Laminopathies, other progeroid disorders, and aging: common pathogenic themes and possible treatments

Protein Lactylation Profiles Provide Insights into Molecular Mechanisms Underlying Metabolism in Yak

Protein lysine lactylation, a recently discovered post-translational modification (PTM), is prevalent across tissues and cells of diverse species, serving as a regulator of glycolytic flux and biological metabolism. The yak (Bos grunniens), a species that has inhabited the Qinghai-Tibetan Plateau for millennia, has evolved intricate adaptive mechanisms to cope with the region's unique geographical and climatic conditions, exhibiting remarkable energy utilization and metabolic efficiency. Nonetheless, the specific landscape of lysine lactylation in yaks remains poorly understood. Herein, we present the first comprehensive lactylome profile of the yak, effectively identifying 421, 308, and 650 lactylated proteins in the heart, muscles, and liver, respectively. These lactylated proteins are involved in glycolysis/gluconeogenesis, the tricarboxylic acid cycle, oxidative phosphorylation, and metabolic process encompassing carbohydrates, lipids, and proteins during both anaerobic and aerobic glucose bio-oxidation, implying their crucial role in material and energy metabolism, as well as in maintaining homeostasis in yaks.

Epidemiological characteristics of patients with Hutchinson-Gilford progeria syndrome and progeroid laminopathies in China

BACKGROUND

Hutchinson-Gilford progeria syndrome (HGPS) and progeroid laminopathies (PL) are extremely rare genetic diseases with extremely poor prognoses. This study aims to investigate the epidemiological and genotypic characteristics of patients with HGPS/PL in China.

METHODS

Using a cross-sectional study design, general characteristics and genotypic data of 46 patients with HGPS/PL from 17 provinces in China were analyzed.

RESULTS

Among the 46 patients with HGPS/PL, 20 patients are HGPS, and the rest are PL; the identified total prevalence of HGPS/PL is 1/23 million. Among 42 patients with gene reports, 3 carried compound heterozygous mutations in the ZMPSTE24 while the other 39 carried LMNA mutations. Among PL, LMNA c.1579 C > T homozygous mutation was the most common. The onset of classic genotype HGPS is skin sclerosis in the first month after birth. The primary clinical manifestations of PL patients include skin abnormalities, growth retardation, and joint stiffness. The median age of onset for PL was 12 (6,12) months.

CONCLUSIONS

In China, the identified total prevalence of HGPS/PL is 1/23 million. 92.8% of the genetic mutations of HGPS/PL were located in LMNA, and the rest in ZMPSTE24. Most patients of HGPS/PL have skin abnormalities as the earliest manifestation. Compared to PL, the classic genotype HGPS starts earlier.

IMPACT STATEMENT

Hutchinson-Gilford progeria syndrome (HGPS) and progeroid laminopathies (PL) are extremely rare genetic diseases with extremely poor prognoses. To date, there is a paucity of epidemiological data related to HGPS/PL in China. This study first examined the genotypic, phenotypic, and prevalence characteristics of 40-50% of the cases of HGPS/PL in mainland China through a collaborative international registry effort. In China, the identified total prevalence of HGPS/PL is 1/23 million. 92.8% of the genetic mutations of HGPS/PL are located in LMNA. LMNA c.1579 C > T homozygous mutations are the most common form of gene mutations among the Chinese PL population.

Loss of Mature Lamin A/C Triggers a Shift in Intracellular Metabolic Homeostasis via AMPKα Activation

The roles of lamin A/C in adipocyte differentiation and skeletal muscle lipid metabolism are associated with familial partial lipodystrophy of Dunnigan (FPLD). We confirmed that LMNA knockdown (KD) in mouse adipose-derived mesenchymal stem cells (AD-MSCs) prevented adipocyte maturation. Importantly, in in vitro experiments, we discovered a significant increase in phosphorylated lamin A/C levels at serine 22 or 392 sites (pLamin A/C-S22/392) accompanying increased lipid synthesis in a liver cell line (7701 cells) and two hepatocellular carcinoma (HCC) cell lines (HepG2 and MHCC97-H cells). Moreover, HCC cells did not survive after LMNA knockout (KO) or even KD. Evidently, the functions of lamin A/C differ between the liver and adipose tissue. To date, the mechanism of hepatocyte lipid metabolism mediated by nuclear lamin A/C remains unclear. Our in-depth study aimed to identify the molecular connection between lamin A/C and pLamin A/C, hepatic lipid metabolism and liver cancer. Gain- and loss-of-function experiments were performed to investigate functional changes and the related molecular pathways in 7701 cells. Adenosine 5' monophosphate-activated protein kinase α (AMPKα) was activated when abnormalities in functional lamin A/C were observed following lamin A/C depletion or farnesyltransferase inhibitor (FTI) treatment. Active AMPKα directly phosphorylated acetyl-CoA-carboxylase 1 (ACC1) and subsequently inhibited lipid synthesis but induced glycolysis in both HCC cells and normal cells. According to the mass spectrometry analysis, lamin A/C potentially regulated AMPKα activation through its chaperone proteins, ATPase or ADP/ATP transporter 2. Lonafarnib (an FTI) combined with low-glucose conditions significantly decreased the proliferation of the two HCC cell lines more efficiently than lonafarnib alone by inhibiting glycolysis or the maturation of prelamin A.

Bypassing Border Control: Nuclear Envelope Rupture in Disease

Recent observations in laminopathy patient cells and cancer cells have revealed that the nuclear envelope (NE) can transiently rupture during interphase. NE rupture leads to an uncoordinated exchange of nuclear and cytoplasmic material, thereby deregulating cellular homeostasis. Moreover, concurrently inflicted DNA damage could prime rupture-prone cells for genome instability. Thus, NE rupture may represent a novel pathogenic mechanism that has far-reaching consequences for cell and organism physiology.

The nuclear envelope

The nuclear envelope (NE) is a highly regulated membrane barrier that separates the nucleus from the cytoplasm in eukaryotic cells. It contains a large number of different proteins that have been implicated in chromatin organization and gene regulation. Although the nuclear membrane enables complex levels of gene expression, it also poses a challenge when it comes to cell division. To allow access of the mitotic spindle to chromatin, the nucleus of metazoans must completely disassemble during mitosis, generating the need to re-establish the nuclear compartment at the end of each cell division. Here, I summarize our current understanding of the dynamic remodeling of the NE during the cell cycle.