfertility in Mice

Mice lacking the RNA-binding protein LARP1 produce sperm with defective flagella, malformed heads, and poor motility — females are unaffected

Journal: FASEB Journal | Published: 2026-04-15 | Type: Journal Article | PMID: 41934340 Authors: Fan Xu, Yang Ling, Li Hong, Wang Zhengpin (Shandong Provincial Key Laboratory of Development and Regeneration, School of Life Sciences, Shandong University) Funding/COI: National Natural Science Foundation of China (NSFC); no COI declared

Summary

Knockout of the RNA-binding protein LARP1 in male mice derails spermatogenesis at multiple levels: meiosis stalls, germ cells undergo apoptosis, and the sperm that do form have malformed heads, broken flagella, and defective acrosomes. Transcriptomic analysis points to hyperactivated p38 MAPK/p53 signaling as the likely driver of the apoptotic cascade, alongside loss of expression for genes governing flagellar assembly and acrosome biogenesis. Female knockouts are fully fertile, making this a male-specific dependency.

Claims

• Larp1 deficiency in male germ cells disrupted meiotic progression and triggered apoptosis, leading to germ cell depletion
• Knockout sperm exhibited defects in flagella assembly, sperm head morphology, and acrosome structure
• Sperm motility was significantly impaired (quantitative motility data not reported in abstract)
• Transcriptomics identified upregulation of pro-apoptotic genes and hyperactivation of the p38 MAPK/p53 pathways
• Genes essential for flagellar assembly, acrosome formation, and sperm motility were downregulated in knockouts
• Female Larp1 knockout mice showed normal oocyte development and fertility — the phenotype is male-specific

Study Quality

This is a mouse genetic knockout study — appropriate methodology for establishing that a gene is necessary for a biological process. Combining phenotypic characterization (morphology, motility) with transcriptomics strengthens the mechanistic argument. However, the abstract reports no quantitative effect sizes: how much did motility drop, what fraction of germ cells were depleted, how many mice per group? Without those numbers, the magnitude of the effects cannot be evaluated independently.

The study makes no attempt to connect LARP1 to human infertility, which is methodologically honest but limits clinical relevance.

Red Flags

• Mouse model only — whether LARP1 loss-of-function variants contribute to human male infertility is unknown
• No sample sizes or quantitative motility data reported in abstract
• COI field listed as "not listed" — unclear if omitted by authors or absent; should have been declared either way
• Describes "significant reduction in male fertility" without specifying litter rates or pregnancy outcomes

Strengths

• Genetic knockout establishes causality, not mere correlation
• Sex-specific phenotype (fertile females, subfertile males) sharpens the spermatogenesis-specific claim considerably
• Transcriptomic analysis provides mechanistic grounding beyond phenotype description
• Multi-level phenotyping covers meiosis, apoptosis, morphology, and motility — not just one endpoint

Verdict

Competent mechanistic mouse work. The sex-specificity finding is the sharpest result here: a protein whose loss wrecks spermatogenesis while leaving oogenesis intact is worth understanding. The transcriptomic pathway data (p38 MAPK/p53, flagellar assembly genes) gives future researchers something concrete to test. This paper doesn't touch human infertility and doesn't pretend to — it lays groundwork. Whether that groundwork leads anywhere depends on whether LARP1 variants show up in idiopathic azoospermia or oligospermia cohorts. That study hasn't been done yet.